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1
Hageman, John. "The Reproductive Biology of the Paddlefish, Polyodon Spathula (Walbaum), in Lake Cumberland, Kentucky." TopSCHOLAR®, 1985. https://digitalcommons.wku.edu/theses/2427.
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The reproductive biology of the paddlefish (Polyodon spathula) was studied on specimens collected from Lake Cumberland, Kentucky, from September 1983 to July 1984. A total of 500 specimens was studied. Reproductive activity was observed on 17 April 1984 in the Big South Fork of Lake Cumberland. Seasonal differences were observed in sex ratios with more males than females occurring in the winter and spring. Movements were observed throughout the year, but these were accentuated prior to reproduction in the spring. Lake Cumberland paddlefish became sexually mature by Age Group V in males and VIII in females. In the spring, gravid females were found only in upstream spawning areas while non-gravid females occurred throughout the rest of the lake. This supported the alternating year spawning hypothesis for females of this species; mature males were found in all lake locations sampled at this time. Gonad development in Lake Cumberland paddlefish started in September-October and continued progressively throughout the year until egg release. Gonad fat bodies responded inversely with gonad development, progressively decreasing in size as the gonads increased. The liver and throat fat bodies did not show this weight correlation but were concluded to be important in the energetics of the gonads. Coefficients of condition for Lake Cumberland paddlefish corresponded closely with gonad development. Condition values for Lake Cumberland paddlefish were greater than those reported in the literature. This supported the idea that the optimum habitat for paddlefish is in lakes rather than rivers. The estimated average annual fecundity for Lake Cumberland paddlefish was similar to that reported in other studies. No relationship was seen between number of eggs and fish size. All sexually mature males and some females exhibited prominent secondary sexual characteristics.
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Szedlmayer, Stephen T. "Early life history of weakfish Cynoscion regalis (Bloch and Schneider)." W&M ScholarWorks, 1988. https://scholarworks.wm.edu/etd/1539791567.
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Juvenile weakfish Cynoscion regalis, life history was studied in the York River estuary, Virginia. to verify daily aging methods of juvenile fish, both male and female adults were induced to spawn by injection of 200 IU Human chorionic gonadotropin/Kg wet weight. Subsequent larval and juvenile fish were reared up to 275 days with wild plankton and a daily rotating diet of squid, liver, Anchoa mitchilli, and Menidia menidia. Otoliths and scales were examined for daily microincrements patterns. Otolith ring counts were highly variable (31% varied by &>& 15% among 3 counts). Two problems were evident: (1) Microincrements frequently split to form two increments; and (2) Otoliths from a size series of fish (6.12-13.1 mm) indicated that weakfish otoliths grew by bud formation rather than concentric deposition. Scale circuli showed little variation between counts (99.5% of 2 counts from an individual scale were the same). Daily scale deposition was suggested by rearing up to 100 days, after which ring deposition was less than daily, however further research is needed because only one fish was reared past 25 days. The advantages of scale circuli counting over otolith increment counting were increased precision and ease of preparation. Field samples were collected weekly from the York River channel, at night using a 4.9 m, 1.5 mm cod end, trawl, during the weakfish nursery period (Aug-Oct 1983). The new technique of daily aging by scales, was applied to 845 of 922 weakfish collected. Counts ranged from 3 to 100 circuli/scale. Three cohorts were defined from the 1983 0-age fish. Growth rates estimated from scales (0.76-1.13 mm/d) were similar to those from length frequencies (1.0-1.2 mm/d). Analysis of covariance showed a significant difference (0.05 level) in growth rates among cohorts and among stations, but third order interactions (station, cohort, growth rate) were not detected. Mortality/migration rates estimated from decline in mean catch were significantly different between cohorts 1 and 2 (0.05 level, t-test). Weakfish were first abundant as new recruits at the river mouth, and moved upriver as they grew. In the fall a reverse migration occurred. Birthdate frequency by station and date indicated that different cohorts used different areas of the York River.
3
Purkey, Kathie Lyn. "The underwater life off the coast of Southern California." CSUSB ScholarWorks, 2005. https://scholarworks.lib.csusb.edu/etd-project/2752.
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This project reviews the basic chemical and geographical features of the ocean, biological classification of marine life, background of the ocean's flora and fauna, and the ocean's environment. These facts are presented through an underwater documentary filmed at various sites along Southern California's coast and complemented with lesson plans designed for grades K - 4.
4
Rhodes, Dolores Y. "The family Haplosplanchnidae Poche, 1926 with special reference to Haplosplanchnids from Suva, the Fiji Islands." Scholarly Commons, 1993. https://scholarlycommons.pacific.edu/uop_etds/2254.
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Six species of haplosplanchnids are reported in this study. Haplosplanchnus caudatus (Srivastava, 1939) Skrjabin and Guschanskaja, 1955 was found in large numbers in 8 of 9 Mugil cephalus. H. purii Srivastava, 1939 was found in small numbers in 2 of 9 Liza vaigiensis and 1 of 9 Mugil cephalus. Both of these findings represent a new locality record. Schikhobalotrema southi n. sp. is described from a single specimen from Scarus rivulatus. S. scari n. sp. from the same host is also described from a single specimen. Schikhobalotrema sp. is described but not named because of insufficient data. Hymenocotta mulli Manter, 1961 from Mugil cephalus and Liza vaigiensis is also reported, based on one specimen from each host.
New synonyms: Haplosplanchnus stunkardi Gupta and Ahmad, 1979 is a synonym of H. caudatus (Srivastava, 1939) Skrjabin and Guschanskaja, 1955. H. otolithi Gupta and Ahmad, 1979 is a synonym of H. purii Srivastava, 1939. Neohaplosplanchnus ablennis Abdul-Salam and Khalil, 1987 is transferred to the genus Schikhobalotrema becoming S. ablennis n. comb.
A key to the genus Schikhobalotrema including the new species is included.
5
Carlson, Kimberly. "Digenetic trematodes of marine fishes of Jamaica, West Indies." Scholarly Commons, 1992. https://scholarlycommons.pacific.edu/uop_etds/2238.
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Gaugler, Michael Scott. "Marine interstitial tardigrades and other meiofauna of Huntington Beach, South Carolina." [Johnson City, Tenn. : East Tennessee State University], 2002. http://etd-submit.etsu.edu/etd/theses/available/etd-1216101-222846/unrestricted/gauglerms030402a.pdf.
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Grewal, Amardeep K. "Digenetic trematodes from marine fishes of Fiji : subfamily Hurleytrematinae (Family Monorchiidae): a review and description of four new species of Hurleytrematoides." Scholarly Commons, 1998. https://scholarlycommons.pacific.edu/uop_etds/2336.
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Four new species of Hurleytrematoides Y amaguti, 1954 are described: H. fl}iensis from Heniochus acuminatus pnd Chaetodon citrinellus, H. prevoti from Chaetodon melannotus; H bartolii from Heniochus acuminatus and H monoceros, and H. zebrasomae from Zebrasoma scopas. The hurleytrematine genera Hurleytrema, Hurleytrematoides, Pseudohurleytrema and Parahurleytrema are briefly discussed and their validity accepted based chiefly on the structure of the male and female terminal structures. Hurleytrema pyriforme Overstreet, 1969 and H. catarinensis Amato, 1982 are transferred to Pseudohur/eytrema as new combinations. The generic diagnosis of Hurleytrematoides is emended to include cirrus with large and extensive spines or small ones with limited distribution, and a spiny or aspinose unipartite terminal organ. A key to the hurleytrematine genera with single testis and their species is given. A parasite-host list of all monorchiid species reported to date is included.
8
Maloney, Barbara A. "Population Dynamics, Life Histories, and Patterns of Emergence in an Assemblage of Inshore Cumaceans (Crustacea: Percarida) in South Florida." NSUWorks, 1996. http://nsuworks.nova.edu/occ_stuetd/335.
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The population dynamics, life histories, and patterns of emergence in an assemblage of inshore cumaceans (Crustacea, Peracarida) in Dania, Florida (the boat basin at Nova Southeastern University Oceanographic Center) were investigated over the course of 13 months. Three sampling methodologies were employed. Replicate box sampling (bimonthly, Mar 91-Mar 92) determined seasonal variations in population composition and density. Surface plankton net tows (monthly, Dec 90-Feb 92) determined seasonal recruitment and spawning cycles. Demersal emergence net sampling (twice - June and July 91) examined the time structure of emergence of cumaceans into the plankton.
9
Young, Kathryn. "Identification and Estimation of Sensitive Life History Parameters for Cetaceans in Response to Acoustic Disturbances with Implications for Conservation." NSUWorks, 2008. http://nsuworks.nova.edu/occ_stuetd/238.
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Meta-analyses of published cetacean life history data and original modeling efforts have been conducted to determine which vital rates are most important in determining the growth and sustainability of both odontocete and mysticete populations. In particular, the role of anthropogenic sound in the ocean was examined in relation to cetacean population trends, with specific implications for life functions, vital rates, and population sustainability. Elasticity and sensitivity analyses of Leslie matrices suggested that most cetacean populations appear to be most sensitive to changes in the adult female survival rate, and least sensitive to calf survival. A secondary factor to which whale populations are sensitive is a change in juvenile survival or growth. With the exception of the North Atlantic right whale (Eubalaena glacialis), most cetaceans are not sensitive to changes in fecundity at any age stage. Of particular concern for depleted cetacean species, adult females may be sensitive to changes in foraging success which limit their ability to acquire sufficient body fat to reproduce and raise calves successfully. These results are similar to those for other species with similar life histories, such as terrestrial vertebrates and non-mammalian marine predators.
The resulting model outputs have direct implications for the management of marine mammals, particularly in regions where acoustic disturbances are likely in the future or are currently prevalent. Additionally, information gained from these modeling exercises may aid in the transition of the Population Consequences of Acoustic Disturbances (PCAD) model from qualitative to quantitative, as well as provide useful values for the parameterization of population viability analyses (PVAs) in cetacean management. The implications of these model findings to cetacean conservation are many, and include: 1) Increases in anthropogenic noise in the marine environment which have the capacity to limit adult female survival should be avoided at all costs, 2) Due to the inexact nature of cetacean population modeling, changes in vital rates may induce undetectable or unpredictable changes in population growth rate, so use of the precautionary principle is strongly advised in management decisions, 3) There are likely thresholds within which population vital rates can change without a resulting change in the growth rate, but these are not indicated by traditional sensitivity and elasticity analyses. Future studies are needed focusing on the likely intricate relationships between anthropogenic ocean noise and both adult female and juvenile cetacean survival. Additionally, improvements in cetacean modeling resulting in more precise and robust population and vital rate estimates would prove invaluable to the conservation of these species.
10
Keith, Anna. "Molecular Responses to Catastrophic Molting in a Wild Marine Mammal." Scholarly Commons, 2021. https://scholarlycommons.pacific.edu/uop_etds/3745.
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While most mammals shed their hair and skin either continuously or seasonally, northern elephant seals (Mirounga angustirostris) undergo an annual catastrophic molt, in which they shed their entire fur and underlying skin layer in the span of just three weeks. Due to the energetic and thermoregulatory constraints of molting and the large distances between their coastal rookeries and foraging grounds, elephant seals must remain on land and fast for the duration of their molt. Previous studies of molting northern elephant seals have examined endocrine and metabolic adjustments to fasting, but not the molecular processes underlying molting. We examined changes in the skin and underlying blubber tissues using histological, endocrine, and proteomic analyses during molting to provide a more in-depth understanding of the cellular mechanisms enabling rapid skin shedding and regeneration in this marine mammal. Shotgun proteome sequencing by LC-MS/MS identified 47,671 peptides and 573 protein groups in skin and outer blubber that were associated with lipid metabolism, protein processing in the endoplasmic reticulum, and collagen regulation. Label-free quantification and differential protein expression analyses identified 23 and 21 proteins that were differentially expressed during molting in the skin and outer blubber, respectively. Proteins downregulated over molting included those associated with inflammation, angiogenesis, and cellular proliferation, whereas proteins upregulated over molting included those associated with cytoskeletal remodeling, collagen synthesis, and lipid metabolism. This suggests that rapid skin regeneration involves intensive protein synthesis and increased vascularization that may be supported by fatty acid substrates from underlying blubber tissue. These data provide insights into cellular and molecular mechanisms that govern unusually rapid skin regeneration in mammals, which may further understanding of disorders affecting the skin and hair of humans and other mammals.
