The present study described the gametogenesis and assessed the pattern of energy storage throughout the reproductive cycle of the golden carpet shell (Polititapes aureus) from the Ria Formosa lagoon (southern Portugal). Monthly sampling was performed for two years (March 2016–February 2018) and the study was based on gonad histology, complemented by the estimation of the mean gonadal index, body condition index and biochemical composition. The species’ reproductive cycle presented a seasonal pattern, with a resting period mainly between October and January and gametogenesis beginning around February–March. The spawning season of P. aureus was shorter in 2016 (June–September) than in 2017 (May–October). Furthermore, ripe individuals were very scarce (1.3%) in 2017 compared with the previous year (11.4%). Mean gonadal index (GI) reflected the species’ reproductive cycle and the body condition index (CI) and biochemical composition of the individuals exhibited high variation between years. Regarding the biochemical composition, proteins ranged between 190.6 and 595.2 μg mg−1, glycogen from 5.7 to 102.6 μg mg−1 and total lipids between 31.6 and 80.7 μg mg−1. The reproduction of P. aureus was strongly influenced by fluctuations in both seawater temperature and chlorophyll a, as reflected through the temporal variation in the gonadal cycle, condition index and biochemical composition. Overall, the information gathered in this study is valuable to propose scientifically based harvesting management measures for the long-term sustainable exploitation of this shellfish resource, further reinforcing the importance of implementing adaptive fishery management strategies to cope with global climate change.

Although hay is the foundation of most equine diets, horse owners rarely ask for biochemical analysis and the routine practice is to choose hay based on its ‘perceived‘ nutritional value. The present study aimed at exploring the relationship between sensory properties as perceived by sight, touch and smell, and the nutritional value of hay measured by biochemical analysis using a ‘free sorting task’ method. Fifty-four non-expert participants were asked individually to: (1) observe 21 hays samples, (2) group together hays that they perceived as similar for each of the three modalities (hay appearance, odour or texture) and (3) characterize each formed group with a maximum of five descriptive terms. For each modality, results were recorded in a contingency matrix (hays × terms) where only terms cited at the minimum five times for at least one sample, were kept for data analysis. A correspondence analysis (CA) was performed on the contingency matrix to plot both samples and descriptive terms on a χ2 metric map. Then, a Hierarchical Ascending Classification (HAC) was performed on the coordinates of samples in the CA space. Clusters were identified by truncating the HAC tree-diagrams. The attributes that defined the best resulting clusters were identified by computing their probability of characterizing a cluster. Correlations were computed between each biochemical parameter on one hand, and the first two dimensions of the CA map on the other. Finally, correlations between the values of each hay on the first dimension of the three CA maps (appearance, odour and texture) were computed. Hedonic descriptive terms were primarily used for describing odour and texture modalities. For describing hay appearance, participants spontaneously used visual cues referring to colour or aspect. Based on the tree-diagrams resulting from the HAC, 3, 5 and 2 groups were clustered, respectively for appearance, odour and texture description. Digestible energy was correlated to the first dimension on the three CA maps, whereas CP was correlated to the first dimension of the CA appearance map only. While NDF value was correlated to the first and second dimensions on the CA odour map only, ADF content was correlated to the first dimension on the three CA maps. Non-fibre carbohydrates were correlated to the first dimension of the CA appearance map only. The similarity-based approach which is part of the standard toolbox of food sensory evaluation by untrained consumers was well adapted to animal feeds evaluation by non-experts.

Eggs of Marphysa gravelyi are spawned in gelatinous masses and the developing larvae are harboured in them until they are ready to undergo settlement. In order to understand the function of the jelly mass, morphometric, histochemical, biochemical and antimicrobial analyses were performed. The observations indicate the fibrous jelly mass is composed of carbohydrate, protein and lipid, and size is correlated to number of eggs present within. Extracts from the jelly mass of Marphysa gravelyi exhibit inhibitory activity against Escherichia coli, Vibrio vulnificus and Candida albicans but no activity was seen against seven other microorganisms tested. The results show that the function of the jelly mass is to nourish the developing embryos, protect against desiccation and predation from macrofauna, and most importantly prevent the dispersal of the juveniles from the desirable habitat.

