Academic literature on the topic 'Sea squirts. Ascidies Ascidies'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the lists of relevant articles, books, theses, conference reports, and other scholarly sources on the topic 'Sea squirts. Ascidies Ascidies.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Journal articles on the topic "Sea squirts. Ascidies Ascidies"
1
Bates, William R. "Environmental factors affecting reproduction and development in ascidians and other protochordates." Canadian Journal of Zoology 83, no. 1 (January 1, 2005): 51–61. http://dx.doi.org/10.1139/z04-164.
Full textAbstract:
Protochordate reproduction and development are influenced by many kinds of environmental factors. For example, spawning, sexual and asexual reproduction, larval behaviour, and life-cycle transitions (metamorphosis) are key processes known to be affected by environmental factors. This review must be restricted primarily to only one group of protochordates, the ascidians or "sea squirts", because information on the reproductive ecology of hemichordates and cephalochordates is limited to only a few studies. Topics discussed in the present review include (i) environmental factors that regulate larval settlement, (ii) how pelagic embryos avoid damage to DNA caused by UV radiation, (iii) the effect of water temperature and food availability on sexual reproduction in colonial ascidians, (iv) environmental regulation of asexual budding, (v) environmental regulation of metamorphosis, and (vi) the possible role of the environment in the evolution of direct-developing ascidians. A novel role for HSP90 and nitric oxide signaling in the integration of environmental factors with cell signaling pathways in ascidians is discussed near the end of this review. Throughout this review, the multiple roles of environmental stress on ascidian reproduction and development are emphasized.
2
ANZANI, LUTHFI, HAWIS H. MADDUPPA, I. WAYAN NURJAYA, and P. JOANA DIAS. "Short Communication: Molecular identification of White Sea Squirt Didemnum sp. (Tunicata, Ascidiacea) colonies growing over corals in Raja Ampat Islands, Indonesia." Biodiversitas Journal of Biological Diversity 20, no. 3 (February 12, 2019): 636–42. http://dx.doi.org/10.13057/biodiv/d200304.
Full textAbstract:
Abstract. Anzani L, Madduppa HH, Nurjaya IW, Dias PJ. 2019. Short Communication: Molecular identification of White Sea Squirt Didemnum sp. (Tunicata, Ascidiacea) colonies growing over corals in Raja Ampat Islands, Indonesia. Biodiversitas 20: 636-642. Indonesia is at the center of the Coral Triangle, the region with the world’s highest marine biodiversity. The Raja Ampat archipelago in east Indonesia has one of the oldest networks of marine protected areas in the country and is a top priority area for marine conservation. The area is however under anthropogenic pressure from growing tourism, developments and exploration of natural resources. The most likely associated introduction of non-native species is however largely unexplored. Colonial ascidians or ‘sea squirts’ comprise a high number of species, many of them reported as introduced or invasive worldwide. In this study, we investigate the presence of white colonial ascidian colonies noticed to overgrow sections of the coral reefs in central Raja Ampat. We use DNA barcoding to address the colonies’ species identification and explore haplotype diversity to determine the species native or introduced status. We produced 22 DNA barcodes belonging to four potential cryptic Didemnum sp. species present in the Raja Ampat archipelago, Indonesia. Overall, the high number of haplotypes found in the area suggest these to most likely to be native species. The present work represents, as far as the authors are aware, the first time that such species were investigated in Raja Ampat. We hope with this work to create awareness for the topic of introduced and invasive species in the area and motivate further studies in Indonesia.
3
Michibata, Hitoshi, and Tatsuya Ueki. "Advances in research on the accumulation, redox behavior, and function of vanadium in ascidians." BioMolecular Concepts 1, no. 1 (May 1, 2010): 97–107. http://dx.doi.org/10.1515/bmc.2010.003.
Full textAbstract:
AbstractThe discovery of high levels of vanadium-containing compounds in ascidian blood cells goes back to 1911. Ascidians, which are also known as tunicates or sea squirts, belong to a subphylum of the Chordata, between the vertebrates and invertebrates. This discovery attracted the attention of an interdisciplinary group of chemists, physiologists, and biochemists, in part because of interest in the possible role of vanadium in oxygen transport as a prosthetic group in respiratory pigments, which was later shown not to be such a role, and in part because of the fact that high levels of vanadium were unknown in other organisms. The intracellular concentration of vanadium in some ascidian species can be as high as 350 mm, which is 107times that in seawater. Vanadium ions, which are thought to be present in the +5 oxidation state in seawater, are reduced to the +3 oxidation state via the +4 oxidation state and are stored in the vacuoles of vanadium-containing cells called vanadocytes, where high levels of protons and sulfate ions are also found. Recently, many proteins and genes that might be involved in the accumulation and reduction of vanadium have been isolated. In this review, we not only trace the history of vanadium research but also describe recent advances in our understanding of the field from several viewpoints: (i) vanadium-accumulating blood cells, (ii) the energetics of vanadium accumulation, (iii) the redox mechanism of vanadium, (iv) the possible role of sulfate, and (v) the physiological roles of vanadium.