11
Tulchinsky, Alexander. "Phylogeography of Marine Meiofaunal Nemerteans of the Ototyphlonemertes Fila Species Complex." VCU Scholars Compass, 2006. http://hdl.handle.net/10156/1499.
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Koerner, Sarah G. "Timing and Potential Drivers of Symbiont Selection in the Early Life Stages of the Massive Starlet Coral Siderastrea siderea." Thesis, NSUWorks, 2019. https://nsuworks.nova.edu/occ_stuetd/516.
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The ability of corals to build reefs can be attributed to their relationship with single-celled algae of the familySymbiodiniaceae.Through the process of photosynthesis, these algae can provide their coral hosts with over 90% of their daily energy requirements. Most coral species acquire multiple species of symbionts from the surrounding water during their larval stage or immediately after settling. However, over time, the coral will select a dominant symbiont speciesthat can depend on the local environment. Until this study, the size or age of the coral at which this transition from multiple Symbiodiniaceaespecies to one dominant species occurs has remained uncertain. Likewise, it was unclear whether the selection of Symbiodiniaceaespeciesis influenced by the environment. The environmental conditions and symbiont composition of one hundred and eighteen juvenile Siderastrea siderea were assessed across four sites in Broward County, Florida. Presuming newly settled corals acquire multiple symbionts and then select just one dominant species, it was determined that the transition from multiple symbiont speciesto one dominant species in Siderastrea sidereaoccurs in the single polyp stage, between the time of settlement and approximately 4 to 6 months of age. The results also suggest that the selection of these dominant symbiont speciesis influenced by the environment, and that juveniles commonly select the same species as adults inhabiting similar environmental conditions. The selection of symbionts homologous to adult corals combined with environmental influences may be an early indicator of acclimatization in Siderastrea siderea.
13
Lette, Emily D. "Modernising Conservation Through Technology: A metabolomic investigation of a critically endangered freshwater crayfish." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2020. https://ro.ecu.edu.au/theses/2371.
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BACKGROUND: The Anthropocene has seen extinction rates orders of magnitude higher than the background rate; a trend that has been seen in all ecosystems. As a result of human activities, freshwater resources, and many of the species dependent on them have become imperilled. Freshwater crayfish are a dominant aquatic invertebrate due to their significant biomass, and they are globally distributed, highly speciose, and ecologically important. They have been referred to, inter alia, as bioindicators, keystone species, ecosystem engineers, and umbrella species and are also a valuable human food source. However, currently one-third of freshwater crayfish species worldwide are classified as threatened under IUCN criteria, with many species facing possible extinction.
Cherax tenuimanus (hairy marron) is a critically endangered freshwater crayfish found only in a single river in the biodiversity hotspot of south-west Australia. Conservation efforts for this species have included a captive breeding program, which has been largely unsuccessful despite the successful breeding of sister taxon Cherax cainii (smooth marron) for aquaculture. Currently captive breeding, including aquaculture of crayfish, relies primarily upon traditional methods of investigating the impacts of environmental factors through gross trial and error, with little understanding of the physiological state of animals. This study tested the hypothesis that metabolomics could highlight potential biomarkers related to reproduction and stress in two congeneric freshwater crayfish, Cherax tenuimanus and Cherax cainii, for the purpose of providing information to assist with captive breeding.
HYPOTHESIS TESTING: In order to test this hypothesis, four sub-hypotheses were tested in this study. Sub-hypothesis I: C. tenuimanus can be induced to breed in aquaria. This hypothesis was supported, as mating occurred in both species of marron. Timing of reproductive behaviours was later in C. tenuimanus and fecundity was lower than C. cainii. Breeding behaviours were documented in detail. Sub-hypothesis II: The reproductive hormone methyl farnesoate (MF) can be measured in marron haemolymph as a non-lethal, low stress tool to monitor reproduction (i.e. as a targeted metabolomic approach). This hypothesis could not be confirmed or rejected, because MF was not detected using two extraction methods. Sub-hypothesis III: Untargeted metabolomics using liquid chromatography–mass spectrometry (LC-MS) detects differences in the metabolome between species and sexes of marron. The profiles of C. tenuimanus and C. cainii were significantly different, as were the profiles between the sexes of each species.
Sub-hypothesis IV: Untargeted metabolomics using LC-MS detects differential responses in C. tenuimanus females and males in breeding pairs. The metabolite profiles supported this subhypothesis, where three patterns were identified by the behaviour of the metabolites. Metabolites either indicated a response to disturbance (change) where the response was transient or nontransient; differences between sexes where the differences remained unchanged whether the animals were housed on their own or with a potential mate; or a male response to female presence. Metabolites such as inosine, glutathione and arginine were recognised as potentially useful biomarkers.
CONCLUSIONS: This study demonstrates that metabolomics are useful in providing an informative profile and identifying biomarkers that have the potential to assist with the captive breeding of freshwater crayfish. Whilst a single metabolite (MF) could not be directly targeted in this study, an untargeted approach was successful, and by extension the overall hypothesis of this study was successful. Overall, 107 metabolites were detected in marron haemolymph: amino acids, lipids, nucleotides, and other compounds were successfully linked to biologically important processes in the marron life cycle. The metabolites identified by this approach showed differences between two congeneric species, between sexes and over time in response to an environmental stressor. The study highlighted potential biomarkers for targeted metabolomic studies that can be used to test a wide variety of hypotheses, especially when animals are kept in controlled conditions such as in this study. The investigations from this study also contribute to our understanding of the life history of C. tenuimanus, our knowledge of its reproductive biology and the differences with its sister species C. cainii, providing another piece to the conservation puzzle. These methods will be beneficial to species conservationists and aquaculturists alike.
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Deyarmin, Jared. "Blubber transcriptome and proteome responses to repeated adrenocorticotropic hormone administration in a marine mammal." Scholarly Commons, 2019. https://scholarlycommons.pacific.edu/uop_etds/3598.
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Chronic physiological stress impacts animal fitness by catabolizing metabolic stores and suppressing reproduction and immunity. This can be especially deleterious for capital breeding carnivores, such as marine mammals, which rely on lipid stores accrued during intensive foraging to sustain prolonged periods of fasting associated with reproduction. Therefore, chronic stress may cause a decrease in fitness in these animals, leading to population declines and potentially detrimental shifts in food web dynamics as a result. However, the impacts and indicators of chronic stress in animals are currently poorly understood. To identify downstream mediators of repeated stress responses in marine mammals, adrenocorticotropic hormone (ACTH) was administered once daily for four days to free-ranging juvenile northern elephant seals (Mirounga angustirostris) to stimulate endogenous corticosteroid release. I then compared blubber tissue transcriptome responses to the first and fourth ACTH administrations to determine the effects of acute and chronic endocrine stress, respectively. Gene expression profiles showed differences in responses to single and repeated ACTH administration, despite similarities in circulating cortisol profiles. We identified 61 and 12 differentially expressed genes (DEGs) in response to the first ACTH and fourth administrations, respectively, 24 DEGs between the first and fourth pre-ACTH samples, and 12 DEGs between ACTH response samples from the first and fourth days. Annotated DEGs were associated with functions in redox and lipid homeostasis, suggesting potential negative impacts of repeated stress on marine mammals. In addition, protein expression profiles were discrete between single and repeated ACTH administrations, and identified changes in expression of extracellular proteins that were not detected at the transcriptome level. We identified 8 and 7 differentially expressed proteins (DEPs) in response to the first and fourth ACTH administrations, respectively, including 5 DEPs in the overall ACTH response, 1 DEP between the first and fourth pre-ACTH samples, and 10 DEPs between ACTH response samples from the first and fourth days. Differentially expressed proteins in response to repeated ACTH administrations were associated with extracellular matrix (ECM) remodeling and suggest a link between glucocorticoid-induced adipogenesis and ECM remodeling in blubber. Other differentially expressed proteins were associated with increased lipid metabolism and decreased immunity, consistent with transcriptome data. Together, the use of transcriptomics and proteomics to detect responses to repeated stress provides more comprehensive insight into the marine mammal stress response and highlights the importance of using multiple discovery-driven approaches for understanding stress physiology. The gene and protein markers identified in this study may be used to identify stressed animals and discriminate between acutely and chronically stressed individuals with higher sensitivity than hormone measurements alone.
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Barbas, Ruthie E. "Tests of Reproductive Isolation Between the Fishes Fundulus heteroclitus and F. grandis." UNF Digital Commons, 2016. http://digitalcommons.unf.edu/etd/624.
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The closely related killifishes Fundulus heteroclitus and F. grandis hybridize in a small region where their ranges overlap in coastal northeastern Florida. Hybrids of these species are rare in frequency within the contact zone, suggesting the presence of relatively strong reproductive isolation between these species. The objective of this study was to elucidate barriers to reproduction between F. heteroclitus and F. grandis in the lab, as well as to quantify the relative strengths and contributions of various isolating barriers. Pre-zygotic (mating and fertilization) and post-zygotic (hatching) barriers were investigated by performing a variety of choice and no-choice laboratory mating experiments. The results revealed that under no-choice conditions, barriers to mating had the biggest influence on hybrid production in F. grandis, whereas hatching barriers contributed to the majority of reproductive isolation in F. heteroclitus. However, under choice conditions pre-zygotic barriers had the greatest influence on both species’ ability to produce hybrids. The total relative reproductive isolation that was observed in females of each species was stronger in F. heteroclitus than in F. grandis overall, and was nearly complete in F. heteroclitus females under choice conditions while moderate in F. grandis females. These results reveal an asymmetry in the potential gene flow between these two species, with F. grandis being more likely to hybridize than F. heteroclitus in the absence of environmental influences.
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McCulloch, Danielle. "PELAGIC FISH DIVERSITY AND DENSITY ON AND OFF RESTORED OYSTER REEF HABITAT." VCU Scholars Compass, 2017. https://scholarscompass.vcu.edu/etd/5180.
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The heterogeneity provided by structured habitats is important in supporting diverse and dense fish communities. The biogenic reefs created by the native Eastern Oyster, Crassostrea virginica, were once the dominant structural habitat in Chesapeake Bay, and have since declined to less than 1% of historic estimates. Conflicting results on the effects of oyster reef restoration on pelagic fish assemblages make further investigation necessary. Incorporating multiple sampling strategies may help elucidate oyster reef habitat influence on fish assemblages. This study used multi-panel gillnets, hydroacoustic technology, and day-night sampling to describe pelagic fish assemblages on and off oyster reef habitat in the lower Piankatank River, VA. Data from oyster reef habitat, adjacent sandy-mud bottom habitat, and unstructured sandy habitat outside of a reef restoration area compared fish diversity, species composition, and density among habitat types. A multivariate analysis using day of the year, day or night, and habitat type as model terms found temporal factors explained variation in fish distribution more than habitat. Fish diversity varied significantly with day or night and habitat type. Diversity and density were significantly higher at night, demonstrating the necessity of nocturnal sampling in fish assemblage research. Results from this study conclude that fish assemblages were not significantly more diverse or denser on reef than non-reef habitat. We suggest that future work should concentrate on studying areas where oyster reef habitat comprises a larger proportion of the study area.
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Samsonova, Maria. "Tropicalisation of temperate seagrass meadows in Western Australia: Predicting the impact of tropical herbivorous fishes on temperate seagrass meadows." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2020. https://ro.ecu.edu.au/theses/2294.
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Rising sea temperatures through climate change produce shifts in the distribution of tropical species to temperate regions, a process termed “tropicalisation”. The poleward expansion of tropical herbivores into temperate seagrass meadows is predicted to increase grazing pressure and alter ecosystem services and processes in these seagrass systems. This study attempted to examine the effects of tropicalisation on temperate seagrass meadows along the western coast of Australia, where the increasing abundance of tropical consumers such as the herbivorous Siganus fuscescens has already been documented. Through the assessment of fish assemblages in seagrass meadows and the grazing levels on seagrass in 2001 and 2016/17, as well as in situ and mesocosm feeding preference experiments, this study attempted to estimate the grazing rates and impact that the growing abundance of S. fuscescens may have in temperate seagrass meadows.
