Dissertations / Theses: 'Fish larvae'

1

Le, Vay Lewis. "Nutritional studies on fish and crustacean larvae." Thesis, Bangor University, 1994. https://research.bangor.ac.uk/portal/en/theses/nutritional-studies-on-fish-and-crustacean-larvae(7c8004f1-ea27-4a8e-9d38-30c32f9ace4f).html.

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The effects of live foods and microencapsulated diets on growth, survival, body composition and digestive physiology of fish (mirror carp, Cyprinus =LQ) and penaeid shrimp ftna= japQnim) larvae were examined. Raising the lipid content of a microencapsulated enrichment diet from 18.3% to 33.6% improved accumulation of highly unsaturated fatty acids (HUFA) and total lipid in rotifers. Lipids in rotifers were assimilated by carp larvae, as demonstrated by improved growth and accumulation of HUFA in larvae reared on rotifers pre-fed the "high-lipid" diet. Poor diet digestibility coupled with low ingestion rates and low digestive enzyme activity in larvae were identified as contributing to the failure of a microencapsulated diet to support good growth and survival when fed directly to first-feeding carp. Preliminary testing indicates that digestibility of microencapsulated diets for fish larvae can be improved by inclusion of pancreatin. Experiments with Penaeus japonicus indicate that dietary requirements for protein, energy and HUFA by penaeid larvae are lower than previously thought. Foods of low protein content (Chaetoceros gladlia) or low digestibility (microencapsulated diet) elicited high trypsin activity in mysis larvae, compared to those fed Artemia. Larvae receiving both C , gmcilis and Artemi exhibited an intermediate level of trypsin activity - which may explain the superior growth and protein retention in postlarvae reared on the mixed regime. A microencapsulated diet did not support growth and carbon and nitrogen retention equivalent to that in larvae fed live food, despite the strong trypsin response, in mysis larvae. When used together with a low density of _C, p-racilis the microencapsulated diet produced postlarvae of the same size and tissue composition as those reared using live food. It is suggested that the algal co-feed may enhance growth through stimulation of trypsin secretion, supply of extra digestible nutrients or provision of unidentified specific growth enhancing factor(s).

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2

Fjellheim, Anders Jon. "Selection and administration of probiotic bacteria to marine fish larvae." Doctoral thesis, Norwegian University of Science and Technology, Department of Biology, 2006. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-2217.

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3

Uji, Susumu. "Muscle development and muscular abnormalities in the teleost fish larvae." Kyoto University, 2014. http://hdl.handle.net/2433/192130.

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4

Catalán, Alemany Ignacio. "Condition Indices and their Relationship with Environmental Factors in Fish Larvae." Doctoral thesis, Universitat de Barcelona, 2003. http://hdl.handle.net/10803/1422.

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The high variability in the recruitment of marine fishes is probably explained by small fluctuations in the mortality rates of early developmental stages. A popular proxy for the potential mortality of fish larvae is the study of nutritional condition (or simply "condition"). According to the growth-mortality hypothesis, a lowered condition has a high associated probability of total mortality.

This thesis offers new information on several aspects of nutritional condition and growth indices, by working on two main lines:

1) Laboratory Studies: Three main types of condition indices were investigated in larvae of a well-known laboratory-reared species (sea bass Dicentrarchus labrax). Acknowledging for the species-specificity of condition indices, this experimental Chapter was devoted to the study of various properties of morphometric, histological and biochemical indices, in response to several feeding schemes. Also, effort was placed in the improvement of some of the indices and the study of their relationship with survival in the laboratory.
In the last Section of this Chapter (comparative analysis), a model to relate potential survival with the different indices is proposed.

2) Field Studies: the relationships between environmental variables, nutritional status and growth of Sardina pilchardus (Walbaum 1972) larvae in an area of the Catalan Sea (NW Mediterranean) were studied. Pilchard is the most abundant commercial pelagic fish species in the NW Med. Despite its economic importance and the known decline of the stock since 1993, the studies on possible links between environmental conditions and pilchard early life history are hardly developed in this area.
The field studies were based on three oceanographic cruises conducted in November 1998, February 1999 and November 1999. Firstly, biotic and abiotic environmental variables were related to larval distribution, abundance and size-structure. Secondly, the nutritional condition and growth was studied in two of the cruises. Environmental variables considered at each station included potential food, fluorescence, temperature, salinity and the maximum Brünt-Väisälä frequency. Long-term growth was analysed through otolith analyses and muscle fibre growth patterns. Condition was studied through hystological an biochemical (protein ad RNA/DNA ratios) indices. The possible effect of environmental variables on potential survival is discussed.

The main conclusions of the thesis were:

LABORATORY STUDIES

1)Morphometric indices proved useful in distinguishing the shape of larvae subjected to differing feeding conditions. This was done through multivariate analysis on variables from which the effect of size had been completely removed, whilst incorporating the information on allometry.

2)The quantitative determination of muscle fibre separation (MFS) showed to be the best histological method (within those tested) to detect a suboptimal nutritional state.

3)The RNA/DNA ratio is more appropriate in detecting a nutritional deficiency in post-flexion than in pre-flexion larvae.

4)Within the biochemical indices studied in post-flexion larvae subjected to a short-term food deprivation and re-feeding, the RNA/DNA and the LDH/DNA ratios are considered particularly useful.

5)In post-flexion larvae subjected to 2 days of fast, the cell proliferation rate measured in the muscle was significantly lower than in Fed larvae. This was not observed in the brain, which is more conservative to the food withdrawal.

6)The comparison of morphometric, histological and biochemical indices shows that, in pre-flexion larvae, the quantitative determination of muscle fibre separation is the index that soonest detects the effect of food deprivation. For the same age-range, the RNA/DNA yields the maximum correct discrimination percentage (100%). In this study, the MFS was the condition index that held the best correspondence with larval mortality.

7)The larval susceptibility to mortality at sea may be more related to those deficiencies that involve organs or tissues that are of crucial importance for feeding behaviour, escape response or maintenance of floatability, like the muscle. It is here proposed an scheme of how indices could be weighted in order to relate them with survival potential.

FIELD STUDIES

8)In November 1998, certain environmental characteristics were found to be positively associated with nutritional condition of S.pilchardus, measured through histological and RNA/DNA indices. These areas can be characterised by an optimum "environmental window" defined by temperature values under 19ºC, values of the Brunt-Väissälä (B-V) water stability index under 0.8 cycles h-1 and values of potential food abundance over 4.5 nauplii l-1 and 5.5 individuals l-1 of the rest of the microzooplankton. The variables that best related to larval condition were the B-V index and the amount of potential food. Moreover, the larval abundance was higher in those areas. Therefore, it is considered that larval survival would be enhanced in these areas.

9)In February 1999 the eggs and larval abundance was lower than in November 1998.

10)The long-term growth studied through otolith analyses suggests that larval growth was enhanced in November 1998 with respect to February 1999. This result was confirmed by the analysis of the muscle fibre growth patterns. Condition was also better in November 1998, although the February data were less clear.

11)The measures of growth and condition showed a general coincident pattern. The analysis of muscle growth patterns suggests that in pilchard larvae growth is hypertrophic until 6-7 mm SL, becoming hyperplastic at least until 13.5 mm SL. Within the histological measures studied, the MFS was the most informative. The RNA/DNA appeared more useful in larvae over 8-10 mm SL.

12)The amount of larvae in the November 1998 and February 1999 cruises was anomalously low for the time of the year. Hydrographic conditions during both cruises were highly unusual, exhibiting high stratification in November and an inverted salinity pattern in February. The presence of a mesoscale anticyclonic eddy of new AW, that remained in the area from October 1998 to February 1999, is thought to account for the unusual hydrographic conditions and the low numbers of eggs and larvae in some areas.

13)Overall, the data on larval abundance, nutritional condition and environmental characteristics suggest that the spawning season autumn 1998-winter 1999 was characterised by a low larval production of this species. It is concluded, from the joint interpretation of all data, that putative larval survival would be the result of a reduced spawning and nutritional condition in some areas and periods, and a reduced growth in the winter cruise.

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5

Nanton, Dominic André. "Nutritional value of marine harpacticoid copepods as live food for marine fish larvae." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp04/mq24887.pdf.

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6

Theron, Dirk Leopold. "The biological control of malaria mosquito larvae using smaller indigenous freshwater fish species." Thesis, University of Limpopo, 1987. http://hdl.handle.net/10386/2611.

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7

Minkoff, Gideon. "The effect of secondarily enriched rotifers on growth and survival of marine fish larvae." Thesis, University of Stirling, 1988. http://hdl.handle.net/1893/2536.

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Nutritional aspects of three species of marine fish larvae, herring Clupea harengus L., plaice Pleuronectes platessa L. and turbot, Scophthalmus maximus L. were examined. Larvae were fed three different diets all of which were derived from rotifers Brachionus plicatilis (O.F. Mtlller). These rotifers had been mass cultivated on baker's yeast and then enriched with baker's yeast, or with one of two unicellular algae, Isochrysis galbana Park or Nannochloropsis (Nannochloris) oculata (Droop) Hibberd. The biochemical changes that these enrichments conferred on the rotifer were examined. There was little difference in proximate and amino acid compositions. Dry weights, and calorific contents of the rotifers fluctuated according to the type, temperature and duration of enrichment, with the yeast enriched rotifers tending to weigh less (200-320 ng) than their algal counterparts (250-370ng). Major differences were found in the total fatty acid profiles of the rotifers. Yeast-enriched rotifers had no 18:3n-3 or 20:5n-3 and only trace amounts of 22:6n-3 fatty acids. The Nanrinochioropsis-enriched rotifers had substantial amounts of n-3 fatty acids though only of 20:5n-3 (11-14%), while rotifers enriched with Isochrysis had only trace amounts of 20:5n-3 (2-4%). All three species of fish responded similarly to the yeast enriched rotifer diet. Their growth, in terms of length and weight, was minimal and they never developed any fin ray elements. Both flatfishes developed a looped gut in the short growth duration on this diet and some turbot (20%) inflated their swim bladder. This retardation of growth was attributed to the lack of long chain highly unsaturated n-3 fatty acids (n-3 HUFA) in the diet. During one month feeding trials it was shown that herring and plaice were able to exploit both algal-enriched rotifer diets equally well. Turbot, on the other hand grew better, over 14 days, on rotifers enriched with lsochrysis compared with Nannochioropsis. The reaction of the different species was linked to the fatty acid profiles of the diet. Hence, turbot require a dietary input of 22:6n-3 while herring and plaice thrived equally well on diets containing only 20:n-3. Juvenile plaice consistently exhibited improved pigmentation when Isochrysis compared to Nannochloropsis were used as the rotifer enrichment. The effect was attributed to specific nutrients particular to algal chloroplasts, which need to be present in the diet of the larvae up to metamorphosis. Assessment of daily rations, employing the rotifer enriched with Isochrysis diet only, showed herring to reduce their food intake from 46 to 19% body dry weight/d between days 10-21 post hatch while turbot consumed between 34-169% body dry weight/d with no apparent age related effects. The gross growth efficiencies (Ki, Brett & Groves, 1979) for both species were seemingly unaffected by age related processes and fluctuated between 15-50% in turbot and 20-61% in herring according to fluctuations in daily food intake. Ingestion is further described for both species with a linear model that related food intake to larval weight. The weight-specific ingestion was found to be a constant 13% and 43% of body dry weight in herring and turbot respectively. The weight-specific ingestion and specific growth rate estimates were combined with other data available from the literature, revealing that larvae tend to consume food (in dry weight) at a level equivalent to approximately twice their daily dry weight increase.