4
Gregorin, Chiara, Luisa Albarano, Emanuele Somma, Maria Costantini, and Valerio Zupo. "Assessing the Ecotoxicity of Copper and Polycyclic Aromatic Hydrocarbons: Comparison of Effects on Paracentrotus lividus and Botryllus schlosseri, as Alternative Bioassay Methods." Water 13, no. 5 (March 5, 2021): 711. http://dx.doi.org/10.3390/w13050711.
Full textAbstract:
Adult sea urchins and their embryos are ideal targets to investigate the medium- and long-term effects of various toxic agents, such as organic and inorganic pollutants, to forecast and mitigate their environmental effects. Similarly, small colonial tunicates such as Botryllid ascidians may reveal acute toxicity processes and permit quick responses for the management of contaminants impacting coastal waters, to preserve the functional integrity of marine ecosystems. This investigation compares the functional responses of two model invertebrates, the sea urchin Paracentrotus lividus and the sea squirt Botryllus schlosseri, to chronic and acute exposures to organic and inorganic toxic agents. Such heavy metals as copper produce both acute and chronic effects on marine biota, while polycyclic aromatic hydrocarbons (PAHs) mainly produce chronic effects at the concentrations ordinarily measured in marine coastal waters. Both models were tested over a range of concentrations of copper and PAHs. Copper triggered a clear effect in both species, producing a delay in the embryo development of P. lividus and a rapid death of sea squirts. B. schlosseri was less sensitive to PAHs than P. lividus. The results on both species may synergistically contribute to assess the toxicity of organic and inorganic compounds at various concentrations and different physiologic levels.
5
Fukunaga, Yukiyo, Midori Kurahashi, Kenji Tanaka, Kensuke Yanagi, Akira Yokota, and Shigeaki Harayama. "Pseudovibrio ascidiaceicola sp. nov., isolated from ascidians (sea squirts)." International Journal of Systematic and Evolutionary Microbiology 56, no. 2 (February 1, 2006): 343–47. http://dx.doi.org/10.1099/ijs.0.63879-0.
Full textAbstract:
Two bacterial strains, F423T and F10102, were isolated from two ascidians, Polycitor proliferus and Botryllidae sp., respectively, which were collected from a beach on the Boso peninsula in Japan. Cells of both isolates were motile, rod-shaped and formed star-shaped aggregates in the early stage of exponential growth, but were coccoid in stationary growth phase. The results of 16S rRNA gene sequence analysis, fatty acid analysis, DNA–DNA hybridization experiments and physiological and biochemical tests indicated that the two strains were members of a novel species of the genus Pseudovibrio for which the name Pseudovibrio ascidiaceicola sp. nov. is proposed. The type strain is F423T (=NBRC 100514T=IAM 15084T=DSM 16392T=KCTC 12308T).
6
Fukunaga, Yukiyo, Midori Kurahashi, Kenji Tanaka, Kensuke Yanagi, Akira Yokota, and Shigeaki Harayama. "Pseudovibrio ascidiaceicola sp. nov., isolated from ascidians (sea squirts)." International Journal of Systematic and Evolutionary Microbiology 56, no. 4 (April 1, 2006): 923. http://dx.doi.org/10.1099/00207713-56-4-923.
Full text
7
Kanamori, Makoto, Katsuhisa Baba, Masafumi Natsuike, and Seiji Goshima. "Life history traits and population dynamics of the invasive ascidian, Ascidiella aspersa, on cultured scallops in Funka Bay, Hokkaido, northern Japan." Journal of the Marine Biological Association of the United Kingdom 97, no. 2 (April 11, 2016): 387–99. http://dx.doi.org/10.1017/s0025315416000497.
Full textAbstract:
The European sea squirt, Ascidiella aspersa was first found as an alien species in 2008 from Funka Bay, Hokkaido, northern Japan, causing serious damage to the scallop aquaculture industry. We investigated A. aspersa on cultured scallops and larval occurrence from July 2010 to June 2014 to clarify life history traits and population dynamics, and consider the relation between the life history of A. aspersa and the process of scallop aquaculture. Larvae of A. aspersa were found from June to December, and recruitment on cultured scallops occurred mainly between July and October. The ascidians grew well and their weights increased until February. We found that 60–80% of A. aspersa that had settled in summer had eggs or sperm in autumn, and 90–100% of A. aspersa matured early the following summer. Maturity size in September was 17–20 mm as male, 22–24 mm as female. Scallops in Funka Bay are hung in the spring and harvested from winter to the next spring. Ascidiella aspersa settle as larvae in early summer, and grow well until winter, resulting in overgrowth on scallops in the harvest season. The linking of the process of scallop aquaculture and the life history of A. aspersa explains why this invasive ascidian has caused serious damage to the aquaculture industry in the bay. In comparison to the earlier descriptions of the native population, A. aspersa in Funka Bay has longer reproductive and growth periods, earlier initiation of reproduction, and possibly smaller maturity size.