In many coastal areas substrate is the limiting resource for benthic organisms. Some sessile species can be used as secondary substrate, reducing competition and increasing coexistence. In southern Chile, annual populations of Macrocystis pyrifera recruit and grow on the shells of Crepipatella fecunda. This study describes ecological interactions between the kelp and the slipper limpet over an annual cycle. The degree of kelp overgrowth was established by collecting sporophytes and through in situ submarine photography over a 10 month period (starting when kelp recruits became visible and ending when sporophytes were no longer present). Changes in the biochemical composition of the limpet tissue were also recorded by chemical analyses, to evaluate the potential effects (positive/neutral/negative) of kelp on C. fecunda nutritional condition. The results indicate that both species coexist, although kelp overgrowth may cause a decrease in carbohydrates in C. fecunda tissues, restricted to the period when the kelp forest reaches its maximum biomass. Individually, the short duration of the maximum overgrowth period and the size reached by C. fecunda females (up to 65 mm shell length) may enable rapid limpet recovery, avoiding competitive exclusion. On a population level, the M. pyrifera annual cycle generates the needed ‘break’ for C. fecunda populations, reducing the effects of kelp overgrowth. Thus, in the view of the neutral effect of kelp overgrowth, together with the positive effect of C. fecunda on M. pyrifera recruitment described somewhere else, this ecological interaction can be categorized as commensalism.

The Norway lobster, Nephrops norvegicus is a target fishery species in European waters. The stock assessment of N. norvegicus is complicated because it is caught in commercial gear only when it emerges from its burrow. Landings are lower in winter, and feeding limitations have been hypothesized as the cause. Wild large-sized male lobsters were sampled each season (winter, spring, summer and autumn), and two groups of animals were kept in captivity for 90 d (fed and food-deprived). The hepatopancreas and muscle were dissected, weighted, frozen for biochemical analyses (proximal analyses and DNA/RNA) and fixed in Bouin solution for microscopic observations. The oxygen consumption rates in the wild individuals caught in the spring and in the captive animals after the treatments were measured. Significant differences among the experimental groups were observed in the lipid concentration of the hepatopancreas and muscle, the water content in the hepatopancreas, and the numbers of vacuoles and pyknotic nuclei in the cells of the tubules of the hepatopancreas. The results showed that the wild Norway lobsters generally presented intermediate values between those observed in the food-deprived and the fed lobsters kept in captivity, but the values were closer to those obtained for the fed animals. This finding indicates that the wild animals exhibit a good nutritional condition throughout the year. Therefore, the wild males of N. norvegicus do not face food deprivation during winter as is suggested by the pattern of commercial catches, the flow of organic matter, and the moulting period/reproductive behaviour of the species.

In order to study the nutritive value and patterns of variation in biochemical composition of Mesopodopsis zeylanica, the protein, carbohydrate and lipid content of freshly caught mature males, immature males, spent females, brooding females, immature females and juveniles for two seasons were determined. The biochemical composition reveals high nutritional quality of mysid and it varies with different seasons and developmental stages. Among the biochemical composition, protein was the principal component. Significant differences were observed in protein, carbohydrate and lipid content between different developmental stages. Trophic conditions and reproductive strategy were the major factors that determine the seasonal patterns of variation in biochemical composition. Mature males and females showed higher protein content than other stages, while carbohydrate content was high in immature stages, and lipid content was high in brooding females.

Gametogenic cycle, gross biochemical composition, condition indices and soft tissuecaloric value of the brown mussel Perna perna were investigated in thecoastal waters of the Gulf of Aden over ten months, to delineate ecophysiologicalperformance of the bivalve. The timing of reproductive activity and seasonal variations ofphysiological features appear to depend on interaction of environmental (exogenous) andinternal (endogenous) factors. Two major spawning events occurred during seasonal monsoonsi.e. in late summer (SW monsoon, August-September) and early spring (NW monsoon,February-March), although these differed considerably in relative intensity and the extentof the resulting changes in physiology and body weight. The summer breeding, which wascorrelated with low water temperature and abundant food, exerted little effect onbiochemical constituents, indicating protracted and portioned spawning. Reserve stores(lipids, carbohydrates and proteins) accumulated gradually in the cooler inter-monsoonperiod of gametogenic quiescence, to provide energy for periods of natural nutritionalstress when water temperature increased and primary production diminished. The secondspawning in spring was accompanied by a substantial decrease in lipids, carbohydrates andcondition indices of the mussels probably due to the release of nutrient-rich gametes inadaptive response to lower food availability in the environment. High reproductive effortpresumably induced increased mortality of females, which were strongly outnumbered bymales at a ratio of 1.8:1.0. Caloric value of this mussel falls within a range typical formussel species in other subtropical areas, highlighting the importance of Pernaperna as a local food resource and its potential suitability foraquaculture.

