Academic literature on the topic 'Discus (Fish)'

Abstract The Asian fish tapeworm, Bothriocephalus acheilognathi Yamaguti, 1934, was detected for the first time in breeding of discus fish Symphysodon discus (Perciformes, Cichlidae), a popular South American cichlid. In examined samples, the adult and juvenile cestodes of B. acheilognathi with mean intensity of infection 30 (range 19 - 47) individuals per fish were found. The infected fish displayed acute behavioral symptoms. Mortality was significant; it reached almost 80 % in youngest age categories. As treatment, praziquantel immersions in dose 2 mg per liter were well tolerated and efficacious. The risk of spreading pathogens via imported fish is actual menace for ornamental breeding fish, therefore, thorough quarantine and prophylactic measures needs to be done by all fish imports and introductions. Import and subsequent release of infected ornamental fish into freshwater ecosystems may represent serious risk for spread and establishment of the parasite in native fish species. This case study illustrates that ornamental fish play also a key role in national and international movements of parasites in freshwater habitats.

The Neotropical red discus fish, Symphysodon discus, originates from the Amazonian basin and has a discoid body. Although this species is popularly used in aquaria and is exported as an ornamental fish, it has not been intensively studied. The purpose of this work was to study the morphological and histological aspects of the ovarian development in the red discus. Forty females of S. discus of varying body sizes and different stages of gonadal development were used in this study. The ovaries were weighed and examined macroscopically in order to observe the maturation stages. Histological staining of hematoxilin-eosin was used for microscopic observations of the ovaries. Macroscopic observations showed immature, maturing, mature and partially spent stages of ovarian development. Microscopic examination of the ovaries revealed five stages and five phases of ovarian development. The ovaries of the mature females showed all the different phases of oocyte development, indicating the multiple spawning habit of this species.

The global ornamental fish trade is a rapidly growing industry. Cultivation and propagation of ornamental fishes have been increasing in the last 20 years in Iran. Discus (Symphysodon aequifasciatus) from Cichlidae is one of the most popular and expensive aquarium fish. In the past few years farming of this fish has been well developed in Iran. Two breeder discus fish (Symphysodon aequifasciatus) from two different propagation centres (with high mortality) with signs of anorexia, loss of balance, moribundity and darkness in skin colour were referred to Laboratory of Aquatic Diseases of Veterinary Faculty, University of Tehran. After the survey of ectoparasites, necropsy was performed under aseptic conditions; bacterial culture on standard media was done and the alimentary canal was extruded. In both fish no ectoparasite was detected and no bacteria from these cases grew on the standard media. In internal survey 5 and 25 nematodes were detected in each fish. A high number of free eggs were observed in intestine of fish. Regarding morphological characteristics of the nematodes and their eggs, they were identified as Capillaria sp. Treatment of other fish with levamisole was effective and the loss was terminated. Some helminthes like Capillaria pterophylli Heinze, 1933, can cause a high mortality in cichlid aquarium fishes. This study showed that infection with some species of Capillaria could cause a heavy loss in ornamental fish from Cichlidae. Diagnosis of parasites of these fishes can help us to prevent high mortalities.

The selection of ingredients is an important aspect for diets formulation for fish in captivity. The use of fruit industry by-products can be an alternative for inclusion in diets for ornamental fish, as discus fish case, to improve health and reduction of production costs, further to reducing the environmental impacts of fruits industries residues. The objective the studies was to evaluate the bioavailability of fruit industry by-products in the diet for discus fish by coefficients of digestibility. The digestibility of three by-products: pineapple by-product, mango by-product, and passion fruit by-product were evaluated. Thirty-two discus fish (106 ± 26.6 g) were distributed in 4 tanks for feeding and fecal collection, constituting an experimental design in Latin square (4 diets test- x 4 periods of fecal collection x 4 replicates). The three by-products had digestibility coefficients above 80%, 70%, and 69% for dry matter, protein, and fat, respectively, being possible to use them as a source of these nutrients in diets for the discus fish. However, it was observed that the mango and passion fruit by-product had the lowest energy digestibility coefficient, with bioavailabilities less than 50% of utilization. The co-products of the fruit processing industry tested in this work have nutritional conditions to be used as food for root discs. The use of these co-products as food for ornamental fish can be an alternative use and value.

Aquarium is one of the media that is often used as a habitat for various types of animals that live both on land and in water. Many beautiful fish in the scenery are placed in aquariums filled with water as decorations. However, to place fish whose natural habitat is in vast water into an aquarium must require knowledge of the water quality that is suitable for these fish. Clear water is not necessarily suitable for the living conditions of fish. Fish that live in an open water environment grow well because not only is there sufficient food but there is an exchange of matter and energy such as oxygen, carbon dioxide and salts. Whereas in an aquarium environment, as a closed system, sudden and drastic changes to water parameters often occur (such as temperature, ph and ammonia content), which will cause fish stress and often lead to death. Therefore, the knowledge and ability to determine good fish aquarium water quality is an important element for fish keepers, especially hobbyists of ornamental fish such as discus. Classifying quality with a crisp set is a common practice. The number of variables involved in the aquarium (in this case, the object of research is discus) causes determination with a firm (crisp) set to be less appropriate. Therefore, the fuzzy mamdani method will produce outputs that are more suitable for analyzing the quality of aquarium discus. The input variables are density, temperature, and acidity. The outputs used are "Good", "Medium", "Bad".