8
Nadtochy, Victor A., Nickolay V. Kolpakov, and Ilya A. Korneichuk. "Distribution of macrozoobenthic taxa - potential indicators of vulnerable marine ecosystems in the western part of Bering Sea. 1. Anadyr Bay area." Izvestiya TINRO 189, no. 2 (June 30, 2017): 156–70. http://dx.doi.org/10.26428/1606-9919-2017-189-156-170.
Full textAbstract:
Following recent tendencies in fisheries policy to ensure both sustainability of ecosystems and conservation of economically sustainable fisheries, protection of vulnerable resources with low direct economic value comes to the focus of fisheries management on ecosystem principles. One of the problems of modern fishing is a negative impact of bottom trawling because of destruction of benthic organisms vulnerable to mechanical impacts. This by-effect of fishing could affect negatively on functioning of bottom biocenoses, reproduction of exploited species, and decrease generally productivity of vulnerable marine ecosystems (VME). Potential VME indicators are determined for the area of the Anadyr Bay in the Bering Sea on the base of results of 4 benthic surveys using bottom sampler (1985, 2005) and bottom trawl (2008, 2012), as the most common species in some macrozoobenthic groups of epifauna. They are Gersemia rubiformis for soft corals, Myxilla incrustans , Halichondria panicea , Semisuberites cribrosa for sponges, Halocynthia aurantium , Boltenia ovifera for sea squirts, Cystisella saccata , Flustra foliacea for bryozoans, Chirona evermanni for barnacles, and Gorgonocephalus eucnemis for brittle stars. Their distribution is mapped. According to their life history and feeding habits, these species-indicators are divided onto two groups: immobile sestonophages (alcyonarians, sponges, ascidians, bryozoans, cirripedians) and mobile filtrators (brittle stars). The first group prevails on hard and mixed grounds mainly along southwestern and northeastern coasts of the Anadyr Bay at the depths of 80-90 m (sponges and bryozoans - to 250 m in the Navarin Canyon) with relatively warm water, active hydrodynamics and high biological productivity. The second group represented by G. eucnemis dominates on soft sediments in the central part of the Anadyr Bay with the depths of 50-270 m occupied by the cold water pool. Quantitative distribution of brittle star, on the one hand, and barnacles with sea squirts, on the other hand, is alternative to each other. On the contrary, barnacles, sponges and sea squirts have similar distribution of the biomass, being complementary species. Distribution patterns of all species-indicators are stable for many decades. However, biomass of some these species has changed in the southern Anadyr Bay between the similar surveys conducted in the 2008 and 2012: the mean biomass of barnacle Ch. evermanni and sea squirt H. aurantium had decreased in 6.5 and 3.7 times, respectively, whereas the mean biomass of sponges, brittle star G. eucnemis and sea squirt B. ovifera did not change. Bottom trawl fishery is not active in the northwestern Bering Sea, moreover, the habitats of immobile sestonophages with hard grounds are avoided by bottom trawlers being dangerous for fishing gears, so the observed decreasing of two species abundance is presumably caused by natural reasons or is a random error of the mosaic-distributed stocks assessment with insufficiently dense sampling grid.
9
Rueckert, Sonja, Kevin C. Wakeman, Holger Jenke-Kodama, and Brian S. Leander. "Molecular systematics of marine gregarine apicomplexans from Pacific tunicates, with descriptions of five novel species of Lankesteria." International Journal of Systematic and Evolutionary Microbiology 65, Pt_8 (August 1, 2015): 2598–614. http://dx.doi.org/10.1099/ijs.0.000300.