The nutrient status of microalgae inhabiting sea ice in McMurdo Sound, Antarctica was evaluated during the peak and decline of the spring bloom in November and December. Natural populations of microalgae were analysed for C, N, chlorophyll a, protein, lipid, polysaccharide, and low-molecular-weight carbohydrate content, and for the distribution of 14C-labelled photosynthate into macromolecular fractions. Ratios of N:C and protein to carbohydrate (PR:CHO) were similar to values reported for nutrient-limited phytoplankton. Biochemical ratios and 14C-photosynthate allocation patterns suggest that microalgae from congelation ice habitats may be more nutrient-stressed than those from underlying platelet ice habitats. This trend would be consistent with the presumed gradient of seawater nutrient influx through the platelet layer to the bottom congelation ice habitat. Microalgae from congelation ice subjected to an experimental depletion of nutrients (particularly nitrate) showed decreased N:C, PR:CHO, and allocation of 14C-photosynthate to proteins. This evidence suggests that sea ice microalgae are nutrient-stressed during the peak and decline of the spring bloom in McMurdo Sound, which presumably begins when microalgal biomass concentrations and demands for growth reach or exceed the rate of nutrient supply from underlying seawater.

Particulate organic matter was collected in the coastal waters of Terra Nova Bay during the Oceanographic Campaign of the Italian Antarctic Research Programme in summer (January–February) 1990. Particulate matter composition was analysed for organic carbon and nitrogen, carbohydrates, proteins, lipids, nucleic acids (DNA and RNA) and ATP. A vertical stratification was evident in the study area, and resulted from prior melting of the pack ice. Suspended organic matter in the mixed layer and below the mixed layer differed in quantitative and qualitative composition. Except for ATP, all the biochemical components showed higher concentrations in the mixed layer than in the deeper waters. The particulate organic matter in Terra Nova Bay was mostly detrital and of algal origin.

As part of the Ross Sea Marginal Ice Zone Ecology Project (ROSSMIZE) the summer organic matter flux through the water column was measured at 40 m depth in Terra Nova Bay. Water samples and material from a sediment trap on the sea-bottom were analysed for their biochemical composition. A close coupling between biochemical composition of the organic matter in the water column and the material collected in the sediment trap was found, resulting from complex interactions between physical and biological processes. The physical processes are related to break-up and melting of the ice cover and occur mainly in the early summer season, whilst biological processes play a key role in mid summer and, from the evidence from faecal pellets, are related to the primary production and consumption processes.

The biomass and the biochemical composition of periphyton were studied during one year in three streams of Réunion Island. The results revealed that nutritional conditions for fish development were most favourable during the dry season. The nutritive value of periphyton was highest in the Marsouins and Mât streams and remained the lowest in the Roches stream. Food availability was strongly affected by high flow, particularly during the exceptional hydrological events of February 1998 (cyclonic high flows). Study of seasonal variations of morphophysiological characteristics and biochemical composition (lipids, proteins) of the grazer gobiidae Sicyopterus lagocephalus showed that inspite of unfavourable nutritional conditions caused by hydrological disturbances, fish continue their reproduction which coincides with the summer high flow period. The significant depletion of lipid reserves which express a deterioration in animal condition is influenced by flooding period. At this time of gonad development involving an additional energy investment, fish were not able to recover a stable nutritional state after the complete achievement of the reproduction cycle. Except during this period, there is a weak participation of the reproductive physiological processes in the seasonal changes of somatic composition of this fish.