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8

Pham, Cong Tri. "The ecology of fish larvae in Pumicestone Passage : an estuarine system in Southeast Queensland, Australia /." St. Lucia, Qld, 2000. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe16437.pdf.

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9

Omar, Othman Abdu Hashim. "Abundance and distribution of Ichthyoplankton in the Firth of Forth, Scotland." Thesis, Heriot-Watt University, 1988. http://hdl.handle.net/10399/963.

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10

Huebert, Klaus B. "Behavior and Transport of Pelagic Coral Reef Fish Larvae in the Straits of Florida." Scholarly Repository, 2009. http://scholarlyrepository.miami.edu/oa_dissertations/266.

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The supply of coral reef fish larvae from the open ocean to reefs is vital for the persistence of local fish populations. Whether larvae are dispersed over hundreds of km or only few km depends on biophysical interactions between larvae and their environment. Relationships between environmental variables, larval swimming behavior, and larval transport were examined for reef fish larvae in the Florida Straits. In a series of research cruises, the upper 100 m of the water column was sampled with plankton nets fishing at four different depths. Variability in the vertical distributions of most larvae was not consistently related to measured environmental variables. Relative densities of larvae were predictably related to sampling depth in five taxa. In seven taxa, more developed larvae were distributed significantly deeper than less developed larvae, revealing ontogenic vertical migrations. In three taxa, vertical distributions varied significantly between day and night, revealing diel migrations. Since the Florida Current was strongest near the surface, observed vertical distributions and migrations resulted in reduced larval transport relative to surface currents. To identify cues involved in regulating vertical distributions, behavioral experiments were conducted with larvae from four reef fish families. All four groups showed significant responses to pressure cues, swimming up in response to high pressure and down in response to low pressure. In two families there was a significant correlation between capture depth and experimental pressure preference, suggesting that larvae use similar behavior to regulate depth in situ. To study horizontal swimming behavior, late-stage larvae of one species were caught in light-traps and observed by SCUBA divers ~1 km offshore of the Florida Keys barrier reef. All larvae swam remarkably straight, but their swimming directions were distributed randomly. A simulation model was used to generate swimming trajectories of longer duration than could be observed directly. Observed and simulated trajectories indicated that horizontal swimming by larvae with or without an external reference frame was important at spatial scales of several km. Overall, some larvae exercised a strong influence on transport, either by vertical or horizontal swimming. Behaviors varied between species and families, highlighting the need for more species-specific data.

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11

Arndt, Carmen [Verfasser]. "Testing the suitability of harpacticoid copepods as food for marine fish larvae / Carmen Arndt." Kiel : Universitätsbibliothek Kiel, 2013. http://d-nb.info/1034073702/34.

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12

Maneja, Rommel [Verfasser]. "Influence of ocean acidification on otolith calcification and behavior in fish larvae / Rommel Maneja." Kiel : Universitätsbibliothek Kiel, 2012. http://d-nb.info/1027300405/34.

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13

Fahal, Iman Hassan. "Phytoplankton blooms and fish larvae off the Northumberland Coast during the period 1992-1994." Thesis, University of Newcastle Upon Tyne, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.389569.

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14

Llopiz, Joel Kent. "The Trophic Ecologies of Larval Billfishes, Tunas, and Coral Reef Fishes in the Straits of Florida: Piscivory, Selectivity, and Niche Separation." Scholarly Repository, 2008. http://scholarlyrepository.miami.edu/oa_dissertations/130.

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The processes influencing larval fish survival in the low-latitude open ocean are poorly understood, especially with regard to feeding. As part of a large-scale study that included two years of monthly sampling in the Straits of Florida (SOF), the objectives of this dissertation were to elucidate the larval fish feeding behaviors and strategies of 1) istiophorid billfishes, 2) tunas, and 3) coral reef fishes, while also 4) characterizing the feeding environment, synthesizing the dominant trophic pathways to fish larvae, and reviewing the literature for evidence of latitudinal distinctions in larval fish trophodynamics. Larval billfishes exhibited highly selective feeding, and their diets were numerically dominated (90%) by two genera of crustaceans, Farranula copepods and Evadne cladocerans. These prey were consumed throughout early larval ontogeny, from first-feeding through piscivorous lengths (> 5 mm), until piscivory became exclusive near 12 mm. High feeding incidence (0.94) and rapid digestion (~3.5 hrs) suggests frequent and successful feeding by billfish larvae. For tunas, nearly all larvae examined (>98%) contained prey. Thunnus spp. exhibited a mixed diet, while skipjack, little tunny, and Auxis spp. nearly exclusively consumed appendicularians. All four tuna taxa co-occurred in the western SOF where prey was more abundant, while in the central and eastern SOF (where prey availability was lower), only Thunnus spp. and skipjack were present. Additionally, these two taxa exhibited significantly different vertical distributions. Estimates of predatory impact indicated the potential for depletion of resources in the absence of the spatial and dietary niches of larval tunas. Coral reef fish families examined included Serranidae, Lutjanidae, Mullidae, Pomacentridae, Labridae, Scaridae, and Acanthuridae. Feeding incidences were high (0.94 to 1.0) for all taxa except scarids (0.04), and diets were narrow and predator-specific. Cluster analysis yielded clear groupings based on the selective feeding exhibited by the taxa, while within taxa, canonical correspondence analysis illustrated the change in diet with a variety of variables. The physical and biological environment varied markedly across the SOF, largely influenced by the Florida Current. Characteristics examined included thermocline depth, fluorescence, and abundances of total plankton and copepod nauplii. The feeding ecologies of the 21 taxa of fish larvae in this work were synthesized into qualitative and quantitative webs that illustrate the variable trophodynamic strategies of larvae in the SOF and the levels of community reliance upon zooplankton prey types. A review of 170 investigations on larval fish feeding revealed notable distinctions between high- and low-latitude regions, highlighting the substantial variability across environments in the role of larval fishes within the planktonic food web.

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15

Britz, P. J. (Peter Jacobus) 1959. "Environmental requirements for the hatchery rearing of African catfish Clarias Gariepinus (Pisces: Clariidae) larvae and juveniles." Thesis, Rhodes University, 1988. http://hdl.handle.net/10962/d1001964.

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Inadequate seed production has historically been a factor limiting the commercial culture of Clarias gariepinus. The need to determine the environmental requirements of larvae was identified, in order to facilitate their successful mass rearing in hatcheries. The effects of key environmental factors on the growth, survival and aspects of the behaviour of C. gariepinus larvae and juveniles were investigated under controlled conditions. A strong emphasis was placed on the interpretation of the observed responses in terms of the natural history of the animal. Larvae were obtained by artificially inducing and spawning feral adult broodfish. Larval growth rates were highest in the temperature range 26-33ºC, with a peak at 30ºC. Survival of larvae was high between 22 and 33ºC. The final temperature preferendum of juveniles, determined in a thermal gradient was 30ºC, and it was concluded that this temperature is probably optimal for most of the physiological processes of the animal. Larvae and juveniles displayed strong negative phototaxis. When reared under different photoperiod regimes, larval growth increased with longer dark periods, however a similar rate of mortality was recorded in all photoperiod treatments. The provision of cover was found to enhance larval growth under conditions of continual light (24L/OD), however under conditions of continual darkness (OL/24D) similar growth rates were recorded regardless of the presence or absence of cover. All growth rates in continual darkness (OL/24D) were higher than those in continual light (24L/OD), regardless of whether cover was provided or not. It was concluded that a OL/24D photoperiod is optimal for larval rearing. At salinities between 0 and 5% similar growth and mortality rates of larvae were recorded. At 7.5 % larval growth and survival rates were lower, and at 10 % all larvae died within 48 hours. The 96h-LCSO for unionised ammonia was found to be 2.3 mg/l. The cytological effects of unionised ammonia were evident as degenerative changes in the gill and liver tissues. In an investigation of tank hygiene, it was found that larval growth and survival rates were highest in tanks not cleaned at all. As the frequency of tank cleaning increased, the growth and survival rates of larvae decreased. When reared at densities ranging from 45-450/1, larval growth was found to be density dependent. A model of hatchery productivity (number larvae of standard size produced/time/vol.) was developed based on the density dependent nature of larval growth. The model predicts that maximum productivity, will be achieved at a rearing density of 1400/1. The high growth and survival rates obtained over a broad range of each environmental parameter investigated serve to explain how larvae survive and grow in their unstable floodplain habitat in nature. The broad environmental tolerances of C. gariepinus are of benefit with respect to the culture of larvae, as successful larval rearing is possible over a fairly wide range of environmental conditions.

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16

Olne, Karin, and Ida Flenner. "Differences in exocuticle thickness in Leucorrhinia dubia (Odonata) larvae from habitats with and without fish." Thesis, Halmstad University, School of Business and Engineering (SET), 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-169.

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Many prey species are able to develop different morphological structures as defence against

for example predators. Some of these structures are induced only by individuals exposed to a

predator. This phenomenon is called phenotypic plasticity. In this paper we examine whether

cuticle thickness in Leucorrhinia dubia (Odonata) larvae differed between specimens caught

in fish containing lakes and fish-free lakes respectively. We measured the thickness of the

cuticle from four different parts of the larvae; profemur, pronotum, ninth segment sternite and

ninth segment tergite. Our results showed a significantly thicker exocuticle on profemur in

larvae with a head width bigger than 4.5 mm caught in lakes with fish. The smaller larvae

showed a tendency to have thinner exocuticle on profemur in presence of fish. We discuss the

probability that the differences in exocuticle thickness on profemur could be some kind of

trade-off situation. The results also showed a tendency among the large larvae; the large

individuals from lakes containing fish had a slightly thicker exocuticle on pronotum than the

bigger individuals from fish-free lakes.

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17

Jones, David Lee. "Distributional Ecology of Coral Reef Fish Larvae (Labridae, Scaridae) in the Southern Straits of Florida." Scholarly Repository, 2008. http://scholarlyrepository.miami.edu/oa_dissertations/28.

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This study targets the poorly described egg and larval stages of wrasses and parrotfishes that as adults inhabit coral reefs and seagrasses in the western central Atlantic. Descriptions are provided to allow laboratory identification of the egg and larval stages of these fishes. Accounts are given for 16 of the 20 species of labrid and six of the 14 species of scarids that occur here. The biological, hydrographic, and meteorological data from four oceanographic surveys of the southern Straits of Florida were analyzed to provide a synthesis of the effects of the environment on the distribution of larval fishes occupying a region that is influenced by geostrophic currents and mesoscale recirculation features. Results indicate these oceanographic phenomena play an important role in influencing the distribution of these fishes in their pelagic nursery habitat. The most striking evidence for this comes from the close association of high abundances of fish larvae with the Tortugas Gyre, a semi-permanent mesoscale eddy frequently present off the western Florida Keys. Most species were found in greatest abundance near the center of the eddy, while others were limited to offshore waters along its periphery in deeper depth strata. Older larvae occurred more frequently than younger stages. Those taxa most abundant near the center of the eddy were also more often taken as older larvae. Two hypotheses are proposed to account for larval accumulation in the center of the eddy, which are not mutually exclusive. The first is based on advection of passive larvae that are cyclonically entrained into the center of the eddy along the horizontal plane, while the second provides for a cascade of ecological effects that originate from eddy-induced upwelling in the vertical plane. Diel and ontogenetic effects were shown to be important components of the vertical distribution patterns displayed by these fishes. The vertical distribution of most species within the top 115 m of the water column was non-uniform. Mean depths of most larvae were deeper during the day than at night, with older stage larvae occurring deeper than younger stages.