Full textAbstract:
The eugregarines are a group of apicomplexan parasites that mostly infect the intestines of invertebrates. The high level of morphological variation found within and among species of eugregarines makes it difficult to find consistent and reliable traits that unite even closely related lineages. Based mostly on traits observed with light microscopy, the majority of described eugregarines from marine invertebrates has been classified into a single group, the Lecudinidae. Our understanding of the overall diversity and phylogenetic relationships of lecudinids is very poor, mainly because only a modest amount of exploratory research has been done on the group and very few species of lecudinids have been characterized at the molecular phylogenetic level. In an attempt to understand the diversity of marine gregarines better, we surveyed lecudinids that infect the intestines of Pacific ascidians (i.e. sea squirts) using ultrastructural and molecular phylogenetic approaches; currently, these species fall within one genus, Lankesteria. We collected lecudinid gregarines from six ascidian host species, and our data demonstrated that each host was infected by a different species of Lankesteria: (i) Lankesteria hesperidiiformis sp. nov., isolated from Distaplia occidentalis, (ii) Lankesteria metandrocarpae sp. nov., isolated from Metandrocarpa taylori, (iii) Lankesteria halocynthiae sp. nov., isolated from Halocynthia aurantium, (iv) Lankesteria herdmaniae sp. nov., isolated from Herdmania momus, (v) Lankesteria cf. ritterellae, isolated from Ritterella rubra, and (vi) Lankesteria didemni sp. nov., isolated from Didemnum vexillum. Visualization of the trophozoites with scanning electron microscopy showed that four of these species were covered with epicytic folds, whereas two of the species were covered with a dense pattern of epicytic knobs. The molecular phylogenetic data suggested that species of Lankesteria with surface knobs form a clade that is nested within a paraphyletic assemblage species of Lankesteria with epicytic folds.
10
Smith, M. J. "Vanadium biochemistry: The unknown role of vanadium-containing cells in ascidians (sea squirts)." Experientia 45, no. 5 (May 1989): 452–57. http://dx.doi.org/10.1007/bf01952027.
Full textDissertations / Theses on the topic "Sea squirts. Ascidies Ascidies"
1
Davis, Rohan Andrew, and davis_rohan@hotmail com. "Chemical Investigations of Great Barrier Reef Ascidians - Natural Product and Synthetic Studies." Griffith University. School of Science, 2000. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20030102.104858.
Full textAbstract:
This thesis describes the chemical investigations of several ascidian species collected from the Great Barrier Reef, Queensland, Australia. The thesis is divided into two separate components, Part A focuses on the isolation and structure elucidation of 11 previously undescribed ascidian metabolites. All structures were assigned using a combination of spectroscopic and/or chemical methods. Part B relates to the isolation and chemical conversion of a natural product to a combinatorial template. The natural product template was subsequently used in the generation of a solution-phase combinatorial chemistry library. A further two combinatorial libraries were generated from a synthesised model compound that was related to the natural product template. Part A. Investigation of Aplidium longithorax collected from the Swains Reefs resulted in the isolation of two new para-substituted cyclofarnesylated quinone derived compounds, longithorones J (30) and K (31). The former compound had its absolute stereochemistry determined by the advanced Mosher method. From an Aplidium longithorax collected from Heron Island, two new cyclofarnesylated hydroquinone compounds, longithorols C (46) and D (47) and a novel macrocyclic chromenol, longithorol E (48) were isolated. Longithorol C (46) had its absolute stereochemistry determined by the advanced Mosher method. Chemical investigation of the deep-purple colonial ascidian, Didemnum chartaceum collected from Swains Reefs led to the isolation of five new lamellarin alkaloids, which included the 20-sulfated derivatives of lamellarins B (94), C (95) and L (96), the 8-sulfated derivative of lamellarin G (97) and the non-sulfated compound, lamellarin Z (98). The known lamellarins A (63), B (80), C (64), E (65), G (67), and L (71) plus the triacetate derivatives of lamellarin D (82) and N (83) were also isolated. An aberration in the integration of signals in the 1H NMR spectra of the 20-sulfated derivatives (94-96) led to NMR relaxation studies. T1 values were calculated for all protons in the sulfated lamellarins (94-97) and their corresponding non-sulfated derivatives (80, 64, 71, 67). The protons ortho to the sulfate group in compounds (94-97) had T1 values up to five times larger than the corresponding protons in their non-sulfated derivatives (80, 64, 71, 67). A specimen of Eudistoma anaematum collected from Heron Island was shown to contain a new b-carboline alkaloid, eudistomin V (130), in addition to the two known metabolites, eudistomin H (105) and I (106). Part B. The known natural products, 1,3-diphenethylurea (29), 1,3-dimethylxanthine (30), 1,3-dimethylisoguanine (31) and the salts of tambjamine C (16), E (18) and F (19) were isolated from the ascidian, Sigillina signifera collected in Blue Lagoon, Lizard Island. Base hydrolysis on mixtures of the salts of tambjamine C (16), E (18) and F (19) resulted in the production of 4-methoxy-2,2-bipyrrole-5-carbaldehyde (26). This natural product template (26) was used in the generation of an enamine combinatorial chemistry library (98, 103-111) using solution-phase parallel synthesis. The biaryl compound, 4-(2-thienyl)-1H-pyrrole-2-carbaldehyde (59) was successfully synthesised using Suzuki-Miyaura coupling conditions and subsequently used as a template in the generation of an amine (67, 77, 80-87) and imine (78, 92-95) combinatorial library using solution-phase parallel synthesis.
2
Johnson, Sheri L. "Mating System Dynamics in a Free-Spawning Colonial Ascidian." Fogler Library, University of Maine, 2007. http://www.library.umaine.edu/theses/pdf/JohnsonSL2007.pdf.
