Shell malformations and histological effects of environmental concentrations of TBTF (2, 13.1 and 64.8 ng/l) were assessed on adult oysters Crassostrea gigas during a 1-month experiment, including both an exposure and a depuration phase. The results showed that the digestive gland is the primary target organ. Recoverable modifications were observed at the lowest concentration. Limited necrosis was observed at the highest concentration and a longer exposure could have led to extensive and irreversible tissue lesions. Shell malformations (chambering) were observed during the depuration phase. Finally the authors suggest that safe TBT levels in mariculture waters should be lower than 2 ng/1.

Enzymatic polymorphism was studied in nine enzyme systems of four species of large AfricanBarbus (B. bynni occidentalis Boulenger, 1911; B. sacrutus Daget, 1963; B. petitjeani Daget 1962; and B. wurtzi Pellegrin, 1908), two species of small African Barbus (B. guineensis Pellegrin, 1913 and B. cadenati Daget, 1962), and two species of European Barbus (B. barbus Linnaeus, 1758 and B. meridionalis). Like European Barbus, the large African Barbus were found to express more than 20 enzymatic loci for these systems (21 to 23), whereas the small African Barbus only expressed 14. This result suggests that large African Barbus are tetraploid like European Barbus and that small African Barbus are diploid like the Asian species. The two groups of African Barbus do not appear to be phylogenetically closer to each other than they are to European Barbus. Consequently, tetraploidi-zation must have occurred long ago in large African Barbus, and may correspond to the same event responsible for the origin of the European species.

La tolérance aux basses températures des gamétophytes de l'algue alimentaire Undaria pinnatifida est examinée selon différentes méthodes de cryoconservation. La conservation à -80 °C dans une solution glycérolée à 28 % et celle à −196 °C dans une solution en eau de mer de glycérol à 5 ou 10 % ne permettent que des survies de, respectivement, 9 et 4 jours. Par ailleurs, la viabilité n'est pas affectée par un refroidissement de 5 °C/min et une conservation de 15 minutes à −15 °C sans milieu de cryoprotection mais est fortement diminuée par un stockage de 15 minutes à −30 ou −196 °C, même en présence de DMSO. La réduction de la survie des gamétophytes se traduit morphologiquement par une dépigmentation et/ou une contraction des cellules.

Dynamic aspects of an asynchronous cyprinid's ovogenesis, the gudgeon Gobio gobio L., were examined by a histo-morphometrie approach and effects of two factors, temperature and photoperiod, were investigated in respect to the stage of maturation. Four stages of maturity (one protoplasmic or vacuole free oocyte, two vesicle stages, also called in endogenous vitellogenesis and one vitellogenic or in exogenous vitellogenesis) were identified and compared to macroscopic characteristics of maturity (gonadosomatic index and condition coefficients, K and K 1). Growth and relative proportion to the entire ovary of each oocyte stage was measured on the different experimental groups. Relative importanee of temperature and photoperiod were clearly dependent on the gametogenic stage (recrudescence, final maturation and ovulation, and regression). Under constant temperature and photoperiod conditions, a strong vesicle stage oocyte regression was observed; a periode of low temperature or decreasing photoperiod seemed necessary to allow gonad recrudescence to be initiated. An annual cycle contracted into 6 months accelerated gametogenesis and produced off-season spawnings. Contraction of the reproductive cycle did not entail a rduction of oocyte growth or the yolky oocyte proportion. During the spawning period, females ovulated several times with a 15-day interval between successive spawnings. Vesicle and globule stages were induced by increasing temperature or photoperiod, but final maturation and ovulation were primarily dependent on temperature. The regressive stage was caused by a decreasing photoperiod and/or temperature. From a group synchronous distribution of oocytes at the start of recrudescence, the gudgeon's ovary changed to a totally asynchronous distribution at the end of vitellogenesis.

Whitefish (Coregonus lavaretus L.) larvae from Léman (= Lake Geneva) and Lake Bourget (France) have been successfully mass reared in tanks of 50-60 l when fed exclusively on dry experimental and commercial diets. In spring water at 10 °C for three initial densities (100-200-400/l) tested, the survival at 35 days fluctuated generally between 30 and 50%. The final number and biomass harvested has been improved by the use of higher water temperature (14 °C) or by stocking with high initial density (200-400/l) at 10 °C. In Lake Leman, temperature appeared to be the key factor controlling the results of coregonid larvae rearing in submerged illuminated net cages (6 m3) stocked with 50 000 yolk sac fry and harvested at the end of spring. The results fluctuated greatly when stocking was too early (middle of February to beginning of March). They were improved by delaying stocking, to the period "mid-Marc - carly April" for yolk sac fry or to "end of March-April" when fry prefed on dry diet were used.