This study was conducted to evaluate the replacement of fishmeal by black soldier fly larvae (Hermetia illucens) (BSF) meal, frozen beef heart, and commercial pellet on growth performance, survival rate, and feed utilization of discus fish (Symphysodon sp.). Discus juveniles were graded into small, medium and large size groups as block in a completely randomized block design. Five trial diets included frozen beef heart (T1), commercial feed for discus fish (T2) and three diets containing graded levels of BSF as replacements for protein from fishmeal of 0% (T3), 25% (T4), and 50% (T5). The results showed that TAN and nitrite levels in the beef heart treatment were higher than those in the other ones. Moreover, discus fish in treatment 1 had a higher growth rate and a lower feed conversion ratio than those in the other treatments. On the other hand, no statistically significant differences among the pellet treatments were observed for growth rates of discus's weight, length and height and feed conversion ratio (P > 0.05). Moreover, the results showed that discus fish in the two BSF treatments did not suffer from diseases and had higher survival rates than those in the other treatments.

Modern aquaculture is rapidly developing. It includes food fish farming and decorative fish breeding. Like in any fast-growing livestock industry, there may be problems related to the health of fish. Carp is the main object in Russian fish farming, representing the basic type of unpretentious, omnivorous and fast-growing pond polyculture. Tilapia is one of the most preferred species of global aquaculture, due to its hardiness, rapid weight gain and ability to tolerate high planting density. Discus is the most popular of the ornamental fish species; it features a large number of color variations, interesting behavior and is cost-effective in breeding. The authors carried out comparative physiological assessment of bony fish of the cyprinid and cichlid families. Hematological parameters were determined – erythrocyte and leukocyte formulas (by means of differential analysis techniques); biochemical parameters of blood serum (with the analyzer), the average cytochemical coefficient of lysosomal cationic protein content in fish blood neutrophils. The research results showed specific features in the intensity of erythro- and leukopoiesis, the proportion 32 of granular cells of the myeloid series. It was revealed that the peculiarity of discus is the presence of blast forms of white blood cells in the blood: myeloblasts, promyelocytes, and myelocytes. In the blood of tilapia, in contrast to discus and carp, there is a high content of granulocytes: neutrophils, eosinophils and basophils of monocytes and lymphocytes in the leukogram. Differences between species were noted based on the results of the lysosomal cation test. The difference in a number of biochemical parameters can also be seen: in tilapia as compared with other species – in the content of albumins, alkaline phosphatase and ALT, in discus – in the activity of lactate and KK enzymes.

Objective of research. The purpose of the study – screening of new chemotherapeutic agents for the treatment of hexamita ornamental fish. Materials and methods. The test drugs were performed on juveniles of the discus Symphysodon discus a body mass of 15 g, spontaneously infested hexamitidae (Diplomonadida). 35 discus of the infected individuals were divided into 7 groups of 5 copies of the Fish 1, 2, 3, 4, 5, and 6th groups were appointed in the composition of granulated feed, respectively pyrimethamine at a dose of 50 mg/kg albendazole – 50, fenbendazole – 50, mebendazole – 10, magnesium sulfate – 500 and metronidazole in a dose of 50 mg/kg for 5 days. Fish 7 the first group was control and received feed without the drug. The effectiveness was considered after 5 days after the last Dachi medicated feed. Fish were dissected, the intestines were isolated, which were released from the food pulp, homogenized, and were studied by optical microscopy at a magnification of 180 times. Results and discussion. The number of examined in treated fish compared with the control decreased after the application of metronidazole by 95.5 %, mebendazole – 77.8, magnesium sulfate, which is 74.5, fenbendazole – by 56.6, albendazole – 50.5 and pyrimethamine – 24.4 %. Advanced for further testing are mebendazole, magnesium sulphate, fenbendazole and albendazole. The most effective was a basic drug – metronidazole. During the test degradation of fish were noted. Food activity was moderate at the level of 2% of ichthyomass. In fish treated with metronidazole, mebendazole and magnesium sulfate, have improved the condition.

Parental care has evolved across the animal kingdom to increase the probability of offspring surviving in an environment fraught with danger. While parental care is common among mammals and birds, it is relatively rare in fish with the vast majority of fish showing no form of parental care at all, whilst those that do, often just provide parental care to developing eggs pre-hatch. The provision of parental care in discus fish (Symphysodon spp.) is, therefore, interesting in that parents provide mucus to offspring as a source of nutrition during the first few weeks of care. In mammals this post-birth provision of parental care can lead to the development of the parent offspring conflict. It is, however, possible that this conflict is also present in discus fish. This thesis examines both the interesting parental care strategy of discus fish along with the potential for the parent offspring conflict to develop. To examine the dynamics of parental care in discus fish, a range of behavioural and mucus composition studies were carried out. The analysis of mucus revealed that similar to mammals, parents provided offspring with an initial high quantity of nutritional and non-nutritional factors including antibodies (IgM), essential ions and hormones. Behavioural studies also revealed that initially parents were highly diligent in providing care to offspring but that after two weeks of care, the behaviour of parents changed making it harder for offspring to obtain mucus. At this point a weaning period was initiated where offspring began spending less time with parents and more time foraging for external food sources. The initiation of this weaning period suggests the presence of the parent offspring conflict and indicates that a point is reached where the energetic demands of offspring are too great and that energy is better invested in to future offspring. Research into the bite size and feeding rate of fry suggest that during the weaning period fry could demand excessive amounts of mucus, which may be energetically unsustainable leading to the observed offspring avoiding behaviour of parents. As parental care behaviour is known to be intimately associated with mate choice, mate choice behaviour was also assessed in discus fish with the hypothesis that the ability to provide mucus would be selected for by prospective mates. While my dietary experiment did not influence mucus quality, the mate choice experiment did reveal the importance of hierarchies in discus fish, indicating that dominant individuals were significantly more likely to pair than subordinates. This is similar to that observed in closely related cichlids where the ability to be dominant and protect a territory was indicative of the ability to successfully raise offspring. In conclusion, the parental care behaviour of discus fish appears to share more similarities with that seen in mammals than that observed in fish. The implications of these findings indicate that parental care in discus fish could be a new model of parent offspring conflict hitherto unseen in fish which could ultimately help our understanding of the evolution of parental care in fish.