Full text
3
Green, Kathryn Margaret. "Morphological changes during normal and pertubed metamorphosis of the ascidian herdmania curvata /." St. Lucia, Qld, 2001. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe16468.pdf.
Full text
4
Stoner, Douglas Steven. "Life History and Populationi Biology of the Colonial Ascidian Diplosoma Similis." Thesis, University of Hawaii, Honolulu, 1989. http://hdl.handle.net/10125/18144.
Full textAbstract:
This dissertation examines two issues related to the
ecological and evolutionary consequences of sexual and
asexual reproduction in colonial marine invertebrates.
The first two chapters explore the extent to which the
planktonic larval phase limits the distribution and
abundance of a colonial ascidian, Oiplosoma similis. The
third chapter examines some of the fitness consequences
of alterations in the pattern of asexual reproduction by
colony fragmention in similis. All research was
carried out on the fringing coral reef surrounding
Coconut Island which is located in Kaneohe Bay, Oahu,
Hawaii.Typescript. Thesis (Ph. D.)--University of Hawaii at Manoa, 1989. Includes bibliographical references.
5
Parker-Nance, Shirley. "Aplousobranch ascidians (Tunicata: Ascidiacea) from Southern Africa." Thesis, University of Port Elizabeth, 2003. http://hdl.handle.net/10948/311.
Full textAbstract:
The ascidian (subphylum Tunicata: class Ascidiacea) fauna along the southern African coast constitutes an important component of the sessile benthic reef fauna. Little is known of the species composition, biodiversity and distribution of ascidians on southern African intertidal and subtidal reefs. Past research on the ascidian fauna of South Africa was sporadic and limited, with only about one hundred and seventy species recorded during the last one hundred and twenty years. This is the first taxonomic study undertaken by a South African resident scientist. The study focused on six genera in four families (Euherdmaniidae, Polyclinidae, Pseudodistomidae and Didemnidae) belonging to the class Ascidiacea and suborder Aplousobranchia. Five species new to science, two Polyclinum, two Pseudodistoma and one Polysyncraton species are described. New additional information on the distribution of five species previously known to science, including one recorded for the first time along the South African coast, is presented. A literature review and comparison of the taxonomic important characteristics is made of all species known globally for the six genera. These six genera comprise twelve Euherdmania, fifteen Aplidiopsis, forty Polyclinum thirty-one Pseudodistoma, six Atriolum and sixty-eight Polysyncraton species.
6
Sumerel, Andrew N. "Flume study of particle-size-dependent filtration rates of a solitary ascidian the influence of body size, flow speed, and drag /." View electronic thesis (PDF), 2009. http://dl.uncw.edu/etd/2009-3/sumerela/andrewsumerel.pdf.
Full text
7
Swallow, Michael Andrew Carleton University Dissertation Biology. "Determination and differentiation of muscle cells in the tadpole larva of the Ascidian Boltenia Villosa." Ottawa, 1992.
Find full text
8
Bromley, Candice Leigh. "The chemistry of Algoa Bay ascidians." Thesis, Rhodes University, 2016. http://hdl.handle.net/10962/d1020606.
Full textAbstract:
This thesis investigates the chemistry of 25 ascidian species collected from Algoa Bay, South Africa with a concerted focus on metal accumulation by these ascidians and the possible interaction of these metals with ascidian metabolites. Chapter 2 details the screening techniques employed to establish the presence of nitrogenous metabolites (1H- 15N HMBC), hyper-accumulated metal ions (ICP-MS) and potential metal ion/ ascidian metabolite complexes (LC-ICP-MS/ESI-MS). Unfortunately, exhaustive attempts to detect intact metal ion/ascidian metabolite complexes through the use of liquid chromatography with parallel inductively coupled plasma mass spectrometry/electrospray mass spectrometry (LC-ICPMS/ ESI-MS) were unsuccessful. However, the LC-ICP-MS/ESI-MS data obtained for the crude organic extracts of six of the Algoa Bay ascidian species, Distaplia skoogi, Aplidium monile, Aplidium sp., Didemnum sp., Leptoclindines sp. and Polycitor sp. enabled identification of a number of ten halogenated metabolites, namely the indoles 2.28-2.30, and the tyramine and tyrosine derivatives (2.31-2.33, 2.41, 2.43, 2.44 and 2.46), within the ascidian extracts. This study confirmed that LC-ICP-MS/ESI-MS is a powerful tool for the dereplication of halogenated metabolites in complex