Shifts in the grazing rates on seagrass between 2001 and 2016/17 were inconsistent, varying between seagrass species and location. Based on observational data on the bites on seagrass leaves, rates of consumption increased for Posidonia sinuosa while no similar pattern was found for Posidonia australis. This was despite an apparent greater consumption on P. australis compared to P. sinuosa in 2001, and the minimal amount of grazing on tethered seagrass. The higher observed level of P. sinuosa consumption in 2016/17 is likely explained by the changed herbivorous fish species composition, even though no fish were clearly observed feeding on seagrass in the current study. The tropical herbivore S. fuscescens was more abundant in 2016/17 that 2001, although abundances were patchy and no fish was observed feeding on seagrass. The higher level of P. sinuosa consumption in 2016/17, compared to 2001, supports the prediction that with increasing abundances in temperate seagrass ecosystems, tropical herbivores will enhance the consumption of seagrass. However, seagrass consumption is likely to be strongly influenced by the availability of macroalgae which were shown as the preferred food sources.
Feeding trials in mesocosms were compromised by the large number of deaths and the limited grazing on natural food sources by S. fuscescens, suggesting that the population in the Perth region is susceptible to adverse handling and husbandry effects. To maximise the survival rate of captured fish, the fishing and handling procedures were altered to adapt to the ongoing observations in the response of fish to handling in the field or in the mesocosm facilities. Lesson learned from the capture, handling and husbandry of S. fuscescens in feeding trials in the current study will hopefully provide greater success for feeding preference experiments in the future. The sampling program initiated in 2001 and repeated in 2016/17 provides base-line data and the opportunity to monitor and track the shift in abundances of tropical herbivores and resultant increases in grazing rates to test the above predictions. The consequences of tropicalisation will depend on the variety of abiotic and biotic factors, including the fish assemblages in the area, the abundance of tropical species, the availability of food, and the feeding preferences that invading species will develop in response to the changed environmental conditions.
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Pitts, Kelly A. "Early Life History Response of Reef Building Coral, Orbicella faveolata, to Ocean Acidification and Warming." Thesis, NSUWorks, 2018. https://nsuworks.nova.edu/occ_stuetd/490.
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Ocean warming and acidification pose major threats to coral reef organisms. It is unknown how the early life history stages of Atlantic corals cope with the combined effects of these two global environmental stressors. Here, I investigate how these stressors influence the fertilization success, larval survivorship, and settlement of the threatened Atlantic coral, Orbicella faveolata. Gametes from O. faveolata were subjected to a factorial combination of present and future scenarios of oceanic temperatures (28.5° C and 30° C) and pH (8.2 and 8.0) predicted to occur by 2050. Results indicate that treatment type did not significantly affect fertilization success. Elevated temperature caused complete larval mortality and inhibited the settlement of O. faveolata. Interestingly, these negative effects of high temperature were partially mitigated when combined with ocean acidification. Overall, both the larval survivorship and settlement in the combined treatment was reduced to approximately half when compared to ambient treatment. Although ocean acidification may partially mitigate the negative effects of ocean warming during the larval stage, the overall reduced survival and settlement of larvae under future oceanic conditions, coupled to reduced calcification in adults, portends devastating effects on the health of this threatened species.
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Pruzinsky, Nina. "Identification and spatiotemporal dynamics of tuna (Family: Scombridae; Tribe: Thunnini) early life stages in the oceanic Gulf of Mexico." Thesis, NSUWorks, 2018. https://nsuworks.nova.edu/occ_stuetd/472.
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Fishes within the family Scombridae (i.e. tunas, mackerels and bonitos) are of high ecological and economic value, as they are heavily targeted by commercial and recreational fisheries. In coastal and open-ocean environments, adults are high-level predators, while larvae and juveniles serve as prey for numerous species. Much is known about the distribution and abundance of adult tunas, but high taxonomic uncertainty and limited knowledge regarding the distributional patterns of larval and juvenile tunas have led to an “operational taxonomic unit” gap in our understanding of tuna ecology. Scombrids were collected across the Gulf of Mexico (GoM, hereafter) during seven research cruises from 2010-2011, as part of the NOAA-supported Offshore Nekton Sampling and Analysis Program, and during five research cruises from 2015-2017, as a part of the GOMRI-supported Deep Pelagic Nekton Dynamics of the Gulf of Mexico Consortium. In this thesis, species composition, distribution, and abundance of tunas collected from the surface to 1500 m depth are characterized in relation to depth, time of year, and physical oceanographic features. A synthesis of the morphological characteristics used to identify the taxonomically challenging larval and juvenile stages of tunas is presented, along with length-weight regressions to fill the data gap on the growth patterns of these early life stages. A total of 945 scombrid specimens were collected, representing 11 of the 16 species that occur in the GoM. The dominant species included: Euthynnus alletteratus (Little Tunny), Thunnus atlanticus (Blackfin Tuna), Auxis thazard (Frigate Mackerel), and Katsuwonus pelamis (Skipjack Tuna). Evidence of sampling gear selectivity was observed, with a MOCNESS (rectangular, research-sized trawl) collecting larvae predominantly, and a large, high-speed rope trawl catching only juveniles. Scombrids were collected primarily in the upper 200 m of the water column. Species-specific environmental preferences and seasonality were identified as the main drivers of tuna spatial distributions across the epipelagic GoM. Integrating aspects of scombrid ecology in neritic and oceanic environments improves management and conservation efforts for this highly important taxon.
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Cope, Rebecca Weatherall. "Assessing the Responses of Adult, Juvenile, and Larval Fish Assemblages to the Closure of the Mississippi River Gulf Outlet, an Artificial Tidal Pass in Southeastern Louisiana." ScholarWorks@UNO, 2013. http://scholarworks.uno.edu/td/1730.
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The creation of the Mississippi River Gulf Outlet (MRGO) in 1963 by the U.S. Army Corps of Engineers (USACE) represents one of the most catastrophic, anthropogenic stressors ever to impact the Lake Pontchartrain estuary in southeastern Louisiana, USA. The artificial tidal pass provided a direct route from the Gulf of Mexico to New Orleans. It allowed for high saline waters to enter Lake Pontchartrain, resulting in detrimental changes to the biotic community of the Lake and surrounding wetland areas. In July 2009, the USACE closed the MRGO in hopes of restoring natural ecosystems. This study assesses changes in the adult, juvenile, and larval fish assemblages in the Lake from data taken before and after the closure. Water quality data were also examined for shifts related to the MRGO closure. Significant decreases in salinity were found following the closure, however no significant differences were found in adult or larval fish assemblages.
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Chevalier-Billosta, Valérie. "Influence des procédés papetiers et des variations saisonnières sur la structure des fibres – relation avec les propriétés mécaniques des papiers." Phd thesis, Université Joseph Fourier (Grenoble), 2008. http://tel.archives-ouvertes.fr/tel-00352309.
Full textAbstract:
L'objectif de cette étude était de comprendre l'influence des saisons sur la variabilité des propriétés mécaniques des papiers recyclés impliquant l'adjonction de charges en amidon importantes, phénomène ayant des répercussions économiques et environnementales défavorables. Plusieurs voies de recherche ont été explorées comme les conditions de stockage des papiers récupérés après collecte, l'influence des températures des eaux de circuit et l'influence du taux et du type d'éléments fins.Pour atteindre ces objectifs, plusieurs outils permettant une observation à l'échelle de la microfibrille de cellulose (10nm) ont été développés ou adaptés (coloration, immunomarquage, PATAg, marquage fluorescent...) couplés à des techniques de microscopie conventionnelle (optique, transmission, balayage, confocal...) afin de mieux comprendre les modifications de la micromorphologie et de l'ultrastructure des fibres en fonction des différents traitements appliqués et d'établir des corrélations avec les variations des propriétés mécaniques des papiers correspondants. Des techniques d'analyse des fibres de bois et de ses composants ont également été utilisées afin d'étudier la morphologie des fibres (analyseur MorFi) ainsi que d'évaluer de manière plus quantitative leurs différents composants (analyse des sucres, chromatographie en phase gazeuse, 13C RMN). La première partie du projet a permis de mettre en place une démarche méthodologique permettant de corréler les observations au niveau ultrastructural et morphologique des fibres et les propriétés mécaniques des papiers fabriqués à partir de celles-ci. L'application de cette méthode nous a permis dans un second temps de montrer que les papiers récupérés par la collecte devaient être stockés de manière plus protégée en hiver par les centres de tri. De même, nous avons pu mettre en évidence la nécessité de réfrigérer les eaux de circuit dans la machine à papier lorsque la fabrication a lieu en été. Enfin, le dernier chapitre a souligné, par la mise en place d'une nouvelle méthode de marquage (PARA-Gold), le fait que le recyclage entraîne la production d'éléments fins aux propriétés de liaison aux fibres diminuées et des solutions pour réactiver ces derniers ont été proposées aux papetiers.
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Chevalier-Billosta, Valérie. "Influence des procédés papetiers et des variations saisonnières sur la structure des fibres – relation avec les propriétés mécaniques des papiers." Phd thesis, Grenoble 1, 2008. http://www.theses.fr/2008GRE10022.
Full textAbstract:
L'objectif de cette étude était de comprendre l'influence des saisons sur la variabilité des propriétés mécaniques des papiers recyclés impliquant l'adjonction de charges en amidon importantes, phénomène ayant des répercussions économiques et environnementales défavorables. Plusieurs voies de recherche ont été explorées comme les conditions de stockage des papiers récupére��s après collecte, l'influence des températures des eaux de circuit et l'influence du taux et du type d'éléments fins. Pour atteindre ces objectifs, plusieurs outils permettant une observation à l'échelle de la microfibrille de cellulose (10nm) ont été développés ou adaptés (coloration, immunomarquage, PATAg, marquage fluorescent. . . ) couplés à des techniques de microscopie conventionnelle (optique, transmission, balayage, confocal. . . ) afin de mieux comprendre les modifications de la micromorphologie et de l'ultrastructure des fibres en fonction des différents traitements appliqués et d'établir des corrélations avec les variations des propriétés mécaniques des papiers correspondants. Des techniques d'analyse des fibres de bois et de ses composants ont également été utilisées afin d'étudier la morphologie des fibres (analyseur MorFi) ainsi que d'évaluer de manière plus quantitative leurs différents composants (analyse des sucres, chromatographie en phase gazeuse, 13C RMN). La première partie du projet a permis de mettre en place une démarche méthodologique permettant de corréler les observations au niveau ultrastructural et morphologique des fibres et les propriétés mécaniques des papiers fabriqués à partir de celles-ci. L'application de cette méthode nous a permis dans un second temps de montrer que les papiers récupérés par la collecte devaient être stockés de manière plus protégée en hiver par les centres de tri. De même, nous avons pu mettre en évidence la nécessité de réfrigérer les eaux de circuit dans la machine à papier lorsque la fabrication a lieu en été. Enfin, le dernier chapitre a souligné, par la mise en place d'une nouvelle méthode de marquage (PARA-Gold), le fait que le recyclage entraîne la production d'éléments fins aux propriétés de liaison aux fibres diminuées et des solutions pour réactiver ces derniers ont été proposées aux papetiersThe aim of this study was to understand the influence of seasons on the variability of paper mechanical properties, whose influence is normally overcome by important additions of starch with unfavourable economical and environmental repercussions. Several ways of research were explored such as storage conditions of old papers after collecting, influence of circuit water temperatures and influence of the quantity and type of fine elements. To this end, several approaches were developed and adapted (coloration, immunolabeling, PATAg, fluorescent staining, PARA-Gold…) together with conventional techniques of microscopy (optical, transmission, scanning, confocal…). This provided a better understanding of the modifications undergone by fibres in their micromorphology and ultrastructure depending on the different processes in relation with the variations of the mechanical properties of papers. Technical analyses of fibres wood and their components were applied to study fibres morphology (MorFi analyser) and to evaluate quantitatively their different constituents (carbohydrate analysis, gas-liquid chromatography, 13C NMR). In the first part of the project the methodological approach was validated and implemented for correlating observations of fibres at ultrastructural and morphological level with the mechanical properties of papers. The second part has consisted in the study of the influence of old papers storage conditions in fonction of duration, temperature and moisture and pointed out the adverse effects of winter conditions. Also we concluded to the necessity of controlling the circuit water temperature in summer. In the third part of the work devoted to the influence of cellulosic fine elements and their behaviour with fibres in the papermaking, we developed a new method for the specific labelling of fines allowing whereby it was possible to follow their fate when they are added to the fibres. Data on the nature of their interaction at the surface and within the fibres are given
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Olsen, Kevin C. "The Effects of Thermal Stress and Algal Competition on the Early Life-History Stages of Porites astreoides and the Development of Stress-Detecting Biomarkers for Use in Scleractinan Corals." UNF Digital Commons, 2013. http://digitalcommons.unf.edu/etd/460.
