In captive Heterobranchus 1ongifilis females, oocytes maturation and ovulation are induced by a single injection of human chorionic gonadotropin (hCG) at a dose of 1.5 I.U./g body weight. In the present study, three experiments were performed in order to specify the timing of ovulation and the effects of varying latency period on the quantity and quality of the collected ova. The ova quality was estimated by hatching percentage and proportion of deformed larvae obtained after artificial fertilization. The results showed that, in an individual female, ovulation of postvitellogenic oocytes is not synchronous and takes 3 to 4 hours to be completed, between 7–8 h and 11 h after hCG injection at 30 °C. The quantity of ova that could be collected by handstripping increased with the latency period, from 18,000 ± 12,000 to 72,000 ± 29,000 ova per female at 8 h and 11 h after injection, respectively. However, the first ova obtained (8 h after injection) were of good quality (94% hatching) and showed no signs of incomplete final maturation. Eleven hours after injection, the percentages of ovulated oocytes within the whole ovarian population of postvitellogenic oocytes were high in all the females, being generally around 90%. After ovulation, aging of ova occurred rapidly: the proportion of deformed larvae increased significantly (from 4 to 20%) 2 h after completion of ovulation and, 4 h post-ovulation, hatching percentage dropped from 92 to 36%. In H. longifilis, the optimal latency period can be defined as the time, from injection to stripping, allowing the best compromise between quantity and quality of ova released. This latency period was found to be 11 h following hCG injection at 30 °C, and corresponds approximately to the completion of ovulation.

The clown loach Chromobotia macracanthus, endemic to Indonesia, is a major species on the international market of ornamental freshwater fish. In order to satisfy an increasing demand with a sustainable alternative to the massive capture of wild juveniles, research has been dedicated to the artificial propagation and domestication of this species. The present study, the first of a series, focused on favourable maintenance conditions for broodfish sexual maturation, criteria for identification of ripe fish, efficiency of hormone-induced breeding treatments, predictability of their latency response, and on the comparison of reproductive performances of fish from populations of Sumatra and Borneo Islands (in total, 112 females of 46 to 404 g body weight). When reared in fully controlled conditions in large water recirculation systems, broodfish originating from Sumatra had reproductive performances similar to or slightly higher than those maturing in the wild (ovulation rate of 93% vs. 82%, relative fecundity of 109 277 vs. 103 550 ova  kg-1 and fertilization rate of 73% vs. 61%, respectively). In the same rearing conditions, captive females from Borneo (n = 22) showed lower ovulation rate (77%), relative fecundity (76 262 ova kg-1) and fertilization rate (50%) than those originating from Sumatra (n = 28). By contrast, the mean individual weight of ova (around 0.8 mg) was independent from the origin or maintenance conditions of females. An initial modal follicle diameter  ≥1.02 mm generally led to high ovulation success (>80%) after hormonal treatment and is recommended as the main criterion for selecting female broodfish. Two hormonal treatments for inducing oocyte maturation and ovulation (T1: two successive injections of Ovaprim at a 6 h-interval; T2: one injection of human chorionic gonadotropin (hCG)- and one of Ovaprim 24 h later), produced similar results in terms of ovulation rate, quantity and quality of ova collected. With both treatments, the latency decreased with increasing water temperature, then increased again at temperatures  >28–29 °C. To our knowledge, such U-shaped relationship between the latency response and temperature has never been documented in teleost fishes.

The individual growth variability of passive integrated transponder tagged sea bass was studied using data sets from two different experiments. In experiment 1 (n = 485), fish submitted to different photoperiod regimes were held in fourteen groups of individual weight of 88 ± 13 g (mean ± SD). In experiment 2 (n = 748, initial weight 243 ± 30 g) fish were held in fifteen groups and had either free or restricted access to diets with three lipid levels. After adjustment for treatment and tank effects, individual growth curves were analysed using multivariate analysis (principal component analysis and clustering) and were modelled using the summary statistics technique. Different growth profiles where characterized. All of them appeared to be curvilinear. They differed in their level (initial and final weight), slope (slope, specific growth weight, gain) and especially the ratio of males, which showed sexual growth dimorphism. The fish with similar initial weight proved to have very different growth performances, regardless of the treatment effect. Within the same sex, part of the variability between the growth profiles could be explained by differences in the social interactions and in the genetic potential of growth among individuals.