mixtures especially where these compounds are present in very small amounts. This study is also the first report of these compounds (eight of which are known) in African ascidians. Compounds 2.32 and 2.46 have not been reported before from a marine source. Compounds 2.28-2.30 and 2.33 were present in sufficient amounts in the respective ascidian extracts to allow their isolation and structure elucidation using standard spectroscopic techniques Chapter 3 explores the ability of ascidians to accumulate a wide range of metal ions at concentrations which are often orders of magnitude higher than those of the surrounding sea water. Inductively coupled plasma mass spectrometry (ICP-MS) was used to determine the total ion concentrations of 24 metals in 25 Algoa Bay ascidian species. To the best of our knowledge this is the largest and most extensive investigation of metal concentrations in a group of different ascidians occurring in the same area. Hypotheisizing that the metal ion concentrations for each ascidian specimen screened may represent a unique fingerprint for each specimen principal component analysis (PCA) was used in an attempt to establish whether there were spatial, temporal or phylogenetic relationships associated with the metal concentration fingerprints of the ascidians that formed part of this study. The PCA results showed that there were no statistically significant relationships between ascidian metal ion concentrations and either the collection year or the collection site of the ascidians. However, species from the family Didemnidae provided the clearest statistical evidence supporting a phylogenetic relationship between these ascidians and their hyperaccumulated metal ion profiles. Furthermore, these results suggested that ascidian species are indeed actively concentrating metal ions from the surrounding sea water and are not simply sinks for passively accumulated metal ions. Interestingly, the concentration of vanadium in the set of ascidians studied did not appear to correlate with any of the other metals accumulated by these ascidians suggesting that there is possibly a unique method employed for the accumulation of vanadium by ascidians. Chapter 4 investigated this possibility further after the nucleosides 4.10, 4.11, 4.13, 4.15, 4.17 and 4.40 were isolated from the vanadium accumulating ascidian Aplidium monile. Studies into the interactions between nucleosides and vanadyl are unfortunately rare and usually qualitative in nature with limited information provided about the stability or structures of the complexes formed. The vanadyl accumulating aplousobranch ascidians e.g. Aplidium monile dominated our study of Algoa Bay ascidians therefore providing us with the rationale to investigate the relatively little studied binding ability and stability of vandyl-nucleoside complexes. Potentiometric studies were conducted to determine the stability constants of complexes formed between the oxovanadium ion vanadyl (VO2+) and the commercially available nucleosides 4.10-4.14. The data afforded by this analysis clearly confirmed the complexity of the vanadyl/nucleoside complexation and suggested that guanosine (4.12) formed the most stable complex with oxovanadium ions. We were also able to establish a third protonation constant for the hydroxyl moiety in 4.12 with a logK 8.87 which has not been previously reported. Finally, Chapter 5 revisited the cytoxicity two Algoa Bay ascidians, Clavelina sp. and Atriolum marinense the extracts from which produced promising bioactivity results in previous studies against oesophageal cancer cells. The HP-20 fractionated extracts of Clavelina sp. and Atriolum marinense proved to be similalrly cytotoxic to breast cancer cells. With the exception for the 100% acetone(aq)fractions the NMR data for both species suggested that most active non polar fractions were dominated by what appeared to be structurally unremarkable fatty acid glycerides and as such were not pursued further. Purification of the 100% acetone(aq)fraction of A. marinense resulted in the isolation of a styrene trimer, 5.1, common to both ascidian extracts. The NMR simulation software WIN-DAISY was employed to confirm the structure of 5.1. Attempts to establish if 5.1 was an isolation artefact or a product of marine pollution were inconclusive
9
Barnes, Peter Brendan. "Environmental impacts and the ecology of sponges and ascidians in south-eastern Australian coastal lakes and lagoons." Department of Biological Sciences - Faculty of Science, 2009. http://ro.uow.edu.au/theses/849.