The biochemical composition of Daphnia magna Straus, the dominant planktonic crustacean of the waste stabilisation pond of Differdange (Grand-Duchy of Luxembourg), was quantitatively determined from October 1993 to July 1994. Over the sampling period, the average composition (mean ± S.D.) was 271 ± 64 mg proteins.g-1 dry weight (DW), 100 ± 28 mg lipids.g-1 (DW), 96 ± 58 μg carotenoids.g-1 (DW), 49 ± 14 mg chitin.g-1 (DW) and 125 ± 78 mg ash.g-1 (DW). The seasonal variations of the biochemical composition were related to several ecological variables (water temperature, dissolved oxygen concentration, pH, water transparency, chlorophyll a concentration and D. magna biomass). The chitin content was positively correlated to the water temperature as a result of the strong influence of this later variable on the moulting rate of the daphnids and, subsequently, on the chitin synthesis by these organisms. The carotenoid content was positively correlated to the water transparency as a result of their photoprotective role in daphnids. The fluctuations of the lipid, protein and ash levels in D. magna depended to the food availability. Despite a seasonal variation in the biochemical composition, D. magna appeared to have adequate lipid and protein levels to be used in aquaculture. Its carotenoid content is similar to fish meals used to color salmonid flesh and these organisms could be used for this purpose. The prospect of using D. magna for chitin extraction is worth considering with respect to its significant chitin content, especially if highly valuable applications are aimed.

L'évolution de la structure du peuplement zooplanctonique du lac de Pareloup (Aveyron, France) ainsi que la composition biochimique du plancton, ont été suivies au cours de deux années : en 1993, lors de la vidange progressive de cette retenue et en 1994, durant la phase de recolonisation du milieu. Les Crustacés planctoniques sont essentiellement représentés par Daphnia longispina, Ceriodaphnia quadrangula, Bosmina longirostris, Cyclops vicinus vicinus, Acanthocyclops robustus et Eudiaptomus vulgaris. Les Cladocères dominent le peuplement durant l'hiver et le début du printemps 1993. En 1994, leur développement est maximal en mai puis ils restent proportionnellement bien représentés en été. Les Cyclopides constituent la majeure partie de la communauté en juin 1993 et durant le début de la phase de recolonisation (automne 1993 - hiver 1994). La densité moyenne maximale des Crustacés (67 ind./litre) est observée en octobre 1993 juste après la remise en eau. L'impact potentiel du zooplancton sur la communauté phytoplanctonique révèle le rôle prépondérant des petits brouteurs de janvier à juin 1993. En revanche, ce sont les grands brouteurs avec en moyenne 67 % du volume potentiel d'eau filtrée, qui constituent d'octobre 1993 à juin 1994, les principaux régulateurs de la population algale. La biomasse moyenne au printemps 1993 est de 59 µg PS/litre, celle enregistrée pour la même saison en 1994 est de 103 µg PS/litre. Une augmentation significative des teneurs en lipides et protéines est notée dans le plancton en 1994. La diminution du contrôle exercé par les poissons planctonophages éliminés lors de la vidange (80 tonnes) explique les variations de la structure et de la composition biochimique du peuplement planctonique.

Les études menées au cours de quatre années sur la composition corporelle de la perche (Perca fluviatilis, L.) et du gardon (Rutilus rutilus, L.) de la retenue de Pareloup ont révélé certaines années, pendant la période estivale et essentiellement chez la perche, une diminution des lipides somatiques accompagnée soit d'un ralentissement soit d'un arrêt de l'accrétion protéique. En fin d'automne, on a pu observer une croissance compensatrice chez les animaux qui auraient subi des conditions nutritionnelles défavorables en été.La composition biochimique du plancton au cours du cycle saisonnier montre que la valeur nutritive du phytoplancton et du zooplancton est maximale en été. Par contre, on a observé une diminution de la quantité disponible au cours de l'automne, ce qui implique un élargissement du spectre alimentaire des deux espèces. La variabilité interannuelle de la structure du peuplement et de la biomasse planctonique disponible en été pourrait expliquer l'utilisation des réserves énergétiques chez les poissons à cette saison.

In the bay of Marennes-Oléron the dry flesh of Crassostrea gigas ranged from 29 to 52% proteins,10 to 23% ash, 6 to 20% lipids and 0 to 4% carbohydrates of which 48.3 ± 21.6% were glycogen. The energy value ranged from 18.84 to 23.47 joule.mg−1 ash free dry weight (mean 20.27 J.mg−1). Reproductive effort varied from 17.8 to 55.9% dry weight for males, and 43.1 to 61.9% for females during the first and third year of reproduction respectively. A high energy value for female gametes(23.47 to 26.24 J.mg−1 dry tissue) was mainly due to a higher level of lipids (17.3 to 23% of dry tissue) in female gametes as compared to that in male gametes (5.9 to 12.3% of dry tissue). During the period of mass-loss which began in October and finished in March, the poor trophic conditions of the environment resulted in the use of 74.6% of glycogen, 44% of lipids and 36% of proteins to meet more than 50% of the requirements for basal metabolism.