Cette étude analyse le rôle de la seconde et petite saison d'upwelling dans les changements récents de l'écosystème pélagique côtier ivoiro-ghanéen. Depuis le début des années 1980, les captures de Sardinella aurita ont nettement augmenté au Ghana et en Côte-d'Ivoire ou les modifications de l'abondance et de la dynamique de l'espèce ont été les plus surprenantes. La taille des poissons a augmenté et l'activité reproductrice de l'espèce est maintenant d'une intensité équivalente pendant les deux saisons d'upwelling. On observe, entre 1970 et 1990, une tendance à la diminution de la différence entre l'intensité des deux saisons d'upwelling. Le rôle croissant de la petite saison d'upwelling dans l'écosystème permet de donner une interprétation aux changements observés. Cette saison, plus intense en Côte-d'Ivoire qu'au Ghana, intervient en effet pendant la période de l'année défavorable pour la productivité de l'écosystème pélagique et peut être comparée à un "goulot d'étranglement" pour cette productivité.

This work describes the application of a homologous radioimmunoassay (RIA) in the measurement ofplasma and pituitary growth hormone levels of tilapia maintained at 20 and 26 °C, using recombinant tilapia growth hormone (rtiGH). RIA sensitivity (ED90) was 0.08 ng/ml and ED50 was 0.62 ± 0.02 ng/ml. Intra- and inter-assay coefficients of variation were 3.3 and 10.6% respectively, for a plasma sample of 1 ng/ml of tiGH. Mammalian or salmonids growth hormones, thyrotropins or tilapia prolactins did not show cross-reactivity with rtiGH antiserum. Plasma and pituitary extract of Oreochromis niloticus gave inhibition curves parallel to the rtiGH standard curve without interaction with serial dilutions either of tissue extracts or plasma from hypophysectomized tilapia. Pituitary extracts from other cichlid fish showed parallel competitive binding curves. Pituitary extracts of perciform fish exhibited a lower affinity to anti-rtiGH serum, while extracts of species from more distant families showed only negligible cross-reactivity or none at all. The effects of water temperature on plasma concentrations and pituitary contents of GH were investigated in tilapia acclimatized to 26 and to 20 °C. Measurements have been performed at the beginning and at the end of a two-week experiment. Whereas in fish from colder water plasma GH mean values were decreased, only a similar tendency was observed in pituitary GH contents. These results emphasize the hypothesis wich reports that the increase of growth with temperature is, at least in part, controlled by GH.

An integrated research program was initiated to evaluate if the European shagPhalacrocorax aristotelis can be used as a robust indicator of themarine environment in Mor Braz, Brittany, France. This program focuses on aspects of theecology of the shag including its abundance, demography, diet and at-sea distributionmeasured at three breeding colonies. The annual population growth rate was estimated at1.01 for the period 1987–2009. The number of breeding pairs (mean: 565) was highlyvariable from year to year. Part of this interannual variation was explained by variationsin sea surface temperature and sea surface height in winter and spring: the number ofbreeding pairs was negatively related to sea surface temperature and sea surface height.First year, second year and adult survival probabilities were 0.44, 0.76 and 0.81,respectively. Juvenile survival rate varied between colonies, despite the short distancesseparating these islets. Average productivity was one young fledged per nest, but itvaried between years and islets. Density of individuals at sea varied between 1.40ind.km-2 during the breeding season and 3.08 ind.km-2 after thebreeding season had ended. Individuals foraged up to 7 km from the nest and performed onaverage 2.7 foraging trips per day. The average number of dives deeper than 5 m variedfrom 126 to 400 per day. Mean diving depth, dive duration and time spent at bottom were 13m, 28 s, and 19 s respectively. Regurgitated pellets were collected regularly. Four fishfamilies (Gadidae, Gobiidae, Atherinidae and Labridae) represented more than 65% of thepreys throughout the year, a percentage reaching more than 95% of the prey from May toOctober. The other fish in the diet were Cottidae, Ammodytidae, and Clupeidae. The diet ofthe European shag consisted of benthic fish throughout the year, and also included pelagicfish more frequently between June and October. The synchronous variations of productivitybetween colonies suggest that some common environmental factors affect this demographicparameter at the regional scale. Thus, the European shag has a good potential for being areliable ecological indicator of the state of this marine environment. Finally, improvedknowledge on the foraging ecology of shags will be useful in the process of designingMarine Protected Areas in the Mor Braz to help ensure sustainable management of marineresources and biodiversity conservation.