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18

Luizi, Frederic. "Larval development and metamorphosis in Atlantic halibut (Hippoglossus hippoglossus) : influences of nutritional, environmental and physiological factors." Thesis, University of Stirling, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.311703.

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19

Pienaar, Anthony Graham. "A study of coeval sibling cannibalism in larval and juvenile fishes and its control under culture conditions." Thesis, Rhodes University, 1990. http://hdl.handle.net/10962/d1005469.

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The primary objective of this study was to examine environmental parameters thought to affect cannibalism in certain fish species. It was found that environmental, behavioural, genetic and physiological factors all affect cannibalism in the species exhibiting the phenomenon. The diversity of factors nfluencing cannibalism served to illustrate the complexity of this behaviour pattern. Feeding to satiation was found to suppress cannibalism in catfish, trout and koi carp. High population densities were found to increase the rate of cannibalism, thereby acting as a population regulation mechanism for catfish, trout and the common and koi carps. Live food, as compared with dry pelletized feed was found to significantly suppress cannibalistic aggression. Catfish grown in total darkness, provided with refuges and living in turbid conditions were found to exhibit lowered cannibalistic and territorial aggression. Various lines of evidence suggested that cannibalism has a genetic basis, as was shown by the differences in cannibalistic behaviour of the two strains of Cyprinus carpio, viz. common and koi carp, with cannibalism being higher in the latter. This finding substantiates the hypothesis that cannibalism is genetically controlled and therefore open to evolutionary change. It is concluded that cannibalism is adaptive in times of food limitation, but that it is merely a by-product of normal feeding behaviour when food is abundant. Since cannibalism is advantageous and thus adaptive, the question arises ai to whether selection is occurring at the individual or the population level (or both). It was concluded that it is acting at the individual level, and that any benefits accruing at the population level iv were simply the effect of the initial cause, viz. individual selection. One of the aims of this study was to determine whether cannibalistic tendencies in fish are influenced by differing life history style trajectories. Based on the results of this study it is hypothesized that cannibalism is an r-selected trait. wi th the understanding gained from the knowl edge of the fundamental principles governing cannibalism, certain recommendations for its control in fish culture could be made. It is, however, imperative that further intensive studies be carried out to understand more fully this complex subject. General "rules" for regulating cannibalism could be helpful for any given cannibalistic species. However, in considering the differing life-history styles of each species, it becomes evident that species-specific guidelines need to be worked out. Until then, any suggestions for cannibalistic control offered to the aquaculturist can only serve as unrefined tools.

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20

Salze, Guillaume Pierre. "Nutritional control of gene expression, larval development and physiology in fish." Diss., Virginia Tech, 2008. http://hdl.handle.net/10919/29655.

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During preliminary research on cobia (Rachycentron canadum, L.) it became increasingly clear that more in-depth information was required to provide enabling techniques for the cobia aquaculture industry to develop more rapidly. A unifying theme in many of the more important issues facing cobia aquaculture is nutrition. This led to nutritional investigations with larval and juvenile fish highlighting the impacts of dietary ingredients on animal performance. Indeed, nutrition can be viewed as a central lever of action through which many aspects of the physiology and the environmental (water) quality of the animal can be controlled. The first project focused on studying the larval development of cobia, a fish species highly suitable for aquaculture for which the industry is nascent. I described the time-course of development of external sensory organs, gut morphology and relevant digestive enzymes under controlled conditions using electron microscopy, histology and spectrophotometric assays. The developmental sequence of larval cobia could be separated in two phases, with a transition period between 12 and 14 days post hatch (dph). This transition is characterized by the formation of the intestinal loop, the establishment of basic cranial neuromast configuration, leading to the initiation of the onset of pancreatic enzymes and the increase of growth rate. In addition, the effects of dietary taurine supplementation and incorporation of mannan oligosaccharides (MOS) into live feeds on cobia larvae development was examined. Fish fed supplementary MOS did not grow faster but displayed higher microvilli length and density. In addition, MOS-fed fish were more resistant to salinity stress. The dietary supplementation of taurine resulted in a dramatic increase in survival, growth and development rates, and enzymatic activities. The second project aimed at refining cobia juvenile nutrition, assessing fish meal and fish oil replacements. Novel sources, including soy protein and oil, were investigated with and without amino acid and MOS supplementations, yielding promising results. Indeed, both fish meal and fish oil were replaced completely and successfully in feeds for juvenile cobia. In addition, novel ingredients (e.g. marine algae meals and soy protein concentrate) were identified to effectively achieve such replacement. The third and last project dealt with nutrient-gene interactions, specifically centering attention on immunostimulants for which the underlying mechanisms of action remain poorly characterized. Here, dietary MOS, nucleotides and selenomethionine (Se-met) were offered to zebrafish whose transcriptome was analyzed by microarray. The immune system, humoral or cellular, innate or adaptive, exhibited different patterns of response according to the immunostimulating nutrient used. In addition, various genes involved in cell cycle and cytokinesis were concomitantly expressed. An intriguing observation related to the insulinomimetic effect of Se-met. In other words, Se-met impacted pathways normally regulated by insulin, such as the MAPK and PI3K pathways. Some Insulin-like Growth Factors (IGF) and IGF bindgin proteins were up-regulated. Additional research is however necessary prior to advocating for the use of these additives, in order to further investigate their respective pros and cons.
Ph. D.

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21

Kobayashi, Donald R. "The distribution and abundance of certain reef fish larvae adjacent to adult habitats in Kaneohe Bay, Hawaii." Thesis, University of Hawaii at Manoa, 1987. http://hdl.handle.net/10125/18156.

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Plankton samples were taken in Kaneohe Bay, Oahu with a free-fall plankton net to investigate the finescale distribution of larval fishes around coral reefs. Daytime samples indicated that the post flexion larvae of two gobiids (Psilogobius mainlandi and an unidentified species, Goby-l) were significantly more abundant at stations immediately adjacent to reefs (near-reef) than at stations in open water off the reef. Postflexion gobiid larvae appear to be capable of resisting advection/dispersal while remaining in the water column near suitable adult habitats. The larvae of Encrasicholina purpurea (Engraulidae) and Foa brachygrammus (Apogonidae) were significantly more abundant at off-reef stations than at near-reef stations. Nighttime samples indicated that the gobiid larvae depend on visual cues to remain near the reef. The distributions of Encrasicholina and Foa larvae appeared related to their vertical positioning. The near-reef concentrations of the gobiid larvae indicate that reef-based planktivore pressure may be an unimportant factor in reef fish larval distributions. Typical ichthyoplankton surveys which do not sample close to adult fish habitats would greatly underestimate the abundance of larvae such as the gobiids.

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Levasseur, Maurice. "Phytoplankton dynamics and the distribution of fish larvae and their nutritional resources across an estuarine plume front." Thesis, University of British Columbia, 1990. http://hdl.handle.net/2429/30589.

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In the marine environment, export production leading to the traditional food chain is a relatively rare event taking place primarily in hydrographic features such as frontal areas. When export production persists, massive reproduction of herbivores is expected to occur. Since copepod eggs and nauplii are the main prey of a majority of fish postlarvae, the spawning of dominant fish species is expected to be associated with fronts. The aims of this study were to determine the influence of an estuarine plume front upon the phytoplankton dynamics (distribution and physiological status) and to assess the role of the cross-frontal circulation upon the distribution of fish larvae and their prey. The frontal area under study is located in the northwestern part of the Gulf of St. Lawrence, at the interface between a coastal jet (Gaspe Current) flowing along the Gaspe Peninsula and the Anticosti Gyre. In early June, maximum phytoplankton concentrations (up to 35 μg chl a L⁻¹) were found in the Gaspe Current. In the salinity gradient, a significant correlation was found between salinity and phytoplankton concentrations (and seston in general), indicating that physical processes (vertical and horizontal mixing) were more important in controlling the seston distribution than biological processes. The dominance of physical processes is probably due to the high current velocities and shear stress in the Gaspe Current in early June. Later during the season, the cross-frontal mixing was less vigorous due to the lower freshwater runoff, and the front acted as a retention zone for estuarine plankton. Maximum diatom concentrations (up to 50 μg chl a L⁻¹) were measured in the front per se. Measurements of nitrogen and silicate concentrations (ambient and intracellular) and uptake rates suggested that silicate generally limited diatom growth across the front. In June, estuarine larvae (capelin, Mallotus villosus and sand lance, Ammodytes hexapterus) were concentrated in the diatom-rich Gaspe Current and front where immature copepod stages were abundant. The five-fold increase in immature copepod concentrations between the gyre and the current/front resulted probably from a food-induced increase in copepod reproduction. Thus it appears that the dispersion strategy of the estuarine species in relation with local hydrography favours the exploitation of the resource-rich Gaspe current and front by the first-feeding postlarvae. The extrusion of redfish (Sebastes spp.) larvae appears to be synchronized with the copepod reproduction that followed the gyre April/May bloom. Later, redfish larvae were also found in abundance in the resource-rich front.
Science, Faculty of
Earth, Ocean and Atmospheric Sciences, Department of
Graduate

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23

Jaxion-Harm, J. C. "The relationship between coral-reef fish (larvae, juveniles, and adults) and mangroves : a case study in Honduras." Thesis, University of Oxford, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.543014.

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24

Gibson, Suzanne Marie. "Culture of red snapper (Lutjanus campechanus) from rearing larvae with naked ciliates to tracking juveniles with otolith chemistry /." [Pensacola, Fla.] : University of West Florida, 2008. http://purl.fcla.edu/fcla/etd/WFE0000110.

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25

Vine, Niall Gordon. "Towards the development of a protocol for the selection of probiotics in marine fish larviculture." Thesis, Rhodes University, 2005. http://hdl.handle.net/10962/d1005175.