Fundação de Apoio a Pesquisa e à Inovação Tecnológica do Estado de Sergipe - FAPITEC/SE
The objective of this work was to determine the apparent digestibility coefficients of crude protein from alternative ingredients (chrysalis meal of silkworm, shrimp waste meal, isolated soy protein, wheat gluten) to discus (Symphysodon discus Heckel, 1840). Diets with the tested ingredients were composed of 69.5% of the reference diet, 0.5% chromium oxide and 30% of the test ingredient. 25 fish were used (106 ± 26.6 g), over five digestibility tanks with conical bottom and 100 L of capacity. The experimental design was Latin square 5 x 5 (five diets and five periods). The determination of 37 apparent digestibility coefficient was carried out by the indirect method, using 0.5% chromic oxide (Cr2O3), as an indicator. Apparent digestibility coefficients of crude protein and digestible protein were 92.86 and 22.87% for the chrysalis meal of silkworm, 62.44 and 24.46% for the , shrimp waste meal, 93.34 and 84.44% for the isolated soy protein, 86.94 and 72.58% for wheat gluten, and 92.12 and 40.63% for the basal diet, respectively. It concludes from this that the discus uses the isolated soy protein, the chrysalis and wheat gluten in your diet efficiently, which enables its use in feed for this species.
Objetivou-se com esse trabalho determinar o coeficiente de digestibilidade aparente da proteína bruta de ingredientes alternativos (Crisálida do bicho-da-seda, farinha do resíduo de camarão, isolado proteico de soja, glúten de trigo) para o Acará-disco (Symphysodon discus Heckel, 1840). As dietas com os ingredientes testados foram constituídas de 69,5% de dieta referência, 0,5% de óxido de cromo e 30% do ingrediente teste. Foram utilizados 25 peixes (106 ± 26,6 g), distribuídos em cinco tanques de digestibilidade com fundo cônico com capacidade de 100 L. O delineamento experimental foi em quadrado latino 5 x 5 (cinco rações e cinco períodos). A determinação do coeficiente de digestibilidade aparente foi realizada pelo método indireto, com a utilização 0,5% de óxido crômico (Cr2O3), como indicador. Os coeficientes de digestibilidade aparente da proteína bruta e proteina digestivel foram de 92,86 e 22,87% para a farinha de crisálida do bicho-da-seda, 62,44 e 24,46% para a farinha do resíduo de camarão, 93,34 e 84,44% para o isolado proteico de soja, 86,94 e 72,58% para o glúten de trigo e 92,12 e 40,63% para a ração referência, respectivamente. Conclui-se com isso que o acará-disco utiliza o isolado proteico de soja, a crisálida e o glúten de trigo eficientemente em sua dieta, o que viabiliza sua utilização em rações para esta espécie.

This study assessed the occurrence and impacts of maternal metal transfer in live-bearing fish. The occurrence was investigated in two different species (Gambusia affinisand Heterandria formosa), while the impacts were studied only in G. affinis. Occurrence and impacts were addressed by exposing gravid females for 10 days to 0.15 μM of copper or cadmium, transferring the fish to clean water, monitoring their reproduction and collecting newborn offspring for further analyses of their health and reproductive success.

Maternal transfer of copper and cadmium occured in both study species. Metal levels decreased in subsequent broods and in broods born later after a female's exposure. Metal exposure impacted the reproductive success of exposed-females; effects included smaller broods and more broods were aborted broods or contained dead offspring. Many effects remained for second broods developing well after the exposure.

The maternal metal exposure also impacted the offspring's health. Newborn offspring were smaller at birth, had reduced calcium levels, had a lowered metal tolerance, and had cellular membrane damage. When these offspring grew up, they had an increased rate of malformations, a smaller size at sexual maturity, increased gestation time and fewer broods. In spite of the impacts on life history parameters found in the laboratory, effects on population dynamics were very limited for greenhouse mesocosm populations established with the offspring of exposed females.

Effects for the essential metal (copper) and the nonessential metal (cadmium) were generally similar. A few effects, like those on body size, were evident for copper but not for cadmium. However, several of the more severe impacts, like the increase in malformations and reductions in the number of broods, were greatest for the offspring of the cadmium-exposed females.

This is the first report demonstrating negative impacts resulting from a short-term maternal metal exposure in live-bearing fishes. Effects were evident not just for reproduction of exposed-females but also for their offspring's health and reproduction. The latter continued beyond the offspring that were developing during exposure. This study demonstrated that the internal development in live-bearing fish may not spare the developing young from impacts caused by a metal-contaminated environment.

River herring, the collective name given to North American populations of Alewife (Alosa pseudoharengus) and Blueback Herring ( A. aestivalis), are iteroparous, anadromous members of the family Clupeidae, with similar morphology, ecological roles, and overlapping distributions. Once abundant in coastal rivers of New Hampshire, many factors including commercial fishing, habitat degradation, and dam construction resulted in a precipitous decline of the species along the entire coast. Successful efforts to restore populations have included the construction of fish ladders at dams. However, fish ladders require constant operation and maintenance to efficiently pass river herring, and only provide access to spawning habitat up to the next barrier, all too often, man-made.

Alewife passage efficiency in fish ladders of all designs has received little attention historically, but is important to understand how to interpret annual counts, that for many rivers are the only index used in current stock assessments. In this study, passive integrated transponder (PIT) tags were used to assess the passage efficiency of a Denil fish ladder on the Lamprey River in Newmarket, New Hampshire. The data collected allow for a better understanding of the movements and diel behavior of river herring in fishways, as well as insight into how the selectivity of fish ladders my shape the population demographics within a river system.

A breached dam located at Wadleigh Falls on the Lamprey River in Lee, New Hampshire was examined to determine if river herring were able to pass the existing structure or if it should be considered the upper extent of their annual spawning migration. Telemetry data indicated that Alewives were unable to pass the breached Wadleigh Falls Dam site and that it should be considered the uppermost extent of their migratory access. Results also show that migrating fish arriving at the location had a strong preference for the river-right channel when migrating upriver and exhibited very little exploratory behavior to seek alternate pathways upriver before emigrating back downriver, approximately two weeks after river entry. These in-river residence times were very similar to those found in other telemetry studies of anadromous Alewives.