The queen conch, Strombus gigas, is an important fisheries resource in the Western Tropical Atlantic. In order to maintain harvesting success, improve fisheries management and contribute to mariculture pursuits, a detailed understanding of the life history traits of this species is required. Traditionally, this has been achieved by tedious and time-consuming long-term field observations. This study presents a highly versatile and rapid technique to estimate the timing and rate of shell growth based on sclerochronology. The Belizean S. gigas specimens (N = 2) from the offshore atoll, Glovers Reef, reached their final shell size (maximum shell height: 22.7 and 23.5 cm, respectively; completed formation of the flared lip) after only two years. However, seasonal growth rates varied considerably. Shells grew up to 6 mm d−1 during spring (April-June) and fall (September-November) but only 1 to 2 mm d−1d uring July and August. Furthermore, shell growth ceased between December and March. Fastest shell growth occurred nearly contemporaneously with times of maximum precipitation which probably resulted in increased food availability. Slowest shell growth however, occurred during times of reduced rainfall and reduced riverine runoff, i.e. during times of reduced food supply. Sea-water temperature apparently did not exert a major control on shell growth. Notably, the slow winter growth was marked by a distinct purple-colored growth line in the cross-sectioned flared lip. Formation of a second major growth line (brown) fell together with the main reproduction period (late October/early November). Shell microgrowth patterns potentially represent daily or semidiurnal periods but cannot be used to assign exact calendar dates to each shell portion, because they were not visible across the entire cross-section of the whorl. Also, the protruding spines developed on the outer shell surface do not function as time gauges. The time represented by the shell portion between consecutive spines varies greatly from 1 to 72 days. Sclerochronology can potentially facilitate maricultural strategies and aid in site pre-testing and selection to grow S. gigas.

Although there are numerous published accounts of studies utilizing heart rate (fH) transmitters in fish, few of these studies provide sufficient detail to aid other researchers in deploying these devices. Here, we detail the attachment, validation, and preliminary deployment of a commercially available ultrasonic fH transmitter. We used largemouth bass, Micropterus salmoides, for this study because they principally modulate cardiac output using fH, making them logical candidates for this technology. Using an external harness that balanced the battery on one side of the dorsum, and the transmitter on the other, we attached the device to 13 fish. Electrodes were positioned ventral-laterally to the pericardial cavity. Doppler flow probes were used to validate that the transmitter was detecting and emitting a signal when triggered by the depolarization of the ventricle (QRS wave), as indicated by peaks in blood flow. We then deployed the fH transmitters for periods of up to 32 days, generating one of the most complete series of fH data available. We present preliminary data illustrating the information available from fH transmitters at different temporal resolutions (real time vs. hourly means), including relationship of fH to temperature, behavioral correlates of fH, and diel patterns of fH.

The Chilean hake (Merluccius gayi gayi) is the predominant groundfishspecies inhabiting the southern Humboldt, mainly from Coquimbo (29° S) to Puerto Montt(42° S). At present there is only limited knowledge on the spatial distribution ofjuveniles of this species, particularly concerning its dependence on key physicalcharacteristics. On the basis of annual surveys carried out during austral winters from1997 to 2006, changes in the presence of juveniles were studied using Generalized AdditiveModel techniques. Temporal factors and spatial effects were more important than singlephysical variables in explaining the presence of juvenile hake (<34 cm totallength). Juvenile hake had a preference for shallower waters. Although salinity and oxygenwere significant, their contribution was marginal. Juvenile hake seem to prefer shallowoxygenated waters, but the nonlinear relationships and partial secondary peaks detected insalinity and oxygen probably only reflected the influence of three water masses found inthe winter habitat. Endogenous factors could be more important in determining temporal andspatial changes in the proportion of juvenile hake. An important change in the presence ofjuveniles has occurred since 2004, coinciding with a significant decline in biomass ofadult hake. It is postulated that cannibalism pressure from adults has probably declinedand that spatial and temporal changes in the presence of juvenile hake seem to be moreassociated with fishery-induced demographic effects.