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Manipulation or control of the microbiological aquaculture environment has been identified as an important focus area for future hatchery development. Subsequently, alternatives to obtain control of the microbiological environment are being sought of which the field of probiotics appears highly promising. Probiotics are usually selected based on various in vitro characteristics, however, the methods used differ and are sometimes unsuccessful due to poor experimentation. The aim of this work is to contribute towards the development of a protocol for the in vitro screening of bacterial candidate probiotics for marine fish larviculture. To reduce the number of candidate probiotics to be tested in vivo, various in vitro experiments need to be conducted, each screening for a particular mode of action – antagonism towards pathogen through production of antimicrobial compounds, growth and attachment to fish intestinal mucus, and the production of other beneficial compounds such as vitamins, fatty-acids and digestive enzymes. A total of 108 bacteria species were isolated from the digestive tract of the adult common clownfish, Amphiprion percula to screen for potential probiotics to be used in clownfish larval rearing. The antagonistic compounds assay identified twelve isolates which showed antagonism towards two or more aquatic pathogens. This was followed by an in vitro test that involved growing the organisms in fish intestinal mucus and modeling their growth parameters. A ranking index (RI) was developed using the lag period (λ) and doubling time (td) of the organism, where (1over λ x td) x 100. Five candidate probionts (AP1-AP5) with varied growth parameters were used for further in vitro experiments. The attachment to mucus assay introduced a novel tool for quantifying competition for attachment sites between candidate probionts and pathogens on mucus. Candidate probiont Pseudoalteromonas AP5 reduced the attachment ability of Vibrio alginolyticus when added before the pathogen and partially out-competed the pathogen for attachment sites when added second. In vitro screening for the production of beneficial compounds tested the candidate probiotics’ ability to produce digestive enzymes - trypsin, lipase and alkaline phosphatase as well as carotenoids and vitamin C. Candidate probiont Pseudoalteromonas AP5 produced high levels of the enzymes (98.2, 34.1 and 91.3 mU product liberated.ml⁻¹, respectively) and contained carotenoids while Kocuria AP4 contained carotenoids but produced low quantities of enzymes (7.8, 0 and 59 mU product liberated.ml⁻¹, respectively). None of the candidate probiotics produced vitamin C. To eliminate potential pathogenic or toxic candidate probionts, Artemia nauplii were exposed to each candidate probiont and the percentage Artemia mortality after 24-hours was determined. Candidate probiont AP2 caused high mortality of Artemia nauplii (98.4%) and was excluded from further studies. Identification of candidate probionts AP3-AP5 was performed using 16S-rDNA molecular techniques and the bacteria were assigned the names Bacillus AP3, Kocuria AP4 and Pseudoalteromonas AP5, respectively. Two methods of larval probiont delivery were tested – attachment to Artemia, and in-water delivery. Attachment to Artemia was high for both Kocuria AP4 and Pseudoalteromonas AP5 (7.2 x10³ and 2.7x10⁴ bacteria.nauplius⁻¹, respectively) while the in-water viability experiment showed that Kocuria AP4 comprised 23.9% of the total culturable water microflora after 24 hours while Pseudoalteromonas AP5 contributed 100%. To validate the findings from the in vitro experiments, in vivo trials using clownfish larvae were performed. Of the four candidate probiotics tested, only Kocuria AP4 showed potential to increase larval survival. In vitro tests produced a better understanding of the possible mode of action and strategies of competition between bacteria, however, the number of criteria in which a candidate probiont is successful in vitro may not be the best predictor for its effectiveness in vivo. Commercial studies that reduce between-treatment variation are required to test predictions about the most suitable probiont or combinations thereof.

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26

Powell, Frank. "Effects of salinity on eggs and yolk-sac larvae of Atlantic cod, Atlantic halibut, haddock and winter flounder." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape10/PQDD_0004/MQ42426.pdf.

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27

Mayes, Paul John. "The distribution and abundance of larval fish in a canal development and adjacent unmodified habitats." Thesis, Queensland University of Technology, 2001.

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28

Sclafani, Matthew. "The role of osmoregulation and nutrition as determinants of buoyancy and short-term mortality of marine fish larvae." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0033/NQ64664.pdf.

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29

Fox, Clive. "Studies on polyunsaturated fatty acid nutrition in the larvae of a marine fish - the herring, Clupea harengus L." Thesis, University of Stirling, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.280755.

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30

Mendez, Sanchez Jose Fernando. "Environmental Modulation of the Onset of Air-breathing of the Siamese Fighting Fish and the Blue Gourami." Thesis, University of North Texas, 2015. https://digital.library.unt.edu/ark:/67531/metadc822746/.

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This study determined the effect of hypoxia on air-breathing onset and physiological and morphological characters in larvae of the air breathing fishes Trichopodus trichopterus and Betta splendens. Larvae were exposed intermittently (12/12 h daily) to 20, 17, and 14 kPa of PO2 from 1 to 40 days post-fertilization. Survival, onset of air breathing, wet body mass, O2, Pcrit were measured every 5 dpf. Hypoxia advanced by 4 days, and delayed by 9 days, the onset of air breathing in Betta and Trichopodus, respectively. Hypoxia increased larval body length, wet mass, and labyrinth organ respiratory surface of Betta, but did not affect these factors in Trichopodus. Hypoxic exposure increased O2 by 50-100% at each day throughout larval development in Betta, but had no effect on larval Trichopodus. Hypoxia decreased Pcrit in Betta by 37%, but increased Pcrit in Trichopodus by 70%. Larval Betta reared in hypoxia showed a modified heart rate:opercular rate ratio (3:1 to 2:1), but these changes did not occur in Trichopodus. Compared to Betta, the blood of Trichopodus had a higher P50 and much smaller Bohr and Root effects. These interspecific differences are likely due to ecophysiological differences: Betta is a non- obligatory air-breather after 36 dpf with a slow lifestyle reflected in its low metabolism, while Trichopodus is an obligatory air-breather past 32 dpf with an athletic fast lifestyle and accompanying high metabolism.

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31

Scott, Mark Thomas. "Larval fish abundance and habitat associations in backwaters and main channel borders of the Kanawha River." Thesis, Virginia Tech, 1988. http://hdl.handle.net/10919/45967.

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Larval fish distributions were determined in the lower Winfield Pool, Kanawha River, West 85, Virginia, using a 0.5-m plankton net and a 1-m² dropbox. Five habitats were sampled with the plankton net, 3 habitats with the dropbox. The 5 deep water water habitats, greater than 1.5-m in depth, sampled by the plankton net included surface tows in Bill's Creek backwater, main channel border upstream and downstream of Little Guano backwater, and Little Guano Creek backwater, where deep tows (1.5 m deep) were also taken. The 3 shallow water habitats, less than 1 m in depth, sampled by the dropbox included open water over silt substrate, open water over a sand substrate, and emergent vegetation. Lepomis species, emerald shiners (Notropis atherinoides), and gizzard shad (Dorosoma cepedianum) were the dominant taxa. The emerald shiner taxa could also have included some larvae of Notropis species which are also present in the Kanawha River but whose larvae have not been described. Overall, the mean total larval density did not differ between the backwater or the main channel borders but the species associated with each habitat differed greatly. The Lepomis larvae were found predominantly in backwater areas. These areas provide suitable spawning sites for many centrarchids of this river. Upon leaving the nest, the Lepomis larvae moved into the deeper open water areas within the backwater. After reaching the juvenile stage, these same larvae returned to the shallow water habitats where they inhabited vegetated areas. Emerald shiner larvae, while present in both backwater and main channel habitats, were most abundant in the main channel borders. This is probably a result of their parent's pelagic spawning strategy. In all habitats, emerald shiner larvae predominated in the upper 1 m of water. Upon becoming larger, the emerald shiner larvae appeared in the backwaters. This increase in numbers could be due to movement, differential mortality, or higher growth rates. Other cyprinids (excluding emerald shiners and carp) were equally abundant in both backwater and main channel areas. These other cyprinid larvae were also distributed equally, Gizzard shad larvae were found predominantly in the main channel borders. Presumably, these higher densities were the result of main channel spawning. The gizzard shad larvae present in the backwater areas were distributed evenly throughout the water column. Overall, the backwaters were important for the nest-building species found in the river and also for the larger larvae of the pelagic species, and thus acts as a nursery area for these species. Therefore, the backwaters do seem to be important for the fishery of the Kanawha River.
Master of Science

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32

Fiadi, Carla Bertolucci. "Influência do ambiente na higidez de larvas de engraulidídeos coletados na região de Santos (SP)." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/21/21131/tde-19062008-150926/.

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O principal objetivo desse trabalho foi analisar a influência das condições ambientais na higidez das larvas de engraulidídeos da plataforma continental ao largo de Santos (24o49\'S - 23o49\'S e 46o55\'W - 45o24\'W). As coletas foram realizadas em dois cruzeiros oceanográficos (setembro de 2005 e março de 2006). Verificou-se diferença nas condições hidrográficas entre as duas campanhas de coletas, sendo que em setembro de 2005 houve maior influência de descarga de águas estuarinas na plataforma, enquanto em março de 2006 houve intrusão da Água Central do Atlântico Sul. As duas situações geraram estratificação vertical e favoreceram a entrada de nutrientes no sistema, o que gera enriquecimento da zona eufótica e beneficia as cadeias tróficas locais. Para avaliar a condição de higidez das larvas, foram utilizados indicadores morfológicos (relação massa-comprimento, fator de condição, altura do corpo da larva, relação entre altura da cabeça e diâmetro do olho) e bioquímicos (quantidade de proteína e relação proteína/DNA). Os indicadores apontaram melhor condição relativa, para as larvas coletadas em março de 2006, que pode ser conseqüência da ocorrência de uma intensa estratificação vertical na coluna de água e de uma maior estabilidade gravitacional em março de 2006, proporcionando maior concentração de nutrientes e ocasionando aumento na densidade e melhora na condição das populações planctônicas.
The aim of this study was to analyze influence of environmental conditions on health of engraulidid larvae of the continental shelf off Santos (24º49´S - 23º49´S e 46º55´W - 45º24´W). Samples were collected during two oceanographic cruises (September 2005 and March 2006). Differences among hydrographic conditions were verified between surveys: in September there was a major influence of the estuarine water discharge in the inner shelf, whereas in March there was an intrusion of the South Atlantic Central Water (SACW) in the region. The two conditions generated vertical stratification and improved the pelagic food web, in which fish larvae participate. Morphological (weight-length relation, condition factor, larvae body height, head height-eye diameter relation) and biochemical (protein quantity and protein/DNA relation) indicators were used to evaluate the larvae health condition. Results showed better relative condition of larvae collected in March 2006 that can be a consequence of the intense water column vertical stratification and gravitational stability in March 2006, providing higher nutrients concentration, increasing density of organisms and improving condition of planktonic populations.

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33

Sundblad, Göran. "Spatial Modelling of Coastal Fish – Methods and Applications." Doctoral thesis, Uppsala universitet, Limnologi, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-132620.

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Environmental factors influence species and habitats on multiple scales creating a mosaic of distribution patterns. Studying factors shaping these patterns are central to our understanding of population dynamics and ultimately ecosystem functioning. Information on the distribution of resources and conservation values are also highly needed in marine management as coastal areas are increasingly influenced by human activities. In this thesis, large-scale field data is used to explore how strong environmental gradients found on multiple scales in the coastal areas of the Baltic Sea influence fish habitats. The underlying concepts are based in the field of species distribution modelling, whereby habitat maps can be produced using environmental layers in a geographic information system. Distribution modelling is further used to address both ecological and applied questions by examining effects of habitat limitation on fish population sizes and to evaluate management actions aimed at habitat conservation. I show that specific habitat requirements for fish species of both freshwater and marine origin can be described using environmental variables and that species-environment relationships can be used to predict the distribution of early life-stages of fish in the Baltic Sea archipelagos. Further, predicted habitat availability of a specific life-stage was directly related to adult population size of Eurasian perch Perca fluviatilis, signifying that the abundance of large predatory fish can be limited by specific recruitment habitats. Lastly, by predicting the distribution of an assemblage of coastal fish species and their associated habitats, an assessment of a network of marine protected areas was performed. Results revealed large gaps in the current network and identified areas suitable for future protection. By demonstrating how current habitat protection can be improved by including critical habitats for coastal fish population sizes this thesis points to the benefits of integrating nature conservation and fisheries management. Based on these findings I conclude that species distribution modelling provides a suitable analytical framework for assessing the habitat requirements of organisms. An increased understanding of habitat-population relationships and an ability to accurately map ecologically important features will be of great value for an ecosystem-based marine management.
Felaktigt tryckt som Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology 709

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34

Osborn, Joshua Clay. "Effects of Light and Turbidity on Foraging Efficiency of Larval Walleye Sander Vitreus." Bowling Green State University / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1210825318.