Full textAbstract:
Scleractinian coral populations are declining worldwide in response to numerous stressors operating on both global and regional scales. Rising sea surface temperatures associated with global climate change and the increasing frequency of coral-macroalgae competitive interactions are two of the gravest ecological drivers facing coral reef ecosystems. However, little is known about how these stressors interact to impact corals, their health, and potential modes of population recovery. These threats also highlight the need to develop reliable techniques that detect stress in multiple life-history stages of hermatypic corals prior to the degradation of coral reef habitats. To address these concerns we evaluated the effects of elevated sea surface temperatures (+3.5°C), Dictyota menstrualis competition, and their combined impacts on three life-history stages of the reef-building coral Porites astreoides. Elevated temperature induced sub-lethal stress yet had varied responses that were contingent on the life-history stage being examined. Hyperthermal stress did not consistently effect the transcriptional expression of heat shock proteins (Hsp) 16 or 60, but was readily detected utilizing biomarkers of the oxidative stress pathway. The presence of D. menstrualis significantly reduced coral survival and recruitment beyond simple space occupation in every coral life-history stage examined.While macroalgal exposure and elevated temperature had distinct effects on coral survival and physiological condition, the combination of both stressors induced a synergistic impact on biomarkers of oxidative stress in coral larvae. The results highlight the potential of biomarkers of oxidative stress for detecting hyperthermal stress in scleractinian corals. They also support the accepted notion that benthic macroalgae compete with reef-building corals via direct contact for space on coral reefs and that elevated temperatures can reduce the health of the coral holobiont. In addition, the results indicate that larvae from P. astreoides are more susceptible to the impacts of hyperthermal stress compared to established corals and that multiple perturbations can interact to exacerbate coral health.
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Bernard, Andrea M. "Population Connectivity in the Ocean: A Genetic View of Upper Trophic Level Fishes Displaying Contrasting Life Histories." Thesis, NSUWorks, 2014. https://nsuworks.nova.edu/occ_stuetd/86.
Full textAbstract:
Discerning the extent and patterns of genetic connectivity and understanding population demographic processes is essential for framing proper management and conservation measures for species of concern. Although genetic connectivity may be influenced by numerous biotic and abiotic factors, habitat utilization and dispersal potential are often key factors driving connectivity, especially in marine fishes. While dispersal potential is of key importance with respect to shaping connectivity, other extrinsic (e.g., oceanographic processes) and intrinsic (e.g., reproductive behavior) factors may also influence connectivity; however, the relative influence of such factors is immensely variable across species and life-stages. This dissertation explores genetic connectivity and demographic history in marine fishes with diverse dispersal potentials to determine which processes, in addition to the known dispersal potential of the species, may be shaping connectivity. Genetic connectivity and demographic history is assessed for four marine fishes: two shark species with juxtaposing dispersal potentials, the highly migratory tiger shark (Galeocerdo cuvier) and the reef associated Caribbean reef shark (Carcharhinus perezi), which possess high and low dispersal potentials, respectively, and two teleost species, the pelagic roundscale spearfish (Tetrapturus georgii) and the Nassau grouper (Epinephelus striatus), which possess high and low adult dispersal potentials, respectively. This work demonstrates that dispersal potential does, in fact, play a key role in delineating genetic structure for these species; however, other factors, such as contemporary oceanographic currents (e.g., upwelling and temperature), habitat availability (e.g., coral cover), and historical events, such as cyclical glacial cycles, also influence genetic connectivity across variable spatial scales, thereby creating complex patterns of genetic population structure, requiring composite management strategies to ensure the persistence of these species.
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McMahon, Nicholas J. "Optimization of Light Irradiance During the Early Life of Sexually-Produced Porites astreoides and Agaricia agaricites Recruits." Thesis, NSUWorks, 2018. https://nsuworks.nova.edu/occ_stuetd/493.
Full textAbstract:
Current solutions of coral restoration rely mainly on fragmentation. Though a reliable technique, this asexual form of reproduction does not benefit the genetic diversity of the coral reef. With many global and local stressors threatening corals’ existence, the resiliency of corals to future ocean conditions depends highly on sexual reproduction to produce new genotypes. New technology allows coral spawning/larval release, larval settlement and rearing to be carried out in an aquarium system. Many of the techniques necessary to maintain coral recruits are well-established, however the effects of light intensity remain to be studied for these early life stages. Newly settled corals have been found on vertical surfaces and the undersides of ledges and crevices, suggesting full solar irradiance is detrimental to their health. Newly settled Porites astreoides and Agaricia agaricites recruits were placed under varying irradiance levels to test their survivorship, growth and pigmentation. In the first four weeks post-settlement, growth was significantly different between recruits under a PAR of 10 µmol quanta m-2 s-1 and 240 µmol quanta m-2 s-1. In a separate experiment, growth curves were significantly different between six different irradiance increase regimens in the first 14 weeks post-settlement. This study shows, for the first time, a definitive preference by newly settled coral recruits to lower intensity irradiance, devoid of ultraviolet radiation, in the first four weeks post-settlement, and that Porites astreoides recruits can acclimatize to higher intensities at a rate of ~ 11 µmol quanta m-2 s-1 per week for up to 15 weeks.
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Bernasconi, Rachele. "Geographical, temporal and environmental patterns of coral-Symbiodiniaceae-bacteria co-occurrences." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2019. https://ro.ecu.edu.au/theses/2272.
Full textAbstract:
Scleractinian corals harbor an abundant and diverse microbial community that plays a fundamental role in maintaining the fitness of the coral host. While much progress has been made in understanding the interactions between single taxonomic groups symbiotic with the coral host, we need to gain a better understanding of how multiple symbiotic groups interact, with the goal of identifying key symbionts likely to be part of processes that maintain host fitness across space, time and development. Thus, the overall aim of my thesis was to enhance current understanding of diversity of the two coral-associated microbial communities composed of bacteria and Symbiodiniaceae and their patterns of dynamicity and interactions, across different spatial, environmental and development states. This was achieved by analysing existing datasets and using extensive field collections, deep-sequencing techniques, experimental manipulations and network analyses...
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Robinson, Jack S. "Assessing the return of carbon sequestration following the restoration/recovery of Amphibolis antarctica and Posidonia sinuosa seagrass in South Australia." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2023. https://ro.ecu.edu.au/theses/2739.
Full textAbstract:
Occupying < 0.1% of the world’s seafloor, seagrasses provide key ecosystem services including habitat provision underpinning biodiversity, sediment stabilisation, and carbon sequestration. Despite this, seagrasses face significant losses, with an estimated 19% of global seagrass cover lost since the 20th century. Globally, there is an increasing effort to incorporate seagrasses into blue carbon projects through conservation and rehabilitation actions. In Adelaide, South Australia, restoration projects have been conducted using Amphibolis antarctica, with initial results showing the return of structural characteristics comparable to nearby natural meadows. In addition, an unprecedented natural recovery of Posidonia sinuosa has occurred in recent years along the Adelaide coastline. This research assessed the return of carbon sequestration functions and the avoided emissions linked to the restoration of A. antarctica and the recovery of P. sinuosa meadows in Adelaide. Comparisons of organic carbon (Corg) stocks among undisturbed and restored A. antarctica (0.6 ± 0.04 and 1.2 ± 0.4 kg Corg m-2, respectively) and undisturbed and recovering P. sinuosa (1.5 ± 0.4 and 0.5 ± 0.3 kg Corg m-2, respectively) meadows did not clearly show a return of Corg storage within 10-yrs post-recovery. Direct sediment elevation measurements between 2003 and 2019 via sediment elevation rods in P. 47 sinuosa meadows allowed the estimation of sediment and carbon accumulation rates. The rods identified 2 cm of accumulation in the undisturbed site, 20 cm of accumulation post-recovery in the Recovery site, and approximately 32 cm of erosion in the Bare site over 9-years post meadow loss. Based on sediment Corg stocks, the change in elevation across treatments and recent hyperspectral mapping of seagrass along Adelaide’s coastline, we estimated the enhanced sequestration of 231 Mg Corg ha-1 in the recovered meadow between 2011 and 2019, equating to 85,400 ± 6,800 Mg Corg across 876 ha of recovered meadows, while the loss of 188,000 ± 20,500 Mg Corg has occurred from 1406 ha of lost meadows over 9 years. Assuming 50% of this loss was remineralised at a decay rate of 0.0005 yr-1, we estimate 298,500 ± 92,200 Mg CO2-eq emissions from Adelaide’s seagrass loss over a 9-year period. In conclusion, this study is pioneering in demonstrating that the restoration and recovery of seagrasses at scale can lead to large carbon abatement, and thereby supports the development of seagrass rehabilitation in verified carbon crediting schemes. The use of in-situ direct sediment elevation iii measurements, which can be established at the onset of any carbon crediting project, can provide reliable estimates of additionality.
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Maumus, Florian. "Transcriptional and Epigenetic regulation in the marine diatom Phaeodactylum tricornutum." Phd thesis, Ecole Normale Supérieure de Paris - ENS Paris, 2009. http://tel.archives-ouvertes.fr/tel-00475588.
Full textAbstract:
Les océans couvrent plus de 70% de la surface de la Terre (planète bleue) et la productivité primaire nette (PPN) marine est équivalente à celle terrestre. Alors qu‟il ne représente que 1% de la biomasse totale d‟organismes photosynthétiques de la planète, le phytoplancton est responsable d‟environ 45% de la PPN globale. Le terme phytoplancton décrit un assemblage polyphylétique comprenant des eucaryotes et procaryotes photosynthétiques dérivant avec les courants. Dans les océans contemporains, les diatomées constituent un groupe d‟eucaryotes unicellulaires autotrophes très abondant, responsable de 40% de la PPN marine. Les diatomées appartiennent à la lignée des straménopiles qui sont issus d‟un évènement d‟endosymbiose entre une algue rouge et un hôte hétérotrophe. Elles sont classifiées en deux groupes majeurs : les centriques qui son apparues il y a environ 200 millions d‟années (Ma), et les pennées qui ont évolué il y a environ 90 Ma. Deux génomes de diatomées ont récemment été séquencés : celui de la diatomée centrique Thalassiosira pseudonana (32 Mb), et celui de la diatomée pennée Phaeodactylum tricornutum (27 Mb). Mon sujet de doctorat s‟est focalisé sur l‟étude de différents aspects de la régulation de l‟expression génique ainsi que sur la dynamique et l‟évolution de ces génomes. L‟expression des gènes est régulée à différents niveaux: trancriptionel, post-transcriptionel, et épigénétique. Dans le cadre de mon doctorat, une étude de la régulation transcriptionelle chez les diatomées a été effectuée et comprend l‟identification et l‟analyse in silico des facteurs de transcription (FT). Cela a permis par exemple d‟établir qu‟une classe spécifique de FT, les Heat Shock Factors, sont particulièrement abondants chez les diatomées par rapport aux autres eucaryotes. L‟analyse de la représentation des FT identifiés dans différentes librairies d‟EST élaborées à partir de cultures ayant subi divers stress a permis de détecter certaines spécificités d‟expression. L‟évolution des génomes eucaryotes est largement impactée par les effets directs et secondaires des éléments transposables (ET) qui sont des éléments génétiques mobiles se trouvant dans le génome de la plupart des organismes. Dans le but d‟étudier la dynamique des génomes de diatomées, la recherche de différents types d‟ET a permis d‟établir qu‟une certaine classe, les rétrotransposons de type Copia, est la plus abondante dans ces génomes et constitue un part significativement plus importante du génome de P. tricornutum (5,8%) par rapport à T. pseudonana (1%). D‟autre part, des analyses phylogénitiques ont montré que les rétrotransposons de type copia forment deux classes distinctes et éloignées de la lignée Copia. L‟analyse de leurs niveaux d‟expression a montré que la transcription de deux éléments s‟active en réponse à des stress spécifiques comme la limitation en nitrate dans le milieu de culture. Cette activation est accompagnée par un hypométhylation de l‟ADN et l‟analyse de profils d‟insertions chez différents écotypes de P. tricornutum ainsi que l‟étude d‟autres phénomènes suggèrent que les rétrotransposons de type Copia ont joué un rôle important dans l‟évolution des diatomées. Mon grand intérêt pour les ET m‟a ensuite amené à chercher à les caractériser dans d‟autres génomes récemment séquencés tels celui de l‟algue brune Ectocarpus siliculosus. La recherche in silico de différents gènes codant des protéines capables d‟introduire ou de stabiliser des états épigénétiques telle que la modification des histones et la méthylation de l‟ADN a montré leur présence chez P. tricornutum ainsi que leurs particularités. La présence de certaines modifications d‟histones spécifiques d‟une conformation compacte ou ouverte de la chromatine dans le proteome de P. tricornutum a été montrée. De plus, la mise au point de la technique d‟immunoprécipitation de la chromatine chez P. tricornutum a permis d‟établir que les nucléosomes enrobés d‟éléments transposables étaient marqués par des modifications spécifiques. D‟autres expériences ont permis d‟établir que l‟ADN de différents types d‟éléments transposables est marqué par la méthylation de cytosines chez P. tricornutum. Une expérience permettant l‟analyse du profil de méthylation à l‟échelle de génome en utilisant une puce à ADN a été lancée et permettra de découvrir si certains gènes portent aussi des traces de méthylation. Enfin, les ARN interférents constituent un troisième mode de régulation de l‟expression se situant à l‟interface de la régulation transcriptionelle, post-transcriptionelle et épigénétique. Les mécanismes d‟interférences chez les diatomées ont été étudié par la recherche in silico d‟enzymes clés impliquées dans ce processus ainsi qu‟en établissant expérimentalement un lien direct avec la méthylation de l‟ADN.