Successful management and effective stock assessment for any species requires an understanding of its reproduction and recruitment. Fecundity is one measure of the reproductive potential of a species and was assessed in this study. Mature adult Alewives were collected at the head-of-tide dam on the Lamprey River in Newmarket, New Hampshire during the vernal spawning migration in 2012. A gonadosomatic index was used to determine that fish were sampled before spawning occurred, and egg diameters were quantified to examine distribution of eggs throughout the ovary. Fecundity was estimated gravimetrically using two techniques for comparison, and no difference between the methods was found. These findings show that image analysis is a fast and reliable method for fecundity estimation that does not require the use of a commonly used, toxic solution for ovary preservation. Fecundity estimates using image analysis ranged from 147,400 eggs at 24 cm to 332,500 eggs at 34 cm and aligns with previous findings of a clinal trend along the Atlantic Coast. Fecundity increased with total length, somatic weight, and age. Simple linear regressions exhibited good fits for fecundity-total length and fecundity-somatic weight, with age being the best predictor.

The non-local fish-bone potential simulates the Pauli-exclusion principle for composite particle interactions. This model is used to calculate the phase shifts of the neutron-alpha and proton-alpha systems. We propose a local double Gaussian potential with a new parameterization by fitting to experimental results. These parameters are universal to both nucleon-alpha systems and include all partial waves, which is an improvement over previous work in the field.

Researchers on the Northwest Coast (NWC) are often interested in complex questions regarding social organization, resource intensification, resource control, and impacts of environmental change on resources and in turn human groups. However, the excavation strategies used on the NWC often do not provide the spatial and chronological control within a site that is necessary to document their variability and answer these research questions. The Čïx ^wicen site has the potential to address some of the limitations of previous Northwest Coast village site excavations because of its unique and robust sampling strategy, the wide expanse of time that it was occupied, and the multiple house structures present. An on-going project is examining changing human ecodynamics over the breadth of site occupation, focusing on zooarchaeology and geoarchaeological records.

This site, located on the Strait of Juan de Fuca in Port Angeles, WA was excavated in 2004 as part of a Washington State Department of Transportation (WSDOT) undertaking to build parts for the Hood Canal Bridge Large scale excavation (261.4 m³ 528 m²) generated enormous quantities of faunal remains. Radiocarbon dates and historic records show occupation extends from 2750 cal. BP to the early 20^th century.

Statistical sampling methods provide an empirical way to maximize the amount of information obtained with the least amount of effort. My thesis addressed the utility of Sampling to Redundancy (STR) as a statistical sampling method for sampling faunal remains from large village sites. My project has documented the variability of fish family representation across time and space in one part of the Čïx^wicen village, while minimizing the time and effort required to do so. This thesis applies STR to “S” (> 1/4 in.) 10 Liter bucket samples from eight excavation units and a total of 26 separate unique temporal and spatial contexts. I focused on 1/ 4 in. samples for my study for a particular reason. Previous fish faunal studies have focused on effects of mesh size on fish representation; and emphasized the need to use fine mesh (e.g., 1/ 8 in. or finer) to document small-bodied fishes. This focus on fine mesh typically means that only limited volumes of matrix are studied, which in turn may mean that remains of rarer, large- bodied fishes are under- represented. The on-going research project has focused on buckets screened to 1/ 8 in. mesh (called “C” buckets). I used STR to sample additional volumes of matrix screened to 1/ 4 in. to examine whether expanding the volume studied would affect fish representation, which was a second goal of my project.

Overall, I studied remains from 269 “S” buckets out of a total of 419 buckets, or 47% of the buckets. STR was most helpful for six of the high bone abundance and density contexts, where I analyzed less than 50% of the total buckets, was moderately helpful for 14 contexts, and not at all helpful for the six contexts with low fishbone abundance, where I analyzed 100% of the buckets. This analysis took me a total of 154 hours, and based on the percentage of material analyzed, 174 hours were saved.

As to the second project goal, to assess whether adding fish remains documented from additional matrix volume affected fish representation, I found the differences were minimal. Both for my study units as a whole, and for each time period, adding the fish records from the “S” buckets did not alter the main trends in fish representation as documented by the larger study, using a smaller volume. To further examine whether the added volume from >1/ 4 in “S” buckets affected results, I explored specific research questions that are relevant to the larger project regarding environment-animal interactions and fishbone deposition and bone condition inside and outside of a house structure. Adding the “S” bucket samples did not affect fish representation or fishbone distribution and condition, which affirms that the sampling strategy used in the larger research project was sufficient in most cases to characterize the fish record at the site.

My approach to STR has focused on fish remains that were previously excavated from a Pacific coastal village site with dense archaeological deposits. STR could be employed in other types of archaeological settings in a range of environments (coast or interior) representing a range of cultural contexts (from hunting camps to urban centers) to establish sample redundancy after an excavation is complete. STR could be used during on-going excavation. Further research is required to explore the implications of STR in these settings, however it is likely that the success of STR in other contexts will be dependent on the density and overall abundance of remains, the diversity or material types being studied, as well of course in the range and specificity of questions in each case.

This study assed the impacts of 17α-ethinylestradiol in Heterandria formosa. These impacts were addressed through chronic, life-cycle exposures of individuals and populations of least killifish to 0, 5, or 25ng/L EE2. Development, growth, reproduction, survival, and population dynamics were monitored and evaluated for EE2 effects on their health, reproductive success, and population sustainability.