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35

Schlechtriem, Christian [Verfasser]. "The suitability of the free-living nematode Panagrellus redivivus as alternative live food for first feeding fish larvae / Christian Schlechtriem." Aachen : Shaker, 2004. http://d-nb.info/1170529747/34.

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36

Gwak, Woo-Seok. "Evaluation of the nutritional status of Japanese flounder Paralichthys olivaceus larvae and jujeniles, and its application to the wild fish." Kyoto University, 1999. http://hdl.handle.net/2433/181399.

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Kyoto University (京都大学)
0048
新制・課程博士
博士(農学)
甲第8036号
農博第1086号
新制||農||790(附属図書館)
学位論文||H11||N3331(農学部図書室)
UT51-99-T747
京都大学大学院農学研究科応用生物科学専攻
(主査)教授田中克, 教授坂本亘, 教授坂口守彦
学位規則第4条第1項該当

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MUNTONI, MANUEL. "A multidisciplinary approach for puzzling over fish connectivity in the Mediterranean Sea: The role of early life history stages of red mullet (Mullus barbatus)." Doctoral thesis, Università degli Studi di Cagliari, 2015. http://hdl.handle.net/11584/266564.

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Integrating connectivity patterns into marine ecosystem management is a fundamental step, specially for stock subjected to the combined impacts of human activities (overfishing, habitat degradation, etc.) and climate changes. Thus, management of marine resources must incorporates the spatial scales over which the populations are connected. Notwithstanding, studying these dynamics remains a crucial and hard task and the predictions of the temporal and spatial patterns of these mechanisms are still particularly challenging. This thesis aims to puzzle over the red mullet Mullus barbatus population connectivity in the Western Mediterranean Sea, by implementing a multidisciplinary approach. Otolith sclerochronology, larval dispersal modelling and genetic techniques were gathered in this study. More particularly, this research project focused on early life history stages of red mullet and their role in the characterization of connectivity dynamics. The results show that M. barbatus larval dispersal distances can reach a range of 200 km. The differences in early life traits (i.e. PLD, spawning and settlement dates) observed between various areas of the Western Mediterranean Sea suggest a certain level of larval patchiness, likely due to the occurrence of different spawning pulses during the reproductive period. The dispersal of individuals across distant areas, even not significant in demographic terms, is accountable for the maintenance of the genetic flow among different demes. Fluctuations in the level of exchange among different areas, due to the variability of the source-sink dynamics, could have major implications in the population connectivity patterns. These findings highlight the reliability of combining several approaches and represent a benchmark for the definition of a proper resource management, with considerable engagements in effectively assuring the beneficial effects of the existent and future conservation strategies.

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38

Odom, Michael Cooper. "Distribution of larval fishes in the Winfield Pool, Kanawha River, and direct impacts of commercial navigation traffic on larval fish survival." Thesis, Virginia Tech, 1987. http://hdl.handle.net/10919/45899.

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Distributions of larval fishes in the Winfield Pool, Kanawha River, West Virginia, were determined by sampling two sites with bongo and push nets. Cyprinids, clupeids, and Aplodinotus grunniens dominated collections. Main channel densities were a fraction of the densities along the shoreline, indicating the importance of the shoreline as a nursery. Diel trends in abundance were evident for several taxa, but were likely caused by diel changes in gear avoidance and distribution of larvae. Vertical trends in abundance were apparent for several taxa at the deeper and more lentic sampling site (lower pool). Aplodinotus grunniens were generally more abundant near the bottom, especially during daylight. Cyprinids were more abundant near the bottom in mid-June, but displayed no vertical trends on other sampling dates. Clupeids were more abundant at middepth or surface during daylight, while equally dispersed or near the bottom at night. Vertical trends were not evident at the shallower and more lotic site (upper pool) except for Aplodinotus grunniens, which displayed the same preference for the bottom, as at the lower site.

Master of Science

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39

Ferron, André. "An appraisal of condition measures for marine fish larvae with particular emphasis on maternal contribution, circadian periodicity, and the time response of nucleic acids and proteins /." Thesis, McGill University, 2000. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=36540.

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The physical and physiological condition of larval fishes throughout their development is believed to influence their survival, and ultimately to contribute to recruitment to the adult population. The study of larval condition is therefore central to larval fish ecology.
In this thesis I sought to (1) carry out an appraisal of the characteristics and the reliability of condition measures now being used, (2) assess the importance of maternal contribution to the nutritional status of larval fish, (3) evaluate the possibility that diel variability in metabolism could lead to serious biasing of the interpretation of condition measures obtained over time, and (4) assess the time course of the condition of larval fishes subjected to periods of intermittent feeding.
The experiments described in chapter 2 were designed (1) to assess the impact of female nutritional status on the quality of the eggs and larvae they produced, (2) to determine which of a series of nucleic acid and protein measurements were most responsive to post-hatching starvation, and (3) to determine whether the starvation dynamics of those measures was affected by female source. No significant correlation could be found between any of the maternal traits studied and eggs and larval measures. The results did show, however, that egg size was more variable between-clutches than within-clutch, was independent of embryonic developmental rate, but was positively related to larval size.
The existence and ontogeny of circadian (24 hrs.) and ultradian (<24 hrs.) oscillations in the nucleic acids and protein content of larval capelin was investigated in the laboratory experiments outlined in chapter 3. The most obvious long-terms trends occurred during the embryonic period when DNA and RNA content increased constantly, and during the post-yolk-sac period when RNA and protein decreased following sub-optimal feeding.
The objectives of the study described in chapter 4 were threefold, (1) to determine which of a series of nucleic acid and protein measurements were affected by intermittent (delayed-fed and delayed-starved) feeding conditions in capelin larvae, (2) to determine the dynamics and shape of the time response, and (3) to determine whether the empirical data gathered were consistent with models developed as a consequence of the review of the literature (chapter 1). Only the dry weight, and the quantity of DNA, RNA, and protein per dry weight differed significantly between starvation and ad libitum feeding controls. Starvation dynamics were less consistent with predictions. Of the indices investigated, the dynamics of the quantity of DNA and RNA per dry weight were the most consistent dynamics with model predictions. (Abstract shortened by UMI.)

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Dantas, Naiara Silva Menezes, and (92) 992409945. "Larvicultura do pirarucu em sistema de bioflocos." Universidade Federal do Amazonas, 2018. https://tede.ufam.edu.br/handle/tede/6642.

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CNPq - Conselho Nacional de Desenvolvimento Científico e Tecnológico
FAPEAM
Arapaima is considered the largest carnivorous species of Amazon and can reach up to 200 kg in the natural environment. Its high market value is due to its fast growth, the peculiar taste of its flesh and the possibilities of use of its byproducts. One of the main challenges of the Arapaima farming is to offer its early stages because there is a high rate of mortality during the larval phase. In this phase, the larvae are usually in the ponds together with the breeding fish, when they are susceptible to parasites, predators and lack of live food. As an alternative, the intensive larviculture allows the control of the environment, creating appropriate conditions for the larvae development. The biofloc technology (BFT) fits this possibility because it provides a better control of the quality of water and pathogens, and the biofloc could be an additional source of food. The objective of this work is to evaluate the performance of the Arapaima larvae reared in BFT. The experimental design was completely randomized with two treatments, a system with clear water (AC) as control and a system of biofloc (BFT), composed of five replication tanks. Arapaima larvae were (0.778 ± 0.02 g and 4.84 ± 0.11 cm) were housed in PVC tanks (20 L; 25 fish per tank). Initially and at the end of the experiment, water were collected and five fish from each treatment were euthanized for microbiological analyzes of the gastrointestinal tract. At the end of the experiment, the water of the BFT was filtered for determination of the proximate composition of the biofloc. There was no significant difference between the performance variables in both treatments; such result was attributed to the inadequate ingestion of food due to the high need of airing for the biofloc floating, causing stress and possibly altering the immunity of the larvae, making them susceptible to pathogenic bacteria; in addition to the elevated levels of nitrogenous compounds, due to the high excretion of the larvae, becoming toxic to the fish. The BFT presented the greatest diversity of bacteria, being identified the genus Aeromonas, Bacillus, Citrobacter, Enterobacter, Hafnia, Klebsiella, Morganella, Proteus, Pseudomonas, Salmonella, Serratia, Staphylococcus and Yersinia. The biofloc presented 41% of crude protein. Although BFT is an ecologically system for reducing water use and recycling effluents, adjustments are still needed, such as keeping the biofloc at low levels, so that its use is feasible for Arapaima larvicultura.
O pirarucu é considerado a maior espécie carnívora da Amazônia e pode atingir até 200 Kg no ambiente natural. Seu alto valor no mercado deve-se ao bom desempenho zootécnico, sabor peculiar da sua carne e possibilidades para o aproveitamento de seus subprodutos. Um dos maiores desafios da cadeia produtiva do pirarucu é a oferta de formas jovens, pois há um índice elevado de mortalidade durante a fase larval. Geralmente, as larvas ficam nos viveiros junto com os reprodutores, e estão susceptíveis à presença de parasitos, predadores e falta de alimento vivo. Como alternativa, a larvicultura intensiva permite o controle do ambiente criando condições adequadas para o desenvolvimento dos peixes. A tecnologia do BFT se enquadra nesta possibilidade, pois proporciona melhor controle da qualidade de água e patógenos, além do biofloco ser uma fonte adicional de alimento. O objetivo deste trabalho foi avaliar o desempenho zootécnico das larvas de pirarucu no BFT. O desenho experimental foi inteiramente casualizado com dois tratamentos, um sistema com água clara (AC), como controle e, um sistema com a tecnologia bioflocos, composto por cinco repetições (tanques de PVC). Foram selecionadas 250 larvas de pirarucu (0,778 ± 0,02 g e 4,84 ± 0,11 cm) e distribuídas em tanques de PVC (20 L; 25 peixes por tanque). Inicialmente e ao final do experimento, cinco peixes de cada tratamento foram eutanasiados para análises microbiológicas do trato gastrointestinal, assim como amostras de água dos sistemas. Ao final do experimento, a água do BFT foi filtrada para determinação da composição centesimal do floco. Não houve diferença significativa entre as variáveis de desempenho em ambos os tratamentos; atribui-se tal resultado à inadequada ingestão do alimento devido à forte aeração necessária para a flutuabilidade do floco, pois ocasionou estresse e possivelmente alterou a imunidade das larvas, tornando-as susceptíveis a bactérias patogênicas; além dos níveis elevados de compostos nitrogenados, devido à elevada excreção das larvas, tornando-se tóxicos para os peixes. O BFT apresentou a maior diversidade de bactérias dos gêneros Aeromonas, Bacillus, Citrobacter, Enterobacter, Hafnia, Klebsiella, Morganella, Proteus, Pseudomonas, Salmonella, Serratia, Staphylococcus e Yersinia. Os flocos microbianos apresentaram 41% de Proteína Bruta. Apesar do BFT ser vantajoso ecologicamente por reduzir o uso de águas e reciclar efluentes, ainda são necessários ajustes, como manter o biofloco em níveis baixos, para que seja viável sua utilização para a larvicultura.
Achei tranquilo
Primeiro trabalho com a espécie neste sistema

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41

Peterson, Kylie, and n/a. "Environmental impacts on spawning and survival of fish larvae and juveniles in an upland river system of the Murray-Darling Basin." University of Canberra. Resource, Environmental & Heritage Sciences, 2003. http://erl.canberra.edu.au./public/adt-AUC20060713.121419.