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Malarky, Lacey. "Faunal Composition and Distribution of Pelagic Larval and Juvenile Flatfishes (Teleostei: Pleuronectiformes) in the Northern Gulf of Mexico: Connectivity Between Coastal and Oceanic Epipelagic Ecosystems." NSUWorks, 2015. http://nsuworks.nova.edu/occ_stuetd/397.
Full textAbstract:
Pleuronectiformes (flatfishes) occur throughout the global oceans, and have high ecological and commercial importance in some areas. Though much is known regarding life history, abundance, and distribution for the benthic adult stage of flatfish species, much less is known about the pelagic larval phases of flatfishes in the open ocean. Taxonomic uncertainty and limited sampling in the oceanic Gulf of Mexico contribute to data gaps with respect to the distribution of early life history stage of flatfishes in this region. Knowledge of the faunal composition, abundance and distribution of larval flatfishes, such as members of Bothus, which have extended pelagic phases, is important for modeling their population dynamics as well as for understanding the importance of connectivity between neritic and oceanic ecosystems in their life histories. Pleuronectiform specimens utilized in this study were collected in the northern offshore Gulf of Mexico during several cruises conducted throughout 2010-2011 as part of the NOAA Natural Resource Damage Assessment (NRDA) after the Deepwater Horizon Oil Spill (DWHOS). The Offshore Nekton Sampling and Analysis program (ONSAP) was established to determine composition, abundance and distribution of deep-water invertebrates and fishes in Gulf of Mexico waters that were potentially affected by the DWHOS. Results of the first large-scale discrete-depth distributional analysis of fishes in this region revealed that flatfishes were an intrinsic component of the oceanic ichthyofauna of these waters. A total of 2365 flatfish specimens were collected in offshore waters, representing four families and 11 of the 18 genera that occur in the Gulf of Mexico. Species composition was dominated by members of the genus Bothus, which had a high frequency of occurrence in the epipelagic zone throughout the year. Citharichthys spilopterus and Trichopsetta ventralis were the second- and third-most abundant and frequently occurring taxa, respectively. Detailed spatial analyses of taxa in the epipelagic zone revealed that larvae of Citharichthys spilopterus were only collected in winter and occurred most frequently near the continental shelf break, while early life stages of Bothus spp. were more abundant at the northern convergence flow of a large anticyclonic Loop Current eddy during spring and summer.
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Jordan, Lance K. B. "Multi-Experimental Examination of Haemulon Species (Haemulidae) Early-Life Ecology on Southeast Mainland Florida Coral Reefs." NSUWorks, 2010. http://nsuworks.nova.edu/occ_stuetd/83.
Full textAbstract:
Grunts (Haemulidae: Percoidei) represent one of the most abundant and speciose families on western North Atlantic coral reefs including 15 diverse species from the genus Haemulon. For this dissertation focusing on Haemulon, three studies were conducted to examine 1) spatio-temporal distributions of early-life stage (newly settled and early juvenile) individuals throughout the southeast mainland Florida reefscape, 2) species-specific, depth-variable distributional patterns of newly settled individuals and the potential influence of predation on the observed patterns, and 3) the effects of burying nearshore hardbottom settlement habitat and the efficacy of mitigating for the lost habitat using limestone boulder reefs. The combined results of the studies suggest that newly settled Haemulon spp. utilize shallow reef habitats (highest densities on nearshore hardbottom) with peak abundances in summer months. While newly settled individuals were never observed on natural reef habitats below 12 m depth, studies using artificial reefs (ARs) showed that new settlers were commonly recorded at depths of 21 m. Species-specific patterns of new settler depth utilization were found when replicate ARs at three sites (8 m, 12 m, and 21 m depth) were examined. Of the three most abundant species collected during fortnightly sampling of ARs, newly settled H. flavolineatum and H. aurolineatum were found at all three sites while H. striatum was found almost exclusively at the 21-m site. Comparison of caged and noncaged ARs allowed for inferences to be made regarding depth-variable predation pressure on newly settled Haemulon spp. Results (based on delta density differences between caged and noncaged ARs at each site) suggest lower predation pressure at the 8-m site, relative to the 12-m and 21-m sites. Depth-variable predation pressure may, in part, explain the distributional patterns exhibited by newly settled Haemulon spp. on the natural reef. I examined annual change in early-stage Haemulon spp. populations on nearshore hardbottom (NHB) to assess the impact of habitat burial caused by a large-scale beach nourishment. Newly settled Haemulon spp. represented the most abundant fish taxa on NHB. Populations of this life-history stage exhibited high variability among annual surveys and no direct effect of NHB burial was detected. In contrast, early juvenile individuals showed a significant decline during the annual survey corresponding with the timing of the beach construction (burial of NHB habitat). Furthermore, the beach-nourishment activities altered the entire fish assemblage structure of the NHB adjacent to the beach fill area. This change in the NHB fish assemblage structure had not returned to pre-impact conditions three years after the conclusion of the nourishment. Limestone boulder reefs deployed to mitigate for buried habitat exhibited lower newly settled Haemulon spp. abundance than NHB. Contrastingly, early juvenile abundance was higher on the boulder reefs than on the NHB. Fish assemblage structure on the boulder reefs differed substantially from the NHB for which it was intended to resemble; with more mid- and large-bodied predators present on the boulder reefs. The results suggest mitigation boulder reefs did not provide equitable settlement habitat for Haemulon spp. Based on the combined results of this dissertation, it appears that shallow reef habitats (especially NHB) represent important settlement habitat for Haemulon spp. by providing spatial refuge from predators, which were more prevalent at deeper sites. Although burial did not appear to directly cause changes to newly settled Haemulon spp. populations on the NHB, fish assemblage structure was altered. Changes in species composition and abundance can have unforeseen ecological consequences for future Haemulon spp. populations. Relative to other reef habitats, the high densities of new settlers supported by the NHB suggests this unique habitat deserves protection from future nthropogenic impacts.
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Gratwicke, Brian. "Factors affecting fish distribution in coastal habitats of the British Virgin Islands." Thesis, University of Oxford, 2004. http://ora.ox.ac.uk/objects/uuid:f0b83565-7ed9-4612-ac98-b203b19a8be5.
Full textAbstract:
Few studies of tropical fish communities compare fish distributions across the full range of near-shore tropical marine habitats. As a result, our understanding of tropical marine fish communities is often biased towards habitats preferred by researchers. The distribution and habitat preferences of all 136 fish species occurring at 106 stations in three bays off Tortola in the British Virgin Islands were assessed. At a species level, habitat type was often the key factor influencing fish distribution. Of the 44 species occurring at more than 10 stations, 3 were sand specialists, 5 were strongly associated with mangroves, 7 were dependent on seagrass and algal beds and 14 were found only on the forereef. Eleven species were widely distributed both on the forereef and in bays, and 9 of them showed clear evidence of ontogenetic partitioning. The juveniles all preferred bay habitat types and moved onto the forereef as they approached sexual maturity. At a community level, five distinct fish assemblages were found. The assemblage types were classified according to their distribution: 1) forereef, 2) reef flat, 3) non-mangrove associated seagrass, 4) mangrove associated seagrass and 5) eutrophic areas. Forereef stations were the most species-rich with 24 species per station while eutrophic stations had the most depauperate communities with only 4 species per station. Variation in fish species richness at each station was largely explained by a simple habitat complexity index. It accounted for 70% of the variation in fish species richness and 21% of the variation in fish abundance. Rugosity and variety of growth forms were the most important predictors of species richness, but the height of the habitat architecture was the most useful predictor of fish abundance. Artificial reefs were constructed to test the effects of each habitat complexity variable experimentally. Increasing rugosity, variety of growth forms and percentage hard substrate increased the observed number of species but increasing the variety of hole-sizes, and height had no effect. The only complexity variable that had a significant effect on fish abundance was percentage hard substrate. In addition to the static substrate structure, long-spined sea urchins Diadema antillarum affected fish distribution because small fish shelter from predators in their spines. The urchins increase species richness and abundance in low complexity seagrass beds, but on artificial reefs, where shelter was not a limiting factor, the effect was less pronounced. Organic pollution is another factor that negatively affects the fish community by reducing fish species richness and abundance. Poor water quality often alters the natural habitat, confounding observations, but fish species richness was reduced in polluted areas even when artificial reefs were used as habitat controls. The applications of these findings to the management and conservation of fish in the British Virgin Islands are discussed.
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Carpenter, Jeffrey Cohen. "Survey Gear Comparisons and Shark Nursery Habitat Use in Southeast Georgia Estuaries." UNF Digital Commons, 2017. http://digitalcommons.unf.edu/etd/731.
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Gill nets and longlines were compared as shark nursery sampling methodologies in inshore waters of Georgia to (1) assess differences in gear selectivity, bias, and stress of capture and (2) determine potential relationships between habitat features and shark distribution and abundance. Gear selectivity varied between gears as a function of both species and life stage resulting in significantly different estimates of species and life stage compositions. Juvenile bonnetheads (Sphyrna tiburo) and young of the year blacktip sharks (Carcharhinus limbatus) experienced significantly higher stress from gill net capture than longline. Major sources of bias are thought to result from dietary preferences and individual size. Juvenile sandbar shark (C. plumbeus) distribution revealed a potential preference for creeks rather than sounds, between 0.32-0.8km wide and 4.02-8.05km from the ocean. Adult Atlantic sharpnose sharks (Rhizoprionodon terraenovae) appear to prefer larger, open sound waters closer to the ocean. A potential preference for locations in close proximity to jetties over those near oyster reefs was also observed for adult Atlantic sharpnose sharks, and while statistical significance was observed, a stronger pattern may exist, as sample sizes in this study were relatively small yet still able to detect a difference. Future investigations that quantify proportions of habitat availability and shark abundance in a given area may be more useful for identifying preferences for the structures observed in this study. This study also provides strong evidence of finetooth shark (C. isodon) primary and potentially secondary nursery habitat in areas that had not yet been documented. Findings from these investigations can be useful for managers seeking to maintain healthy coastal shark populations.
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Kilfoyle, Audie Kirk. "Exploring the Potential for Artificial Reefs in Coral Reef Restoration: Responses and Interactions of Associated Biota to Varying Experimental Treatments in the Mexican Caribbean." NSUWorks, 2017. http://nsuworks.nova.edu/occ_stuetd/440.