Exposing pairs of least killifish to EE2 resulted in similar increases in time-to-sexual maturity for both sexes. The EE2-exposure had a sex-dependent effect on body size, with standard lengths and wet weights of females significantly reduced and standard lengths of males markedly increased. Offspring production decreased by 50% and 75% for fish exposed to 5 and 25ng/L EE2 respectively. Sexual development was even further delayed in EE2-exposed offspring of exposed fish. EE2-exposure also affected the gonadal and liver development in least killifish. Males exposed to EE2 had delayed sperm maturation and severe intersex (a phenomenon in which eggs and sperm are produced within the same male). These effects were more severe at the 5ng/L than at the 25ng/L EE2 concentration. Exposing females to EE2 resulted in delayed egg maturation. Furthermore, EE2 exposure resulted in changes in liver morphology in both males and females. For both the delay in egg maturation and the changes in liver morphology, the effects were strongest at the higher EE2 concentration.

Effects of chronic EE2-exposure on populations were assessed at the 5ng/L concentration. EE2-exposure caused significant reductions in population size and population growth rates, and caused other changes in population dynamics. Exposed populations had a pronounced female-biased sex ratio and significantly reduced abundances of males and newborns. These responses were observed within one breeding season.

This is the first report demonstrating a variety of negative impacts resulting from chronic EE2-exposure in least killifish at both the individual and population levels. Effects were evident in all stages of development and in all life history stages. This study demonstrated that, similar to the case for other fish, live-bearing fish are likely to be severely affected when their environment becomes contaminated by EE2 and that steps are needed to prevent exposure to this endocrine disrupting chemical.

In this Thesis, we study the accretion of mass and angular momentum onto the disc of spiral galaxies from a global and a local perspective and comparing theory predictions with several observational data. First, we propose a method to measure the specific mass and radial growth rates of stellar discs, based on their star formation rate density profiles and we apply it to a sample of nearby spiral galaxies. We find a positive radial growth rate for almost all galaxies in our sample. Our galaxies grow in size, on average, at one third of the rate at which they grow in mass. Our results are in agreement with theoretical expectations if known scaling relations of disc galaxies are not evolving with time. We also propose a novel method to reconstruct accretion profiles and the local angular momentum of the accreting material from the observed structural and chemical properties of spiral galaxies. Applied to the Milky Way and to one external galaxy, our analysis indicates that accretion occurs at relatively large radii and has a local deficit of angular momentum with respect to the disc. Finally, we show how structure and kinematics of hot gaseous coronae, which are believed to be the source of mass and angular momentum of massive spiral galaxies, can be reconstructed from their angular momentum and entropy distributions. We find that isothermal models with cosmologically motivated angular momentum distributions are compatible with several independent observational constraints. We also consider more complex baroclinic equilibria: we describe a new parametrization for these states, a new self-similar family of solution and a method for reconstructing structure and kinematics from the joint angular momentum/entropy distribution.

In this Thesis, we study the accretion of mass and angular momentum onto the disc of spiral galaxies from a global and a local perspective and comparing theory predictions with several observational data. First, we propose a method to measure the specific mass and radial growth rates of stellar discs, based on their star formation rate density profiles and we apply it to a sample of nearby spiral galaxies. We find a positive radial growth rate for almost all galaxies in our sample. Our galaxies grow in size, on average, at one third of the rate at which they grow in mass. Our results are in agreement with theoretical expectations if known scaling relations of disc galaxies are not evolving with time. We also propose a novel method to reconstruct accretion profiles and the local angular momentum of the accreting material from the observed structural and chemical properties of spiral galaxies. Applied to the Milky Way and to one external galaxy, our analysis indicates that accretion occurs at relatively large radii and has a local deficit of angular momentum with respect to the disc. Finally, we show how structure and kinematics of hot gaseous coronae, which are believed to be the source of mass and angular momentum of massive spiral galaxies, can be reconstructed from their angular momentum and entropy distributions. We find that isothermal models with cosmologically motivated angular momentum distributions are compatible with several independent observational constraints. We also consider more complex baroclinic equilibria: we describe a new parametrization for these states, a new self-similar family of solution and a method for reconstructing structure and kinematics from the joint angular momentum/entropy distribution.

The South Texas Banks are a mesophotic coral ecosystem (30-150m deep). Understanding the community structure, biodiversity and, geographic connectivity of the South Texas Banks is essential with increasing threats from climate change, ocean acidification, invasive species, and pollution. In this study, a remotely operated vehicle (ROV) was used to examine the fish communities at five of the South Texas Banks: Big Adam, Hospital, Mysterious, North Hospital, and Southern. Reef fish were identified to the lowest possible taxon and enumerated from ROV transect video footage. A total of 3,838 demersal and pelagic fishes were recorded representing 61 species in 22 families including invasive Pterois volitans. Bodianus pulchellus, Holocentrus adscensionis, Priacanthus arenatus, and the Gobiidae family were the only fishes observed at all five banks. Habitat suitability models were created that highlight the rich biodiversity found on the South Texas Bank, which will warrant for future research and conservation efforts.

AbstractMicroplastic pollution is a big and rapidly growing environmental problem. Although the direct effects of microplastic pollution are increasingly studied, the indirect effects are hardly investigated, especially in the context of spreading of disease and antibiotic resistance genes, posing an apparent hazard for human health. Microplastic particles provide a hydrophobic surface that provides substrate for attachment of microorganisms and readily supports formation of microbial biofilms. Pathogenic bacteria such as fish pathogens Aeromonas spp., Vibrio spp., and opportunistic human pathogens like Escherichia coli are present in these biofilms. Moreover, some of these pathogens are shown to be multidrug resistant. The presence of microplastics is known to enhance horizontal gene transfer in bacteria and thus, may contribute to dissemination of antibiotic resistance. Microplastics can also adsorb toxic chemicals like antibiotics and heavy metals, which are known to select for antibiotic resistance. Microplastics may, thus, serve as vectors for transport of pathogens and antibiotic resistance genes in the aquatic environment. In this book chapter, we provide background information on microplastic biofouling (“plastisphere concept”), discuss the relationship between microplastic and antibiotic resistance, and identify knowledge gaps and directions for future research.