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Six rivers within the upper Mumbidgee catchment were sampled for larval and juvenile fish. The rivers represented both regulated and unregulated flow regimes and varied widely in size. There was wide variation in the larval fish communities supported by each river, both in terms of the species diversity and total abundance of fish sampled. The highly regulated reach of the Mumbidgee River sampled during this study had the highest numbers of native species and native individuals of any river sampled. In the two rivers selected for further study, the Murmmbidgee and Goodradigbee, there was a high level of inter-annual consistency in the species composition within the reaches sampled, despite considerable change in the temperature and flow regimes of both rivers. This indicates that at least some spawning of those species sampled may occur each year, regardless of environmental conditions. Estimates of the relative abundance of each species sampled changed markedly between years, and it is argued, on the basis of growth information contained in the otoliths, that differential survival of larvae and juveniles was largely responsible for this shift in relative abundance. Otolith microstructure provided information on the date of spawning and early growth patterns of all species sampled in the upper Mumumbidgee catchment. In addition to determining the age and thus 'birth-date' of an individual, the effect of a particular event or series of events has on growth, and subsequent survival, is permanently recorded in the otolith microstructure. This enables accurate back-calculation and correlation to management actions or natural events. No other research tool has this ability to retrospectively assess, on a daily basis, the impacts of management actions on condition and subsequent survival of fish larvae. Species sampled could be separated into three groups based on spawning requirements; those linked with flow, those linked with temperature and generalist species that appear to have river independent cues, such as photoperiod or moon phase. Patterns in growth rate during the early life history stages enabled quantification of the consequences of variation in environmental conditions on the survival and recruitment of various species. Growth was not always highly correlated with water temperature, in fact, for mountain galaxias, high temperatures appear to negatively affect larval condition and subsequent survival. Conversely, carp exhibited a strategy more consistent with common perceptions, with growth and survival increasing with increasing temperature. The study uncovered spawning and growth patterns that were unexpected. Age analysis of western carp gudgeon demonstrated that they had undertaken a mid-winter spawning, when the water temperature in the main channel was far lower than that at which spawning was previously recorded for this species. Redfin perch from the unregulated Goodradigbee River exhibited growth rates exceeding the published upper limits for this and other closely related species. This growth could not be correlated with either temperature or flow, indicating that there are additional factors that dominate growth rates of redfin perch in the Goodradigbee River. The proportion and abundance of native species alone is not necessarily indicative of a 'healthy' or pristine system; some native species may be positively affected by river regulation, at least as juveniles. Comparison of the current larval fish community with likely pre-European fish communities does provide an indication of change to the system. The results of this study suggest that larval fish growth rates can be strongly influenced by environmental conditions, thus providing a powerful tool for monitoring future change and the factors which cause it. This study has demonstrated the value of larval and juvenile fish age and growth information, derived from otolith microstructure techniques, for many aspects of river management. Current river management priorities for which these techniques provide unique information include the determination of environmental flow regimes and the control of undesirable exotic species such as carp.

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42

Cavalcanti, Luciano Pamplona de GÃes. "Potential of five species of fish as method of biological control of Aedes aegypti larvae, in conditions of laboratory, in CearÃ." Universidade Federal do CearÃ, 2006. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=36.

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FundaÃÃo Cearense de Apoio ao Desenvolvimento Cientifico e TecnolÃgico
Dengue fever has been shown to be one of the main public health problems in CearÃ the principal vector is the Aedes aegypti mosquito In recent decades chemical control has been under question, both due to the insectâs selective resistance capacity and for environmental reasons Thus the use of biological alternatives has been encouraged worldwide Consequently the objective of this study was to evaluate 5 fish species that have been used as an alternative for the control of Aedes aegypti larvae in domestic water tanks in the State of CearÃ Brazil The species evaluated were Betta splendens Trichogaster trichopteros Astyanax fasciatus e Poecilias reticulata and sphenops Larvae-eating capacity prefered predation locations and resistence to chlorine were evaluated All five species had a high larvae-eating capacity; Betta splendens and Poecilias were noteworthy for their larger capacity in relation to weight and body size Astyanax fasciatus and Betta splendens appeared to survive well without the presence of larvae or artificial food in the domestic water tanks whilst Poecilias presented a significant weight loss during the 5-week evaluation Regarding the location of predation it was observed that Poecilias spent most of the time at the surface whereas Trichogaster and Betta had greater mobility in the container As to chorine resistance Poecilias had a significant mortality when exposed to concentrations of 0.5mg/litre while other species of Betta and Trichogaster were able to survive concentrations up to 4.00mg/litre Therefore it was possible to demonstrate that the 5 species can be used as biological control alternatives although each one is indicated for different water tanks due mainly to the food available and the chlorine concentrations
O dengue vem se mostrando como um dos principais problemas de saÃde pÃblica no CearÃ e o mosquito Aedes aegypti Ã seu principal vetor Nas Ãltimas dÃcadas o controle quÃmico vem sendo questionado tanto pela capacidade de seleÃÃo de resistÃncia dos insetos quanto por questÃes ambientais Com isso o uso de alternativas biolÃgicas vem sendo incentivado no mundo Desta forma o objetivo deste trabalho foi avaliar 5 espÃcies de peixe que vem sendo utilizados como alternativa de controle para larvas de Aedes aegypti em depÃsitos domiciliares no Estado do CearÃ As espÃcies avaliadas foram o Betta splendens Trichogaster trichopteros Astyanax fasciatus e Poecilias reticulata e sphenops Foram avaliadas capacidade larvÃfaga locais preferenciais de predaÃÃo e resistÃncia ao cloro Todas as cinco espÃcies apresentaram uma elevada capacidade larvÃfaga destacando-se o Betta splendens e os Poecilias por apresentarem as maiores capacidades em relaÃÃo ao peso e tamanho corporal As espÃcies Astyanax fasciatus e Betta splendens parecem sobreviver bem sem a presenÃa de larvas ou alimentos artificiais nos reservatÃrios domiciliares enquanto os Poecilias apresentam uma perda significativa de peso durante as 5 semanas de avaliaÃÃo Em relaÃÃo ao local de predaÃÃo foi possÃvel observar que os Poecilias permaneceram a maior parte do tempo na superfÃcie enquanto o Trichogaster e o Betta apresentaram uma maior mobilidade no reservatÃrio Quanto Ã resistÃncia ao cloro mostrou-se que as espÃcies de Poecilias jÃ apresentam uma significativa mortalidade quando expostos Ã concentraÃÃes de 0,5mg/litro enquanto alguns espÃcimens do Betta e do Trichogaster mostraram capacidade de sobreviver atÃ concentraÃÃes de 4,00mg/litro Desta forma foi possÃvel demonstrar que as 5 espÃcies podem ser utilizadas como alternativa de controle biolÃgico entretanto cada uma se apresenta mais indicada a depÃsitos diferentes devido principalmente a oferta de alimentaÃÃo e concentraÃÃo de cloro

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43

Yanes-Roca, Carlos. "Husbandry and larval rearing of common snook (Centropomus undecimalis)." Thesis, University of Stirling, 2006. http://hdl.handle.net/1893/191.

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Common snook (Centropomus undecimalis) is a relatively new species for aquaculture; considered as a recreational species and not commercial. The aim of this study was to develop common snook larval rearing techniques for stock enhancement. Common snook culture has two main bottlenecks, broodstock management and larval culture. High mortality during the first 6 days is the main limitation for successful larval survival. Broodstock management of common snook is still developing and the only source of common snook eggs is from wild broodstock. Securing a regular supply during the natural spawning was essential to reach the main objective. Finding the optimal spawning sites, as well as optimal spawning time was achieved. Results showed Terra Ceia, Longboat and Cayo Costa to be the best sites for wild broodstock collection. The onset of spawning was triggered by a rise in water temperature. During the 4 years of this study spawning started at the end of May and finished in September. Total capture results and egg quality results, such as fertilization, hatching rate and lipid analysis, indicated June and July as the peak months during the spawning season. Common snook follow a lunar spawning cycle. Results showed that one to three days after the new and full moon were the peak spawning periods and therefore the best days to capture wild stock. Common snook egg lipid composition fits the general marine fish fatty acid composition with saturated fatty acids predominating. On the other hand, the omega 3, omega 6 (n-3/n-6) ratio was lower than the typical marine fish and arachidonic acid values were significantly higher than other marine species. This egg fatty acid profile will be helpful in the future to compare it with captive spawned eggs for egg quality purposes. Description of the common snook embryonic and larval development for the first 14 days was carried out. This has strengthened knowledge for this species’ development, and should provide a helpful tool to identify common snook embryos and larvae in the wild. Novel improvements to existing common snook larval culture protocols were implemented. Larval lipid analysis throughout development, and high mortality around day 6 post hatching, suggested that common snook larvae were dying of starvation. Gross morphological development and ultra-structure findings in the digestive and eye system development during the first three days indicated that day 2 post hatching larvae were capable of capturing and digesting food. Additionally, larval nutritional improvements were made, increasing the larval survival. The most significant ones were: finding a smaller and more nutritional prey (SS type rotifers and copepods), finding an optimal stocking and feeding density and the importance that green water technique has on larval survival. Overall, larval success was improved from a zero percent survival during the first 14 days to a 2% survival rate.

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44

Alvim, Izabela Dutra. "Produção e caracterização de microparticulas obtidas por spray drying e coacervação complexa e seu uso para alimentação de larvas de peixes." [s.n.], 2005. http://repositorio.unicamp.br/jspui/handle/REPOSIP/255984.