Successful commercial aquaculture production of spiny lobster is, for the most part, still constrained by an array challenges including the development of nutritionally complete and cost-effective feeds, control of disease vectors, and the design of larval mass culture tanks. Culture tank designs for larval production are a critical step to facilitating the most favorable combinations of water flow, food contact, and larval survivorship over the course of development. The evolution of new plankton-kreisels that are used by aquariums to culture and exhibit gelatinous zooplankton (e.g., jellyfish) provide a unique opportunity for testing the feasibility for spiny lobster larval culture, particularly with tropical species such as Caribbean spiny lobster (Panulirus argus) whose larval duration, although complex, is comparatively shorter than other spiny lobsters. Here, we report on the feasibility of culturing P. argus larvae (i.e., phyllosoma) from hatch to Stage VI using large (180 L) modified acrylic plankton-kreisels. We compared overall growth and survival of phyllosoma at starting densities of 5000 (~27.8 larvae L-1) and 2500 individuals (~13.8 larvae L-1) and found no significant difference with respect to survival or mortality through to 65 days (χ2 = 1.595; df = 1; p = 0.2066) resulting in mean survival rates of 60.7% (s.e. = ±3.7) and 54.5% (s.e. = ±3.2), respectively. Comparable growth was also achieved between both densities to Stages V and VI (mean body lengths of 7.5 and 10.2 mm, respectively) at 25.1 ± 0.41 °C and pH = 8.1. Phyllosoma utilized the entire tank volume and displayed minimal entanglement. The application of such tank designs for larval spiny lobster culture not only contributes to future designs for aquaculture production, but also provides a useful platform for conducting behavioral studies for this complex larval phase.

This paper describes the suitability of a closed recirculation system to study the development of fish larvae in a strictly controlled environment, where only feeding was varied (fed, starved, delayed and late fast treatments). The system served both as an incubator and hatchery. The time variation of physical and chemical parameters together with survival and growth of reared sea bass larvae (Dicentrarchus labrax) were studied over the first month of life. The recirculation design allowed for the maintenance of levels of ammonia, nitrite and nitrate below those cited as responsible for mortality or decreased feeding ability in other marine fish larvae. Almost no larval mortality occurred in the fed larvae from day 9 after hatching. The starved group of larvae showed a sharp decline in survival after 16 days of food deprivation. Larvae for which feeding was delayed until day 13 ceased dying 4 days after food was supplied. Fast feeding on days 24 and 25 had no effect on larval survival. Growth in length was similar during the first 2 weeks of larval life regardless of feeding treatment. Two days of late fast had no effect on larval growth. Growth patterns of fed larvae in this study were similar to those reported for larvae reared in flow through systems. We believe that survival and growth of the reared larvae was a direct function of diet, and that the type of rearing system did not adversely affect these parameters. The rearing design and the results obtained suggest that future nutritional studies of field-collected larvae will benefit from this kind of rearing experiment.

When reviewing the various fish-based community indicators aiming at assessing the ecological status of marine communities and/or ecosystems, a typology consisting of three major components emerges. The first component highlights the choice of relevant metrics associated with a level of organization (e.g. population or community). The second relies on the method used to combine the metrics (an aggregated indicator or a synoptic table). The third refers to the type of analysis (direct or indirect) that is used to establish the link between the metrics and a given pressure. In this paper we use the Vilaine coastal-estuarine fish communities as a case study to discuss and relate two different approaches to the suggested typology. The first approach (time-trend approach) is based on historical series of data, whereas the second approach (multi-metric index, MMI) is based on a geographic series including various French estuaries. They were developed or adapted from French studies but are representative of the approaches used in Europe. When applied to the case study, they differed in their diagnosis: the time-trend approach indicated that the bay of Vilaine habitat was deteriorating, whereas the MMI, which compares many French estuaries, indicated a good environmental state. Differences and complementarities between the approaches are thoroughly discussed with respect to the three mains components of the typology. This work appears at a particular moment, when several fish-based indicators are being developed in France and the rest of Europe. It intends to serve as an element of the ongoing reflection concerning the limitations of the various approaches that can be used to develop such indicators.