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Coral reefs are being negatively impacted by various causes worldwide, and direct intervention is often warranted following disturbance to restore or replace lost ecosystem structure and function. An experimental coral reef restoration study involving standardized artificial reef modules (ReefballsTM) was conducted in Mexico’s Yucatan Peninsula in the towns of Puerto Morelos and Akumal. The purpose was to explore the use of artificial structure for restoration and mitigation applications in a highly diverse and dynamic Caribbean coral reef environment by applying and evaluating the performance of select experimental treatments hypothesized to accelerate development of the associated biota. The first treatment consisted of invertebrate enhancing artificial substrate padding material, which provided structurally complex refuge space for mobile epifaunal/infaunal invertebrates and other benthic organisms. The second treatment consisted of coral transplants, intended to provide additional structural complexity and kick-start development of stony coral populations. The third treatment consisted of settlement plates which were intended to provide data on coral recruitment and survival rates. Multiple hypotheses relating to the interactions between experimental treatments and the resulting macroalgal, non-coral invertebrate, stony coral, and coral reef fish assemblages were examined, and comparisons were made between natural and artificial substrates. In Puerto Morelos there were 40 modules; 10 controls and 10 of each of 3 treatments: substrate pads, coral transplants, and settlement plates. In Akumal there were 12 modules; 6 controls and 3 of each of 2 treatments: substrate pads and settlement plates. Following module deployment, 6 biannual monitoring trips were made over the course of three years to assess the development of the biota, with a final 7th trip made six years post-deployment. Divers conducted non-destructive visual surveys to evaluate total abundance, species richness, size class distribution, and assemblage structure of coral reef fishes. Other monitoring work included coral recruit surveys, mobile epifaunal invertebrate collections from substrate pads, and digital imaging of coral transplants, natural reef reference corals, and benthic quadrat areas. Hurricane Dean compromised the Akumal study site during the first year of the study, but Puerto Morelos was unaffected. There the modules developed biotic assemblages that differed from what was found on the natural reef, and the data suggests that the substrate pads may have had an effect on the development of faunal assemblages. Lobophora variegata macroaglae and Desmapsamma anchorata sponge were the major contributors to benthic community composition, and both had significantly greater coverage on the substrate pads treatment modules. Lobophora grew rapidly and peaked within the first year, while sponges increased steadily throughout the first three years of the study, surpassing the coverage of macroalgae before the end of the second year, much to the detriment of coral transplants and many coral recruits. By the end of the study, over 75% of the transplants were overgrown by D. anchorata, and density of new coral recruits on the Pads treatment modules was lower than the other treatments and controls. Coral recruitment was dominated by Porites astreoides on all treatments and controls, and the number of corals increased steadily throughout the study. The controls had consistently greater numbers of corals than the treatments, as well as lower percent coverage of macroalgae and sponges. Total abundance and species richness of reef fishes was generally unaffected by the treatments. However, at the family and species level, several differences were detected, particularly for the substrate pads treatment and to a lesser extent for the coral transplants treatment. For future restoration or mitigation efforts utilizing similar or identical treatments to artificial substrates, this study suggests that, in the absence of routine maintenance, greater success may be achieved after waiting several years post-deployment for the initial wave of unchecked growth by benthic organisms (i.e., macroalgae and sponges) to reach a balance point before a large investment of resources is devoted to coral transplanting. Further recommendations include routine monthly or quarterly on-site maintenance to enhance transplant survival, as well as a longer monitoring window to assess community development in response to experimental treatments. The results of this study suggest that the experimental treatments did indeed have an effect on the biota, but whether or not the effect was beneficial largely depends upon perspective. The Pads treatment in particular had the greatest effect on both reef fish and benthic community development, however, it was not beneficial for stony coral recruitment. Additional research is needed to fully understand the long-term performance and effects of the padding material on biotic assemblage development for future restoration or mitigation projects.
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Duchemin, Matthieu. "Validation des outils immunotoxicologiques pour l'étude des effets biologiques des contaminants du milieu marin." Phd thesis, Université de Bretagne occidentale - Brest, 2007. http://tel.archives-ouvertes.fr/tel-00256657.
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Les effluents industriels, agricoles et urbains, chargés en polluants divers, soumettent les écosystèmes marins côtiers à un risque écotoxicologique chronique. Depuis une vingtaine d'années, les effets toxiques des polluants sur le système immunitaire ont été étudiés chez tous les groupes écologiques, notamment chez les bivalves pour caractériser ce risque dans les écosystèmes aquatiques. Pour définir un cadre opérationnel de ces outils immunotoxicologiques, il a fallu d'abord étudier plusieurs questions méthodologiques. Ensuite, il convenait d'étudier l'impact des facteurs endogènes et environnementaux naturels sur le signal immunotoxique généré par un polluant. Dans le cadre d'une collaboration franco-québécoise, un suivi bisannuel, en France (Rade de Brest), chez la moule bleue, Mytilus edulis, et chez l'huître creuse, Crassostrea gigas, a permis de mettre en évidence le rôle critique du sexe et du cycle reproducteur sur les variations saisonnières des paramètres immunitaires, au détriment des paramètres naturels de la colonne d'eau. En parallèle, des séries d'expositions « in tubo » de moules bleues, au Québec, à deux saisons différentes a également mis en évidence le rôle critique du sexe et du cycle reproducteur dans la mesure du signal immunotoxique des xénobiotiques, mais surtout dans la sensibilité immunotoxique. En conclusion, cette recherche a permis de créer un cadre opérationnel d'utilisation des biomarqueurs immunotoxicologiques, pour l'évaluation du risque chimique dans les milieux marins côtiers. Mais ils ont également démontré l'importance capitale des facteurs confondants étudiés pour évaluer, au plus juste, le danger des substances chimiques.
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Likely, Rasheda S. "Functional Characterization of a Putative Disaccharide Membrane Transporter in Crustacean Intestine." UNF Digital Commons, 2014. http://digitalcommons.unf.edu/etd/493.
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The mechanisms of transepithelial absorption of dietary sucrose in the American lobster, Homarus americanus, were investigated in this study to determine whether sugars can be transported across an animal gut intact or as monosaccharides following hydrolysis. Lobster intestine was isolated and mounted in a perfusion chamber to characterize the mechanisms of mucosal to serosal (MS) 14C -sucrose transport across the intestine MS fluxes were measured by adding varying concentrations of 14C-sucrose to the perfusate which resulted in a hyperbolic curve following Michaelis-Menten kinetics. The kinetic constants of the proposed sucrose transporter were KM = 15.84 ± 1.81 µM and Jmax = 2.32 ± 0.07 ρmol cm-2min-1. The accumulation of 14C-sucrose in the bath in the presence of inhibitors, phloretin, phloridzin, and trehalose was observed. Inhibitory analysis showed that phloridzin, an inhibitor of Na+-dependent mucosal glucose transport, decreased MS 14C-sucrose transport suggesting that MS 14C-sucrose radioactive flux may partially involve an SGLT-1-like transporter. Phloretin, a known inhibitor of Na+-independent basolateral glucose transport, decreased MS 14C-sucrose transport, suggesting that some 14C-sucrose radioactivity may be transported to the blood by a GLUT 2-like carrier. Decreased MS 14C-sucrose transport was also observed in the presence of trehalose, a disaccharide containing D-glucose moieties. Thin-layer chromatography (TLC) was used to identify the chemical nature of radioactively labeled sugars in the bath following transport. TLC revealed 14C-sucrose was transported across the intestine largely as an intact molecule with no 14C-glucose or 14C-fructose appearing in the serosal bath or luminal perfusate. Bath samples evaporated to dryness and resuspended disclosed only 15% volatile metabolites. Results of this study strongly suggest that disaccharide sugars can be transported intact across animal intestine and provide support for the occurrence of a disaccharide membrane transporter that has not previously been functionally characterized.
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Defer, Diane, Professeur Nathalie Bourgougnon, and Mcf Yannick Fleury. "Recherche d'activités antimicrobiennes chez des mollusques marins. Purification et caractérisation partielle de peptides antimicrobiens isolés à partir de l'hémolymphe de Crassostrea gigas et de bactéries associées." Phd thesis, Université de Bretagne Sud, 2009. http://tel.archives-ouvertes.fr/tel-00485008.
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Les systèmes de communication chimique constituent un élément indispensable dans l'établissement des relations intra- ou inter-espèces en milieu marin, tissant un réseau de relations entre individus, au sein d'un écosystème. Les invertébrés dépourvus de système immunitaire à mémoire et au mode de vie sessile produisent des métabolites bioactifs jouant un rôle essentiel dans la réponse aux pressions environnementales telles que la prédation et la défense vis-à-vis d'autres organismes potentiellement pathogènes. L'objectif de ces travaux a été d'identifier la présence de peptides antimicrobiens chez des mollusques bivalves et des gastéropodes d'importance commerciale. Ainsi, la recherche de molécules de défense antimicrobiennes de nature peptidique a été conduite dans des extraits acides des mollusques bivalves, Cerastoderma edule, Ruditapes philippinarum, Ostrea edulis et gastéropodes, Buccinum undatum, Littorina littorea et Crepidula fornicata, ainsi qu'à partir de l'hémolymphe de Crassostrea gigas. Les extraits ont été pré-purifiés par extraction sur phase solide C18 (SPE) et l'élution a été réalisée par 3 paliers successifs de 10%, 40% et 80% d'ACN-0,1% TFA. L'activité antibactérienne a été évaluée via la détermination de la CMI sur un ensemble de bactéries à Gram+ et à Gram- ; et l'activité antivirale a été déterminée in vitro sur le modèle virus Herpes simplex type 1/cellules Vero via la viabilité cellulaire. Les espèces C. edule, L. littorea et C. gigas se sont révélées être les espèces les plus efficaces et non cytotoxiques. Une caractérisation partielle de l'activité détectée chez ces espèces a permis de déterminer la nature peptidique des molécules actives. La purification des peptides antimicrobiens a été conduite sur l'hémolymphe de C. gigas et a permis l'identification d'un peptide dont la structure de type lantibiotique laisse présager une origine bactérienne. L'hypothèse d'une association entre C. gigas et des bactéries nous a conduit, à partir de cultures d'huîtres non axéniques, à rechercher des bactéries antagonistes dans l'hémolymphe et a permis d'isoler 2 Vibrio spp. et 3 Pseudoalteromonas spp. A partir de la bactérie Pseudoalteromonas spp. souche hCg 5, un composé actif a été partiellement caractérisé. L'ensemble de ces résultats suggère que les bactéries associées au système immunitaire pourraient jouer un rôle essentiel dans la défense des bivalves.
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Di, Lauro Steven. "Time-Series Evaluation of Suspect Rickettsiales-like Bacteria Presence in Acropora cervicornis off of Broward County from Years 2001–2012." NSUWorks, 2015. http://nsuworks.nova.edu/occ_stuetd/379.
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Rickettsiales-like organisms (RLOs) are thought to be related to bacteria in the order Rickettsiales. They have been reported to occur in the staghorn coral (Acropora cervicornis), and this study investigated trends of infection over time, and in relation to the health of infected corals. This study focuses on tissue samples taken mostly from visibly healthy A. cervicornis thickets in Broward County, Florida, and processed for histological examination. Samples were originally collected and analyzed to document reproduction during years 2001 through 2012, and tissue loss diseases (white-band disease [WBD] types I and II, and rapid tissue loss). The presence of suspect RLOs, the presence of ovoid bacterial aggregates in the basal body wall, and the condition of the coral tissue were examined in hematoxylin and eosin (H&E) and Giemsa-stained sections. Determination was made as to whether suspect RLO infection severity, location, or the presence of bacterial aggregates are correlated with changes in tissue condition associated with WBD. To better understand progression, trends, and periodicity in bacterial presence and coral tissue health, these data were then further analyzed for potential correlation with the month, year, and average monthly nighttime sea surface temperatures (categorized into ranges above, within, or below 24–29°C) when samples were collected. The severity of suspect RLO infections and the presence of bacterial aggregates in A. cervicornis varied over time, with no correlation with the location of suspect RLOs within the polyp. High suspect RLO prevalence was correlated with normal tissue conditions, while low suspect RLO prevalence was correlated with abnormal tissue conditions. However, high prevalence of bacterial aggregates was correlated to abnormal tissue conditions. Epidermal RLO and overall suspect RLO prevalence severity scores were significantly higher among samples collected when monthly average nighttime sea surface temperatures were below 24°C in contrast to samples collected when temperatures were between 24–29°C, suggesting direct or indirect effects of sea surface temperatures on infection severity. The areas of suspect RLO intracellular bodies within infected mucocytes were measured using digital image analysis software and found to be positively correlated with worsening coral tissue condition. Semiquantitative variable scores for histoslides stained with H&E were significantly different from those stained with Giemsa, indicating that these stains cannot be used interchangeably to study the presence of bacteria and the condition of coral tissue. Overall, the results of this study indicate that infection severity of suspect RLOs and the presence of bacterial aggregates are variable and correlated with the incidence of WBD-I in A. cervicornis. However, the exact nature of this relationship remains unclear. Further studies are necessary to interpret trends detected during this analysis to develop a better understanding of what contributes to the severe tissue-loss outbreaks and mortalities of A. cervicornis.