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Orientador: Carlos Raimundo Ferreira Grosso
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos
Made available in DSpace on 2018-08-05T13:49:57Z (GMT). No. of bitstreams: 1 Alvim_IzabelaDutra_D.pdf: 8886794 bytes, checksum: 16da2e8dd31802c6ce217aae14d9e70f (MD5) Previous issue date: 2005
Resumo: A microencapsulação é uma técnica para recobrimento de substâncias para a proteção e/ou liberação controlada das mesmas. As microcápsulas podem ser uma alternativa para obtenção de uma dieta para alimentação das larvas de peixe na piscicultura intensiva. Dois métodos de microencapsulação foram empregados para produção de micropartículas, potenciais na substituição do alimento vivo (rotíferos e artêmias) oferecido às larvas de peixe nos primeiros estágios de desenvolvimento. O primeiro baseou-se na secagem em spray dryer de uma dieta líquida. Essa dieta desidratada sofreu aglomeração e recobrimento para manipulação do diâmetro médio das partículas e solubilidade. Os diâmetros médios dos aglomerados foram significativamente maiores que da dieta desidratada sem aglomeração. As solubilidades em sólidos solúveis e em proteínas solúveis da dieta sem recobrimento foram altas para 120 minutos de permanência em água. A adição de óleo à dieta desidratada e o recobrimento polimérico reduziu esses valores de solubilidade. O aspecto apresentado pela dieta desidratada sem recobrimento foi característico de produtos desidratados por spray dryer. Os aglomerados apresentaram camada de recobrimento com falhas, o que justificou as baixas diminuições de solubilidades observadas. O segundo processo de microencapsulação foi a coacervação complexa entre gelatina e goma arábica, e como recheios foram utilizados uma mistura de oleoresina de páprica e óleo de soja e dois compostos hidrofílicos (glicose ou isolado protéico de soro de leite) retidos em matrizes lipídicas sólidas. Por microscopias diversas (confocal, ótica e eletrônica de varredura) as micropartículas coacervadas se apresentaram esféricas e multinucleadas. As micropartículas coacervadas contendo oleoresina de páprica e óleo de soja foram reticuladas com glutaraldeído ou com transglutaminase, e submetidas à secagem por estufa com circulação de ar, liofilizador e spray dryer. A secagem em estufa não permitiu a obtenção de um material com micropartículas individualizadas enquanto a liofilização permitiu a manutenção da estrutura esférica para todas as amostras inclusive a sem reticulação. A secagem em spray dryer apresentou baixíssimo rendimento, e só foi possível para micropartículas reticuladas, com integridade das estruturas associada ao tipo/concentração de reticulante. A liberação da oleoresina foi avaliada em etanol absoluto por 120 minutos, para as micropartículas coacervadas úmidas com e sem reticulação e suas respectivas amostras desidratadas. A liberação do recheio foi alta (acima de 95%) para todas as amostras úmidas, exceto para a amostra reticulada com 1,0mM/g.ptn de glutaraldeído. As amostras desidratadas por liofilização tiveram liberação de seu conteúdo reduzida, não ultrapassando 35,4% após 120 minutos para todos os tratamentos. A liberação do recheio das micropartículas desidratadas por spray dryer foi baixa e proporcional a manutenção da integridade das partículas. Para veiculação dos compostos hidrofílicos nos coacervados, foram produzidas micropartículas lipídicas (spray chilling). Essas micropartículas lipídicas foram incorporadas com sucesso nos coacervados. A liberação dos compostos solúveis do interior dos coacervados foi maior para glicose que para a proteína, para 20 horas de permanência em água. A aceitação das micropartículas produzidas foi avaliada em um ensaio biológico in vivo com larvas de pacu. Foram testadas uma dieta aglomerada e quatro coacervados produzidos utilizando gelatina bovina ou gelatina de peixe na parede e óleo de soja ou gordura de peixe como recheio. O nível de aceitação das dietas foi de maiores valores para os coacervados produzidos com gelatina bovina/gordura de peixe e gelatina bovina/óleo de soja, seguidos pelo coacervado produzido com gelatina de peixe/óleo de soja, pelo aglomerado e por último o coacervado produzido com gelatina de peixe/gordura de peixe. Os coacervados produzidos com gelatina bovina contendo óleo de soja ou gordura de peixe apresentaram-se promissores como dietas necessitando ainda de ajustes nutricionais para atenderem as exigências das larvas em crescimento
Abstract: The microencapsulation is one technique for covering or evolving substances with the aim to provide protection and/or controlled release of the same ones. The microcapsules can be an alternative for attainment of a diet for feeding of the larvae of fish in the intensive aquaculture. Two methods of microencapsulation had been used for production of microparticles in the substitution of the alive food (rotifers and artemias) offered to the larvae of fish in the first periods of growing. The first one was based on the spray drying of one nutritionally and balanced liquid formulation. The dehydrated diet was agglomerated adjust the average size and solubility of the particles. The size of the agglomerated particles was increased efficiently. The solubilities in total soluble solids and soluble proteins of the diet without covering had been high with values (above 50%) for 120 minutes of permanence in water. The addition of oil to the dehydrated diet (OD) and the agglomation with pectate and calcium reduced the values of solubility. The aspect presented for the diet dehydrated without covering was characteristic of products dehydrated by spray dryer. The surface of the agglomerated particles presented some imperfections, which justified the low reductions of solubilities. The second process used was the complex coacervation between gelatin and acacia gum and as a core materials, a mixture of paprika oleoresin and vegetable soy oil and two hydrophilic composites (glucose or whey protein isolate). After, the lipidic microparticles were used as core material for microparticles obtained using complex coacervation. Using different types of microscopies (confocal, optical and scanning electronic microscopy) it was possible to characterize the coacervated microparticles that showed spherical geometry and multinuclear distribution of the core material. The microparticles containing paprika oleoresin of paprika and vegetable soy oil as core material had been crosslinked with glutaraldehyde or transglutaminase, and were dried using one oven with air circulation, spray dryer and freeze drying processes. The drying using oven did not allowed the attainment of a dry material presenting free flowing. The freeze drying, on the other side, allowed the attainment of microparticulated material showing spherical structure and free flowing for all samples including samples without cross-linking. The yield of the spray drying process was very low. This process did not work when non crosslinked samples were dried. The high level of cross-linking using 1.0mM/g of ptn showed the best results compared with transglutaminase or glutaraldehyde at 0.1mM/g of protein (reaction time of 18 hour for both) showing the maintenance of the moist microparticles structure. The release of the oleoresin was evaluated for the moist and dehydrated samples with and without crosslinking using ethanol as the release medium during 120 minutes. The core release observed was above 95% for moist coacervated without crosslinking, crosslinked using transglutaminase and for samples crosslinked with the low level of glutaraldehyde. The release level decreased when concentration of glutaraldehyde was increased. Dryed samples using freeze drying showed a great decrease on the release amount, not exceeding 35.4% after 120 minutes for all the treatments. The release of the core from the dehydrated microparticles using spray dryer was proportional to the maintenance of the integrity of particles. Again, cross-linking using high concentration of glutaraldehyde/g.ptn produced the best results.Lipídic microparticles had been incorporated successfully in the coacervated microparticles. The amount of released soluble composites using water solution was high to glucose and relative low for the protein after 20 hours of experiment. The acceptance of the microparticles was evaluated in a live biological assay using larvae of pacu. A diet agglomerated with calcium pectate and four coacervated microparticles using bovine gelatin or fish gelatin as the wall materials and vegetable soy oil or fat fish as core materials had been tested. Ranking of acceptance of the diets showed bigger values for the coacervated microparticles produced with gelatin/fat fish or gelatin/soy oil, followed by the microparticles produced with fish gelatin/soy oil, agglomerated particles and finally coacervate particles using fish gelatin/fat fish. The coacervation process showed interesting results but improvement on the nutritional balance needs to be done
Doutorado
Nutrição Experimental e Aplicada à Tecnologia de Alimentos
Doutor em Alimentos e Nutrição

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45

Sutherland, Kate. "The dynamics of Larval fish and Zooplankton assemblages in the Sundays Estuary, South Africa." Thesis, Nelson Mandela Metropolitan University, 2010. http://hdl.handle.net/10948/1119.

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The larval fish and zooplankton assemblages were studied in the permanently open Sundays Estuary on the south-east coast of South Africa, using standard boat-based plankton towing methods. A total of 8174 larval and early juvenile fishes were caught, representing 12 families and 23 taxa. The Clupeidae, Gobiidae and Blenniidae were the dominant fish families. Common species included Gilchristella aestuaria, Caffrogobius gilchristi, Omobranchus woodi, Liza dumerilii, Glossogobius callidus and Myxus capensis. Estuarine resident species (Category I) predominantly in the preflexion developmental stage, dominated the system. A total of 19 zooplankton taxa were recorded. Copepoda dominated the zooplankton community. Dominant species included Pseudodiaptomus hessei, Acartia longipatella, Halicyclops sp., Mesopodopsis wooldridgei, and the larvae of Paratylodiplax edwardsii and Hymenosoma orbiculare. Mean larval fish density showed similar trends seasonally, spatially and across salinity zones, with mean zooplankton density in the Sundays Estuary. Gut content analysis of five larval fish species: Gilchristella aestuaria, Pomadasys commersonnii, Monodactylus falciformis, Myxus capensis and Rhabdosargus holubi, revealed species specific diet and prey selection. Although larval fish diet contained a variety of prey items, guts were dominated by P. hessei, chironomid larvae, Corophium triaenonyx, copepod eggs and insect larvae. Physico-chemical drivers and the interactions between these two plankton communities provide information that enables a more holistic view of the dynamics occurring in the Sundays Estuary planktonic ecosystem.

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46

Woods, Nielsen Chelsea. "Identification and assessment of potential probiotics for the use in rotifers (Brachionus plicatilis) and Artemia used as feed for marine fish larvae." Thesis, Woods Nielsen, Chelsea (2021) Identification and assessment of potential probiotics for the use in rotifers (Brachionus plicatilis) and Artemia used as feed for marine fish larvae. Honours thesis, Murdoch University, 2021. https://researchrepository.murdoch.edu.au/id/eprint/63705/.

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Probiotics are microorganisms which have beneficial effects on the host, including increased host response to pathogens and prevention of disease. Marine larval fish are susceptible to bacterial and viral infections during early development as they hatch underdeveloped with an immunologically naïve immune system. The use of live feeds in marine larval rearing transfers potentially harmful bacteria into the larval rearing tank. Live feeds, such as rotifers and Artemia, are non-selective filter feeders therefore enriching live feeds with probiotics is a way to both remove unwanted, and introduce beneficial, bacteria to newly hatched larvae. A screening process was used to select potential probiotics from the genera Shewanella, Vibrio and Pseudoalteromonas. Culture dependant techniques identified an isolate from each genera that demonstrated the highest inhibition properties against common marine fish pathogens. MALDI-TOF mass spectrometry and Sanger sequencing were used to determine the identity of these three isolates, the Vibrio isolate was successfully identified as V. scophthalmi, however the species of the Shewanella and Pseudoalteromonas isolates remain unresolved. Due to the nature of their culture, rotifers have an inherently high bacterial load which can be easily transferred to the fish larvae to which they are fed. Minimising these potentially harmful bacteria allows for beneficial probiotic bacteria to proliferate in the rotifer culture. However, disinfection techniques commonly used in fish hatcheries are often ineffective at low doses or lethal to the rotifer at higher doses. A minimum inhibitory concentration assay for antimicrobial peptides was performed against bacterial species common in rotifer cultures, however the peptides were ineffective under normal rotifer culture conditions (salinity at 25‰). Disinfection techniques can be used more favourably in Artemia enrichment. This study found, a short-term probiotic enrichment method resulted in a high probiotic retention in the Artemia at commercially relevant densities (500 – 5000 Artemia/ mL). Probiotic retention was improved when Artemia were disinfected with sodium hypochlorite after the fatty acid enrichment, whilst also reducing the unwanted bacteria species common to Artemia cultures. The use of a probiotic selection process identified candidate probiotics to be administered into the most common live feeds used in marine larviculture, rotifers and Artemia. Importantly, this study found the successful enrichment of probiotics in Artemia at high retention yields which may have significant positive impacts to the performance of marine finfish larvae.

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47

Pattrick, Paula. "Larval fish dynamics in the shallow nearshore of Eastern Algoa Bay with particular emphasis on the effects of currents and swimming abilities on dispersal." Thesis, Rhodes University, 2008. http://hdl.handle.net/10962/d1005139.