Cinq mille larves de poisson-spatule Polyodon spathula agées de 3–4 jours, en provenance du Missouri aux États-Unis, ont été introduites dans l’ex-URSS, en 1974 dans le cadre des accords de coopération scientifique entre les deux pays. Cette première tentative n’a été que partiellement réussie ; seuls quelques survivants ont atteint 600–900 g après 2 ans puis la maturité sexuelle et se sont reproduits en 1984 et 1986. L’élevage de cette espèce étant apparu possible, de nouvelles introductions ont eu lieu, l’une en 1976, qui fut sans succès et une autre en 1977, réparties dans deux écloseries (Goreachi Cluch et Krasnodar-Ikreanoe). En 1978, une centaine des spécimens de Goreachi Cluch ont été exportés en Moldavie et élevés en polyculture dans plusieurs piscicultures où la reproduction de trois femelles a été obtenue en 1988 et 1989. Des juvéniles issus de ces reproductions ont été exportés en URSS (Ikreanoe) et en Roumanie et Hongrie. Par ailleurs, la station de recherches de Nucet en Roumanie a importé des larves de poisson-spatule des États-Unis en 1992, 1993 et 1994 (environ 2000 larves à chaque introduction). Dans ces différents pays, des recherches ont été conduites sur cette espèce. Actuellement, la production commerciale a débuté en Russie et Moldavie pour la chair, et il a été montré, dans le cadre d’un projet CE Copernicus, qu’il était possible de produire du caviar. P. spathula peut venir en complément ou en substitution partielle de carpes, en polyculture et a une valeur commerciale plus élevée. Le problème est que la seconde génération présente en Russie, Moldavie, Roumanie, et peut être en Hongrie, est dérivée d’un nombre limité de parents, avec des risques de perte de variabilité génétique.

Les variations de la diversité spécifique entre les assemblages depoissons démersaux du golfe de Gascogne (océan Atlantique) et du golfe duLion (mer Méditerranée) sont analysées à l'échelle d'unedécennie. L'objectif est d'interpréter la dynamique de ces peuplements dontles niveaux d'exploitation par la pêche diffèrent. Les donnéesutilisées sont issues des campagnes de chalutages réalisées de 1983à 1997 pour l'évaluation des stocks de poissons démersaux. Lesindicateurs de diversité analysés sont les indices N1 etN2 de Hill, la richesse spécifique S, la régularitéJ’, les courbes K-dominance et les stratégiesdémographiques des principales espèces. Chacun des deux peuplements estconstitué de trois assemblages d'espèces (assemblage côtier, duplateau et de la pente continentale). Il n'existe de différence significative nientre les assemblages du golfe de Gascogne, ni entre ceux du golfe du Lion. Il n'y apas non plus de différence significative entre les années. L'ensemble dugolfe du Lion est caractérisé par des valeurs N2 et des indicesS plus élevés que dans le golfe de Gascogne. Selon lescourbes K-dominance, le peuplement du golfe de Gascogne est caractérisé parun plus petit nombre d'espèces dominantes que dans le golfe du Lion. Enfin, lesespèces dominantes du golfe du Lion sont caractérisées par unelongévité et/ou une taille maximale plus grande que celles du golfe deGascogne. Le golfe de Gascogne correspondrait à un système adaptéà l'existence de perturbations (mortalités imprévisibles), tandis quele golfe du Lion correspondrait à un système adapté à unenvironnement moins perturbé. Un impact de l'exploitation n'a pu êtreinterprété à partir des indices choisis, utilisés à cetteéchelle. Toutefois, lorsque les indices de diversité sont mis en relationavec la stratégie démographique des espèces, des éléments dedynamique des peuplements sont mis en évidence.