Abstract Aquaculture of ornamental fishes is rapidly expanding because of large demand and the much greater value of ornamentals relative to seafood fishes (per kg fish produced). Aquaculture of ornamental fishes is well suited for ecologically sustainable recirculating aquaculture systems (RAS). Technological innovations have made marine aquaria readily accessible for hobby aquarists, but they are still more challenging to maintain than freshwater aquaria. Thousands of different marine and freshwater ornamental fish species are being traded. Aquaculture accounts for >90% of all ornamental freshwater fishes but <10% and fewer than fifty species of all marine ornamental fishes. Several ornamental freshwater fishes have been domesticated, including betta fish, freshwater angelfish, guppies, and discus cichlids. Ornamental fish domestication is facilitated by short generation times. For marine ornamentals, research on husbandry and hatchery methods is needed to address environmentally destructive methods of capture fisheries in coral reef habitats. Advantages of ornamental fishes produced by aquaculture include species and habitat conservation, reduction of transport-related stress and mortality, improved animal welfare, elimination of pathogens and better health, known young age, being accustomed to life in aquaria and the presence of people, and being amenable to domestication for artificial selection of desirable traits. Diversification is essential for ornamental aquaculture to accommodate large fluctuations in demand for certain species. Many ornamental species have become invasive. Their management and preventative measures for avoiding future invasions of additional ornamental species are very challenging but essential for supporting the ecological sustainability of ornamental fish aquaculture.

<em>Abstract.</em>—The native freshwater fish assemblage in Puerto Rico is limited to a few catadromous species; consequently, many species have been introduced from other regions of the world. In this case study, we examine the use of fish species introduction and propagation in the management of freshwater systems in Puerto Rico. The history of importation, propagation, and introduction is organized into four primary phases: (1) the prehatchery phase, with limited introductions from the United States to rivers and earliest reservoirs; (2) the coldwater phase, with primary emphasis on trout species for high-altitude river introductions; (3) the early warmwater phase, with generous species introductions and supplementation without significant evaluation; and (4) the current modern phase, with primary focus on largemouth bass and prey species with significant assessment, evaluation, and research on stocking efficacy. We describe previous research that has guided the use of fish propagation in Puerto Rico, and we discuss the future of propagated fishes in fisheries management.

<em>Abstract.</em>—Substantial disagreement and uncertainty attend the question of whether the benefits from supplementing wild populations of anadromous salmonids with hatchery fish outweigh the risks. Prudent decisions about supplementation are most likely when the suite of potential benefits and hazards and the various sources of uncertainty are explicitly identified. Models help by indicating the potential consequences of various levels of supplementation but perhaps are most valuable for showing the limitations of available data and helping design studies and monitoring to provide critical data. Information and understanding about the issue are deficient. I discuss various benefits, hazards, and associated uncertainties for supplementation, and implications for the design of monitoring and research. Several studies to reduce uncertainty and facilitate prudent supplementation are described and range from short-term reductionistic studies that help define the issue or help avoid deleterious consequences from supplementation to long-term studies (ca. 10 or more fish generations) that evaluate the net result of positive and negative genetic, behavioral, and ecological effects from supplementation.

<em>Abstract.</em>—In December 1991, the National Marine Fisheries Service listed Snake River sockeye salmon <em>Oncorhynchus nerka </em>as endangered under the U.S. Endangered Species Act. Snake River sockeye salmon are a prime example of a species on the threshold of extinction, with the last known remnants of this stock returning to Redfish Lake, Idaho. On the basis of critically low population numbers and coincident with the listing, a captive broodstock project was implemented by federal, state, and tribal partners as an emergency measure to save Redfish Lake sockeye salmon. During the decade of the 1990s, a total of 16 wild fish returned to Redfish Lake (0–8 per year); all were captured for the broodstock program. Amplification of the population through captive broodstocking resulted in hundreds of thousands of progeny (prespawning adults, eyed eggs, presmolts, and smolts) replanted to habitats. Between 1999 and 2002, more than 300 adults returned from the ocean from captive broodstock releases—an amplification of almost 20 times the number of wild fish that returned in the 1990s. Important lineages of Redfish Lake sockeye salmon continue to be maintained in culture as preserves for genetic variability and for numerical and demographic amplification of releases to the habitat. It is virtually certain that the broodstock program has, at least for the short-term, prevented extinction of Redfish Lake sockeye salmon. Over the course of the program, operational issues included development of successful captive husbandry procedures, maintenance of genetic diversity, assessment/enhancement of habitat carrying capacity, and intensive evaluation of restocking efforts. In this paper, we discuss these issues as a model approach.

<em>Abstract</em>.—Nonpoint source pollution in the form of stormwater runoff is one of the most important emerging threats to ecosystems along the coastal margins of the United States. A wide diversity of potentially toxic chemicals is commonly found in stormwater. These include the various pesticides, petroleum hydrocarbons, heavy metals, and other common contaminants that originate from commercial, industrial, residential, and agricultural land-use activities. These chemicals are mobilized from roads, lawns, crops, and other surfaces by rainfall and then transported to aquatic habitats via terrestrial runoff. The ongoing development of coastal watersheds nationwide is increasing the loading of nonpoint source pollutants to rivers, estuaries, and the nearshore marine environment. A central aim of the National Oceanic and Atmospheric Administration’s national Coastal Storms Program (CSP) is to enhance the resiliency of coastal ecosystems by improving the ability of coastal communities to anticipate and reduce the impacts of contaminated terrestrial runoff. Toxic chemicals in stormwater can adversely impact the health of fish, including threatened and endangered species. Nonpoint source pollution can also degrade the biological integrity of aquatic communities that support productive fish populations. This article examines the effects of stormwater runoff on fish and fisheries. Using case studies drawn from CSP project work in the Pacific Northwest and Southern California pilot regions, we show how degraded water quality can impact the health of fish during critical life history stages (i.e., spawning and rearing) as well as limit the overall effectiveness of fish habitat restoration. We also discuss some of the resources currently available to local communities to reduce the loading of toxics in stormwater, thereby increasing the resilience of aquatic communities. Finally, we identify priority areas for new research to help guide the future conservation and recovery of at-risk fish populations.