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The larval fish assemblage in the shallow, nearshore region of a proposed marine protected area (MPA) in eastern Algoa Bay, temperate South Africa was investigated. Current velocities and direction and the swimming abilities of late-stage larvae were further assessed to determine potential larval movement to and from the MPA. In total, 6045 larval fishes were collected along two depth contours (~5m and ~15m) in the shallow nearshore of eastern Algoa Bay using stepped-oblique bongo net tows, twice per season for two years (March 2005 – January 2007). These larvae represented 32 families and 78 species. The Gobiidae, Cynoglossidae, Clupeidae, Engraulidae and Sparidae were the dominant fish families. Catches varied significantly between seasons peaking in spring with a mean of 64 larvae/100m3. Preflexion stage larvae dominated catches (75%). All developmental stages of Diplodus capensis, Engraulis capensis, Heteromycteris capensis, Sardinops sagax and Pomadasys species were found in the study area. It appears that these species use the shallow nearshore as a nursery area. Analysis of 12 months (May 2006 – May 2007) data from a bottom-moored Acoustic Doppler Current Profiler within the study area showed that offshore south eastward (39%) and onshore north westward currents (33%) dominated. The south westward current (15%) and north eastward current (12%) occurred less frequently. Current velocity decreased with depth in the nearshore, with a mean velocity of ~29 cms⁻¹ recorded at a depth of 4 m and a mean velocity of ~11 cms⁻¹ recorded at a depth of 14 m. Understanding the dispersal and movement of marine fish larvae in coastal habitats requires knowledge of active swimming abilities. The critical speed and endurance swimming of late stage larvae of two common inshore species occurring in the study area, Diplodus capensis and Sarpa salpa (Family Sparidae), were measured in a laboratory swimming chamber. The mean U-crit value for D. capensis (18.6 cms⁻¹) was similar to that of S. salpa (18.0 cms⁻¹), whereas mean endurance (km swum) was greater in S. salpa (8.4 km) than D. capensis (5.9 km). These swimming abilities exceed the average current velocities observed in the shallow nearshore providing larvae with the ability to greatly alter their passive dispersal trajectories and ultimately influence their distribution in the nearshore.

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48

DeKluyver, Tertius Vitus. "Development of larval barramundi under conditions of intense culture." Thesis, Queensland University of Technology, 1998.

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49

Faillettaz, Robin. "Estimation des capacités comportementales des larves de poissons et leurs implications pour la phase larvaire : un cas d'étude d'espèces démersales de Méditerranée Nord-Occidentale." Thesis, Paris 6, 2015. http://www.theses.fr/2015PA066342/document.

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La majorité des espèces de poissons côtiers a un cycle de vie comprenant une phase juvénile et adulte démersale et une phase larvaire pélagique. Cette seconde phase représente l’unique opportunité de dispersion pour de nombreuses espèces mais est soumise à une forte mortalité. Aujourd’hui, il est toujours délicat de prédire la connectivité entre les populations car tous les processus influençant la survie et le transport des larves durant leur phase pélagique ne sont pas encore décrits. Les larves de poissons possèdent des capacités comportementales non-négligeables (de nage, d’orientation, etc.) qui pourraient leur permettre de contrôler leur dispersion au cours de leur épisode pélagique. Cependant, les observations in situ de ces comportements ont principalement été faites en milieu tropical. Elles sont nettement plus rares en milieu tempéré, notamment chez les poissons Perciformes. Dans cette thèse, nous cherchons à décrire l’écologie et les capacités comportementales des larves de poissons en Mer Méditerranée Nord-Occidentale, un milieu tempéré où elles n’ont pas encore été décrites.La première partie de cette thèse vise à décrire la distribution des jeunes stades larvaires le long d’un transect côte-large traversant un front hydrologique. Nous nous intéressons également à leurs comportements de migration nycthémérale et d’évitement des prédateurs. La méthode d’imagerie utilisée pour décrire leur distribution à microéchelle génèrant des quantités de données considérables, nous avons développé une méthode de classification automatique pour accélérer le traitement de ce type de données. La seconde partie se concentre sur la phase d’installation, c’est-à-dire lorsque les larves arrivent à la côte à la fin de leur phase pélagique. Nous avons suivi l’arrivée des larves à la côte afin de déterminer les périodes d’installation des différentes espèces ainsi que les facteurs influençant leur arrivée. Nous avons également testé in situ les capacités d’orientation des espèces les plus abondantes, en se focalisant sur les mécanismes d’orientation à large échelle. En laboratoire, nous avons mesuré les vitesses de nage de plusieurs espèces, incluant celles testées pour l’orientation. Nous avons ensuite implémenté ces comportements observés dans un modèle biophysique afin de tester leur l’influence combinée sur le taux d’installation. Pour finir, nous discutons de l’influence que peut avoir le comportement sur la survie des larves de poissons tout au long de la phase pélagique, ainsi que de l’importance de sa prise en compte dans les modèles de dispersion
Most coastal fish species have a bipartite life history, with a demersal phase as juvenile and adult and a pelagic larval phase. Dispersal is often limited to this pelagic phase, which is also the phase experiencing the highest mortality rates. Predicting the connectivity between populations remains difficult because not all processes determining larval fish survival and transport during the pelagic phase are understood. Besides the environmental conditions that may influence the journey of fish larvae in the open ocean, these tiny organisms possess high behavioural abilities (swimming, orientating, etc.) that have the potential to shape their dispersal. However, the vast majority of in situ observations of these behaviours have been conducted in tropical environments and very little data exists on temperate Perciformes fish larvae. In this dissertation, we aim to describe the ecology and behavioural abilities of fish larvae from the Mediterranean Sea, a temperate environment where they have never been studied.The first part of this dissertation describes the distribution of young fish larvae along an inshore-offshore transect crossing an hydrological front. We also describe their diel vertical migration and predatoravoidance behaviour. The high-frequency imaging techniques used to capture their distribution at miscroscale generated huge amount of data. It lead us to modify an automatic classification method to reduce the time required to processes these kind of data. The second part focuses on the settlement phase, when fish larvae come back to the coast at the end of their pelagic journey. To shed light on the factors influencing the settlement process, we monitored the supply of fish larvae to a coastal habitat, on a weekly basis for three years and at higher frequency over shorter periods of time. Additionally, we tested the in situ orientation abilities of the most abundant species, focusing on large scale orientation mechanisms. In the laboratory, we measured the swimming speeds of several species, including the ones tested for orientation. Then, we implemented these observed behaviours in a biophysical model to explore their combined influence on settlement rate. To finish, we discuss on how larval fish behaviour may influence survival throughout the pelagic larval phase and insist on the importance of considering behaviour to improve larval dispersal models

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50

Dardengo, Gian Marco. "How to improve fish robustness through nutritional supplementation in fish larvae." Master's thesis, 2020. http://hdl.handle.net/10400.1/15220.

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The concept of nutritional programming began to arouse interest around larviculture sector due to the high metabolic plasticity of larvae. At this life stage, specific methabolic pathways of young organisms are more proned to be alterated with effects that may be propagated in the long terms. The aim of the present study was to assess the effect of dietary curcumin as promoter of both gut maturation and antioxidant status of gilthead seabream larvae (Sparus aurata). Curcumin was delivered through microdiet since mouth opening (4 Days After Hatching, DAH) in two levels of supplementation (LOW and HIGH) and the effects were compared with larvae fed on commercial diet (CTRL). Feeding plan consisted of a short period of co-feeding with live preys (rotifers and Artemia nauplii) and inert diet until 24 DAH, when larvae were weaned. Results on survival rate showed that, curcumin did not influence this paramenter. Key performance parameters did not reveal statistical differences between treatments, although a positive trend was detected in larvae fed on LOW curcumin supplementation. Proteolytic enzymes, such as trypsin and chymotrypsin, were positively influenced by curcumin being significantly higher in larvae fed on HIGH curcumin supplementation. Despite this, curcumin did not influence the activity of the remain digestive enzymes analysed (aminopeptidase, amylase, 4C and 18C-like lipases and alkaline phosphatase). Curcumin did not change the larval feeding habits or diet palatability; results revealed that weaning larvae at 24 DAH did not influence their feeding incidence. Overall, antioxidant status biomarkers (TG, TAC, PC and MOS) did not reveal significant differences between treatments. In summary, although results did not prove significant effects of curcumin on most of the parameters under investigation, some positive trends leave open the possibility of further investigations. These future trials may be addressed independently, or in combination, on both, early programming and new dietary additives, to test different curcumin concentrations.
O conceito de programação nutricional refere-se a possíveis estímulos durante fases precoces do desenvolvimento do animal que irão ter repercussões em fases mais tardias da vida do mesmo. O conhecimento dos mecanismos que controlam o desenvolvimento e o crescimento e sua relação com a nutrição são fundamentais para a identificação de fases de desenvolvimento que introduzam variação de crescimento, que impactem o potencial do mesmo e/ou que afetem a viabilidade e a qualidade dos juvenis. A perspectiva de aplicar este conceito à aquacultura oferece inúmeras possibilidades, principalmente focadas na modulação de vias metabólicas, tais como a acreção proteica, a homeostase oxidativa e a maturação precoce do sistema digestivo. A nutrição é o factor ambiental mais importante que determina o crescimento e o desenvolvimento dos animais. Nos últimos anos, foi reportado que a inclusão de extractos de origem vegetal em alimentos inertes estimula o apetite e promove o ganho de peso em peixes devido a moléculas bioactivas. O objetivo do presente estudo foi avaliar o efeito da inclusão de curcumina na dieta para larvas de dourada (Sparus aurata) como promotora da maturação intestinal e do estado redox, e melhorar o conhecimento das várias vias fisiológicas que medeiam as relações entre dieta, nutrição e metabolismo, apontando para a biologia oxidativa, a capacidade digestiva e a plasticidade do crescimento. A curcumina foi suplementada nas microdietas desde abertura da boca (4 dias após eclosão, DAE) em dois níveis de suplementação (LOW e HIGH), os efeitos foram comparados com larvas alimentadas com dieta comercial (CTRL). O plano alimentar consistiu em um curto período de co-alimentação com presas vivas (rotíferos e Artemia nauplii) e dieta inerte até os 24 DAE. Após esta idade as larvas foram alimentadas exclusivamente com dieta inerte. A taxa de sobrevivência confirmou que a curcumina não afetou este parâmetro. Os principais indicadores de desempenho de crescimento não revelaram diferenças estatísticas entre os tratamentos, embora tenha sido observado uma tendência positiva em larvas alimentadas com suplementação de curcumina LOW. As enzimas proteolíticas, como a tripsina e a quimiotripsina, foram positivamente influenciadas pela curcumina sendo a actividade enzimática significativamente mais elevada em larvas alimentadas com suplementação HIGH de curcumina. A suplementação de curcumina não influenciou a actividade das restantes enzimas digestivas analisadas (aminopeptidasa, amilasa, lipasas e fosfatasa alcalina). A curcumina não alterou os hábitos alimentares das larvas ou a palatabilidade da dieta; os resultados revelaram alteração na sua incidência alimentar quando alimentadas exclusivamente com dieta inerte. No geral, os biomarcadores do estado redox (TG, TAC, PC e MOS) não revelaram diferenças significativas entre os tratamentos. Em resumo, embora os resultados não tenham demonstrado efeitos significativos da curcumina na maioria dos parâmetros sob investigação, algumas tendências positivas deixam em aberto a possibilidade de novas investigações. Esses ensaios futuros podem ser abordados de forma independente ou combinada, tanto na programação inicial quanto em novos aditivos alimentares, para testar diferentes concentrações de curcumina. Os resultados serão traduzidos em estratégias alimentares eficazes de modo a promover a robustez e a resiliência dos peixes num futuro próximo e a transferir e aplicar o conhecimento e a tecnologia de modo a garantir o desenvolvimento de um sector mais sustentável, vital para o futuro da indústria da aquacultura.

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Dissertations / Theses on the topic 'Fish larvae'

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