Three species in the group of "small" Barbus from West Africa were analyzed by enzyme electrophoresis to assess their genetic differentiation. Comparison with a species of "large" Barbus from the same region showed that the "small" Barbus are certainly diploid and the "large" tetraploid. They clearly form two distinct lineages. Phenetic dendrograms (Nei distances) and cladograms (compatibility networks) of the genus Barbus are proposed, based on three African diploid species, two diploid species from Saudi Arabia and Southeast Asia, one African tetraploid species, and two French tetraploid species. These trees reveal two sets of species, i.e. diploid and tetraploid. Several methods of data processing are suggested for overcoming the difficulties involved in simultaneously analyzing species with different ploidy levels.

About 60 papers and reports dealing with heavy metal contents in different eel species were reviewed in order to document various patterns of uptake, elimination and accumulation of these metals and to underline their detrimental effects (lethality, histo-pathology). Two main toxicological topics were considered: observations on contaminant levels in eels taken from the wild, mainly from contamined waters, and experimental studies under laboratory conditions.

Common carp larvae were fed artificial diets over 28 days at about 24 °C. Diets were based on yeast and either beef liver or casein. Survival rates of larvae were 76-92% with liver diets and 87-96% with casein diets. Larval growth was superior with liver diets (mean final weights 720-880 mg) than with casein diets (130-340 mg). Within-tank coefficient of variation of body weight increased with mean weight according to a generalized S-shaped curve. The skewness coefficient tended to increase with the mean weight, with higher values in the casein-fed group than in the liver-fed group. It is concluded that liver is not strictly indispensable for carp larvae diets and may be replaced by less complex components.

F1 hybrids were produced by crossing, in artificial conditions, female Barbus barbus and male B. meridionalis. Results from the genetic study describing enzymatic patterns produced after electrophoresis of experimental F1 hybrids confirmed a great part of the original interpretation of patterns observed in the natural population. Morphological studies which examined denticle length on the last hard ray of the dorsal fin (well developed in B. barbus and absent in B. meridionalis), showed that F1 hybrids' values were not exactly intermediate between the parental values. Up to two years old, experimental hybrids displayed identical growth rates and sexual dimorphism of length (in favour of the females) as B. barbus growing in the same conditions. At this age, in female hybrids, the ovaries matured and produced fertilizable ovules: in male hybrids, the testicles were morphologically normal but no sperm was produced. If this sterility is confirmed in the reciprocal cross (male B. barbus × female B. meridionalis), the phenomenon would be an essential feature in understanding this hybridization.

Carob seed germ meal (CSGM), and soybean meal (SBM), were tested as ingredients of diets for rainbow trout (Oncorhynchus mykiss) fingerlings at three levels of inclusion, contributing 20 to 50% of the total protein of the diet. Fish growth decreased as the level of the plant by-product in the diet increased. Diets containing CSGM resulted in lower growth than comparable SBM diets, especially at inclusion levels contributing 37 and 53% of the total protein. High dietary CSGM levels decreased body protein and increased liver protein indicating possible amino acid deficiencies and/or imbalances at high inclusion levels. Mortality was also high at the high dietary CSGM level. The results are discussed with référence to the antinutritional factors contained in the raw materials tested and their possible effects on protein availability.

Se estudió de contenido en ácidos grasos de los lípidos totales, polares y neutros en músculo, hepatopáncreas y ovario de hembras de Penaeus kerathurus antes y después de la puesta. El ovario fue el organo que presentó un mayor descenso del contenido lipídico total (50,9%), que se transfirió a los huevos durante la oogénesis. En los diferentes organos estudiados, el contenido de lípidos polares fue superior al de lípidos neutros. Sin embargo, durante la puesta se transfirieron mayores cantidades de lípidos neutros que de polares tanto en el ovario como en el hepatopáncreas. El contenido de los ácidos grasos saturados de los lípidos totales del ovario disminuyó un 66,3%, el de monoinsaturados un 56,5% y el de los poliinsaturados un 62,6%. Acidos grasos como el 16:0, 16:1 n − 7 y 18:1 n − 9 contribuyeron de una forma importante a la compositión lipídica de los huevos. Mientras que el 20:5 n − 3 y el 22:6 n − 3 significaron un 4% y un 4,5% respectivamente de los lípidos totales del ovario que se aportaron a la puesta.