<em>Abstract</em>.—Native fish conservation areas (NFCAs) are watersheds where management emphasizes proactive conservation and restoration for long-term persistence of native fish assemblages while allowing for compatible uses. Native fish conservation areas are intended to complement traditional fisheries management approaches that are often reactive to population stressors and focused on single-species conservation efforts rather than complete assemblages. We identified potential NFCAs in the upper Snake River basin above Hells Canyon Dam using a process that ranked all subwatersheds (Hydrologic Unit Code 12) and used empirical data on distribution, abundance, and genetics for three native trout species (Bull Trout <em>Salvelinus confluentus</em>, Columbia River Redband Trout <em>Oncorhynchus mykiss gairdneri</em>, and Yellowstone Cutthroat Trout <em>O. clarkii bouvieri</em>, including the fine-spotted form) and both known occurrences and modeled potential distributions of native nongame fishes. Rankings also incorporated drainage network connectivity and land-protection status (e.g., national park, wilderness). Clusters of high-ranking subwatersheds were identified as potential NFCAs that were then classified according to the presence of nongame fishes identified as species of greatest conservation need in state wildlife action plans. The Pacific Creek and Goose Creek watersheds ranked high in the upper basin (above Shoshone Falls), and Little Jacks Creek and Squaw Creek ranked high in the lower basin. We then contrasted characteristics of a select few potential NFCAs, discuss the practical implementation and benefits of NFCAs for both fishes and other aquatic species in the upper Snake River basin, examined how the NFCA approach could enhance existing conservation partnerships, and discuss how designating select watersheds as NFCAs can create higher public awareness of the value of native fishes and other aquatic species and their habitats.

<em>Abstract.</em>—The use of cultured fishes by fisheries agencies is a long-standing management technique. In recent decades, however, potential negative impacts of fish stocking programs have received increased attention, particularly as they affect native fish communities and the genetic integrity of wild fish populations. In 1994, a facilitated workshop was organized to develop recommended procedures for the use of cultured fishes that would be compatible with these broader environmental concerns. We administered a survey to state and provincial fisheries management agencies in the United States and Canada to determine the current status of fish culture and stocking programs and assess progress toward adoption of these procedures. With 54 of 62 agencies reporting, our results indicated that stocking programs continue to be an integral part of management programs, but that substantial progress has been made toward addressing concerns about potential negative effects of cultured fishes. The percentage of responding agencies reporting use of management plans in which stocking was considered as part of a larger management program more than doubled in the years since 1980. Consistent with this finding, agency emphasis on alternative management approaches was evidenced by a twofold greater increase in expenditures on habitat management programs relative to culture programs in six agencies that provided budget figures. The percentage of responding agencies evaluating appropriateness of stocking through the use of formal criteria on at least half the waters where cultured fish were used tripled since 1980, and decisions not to stock due to potential impacts on biodiversity or the genetic integrity of recipient fish communities were reported to be four times more likely today than in 1980. Emphasis on the use of native fishes in stocking programs since 1980 was reported to have increased for more than half the agencies responding to our survey, and the number of agencies reporting development of broodstock plans for at least some of the species they cultured also doubled since 1980. Agency perceptions of angler attitudes concerning the importance of stocking indicated that the percentage of anglers who believed that stocking was the primary or only solution to low fish abundance remained high, at 61%, a decline of only 27% from reported attitudes in 1980. While positive strides have been made by agencies toward more careful evaluation of the appropriateness of stocking for achieving management objectives and in the institution of programs to minimize impacts of cultured fishes, these policies have not been adopted by all agencies, nor are they routinely used on all stocked waters by the agencies that have them. To make continued progress, agencies may be required to make difficult decisions regarding allocation of funding, and a more concerted effort to educate anglers and reduce public pressure for stockings will be needed to create an atmosphere where reduced emphasis on stocking is possible. The American Fisheries Society should play a continuing role in providing opportunities for scientists and policy makers to interact and discuss prevailing and emerging issues relative to the use of propagated fishes in resource management.

Reduction of deficiency of macro- and microelements in foodstuffs (in particular, iodine and fluorine) of ecologically impoverished regions is possible in the development of new products. In this regard, dietary supplements have been introduced into the recipes of meat, fish, vegetable, cereal and curd dishes. The combination of the main raw materials and additives, the functional properties of the products have been studied, and the optimal organoleptic, structural-mechanical, and rheological properties have been established. Additive "Mobi-lux Universal", containing heme iron, organic calcium and iodine, enrich a wide group of products with minerals by creating protein-vegetable combined compositions. Recipes have been developed and technologies have been substantiated for “Morskie” fish cakes, “Pikantny” meat steak, “Raduzhny” fruit and curd dessert, fruit mousses, and “Appetitnaya” rice casserole with apples. The results of a study of the nutritional value of specialized food products based on meat, fish, vegetable, fruit, cereal products and cottage cheese, enriched with the Mobi-lux Universal complex functional additive, vegetable and fruit powders, are presented. More than 20 dishes have been developed and included in corrective diets for schoolchildren. It has been established that the maximum enrichment of meat and fish products is carried out with vitamins: Betacarotene, B6, B12, as well as macro- and microelements: iron, iodine, calcium, sodium, magnesium and fluorine. Protein-containing fish and meat dishes, due to the included additive, make up for 15% of the daily deficiency in these nutrients (iodine, calcium and iron). Dessert, mousse and casserole - to dishes-sources of bio-organic iodine, calcium and iron. This will fully balance the diet of students in the category of 7-11 years old. The developed dishes were tested in the production conditions of catering establishments of educational organizations.