Microsatellites are one of the most popular markers in genetic studies but typically theyneed to be isolated and characterized de novo for each species. In thiswork, a genomic library enriched for a trinucleotide motif was constructed to identifypolymorphic microsatellite loci in Aequipecten opercularis, a scallopspecies commercially fished in Europe, and to examine the level of genetic variation andgenetic differentiation in samples from Spain and Northern Ireland. Sequencing of 83clones led to the identification of 30 microsatellite-containing sequences which showedoften other repeated sequences. Five microsatellite loci were successfully amplified andfound polymorphic. The number of alleles and the expected heterozygosity per locus rangedfrom 9 to 86 and 0.341 to 0.927, respectively, all localities showing similar levels ofgenetic variation (allelic richness, 13.164–15.487; expected heterozygosity, 0.527–0.638).Discrepancies in genotype proportions from Hardy-Weinberg equilibrium were observed in 11out of 25 locality-locus combinations, a heterozygote deficiency occurring in all casesprobably due to null alleles. Significant genetic differentiation was detected amongA. opercularis from Northern Ireland, Fuengirola (southern Spain) andthe homogeneous samples from northwest Spain. Isolation by distance was the most likelyhypothesis to explain the differentiation detected.

The induction of gynogenetic diploids during meiosis II in the scallop Chlamys farreri was attempted using the treatments of cytochalasin B (0.5 μg ml−1; CB) and 6-dimethylaminopurine (60 μg ml−1; 6-DMAP). The effects of CB and 6-DMAP treatments on meiosis and fertilization of eggs were also examined. Haploid gynogenesis was induced by sperm which were ultraviolet-irradiated for 30 s at an intensity of 2561 μW cm−2 s−1. CB and 6-DMAP treatments were highly effective in suppressing meiosis II, yielding 19% and 28% gynogenetic diploids, respectively. Compared with the CB treatment, the 6-DMAP treatment produced more expected D-shaped larvae. Cytological observations revealed that 6-DMAP inhibited pronuclear movements and the segregation of chromosomes, resulting in the formation of one big diploid female pronucleus with strong fluorescence, while CB inhibited cytokinesis, resulting in two female pronuclei formations. The UV-irradiated sperm nucleus developed into a male pronucleus, but did not participate in karyokinesis at mitotic anaphase, suggesting that gynogenetic diploids were induced in the scallop.

Converging results in different scientific fields (behavioural ecology, fisheriesbiology, acoustic tagging, fisheries acoustics, behavioural modelling) suggest theexistence of “micro-groups” inside fish schools. These would comprise a few (5–10) fishmaintaining contact during a period long enough to allow individuals to recognise eachother. It is hypothesised that they would prefer to share the space with familiar ratherthan anonymous conspecifics. To evaluate whether acoustic methods could be used torecognise “micro-structures” inside fish schools and help test the “micro-group” hypothesiswe analysed acoustic data from anchovy schools off Peru, and gadoids in the North Sea.Data collection used a multibeam sonar (Reson SeaBat 6012). In the Peruvian case study,the sonar was mounted set horizontally on a drifting research vessel and the internalstructure of the schools of anchovies was analysed, although individual fish could not bediscriminated. In the North Sea case study, the sonar was orientated vertically above ademersal trawl to allow observation of individual fish entering the trawl. Geostatisticalanalyses were used to evaluate the existence of small spatial structures in anchovyschools. In these schools, “micro-structures” with a scale as small as 0.5 m were observedacoustically. For the gadoids nearest neighbour distance (NDD) measurements were carriedout, suggesting that the fish aggregated in small groups (2 to 25 individuals, with anaverage of 3.7 fish per group) in the trawl catches. The perspectives and limitations ofthese results are discussed.