Full textAbstract:
Estuaries worldwide are under threat from urbanisation and development and will need effective management for their successful conservation. Coastal lakes and lagoons have been identified as one of the estuary types most susceptible to human impacts largely because of their isolated nature and slow flushing times. Management of estuaries will be most effective when based on a sound scientific understanding of the patterns of distribution, biology and ecology over the full range of biodiversity of these systems, however, such an understanding is lacking for many systems and many taxa. Studies of sponges and ascidians in coastal lakes and lagoons are rare compared to other taxa, particularly in the southern hemisphere. This study represents the first detailed scientific investigation of the ecology of sponges and ascidian in coastal lakes and lagoons of southeastern Australia. Consequently, a large part of this thesis was devoted to quantifying basic patterns of distribution. I started with a pilot study to develop an effective sampling design, followed by large-scale comparisons among different types of lake, comparisons among habitats within lakes and an environmental impact study. I concluded with a manipulative experiment to examine processes responsible for smallscale patterns of distribution of sponges in seagrass meadows.In the pilot study, distributions of sponges and ascidians were quantified at a hierarchy of three spatial scales in each of two coastal lakes. Nested analyses of variance were then used to identify spatial scales at which variation was significant. Most sponges and ascidians were very patchily distributed at a range of spatial scales from 10s of metres up to 100s of kilometres. Unlike other published examples of cost– benefit analyses, very few taxa were widespread over the larger spatial scales. Cost– benefit analyses done to determine the optimal sampling design revealed inclusion of patchily distributed taxa in analyses improved the overall precision of sampling for comparisons of assemblages among lakes.Large-scale comparisons of assemblages of sponges and ascidians were made among lakes of different size (big versus small), opening regime (mostly open to the ocean versus mostly closed) and level of environmental modification (extensively modified versus more pristine). Similar to other taxa studied in coastal lakes, in general there were more species in lakes mostly open to the ocean compared to the mostly closed lakes, and importantly, no sponges and only one species of ascidian was found in the small closed lakes. There also appeared to be an effect of the level of modification of a lake with relatively smaller abundances of ascidians in extensively modified lakes, and a complete absence of sponges from one of the extensively modified lakes.Habitat-associated patterns were examined at smaller spatial scales by comparing the distributions of sponges and ascidians with the species composition and percentage cover of seagrass and macroalgae within two lakes; St Georges Basin and Wallis Lake. Several patterns of association were observed, but these varied among species of sponge and ascidian. In St Georges Basin, the most common sponge, Aplysinella cf. rhax and the native ascidian Pyura stolonifera were positively correlated with the seagrass, Posidonia australis. In contrast, the introduced ascidian, Styela plicata was more abundant in areas dominated by the seagrass, Zostera capricorni. In Wallis Lake, sponges were most diverse and some species most abundant in large beds of the macroalga, Lamprothamnion sp., while other sponges were found only on the holdfasts of brown macroalgae. In both lakes, sponges were generally less common in areas dominated by dense meadows of the seagrass, Zostera capricorni.Among the many anthropogenic impacts threatening the ecology of coastal lakes, the discharge of cooling water from coal-fired power stations represents an almost ideal case study from which to develop appropriate sampling regimes for detecting impacts on sponges and ascidians. Using reference locations both within and outside Lake Macquarie which has two cooling water outlets, I found assemblages of sponges and ascidians were often more diverse, more abundant and less temporally variable near to the outlets compared to reference locations.Based on the observation that the sponge, Suberites sp. which contains photosynthetic symbionts was absent from meadows of dense Zostera capricorni, I used in situ manipulative experiments in Smiths Lake to investigate processes which maybe affecting their distribution. Individual Suberites sp. were shaded, had water flow reduced and were transplanted into areas of dense Z. capricorni. There were no measurable short-term effects of shading or reduced water flow, but transplanted sponges were quickly eaten and I concluded predation by fish was likely to be a key process determining small-scale patterns of distribution of Suberites sp. in seagrass meadows. This result was in stark contrast to the majority of previous studies of the effects of seagrass habitat complexity on predation which have found predation to decrease with increasing density or complexity.In conclusion, I have sought to provide sound scientific information to aid in the management of these systems. A simple, but nevertheless key finding was that sponges and ascidians are indeed present and widespread in coastal lakes and lagoons of southeastern Australia and should not be continually overlooked in the management and conservation of these systems. Conservation will be complex and requires an understanding of environmental impacts and the consequences of management on the full range of biodiversity. The distributions of sponges and ascidians at large ‘lakewide’ scales appear to behave similarly to other taxa. Management strategies which change the characteristics of a lake at these large spatial scales such as artificial openings of entrances could therefore be predicted to have similar effects across a range of taxa including sponges and ascidians. In contrast, at smaller spatial scales such as the complexity of seagrass meadows, some species of sponges and ascidians may behave very differently from other taxa. At present, our understanding of these naturally variable and complex systems is incomplete and will require ongoing scientific investigation to identify natural patterns of distribution, environmental impacts, important natural processes and the ecological consequences of management strategies.
10
Kincaid, Erin Suzanne. "Biofouling Management in the Pacific Northwest and Predation on Native versus Non-native Ascidians." PDXScholar, 2016. http://pdxscholar.library.pdx.edu/open_access_etds/3069.
Full textAbstract:
Marine non-native species threaten economic and environmental health, making it crucial to understand factors that make them successful. Research on these species, therefore, allows for greater preparedness and informed management of biological invasions and increases understanding of elements structuring biological communities. Among the marine non-native species, and particularly the fouling community, non-native ascidians are a taxon of particular concern because they can crowd out native benthic species and smother mariculture products. This thesis addresses management for ascidians and other fouling organisms and includes research on the invasiveness of this taxon in addition to the invasibility of recipient fouling communities. On the West Coast of the U.S., limited efforts have been made to coordinate biofouling management across states, despite the myriad vectors increasing propagule pressure over time along coastal states. Building on recent state and local efforts, I developed a Pacific Regional Biofouling Plan for the states of Oregon and Washington to help start a consensus-driven process by which these states could create a forum for more comprehensive coordination efforts, following California's lead. As states address authority gaps, the biofouling management framework I've written is meant to be used to guide the conversation between managers as various stages of coastal management are realized.