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Jacobs, Maria-Flora. "Effects of Aquatic Acidification on Calcium Uptake in White River Shrimp Litopenaeus setiferus Gills." UNF Digital Commons, 2019. https://digitalcommons.unf.edu/etd/870.
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Previous research regarding aquatic acidification has examined the protonation of the carbonate and does not consider calcium to be a limiting factor. This is the first study to suggest that pH may affect the uptake of calcium in crustacean gills. This project describes ion transport mechanisms present in the cell membranes of white river shrimp Litopenaeus setiferus gill epithelium, and the effects of pH on the uptake of calcium by these means. Partially purified membrane vesicles (PPMV) of shrimp gills were prepared through a homogenization process that has been used previously to define ion transport in crab and lobster gill tissues. In the current study, shrimp gill PPMV calcium uptake at 50 µM, and 250 µM was greatest at pH 7.0 (p=0.01, p=0.0001). A valinomycin/K+ induced membrane potential (PD) at pH 7.0 significantly increased (p=0.003) calcium uptake from that observed in the absence of a PD. An induced PD at pH 8.0 significantly increased (p=0.003) calcium uptake from that observed in the absence of a PD, however, was not significantly greater than uptake at pH 7.0 in the presence of a PD (p=0.05). Amiloride (2mM) treatments, and amiloride (2mM) + verapamil (100µM) cocktail treatments showed significant decrease in calcium uptake from the control (p=0.03), however, they were not different from each other. This indicates an electrogenic carrier with two driving forces: calcium concentration, and asymmetric exchange stoichiometry.
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Houdan, Aude. "Cycle biologique et stratégies de développement chez les coccolithophores (Prymnesiophyceae, Haptophyta) . Implications écologiques." Phd thesis, Université de Caen, 2003. http://tel.archives-ouvertes.fr/tel-00009000.
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Les coccolithophores sont des microalgues calcifiées constituant un des principaux groupes phytoplanctoniques marins. Ces organismes restent cependant encore mal connus, du fait du peu d'espèces cultivées. Dans ce travail, les connaissances sur la biologie et l'écologie de ce groupe ont été approfondies à travers l'étude du cycle de vie et de ses implications écologiques pour quatre coccolithophores en culture : Coccolithus pelagicus, Calcidiscus leptoporus, Coronosphaera mediterranea et Emiliania huxleyi. Un cycle digénétique haplo-diplophasique hétéromorphe a d'abord été démontré par différentes techniques. Des expériences écophysiologiques sur des facteurs abiotiques (température, lumière, turbulence, nutriments) ont ensuite permis d'émettre des hypothèses sur l'influence du cycle digénétique sur l'écologie de ces espèces et d'établir un cycle écologique. Enfin, une étude préliminaire de la toxicité a été réalisée, démontrant la toxicité de cinq espèces côtières de coccolithophores.
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Ostroff, Zachary. "Evaluating Acropora cervicornis Growth and Survivorship in a Line Nursery." NSUWorks, 2013. http://nsuworks.nova.edu/occ_stuetd/158.
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Acropora cervicornis and A. palmata were once dominant, reef-building corals of Caribbean reefs. Over the last several decades, population declines of Caribbean Acropora have been dramatic, and both species are now listed as “Threatened” under the United States Endangered Species Act. Numerous restoration efforts now utilize coral gardening techniques to cultivate these species for transplantation, in which A. cervicornis is primarily cultivated both on fixed structures and in line nurseries. This study evaluates growth and survivorship of multiple A. cervicornis genotypes grown via two line nursery techniques, and compares the efficacy of each against the conventional method of fixed nursery puck-mounted culture. Suspended nursery culture resulted in higher post-fragmentation survivorship of corals than puck culture, especially in warmer conditions. Disease incidence was significantly reduced by suspended culture, which also prevented predation from fireworms (Hermodice carunculata) prevalent in puck corals at the same nursery. Genotypic growth rate differences persisted among techniques, and suspended coral growth was comparable to puck culture. Suspended colonies may need more frequent pruning to avoid branch abrasion and breakage, but the technique is an effective means to reduce disease, predation, and post-fragmentation mortality in A. cervicornis nursery culture.
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Péton, Loïc. "Penser l'existence de vie dans les profondeurs marines au XIXe siècle : entre abîme impossible et origine du vivant (1804-1885)." Thesis, Brest, 2016. http://www.theses.fr/2016BRES0001/document.
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Abîme : gouffre, enfer, chaos. En marge de la civilisation occidentale, ténébreuses et dévalorisées, les profondeurs marines furent pensées et expérimentées au cours du XIXe siècle. Sur le pont du navire, le naturaliste s’appropriait les techniques de pêche et fouillait les antres d'un univers obscur pour récolter une faune méconnue.Cette thèse démontre l'importance de diverses influences, provenant de contextes différents, qui modelaient les théories au sujet de l'existence de vie dans cet univers. L'idée d'une vie limitée, à partir d'un certain niveau de profondeur, domina, notamment avec la théorie azoïque (1843) du Britannique Edward Forbes (1815-1854). Selon nous, elle formait un horizon ultime, telle une finitude anthropomorphique appliquée à la répartition des animaux. Par la suite, la représentation d'une vie présente en tous lieux – une « vie triomphante » – la remplaça au cours de la décennie 1860 pour former la base de notre savoir actuel, à un moment où l'abîme était perçu tel un antre du passé hébergeant des « fossiles-vivants ». Ces représentations constituaient les réverbérations d'une culture et d'intérêts que nous explicitons.Ce travail révèle également une focalisation des savants sur certains objets, comme le fond marin, repère fixe perçu par un filtre terrestre couplé à une analogie avec l'altitude. Le visage bathymétrique de l'océan profond se dessinait alors, tandis que le câble télégraphique devenait une interface de renouveau pour le savoir propre à l'abîme. Une volonté d'ériger un panorama absolu de l'océan parcourait cette période, cela par une extrapolation horizontale (toutes mers) et verticale (toutes profondeurs) de quelques observations relevéesAbyss : chasm, hell, chaos. On the fringe of the western civilization, the marine depths were regarded as impenetrable and were depreciated before being studied during the 19th century. At sea, the naturalist took over fishing techniques and rummaged through a dark universe to collect an unknown fauna.This thesis shows the importance of the various influences that shaped the scientific theories about the existence of life in the abyss.The idea of a limit for marine life, beneath a given depth, dominated, notably using the azoic theory (1843) of the British Edward Forbes (1815-1854). According to us, this theory was a “final horizon”, that is to say an anthropomorphic finitude placed on the animal distribution. Later, the representation of a life inhabiting every place – a “triumphant life” – replaced it during the 1860s to form the basis of our current knowledge, at a time when the abyss was regarded as a “lair of the past” containing “living-fossils”. These representations were reflections of a culture and of interests.This work also reveals that the scientists focused on some objects like the seabed, which was a fixed mark considered through a terrestrial view linked to an analogy with altitude. The bathymetric face of the ocean emerged while the submarine cable became an “interface of revival” for the knowledge about the abyss. The will to design an “absolute panorama” of the ocean was present in this period, using horizontal (every sea) and vertical (every depth) extrapolations from a few facts
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Mattio, Lydiane. "Taxonomie du genre Sargassum (Fucales, Phaeophyceae) en Nouvelle-Calédonie et dans le Pacifique Sud : approches morphologique et moléculaire." Phd thesis, Université de la Méditerranée - Aix-Marseille II, 2008. http://tel.archives-ouvertes.fr/tel-00589775.
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Sargassum C. Agardh est un genre de macrophyte marine appartenant à la classe des Phaeophyceae. Ce genre est réparti mondialement et reconnu comme un des plus diversifiés de l'ordre des Fucales. Il est particulièrement bien représenté dans le Pacifique tropical et intertropical où il forme de grandes algueraies dont l'importance écologique et l'intérêt économique sont reconnus. Néanmoins, avec près d'un millier de taxons décrits depuis 200 ans, et une classification complexe et ancienne, identifier une espèce de Sargassum est une tâche difficile. La diversité du genre Sargassum des îles du Pacifique Sud a été analysée ici dans son contexte biogéographique Indopacifique. L'étude a été réalisée grâce à une méthode combinée utilisant des analyses morphologiques et ADN sur des collections récentes provenant de plusieurs régions du bassin Pacifique. La classification ainsi que la valeur taxonomique des caractères morphologiques traditionnellement utilisés ont été remis en question. Plus de 52 nouvelles synonymies ont été proposées ainsi que des révisions significatives de la classification traditionnelle du sous-genre Sargassum.
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Fournier, Jean-Baptiste. "Evolution des mécanismes d'accumulation et de transport de l'iode dans les organismes marins : étude de la structure/fonction des protéines du métabolisme iodé chez la bactérie zobellia galactanivorans." Electronic Thesis or Diss., Paris 6, 2014. http://www.theses.fr/2014PA066065.
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Dans le milieu marin, les émissions biogéniques de composés iodées jouent un rôle essentiel dans le cycle biogéochimique de l’iode. Cependant les processus enzymatiques responsables de l'absorption, du stockage ou de la synthèse de métabolites iodés restent mal connus chez les chez les organismes marins, et plus encore chez les bactéries. Plusieurs gènes, potentiellement impliqués dans le métabolisme de l’iode, ont été identifiés dans le génome de la bactérie marine, Zobellia galactanivorans, dont celui codant une iodoperoxydase à vanadium (VIPO), enzyme spécifique de l'oxydation des iodures. La partie principale du projet de thèse a consisté à comprendre les mécanismes moléculaires contrôlant la spécificité pour certains halogénures des haloperoxydases à vanadium, en étudiant la VIPO de Z. galactanivorans par des approches de mutagénèse dirigée et de biologie structurale. Les douze enzymes mutantes produites et caractérisées au niveau biochimique montrent soit une perte d’activité, soit des modifications de leurs propriétés catalytiques, soit encore une faible activité bromoperoxydase. Les enzymes sauvage et mutantes ont également été étudiées par diffraction et absorption des rayons X, afin de relier les modifications structurales à leurs propriétés catalytiques. Les résultats suggèrent que le principal facteur modulant la spécificité chez ces enzymes est le potentiel d’oxydoréduction de l’intermédiaire réactionnel, le peroxovanadate. Des analyses biochimiques ont aussi été entreprises pour deux autres protéines identifiées sur le génome de Z. galactanivorans. La première protéine s’est révélée être une seconde VIPO. Pour la deuxième protéine, similaire à une iodotyrosine déiodinase, l’activité biochimique reste encore à être caractérisée. Z. galactanivorans posséderait plusieurs enzymes pouvant oxyder l’iodure, ainsi qu’une permettant de cliver les liaisons C-I. En parallèle à ce travail, la localisation et la spéciation de l’iode ont été étudiées par imagerie chimique chez Z. galactanivorans et chez l’algue brune, Laminaria digitata, connue pour ses fortes teneurs en iode. Les résultats de ce travail apportent un nouvel éclairage sur les mécanismes contrôlant la spécificité des haloperoxydases à vanadium envers les halogénures, et également sur l’origine bactérienne de cette famille d’enzymes. Plus globalement, ces études permettent de mieux appréhender le rôle du métabolisme de l’iode chez certaines bactéries marines et leurs importances dans le cycle biogéochimique de l’iodeIn marine environment, biogenic emissions of iodinated compounds play an essential role in biogeochemical cycle of iodine. Nevertheless, enzymatic process involved in absorption and storage of iodine or in the synthesis of iodinated compounds are unknown marine organisms, especially in bacteria. Several genes, potentially involved in iodine metabolism, have been identified in the genome of a marine bacterium, Zobellia galactanivorans. One of these genes codes for a vanadium iodoperoxydase (VIPO), an enzyme specific of iodide oxidation. The main part of the thesis project was to understand molecular mechanisms controlling the specificity vanadium halopéroxydase (VHPO) for some halide, by studying the VIPO from Z. galactanivorans by directed mutagenesis and structural biology. To lead this project, twelve mutated enzymes were produced and characterized at biochemical level. For some of them, mutations lead to a loss of activity or to modification of catalytic properties or to a slight VBPO activity. The wild type enzyme and three mutants were also analyzed by X ray absorption and diffraction spectroscopy in order to link the structural modifications to their catalytic properties. The results of this study suggest that the main factor modulating the specificity in these enzymes is modification of redox potential of the peroxovanadate. Biochemical analyses lead with two other proteins identified in the genome of Z. galactanivorans. The first protein was characterized as a new VIPO. For the second protein, similar to mammal iodotyrosine deiodinase, the biochemical activity remains to be characterized. Z. galactanivorans seems to have several enzymes which oxidize iodide or split C-I bond. In parallel at this work, the localization and speciation of iodine were analyzed by chemical imaging in Z. galactanivorans and in the kelp L. digitata, known to concentrate highly iodide. All this information allow to a better understanding of molecular mechanisms involved in the specificity for halide in VHPO and the bacterial origin of these proteins. More generally, these studies assess to understand the role of iodine metabolism in some marine bacteria and there role in biogeochemical cycle of this element
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Peterson, Maria Louise. "Effect of Feed Additives on Amino Acid and Dipeptide Transport by Intestines of American Lobster and Atlantic White Shrimp." UNF Digital Commons, 2014. http://digitalcommons.unf.edu/etd/497.