Adenylate Energy Charge (AEC) values of Crassostrea gigas (9 and 18 months old) cultured in ponds in Marennes-Oléron Bay (Atlantic coast, France) are reported. Two ponds were loaded with two different initial oyster biomasses in order to obtain different food conditions. The growth of oysters was different in the two ponds which corroborated the effectiveness of attaining different food conditions. AEC level was different depending on the pond and was therefore related to food availability per unit oyster biomass. Well-fed oysters exhibited greater AEC values than poorly-fed oysters, throughout the study. Information on nutritional situations for wild or cultured populations can therefore be obtained by AEC. In each pond, the seasonal AEC variations were similar for both age-groups and were characterized by a minimum value in summer and a maximum value in winter. The influence of reproduction on these variations cannot be ruled out as for all the batches maturation processes were evidenced. Research will be done on a temperature effect to try to distinguish these seasonal variations. A strong correlation between adenylate energy charge (AEC) and guanylate energy charge (GEC) was demonstrated; it was similar for both ponds. The levels of nucleotide concentration were relatively stable during the survey except in September and December for oysters in the low density pond. Among nucleotides, adenylate pool represented the major part (80%). A decrease in the total concentration of adenylates was observed in August. The best growth correlated with the lowest adenylate percentage and a better GTP/ATP ratio, suggesting that this ratio could be a useful index for growth.

L'affinage traditionnel des huîtres creuses, pratiqué dans lesclaires ostréicoles de la façade Atlantique française, est soumis auxfluctuations des facteurs environnementaux. Un procédé d'affinagecontrôlé en terme de matières organique et inorganique particulaires(MOP et MIP) et de température a étédéveloppé afin de réduire la variabilité de croissance de lachair des huîtres. Cet élevage intensif repose sur la production de ladiatomée Skeletonema costatum, distribuée aux huîtres avecune concentration moyenne de 4–5 mg deMOP·L–1. Un modèle écophysiologique del'huître Crassostrea gigas, simulant les croissances du soma et desréserves–gonades, a été appliqué aux conditions d'affinagecontrôlé dans le but d'analyser les réponses du bivalve. Sonélaboration a nécessité un retour à l'expérimentation. Deuxfonctions d'alimentation ont été étudiées au laboratoire : lafiltration et la production de pseudofèces, intervenant dans la régulationde l'ingestion. Les résultats, pour une température de 14 °C, etpour une gamme de MOP et de MIP variant respectivement de 4 à18 mg·L–1 et de 15 à55 mg·L–1, montrent que l'ingestion est réguléepar la production de pseudofèces, la filtration ne présentant pas devariation significative (moyenne de2,09 ± 0,11 L·h–1·g–1, avec un taux d'activité de 59%). Cette production de pseudofèces, quiengendre une augmentation de la fraction organique ingérée par lemécanisme de sélection pré-ingestive, permet de compenser lavariabilité des concentrations en MIP. Des simulations ont permisd’analyser les effets négatifs de ce facteur environnemental sur lacroissance du bivalve. Il apparaît alors que la ration utilisée en affinagecontrôlé (4–5 mg de MOP.L–1) permet unecroissance en chair sèche malgré des concentrations simuléesatteignant 50 mg·L–1 de MIP. Lors del'élaboration du modèle pour les conditions spécifiques àl'affinage contrôlé, la gamétogenèse est apparue comme unprocessus déterminant pour la répartition de l'énergie chez lebivalve.

Carps, Cyprinus carpio L., were exposed to a sublethal concentration of ammonia NH3 (0.102±0.059 mg.dm−3) during 3 weeks. The sensitivity of the blood picture and haemopoietic organs were evaluated. Ammonia intoxication resulted in erythroblastosis of circulating blood. Concurrently, a significant decrease in polychromatophilic erythroblasts in kidney and orthochromatic erythroblasts in spleen tissues were observed in exposed fish compared with controls. The relative proportion of erythrocytes in peripheral blood decreased and coincided with a highly significant (p < 0.01) increase of erythrocytes in spleen imprints of intoxicated carps compared with controls. Peripheral leucopenia, mainly lymphopenia as an intoxication response, was observed. In the pronephric cells significant differences in the proportion of young and adult eosinophils and the proportion of plasmocytes with vacuolized cytoplasm were found between those animals exposed to the toxic stress and the controls. Thus, the examination of haemopoietic organs has a great potential in carp health assessment.