To better inform the scope and efficacy of management and regulatory efforts, the study of invasions ecology asks and aims to answer questions regarding recipient community interactions and characteristics of the non-native species themselves. Studies that identify characteristics that make ascidians successful (invasiveness) and determine the influence native communities have on their success (invasibility) are important for assessing overall risk of establishment and spread from non-native ascidians. Therefore, I aimed to: 1) explore the hypothesis that fouling communities on suspended, artificial structures are more invasible than benthic habitats; and 2) identify characteristics influencing predation patterns on the native Distaplia occidentalis versus non-native ascidian species using mensurative and experimental studies in Charleston Marina, Oregon. I conducted a series of feeding assays, surveys, and a caloric content analysis. Feeding assays were conducted with a suite of predators. The flatworm predator (Eurylepta leoparda) was found to be highly selective on the native ascidian Distaplia occidentalis, and only preyed on whole colony samples. Feeding assay data suggest that test (tunic) structure or thickness may be an influential factor affecting nudibranch (Hermissenda crassicornis) predation rates on native versus non-native ascidians, with greater predation on the native ascidian species. Non-native ascidians may escape predation in floating but not benthic environments on the Oregon coast due to their palatability characteristics, likely tunic structure and low caloric content. In this case, this suite of predators may indirectly facilitate the invasion of docks but provide at least partial resistance to the invasion of natural benthic areas.
The chapters herein address gaps in management and scientific knowledge regarding non-native species of the marine fouling community. Future work enhanced by my efforts could include the development of the coastal biofouling management plan, coordinated by the Western Regional Panel on Aquatic Invasive Species Coastal Committee, and broadening the geographic and taxonomic scope of my research with a more comprehensive study of predator-prey interactions involving non-native ascidians and a diverse suite of predators. These interactions may be an important factor in explaining the success of ascidians and other fouling organisms on floating structures and lack of success on nearby benthic substrata.
Books on the topic "Sea squirts. Ascidies Ascidies"
1
Monniot, Claude. Les Ascidies de Polynésie française. Paris: Editions du Muséum, 1987.
Find full text
2
Developmental biology of ascidians. Cambridge [England]: Cambridge University Press, 1994.
Find full text
3
Groepler, Wolfgang. Die Seescheiden von Helgoland: Biologie und Bestimmung der Ascidien. Hohenwarsleben: Westarp Wissenschaften, 2012.
Find full text
4
Kühne, Stephan. Solitäre Ascidien in der Potter Cove (King George Island, Antarktis): Ihre ökologische Bedeutung und Populationsdynamik = Solitary Ascidians in the Potter Cove (King George Island, Antarctica) : their ecological role and population dynamics. Bremerhaven: Alfred-Wegener-Institut für Polar- und Meeresforschung, 1997.
Find full text
5
Monniot, Claude. Coral reef ascidians of New Caledonia. Paris: Éditions de l'ORSTOM, Institut français de recherche scientifique pour le développement en coopération, 1991.
Find full text
6
Bullard, Stephan Gregory. A guide to the larval and juvenile stages of common Long Island Sound ascidians and bryozoans. Groton, Conn: Connecticut Dept. of Environmental Protection, 2004.
Find full text
7
Daley, Bryon A. An integrated assessment of the continued spread and potential impacts of the colonial ascidian, didemnum sp. A, in U.S. waters. [Silver Spring, Md: U.S. Dept, of Commervce, National Oceanic and Atmospheric Administration, National Ocean Service, 2008.
Find full text
8
Ali, H. Abdul Jaffar, and M. Tamilselvi. Ascidians in Coastal Water: A Comprehensive Inventory of Ascidian Fauna from the Indian Coast. Springer, 2018.
Find full text
9
Ali, H. Abdul Jaffar, and M. Tamilselvi. Ascidians in Coastal Water: A Comprehensive Inventory of Ascidian Fauna from the Indian Coast. Springer, 2016.
Find full text
10
A, Ettensohn Charles, Wray Gregory A, and Wessel Gary M, eds. Development of sea urchins, ascidians, and other invertebrate deuterostomes: Experimental approaches. Amsterdam: Elsevier Academic Press, 2004.
Find full textBook chapters on the topic "Sea squirts. Ascidies Ascidies"
1
Jung, Sung-Ju, Myung-Joo Oh, Tashuya Date, and Satoru Suzuki. "Isolation of Marine Birnavirus from Sea Squirts Halocynthia roretzi." In The Biology of Ascidians, 436–41. Tokyo: Springer Japan, 2001. http://dx.doi.org/10.1007/978-4-431-66982-1_64.
Full text