Full textAbstract:
Previous nutritional physiology research using L-histidine and zinc in American lobster intestine (Homarus americanus) has suggested that these solutes can be co-transported as complexes (Histidine-Zinc-Histidine) across the intestine using a peptide transporter. Furthermore, transport of L-leucine was shown to be inhibited by high calcium concentrations. Dipeptide and bis-complex transport and the role of calcium were investigated in the perfused intestines of lobster and Atlantic white shrimp (Litopenaeus setiferus). Following trans-intestinal transport, serosal medium was analyzed for amino acid composition by gas chromatography. In lobster, the transport of glycylsarcosine (Gly-Sar) from mucosa to serosa was stimulated two-fold with luminal pH 8.5, compared to the pH 5.5 control. Mucosa to serosa and serosa to mucosa fluxes of Gly-Sar were measured; the dipeptide was transported intact in both directions, but the net flux was from mucosa to serosa. The use of 0.5mM calcium chloride stimulated Gly-Sar transport two-fold, compared to 25 mM. In shrimp, the addition of 50 µM zinc chloride increased the rate of L-histidine transport, while Gly-Sar inhibited histidine transport in the presence of zinc. The rate of histidine transport was significantly higher with 1mM calcium chloride than with 25mM. These results suggest that shrimp transport bis-complexes in a manner similar to lobster. High calcium concentration had an inhibitory effect on both amino acid and dipeptide transport. Proposed mechanisms accounting for the effects of metals and calcium on trans-intestinal transports of both amino acids and dipeptides by lobster and shrimp digestive tracts are discussed.
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Duvall, Amanda Dawn. "A Comparison of the Pectoral Spines in Virginia Catfishes." VCU Scholars Compass, 2007. http://scholarscompass.vcu.edu/etd/1297.
Full textAbstract:
Catfish pectoral spines are an anti-predator defense mechanism. They can be bound or locked, making the fish harder to swallow, or used to produce distress calls by rubbing ridges on the dorsal process against a channel in the wall of the pectoral girdle. Growth of the pectoral spine and girdle were examined in relation to fish size within and across species that occur throughout central and eastern Virginia. These included blue catfish (Ictalurus furcatus), channel catfish (Ictalurus punctatus), white catfish (Ameiurus catus), brown bullheads (Ameiurus nebulosus), yellow bullheads (Ameiurus natalis), flathead catfish (Pylodictis olivaris), margined madtom (Noturus insignis), and tadpole madtom (Noturus gyrinus).Pectoral spines and girdles grow as catfish increase in size. In larger species spine length and weight increase nonlinearly with fish size, suggesting that maintaining spine dimensions becomes less important in bigger individuals less likely to suffer predation. The incidence of spine breakage also increases in larger fish. In smaller species spine length increases linearly in our samples (brown and yellow bullheads and margined and tadpole madtoms). In all species spine width increases linearly with total length. The spine base (dorsal process width and depth and dorsal-ventral length) grows linearly with total length in most species. However, measurements of the spine base increase nonlinearly in white catfishes, and dorsal process width increases nonlinearly in wild channel catfish although the increase was linear in cultured channel catfish.Girdle depth increased linearly with total length in all species except for wild channel catfish, and the ratio of coracoid to cleithrum depth varied among species. Pectoral girdle weight increased linearly with fish weight in blue catfish, cultured channel catfish, brown bullheads, and margined and tadpole madtoms. However, girdle weight, a major component of the body, increased nonlinearly in wild channel, white, yellow bullheads, and flathead catfishes. Cultured channel catfish had smaller pectoral spines and girdles than wild channels, a likely epigenetic response to predators. Catfish spines were identified to species, allowing determination of catfishes eaten by bald eagles (Haliaeetus leucocephalus) using spines collected near their nests. Bald eagles ate blue catfish (60%), channel catfish (27%), white catfish (9%), brown bullheads (4%) and yellow bullheads (0.5%). Madtom and flathead catfish were not consumed. Mean sizes captured were: Blue catfish (366 mm, 414 g), channel catfish (417 mm, 618 g), white catfish (320 mm, 591 g), brown bullheads (278 mm, 277 g) and yellow bullhead (203 mm, 192 g).
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Ripley, Bonnie J. (Bonnie Jo) 1970. "Life history traits and population processes in marine bivalve molluscs." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/47425.
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Sankar, Kishan. "Life on a gradient : activity levels of the seastar Patiriella exigua in different abiotic conditions." Bachelor's thesis, University of Cape Town, 2005. http://hdl.handle.net/11427/26051.
Full textAbstract:
Two morphs of Patiriella exigua occur in South Africa. These morphs occur on opposite sides of a temperature divide present at Cape Point. The green morph occurring on the West Coast (cold temperate) and the mottled morph occurring on the South Coast (warm temperate). In a previous study by Katherine Dunbar these two morphs were shown to be the same species. This project tests if there is a physiological difference between the two morphs of P. exigua. This was achieved by observing the activity coefficient of righting response of the two morphs of P. exigua under different temperatures and dissolved oxygen concentrations. The green morph was collected from Green Point (West Coast) and the mottled morph from Kalk Bay (South Coast). The results of a general linear model indicated that temperature and dissolved oxygen were significant factors determining righting time of P. exigua with P-values of less than 0.05. AT-test indicated that there was a significant difference between the righting times of the two morphs of P. exigua with the green morph turning at a faster rate than the mottled morph when placed under similar conditions.
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Goldman, Ryan A. "Small Mammal Survey of John U. Lloyd Beach State Park, Dania Beach, Florida." NSUWorks, 2013. http://nsuworks.nova.edu/occ_stuetd/166.
Full textAbstract:
Urban development and human encroachment on the natural habitats along the coastline of Florida combined with invasive exotic pressures have resulted in the fragmentation and degradation of habitat quality within Broward County. Native habitats have been significantly altered and fragmented to a fraction their previous size. With loss of habitat area and quality, isolation of breeding populations and anthropogenic pressures, it is important to determine species composition and habitat utilization in order to conserve the remaining biological diversity. It was the intent of this study to determine the small mammal species’ population structure and habitat utilization by season in the four sampled habitats. Previously undocumented species and/or extralimital populations were predicted prior to sampling.
John U. Lloyd Beach State Park in Dania Beach, Florida is an understudied location for small mammals. This study surveyed four terrestrial habitats for small mammal species using live trapping and mark/recapture techniques. Data were collected monthly over the span of thirteen months to determine habitat use from maritime hammock, mangrove swamp, coastal dune and ruderal habitat types to determine species composition and mass of individual captures and recaptures.
Trapping (3749 trap nights) produced twenty-four captures (including recaptures) in two of the four habitat types: maritime hammock and coastal strand. No animals were captured in the mangrove swamp or ruderal habitats, both of which were dominated by invasive Australian pine (Casuarina equisetifolia) monocultures.
Post study, a large habitat restoration project restored the habitats impacted by invasive exotic flora. This survey serves as a baseline for small mammals in the park, documenting the pre-restoration habitat use and species composition. Future study to determine changes in species composition post-restoration is recommended.
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Lowerre-Barbieri, Susan. "Life history and fisheries ecology of weakfish, Cynoscion regalis, in the Chesapeake Bay region." W&M ScholarWorks, 1994. https://scholarworks.wm.edu/etd/1539616753.
Full textAbstract:
Otoliths, scales, dorsal spines, and pectoral fin rays were compared to determine the best hardpart for ageing weakfish, Cynoscion regalis. Sectioned otoliths showed the clearest marks and were validated by the marginal increment method for ages 1-5. Traditionally-used scales were found to be less-precise and to underage older fish. Most weakfish from the Chesapeake Bay region were 200-600 mm TL and ages 1-4. Weakfish were not fully-recruited to commercial foodfish grades until age 2. Maximum observed age was 17 from a Delaware Bay fish collected in 1985. Current maximum observed ages were age 12 in Chesapeake Bay and age 11 in Delaware Bay. Fish older than age 6 were rare in both areas. Weakfish growth was well-described by the von Bertalanffy growth model (R&\sp2& = 0.98, N = 857). There was no evidence Delaware Bay weakfish reached a larger asymptotic length or size-at-age than Chesapeake Bay fish. However, maximum size and age from both areas has fluctuated in the past thirty years. Maximum size greatly increased from the late 1960's until roughly 1985, as did the numbers of large fish, apparently due to a series of strong year-classes, beginning in the late 1960's. Weakfish are multiple spawners with indeterminate fecundity and a spawning season from May to August, in the Chesapeake Bay region. Sex ratios were approximately 3:1, females to males, in 1990-1992. Mean length at first maturity for males and females was 164 and 170 mm TL, respectively. Most fish were mature by age one and all fish were mature by age 2. Spawning activity was not consistent throughout the spawning season or between 1991 and 1992. Batch fecundities ranged from 75,289-517,845 eggs/female and significantly increased with both TL and somatic weight. Spawning frequency was every 2-3 days in 1991 and every 12-13 days in 1992, leading to an average annual fecundity of 7,369,750 eggs/females in 1991 and 1,808,056 eggs/female in 1992. Patterns of spawning activity within and between years appeared closely associated with feeding success. Yield-per-recruit analysis indicated that, over a likely range of natural mortality rates, growth overfishing is currently occurring in the Chesapeake Bay region. Current t&\sb{lcub}\rm c{rcub}& is &\le& age 2, whereas maximum yield consistently occurred at t&\sb{lcub}\rm c{rcub}& &\ge& age 6.
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Guillet, Virginie. "Métabolisme énergétique mitochondrial dans les neuropathies héréditaires associées aux mutations des gènes OPA1 et MFN2." Phd thesis, Université d'Angers, 2009. http://tel.archives-ouvertes.fr/tel-00459846.
Full textAbstract:
L'atrophie optique autosomique dominante (ADOA) et la maladie de Charcot-Marie-Tooth de type 2A (CMT2A) sont deux neuropathies héréditaires respectivement liées aux mutations des gènes OPA1 et MFN2. Les protéines OPA1 et MFN2 sont impliquées dans la dynamique de fusion des mitochondries. Ces organites intracellulaires sont essentiels dans les processus de synthèse d'ATP. L'hypothèse d'un déficit énergétique impliqué dans la physiopathologie de ces neuropathies devait alors être testée. Nous avons mis en évidence une baisse d'efficacité des phosphorylations oxydatives dans les fibroblastes de peau de patients atteints d'ADOA et de CMT2A. Ce découplage est associé à une baisse d'activité du complexe IV et à une augmentation de l'activité du complexe V dans le cas de l'ADOA. Dans le cas de la CMT2A, le découplage est associé à une augmentation de l'activité et de la quantité de la translocase des nucléotides adényliques (ANT). Une étude sur mitochondries isolées de cerveaux d'un modèle murin MFN2(R94Q) de CMT2A montre une baisse d'activité des complexes II et V associée à l'ouverture du canal mitochondrial potassique sensible à l'ATP (mKATP). Nos résultats montrent qu'OPA1 et MFN2, deux protéines de la dynamique mitochondriale ont un rôle majeur dans la régulation énergétique mitochondriale.