Fish farming in exposed and offshore waters are potential solutions to many biological and environmental problems currently facing marine aquaculture. Offshore fish farming will require development of larger, more complex marine structures and elaborate logistical support systems, including service vessels. While innovation in concept design for these systems are currently awarded by regulators, production costs that are substantially higher than for existing fish farming system represent a barrier to competitiveness. In this paper, we show that offshore fish farming can become competitive when global seafood demand grows, due to cost-learning dynamics previously documented in a wide range of industries. Using historical time series for production and costs, we find evidence of cost-learning curves in existing aquaculture, suggesting that unit capital expenditures decline at a given rate every time cumulative production capacity doubles. To investigate the potential for offshore fish farming, we develop a simple system dynamics model of key trends and important feedback mechanisms that drive investments in technologies for offshore fish farming. The analysis indicates that policies that reward novel concepts, like license waivers or subsidies, can trigger cost-learning dynamics and move offshore fish farming towards competitiveness. We also find that design novelty may limit the cost reductions that accrue from cost-learning effects. Following the quantitative results, we discuss how the forecasted cost-learning dynamics can be exploited under a regulatory regime that favors innovative concepts. Finally, we reflect on the opportunities an emerging offshore fish farming industry provides for ship design and for the re-use of vessels that have become stranded assets.

A succinct non-interactive argument of knowledge (SNARK) enables a party to convince another of some statement (typically, knowledge of some information) by means of a short argument, while ensuring it is infeasible for an adversary to create a short argument of the opposite statement. We hereby describe a SNARK for CSI-FiSh signatures, whose security stems from hard problems involving supersingular isogenies. Although the scheme looks analogous to a SNARK for conventional Schnorr signatures, it is non-trivial in that, as we also show, a similar SNARK for another isogeny-based signature scheme (SQISign) is not viable. As a bonus, we also discuss how to drastically reduce the memory needed to implement the CSIDH framework required by CSI-FiSh signatures.

This report will reveal a series of fatigue test results for high-strength steels at 100 Hz and 20 kHz and discuss frequency effects on gigacycle fatigue properties. The 20 kHz fatigue testing machine is an effective tool to conduct gigacycle fatigue tests in a reasonable term, while frequency effects have to be carefully investigated before applying the machine. The fatigue tests were conducted for two kinds of high-strength steels, that were a low-alloy steel and a spring steel. These fatigue test results showed that the frequency effects were negligible even at 20 kHz in case of fish-eye fracture. The fatigue properties in the fish-eye fracture region showed a good agreement between the 100 Hz and 20 kHz tests. Besides, ODAs (Optically Dark Areas) were also observed on the fracture surface even in 20 kHz tests and no difference was found in the ODA sizes between the 100 Hz and 20 kHz tests. These results meant that the 20 kHz tests could provide us appropriate results at least in the fish-eye fracture region. Therefore, the 20 kHz tests were applicable on the evaluation of gigacycle fatigue properties in high-strength steels.

The aftmost part of a trawl fishing gear, the cod-end, has been successfully modelled as an axisymmetric network. Here we investigate the influence that the bending stiffness of the component twines has on the deformation of the network and accordingly on the degree to which the netting meshes open. A non-dimensional parameter EI/NM4P, where EI is the twine bending stiffness, N is the number of meshes around, M is the mesh size, and P is the internal pressure, is shown to characterize network deformation. We identify upper bounds on the network radius when subject to a constant internal pressure and demonstrate numerically how this varies as the value of this non-dimensional parameter increases. We also look at some specific examples and discuss how an increase in twine bending stiffness may affect fish escape from the cod-end.

Cooling water intake problems come in many forms. These problems can include large schools of fish or jellyfish, seaweed, lake grass, sand, and silt buildup or carryover in the cooling water intake and screen house. Lower lake levels and higher average temperatures, zebra mussel infestation, and non-uniform flow rates between traveling water screen (TWS) bays and circulating water pump bays due to under-sized intake structures can also affect cooling water intake. Downstream of the cooling water intake, flow imbalances caused by entrained debris challenge heat exchanger designs and aging equipment. One Midwestern plant developed an integrated approach to improve the overall performance of the cooling water intake which will result in increased operating efficiency. For the subject plant, this paper will discuss specific modifications planned or undertaken and their benefits and limitations, flow modeling and design margin analyses completed and in process, anticipated reduction in debris carryover, impingement, and entrainment, and suggested further improvements. The majority of modifications undertaken or planned at the subject plant are generally intended to minimize debris carryover and to reduce problems associated with system blockages and heat exchanger tube fouling. Specific modifications to be discussed include: an acoustic fish deterrent system at the inlet tunnel entrance, replacement of the flow-through TWS’s with an industry first-of-a-kind design screen technology, screen wash, and debris transport and removal system modifications, service water system strainer basket modifications, service water system heat exchanger repairs and modifications, and installation of a sodium hypochlorite system.

Research during the last four decades has demonstrated that oils rich in the highly polyunsaturated marine omega-3 fatty acids, EPA and DHA, have several health benefits. The positive health benefits of omega-3 fatty acids have led to increased use of omega-3 oils for functional foods. However, due to their polyunsaturated nature, omega-3 oils are highly susceptible to lipid oxidation, which decreases their nutritional value, gives rise to off-flavors and leads to the formation of toxic aldehydes during food enrichment and digestion. Development of delivery systems, which allows food fortification with omega-3 PUFAs is a possible strategy to reduce lipid oxidation. This presentation will discuss different types of delivery systems including low and high fat emulsions and micro-encapsulated fish oil using different encapsulation techniques such as spray drying and electrospraying. It will be discussed how different emulsifiers and encapsulating materials will affect the oxidative stability of the delivery emulsion.