Combined effects of temperature and diet on the performance of larvae produced by young and old Palaemon serratus females.

Seasonal variations in environmental conditions determine the success of decapod larval development, and females transmit more energy in sub-optimal conditions to maximise the fitness of their offspring. The objective of this study was to focus on the combined effects of temperature (14, 18 and 22 °C) and food quality on the performance of larvae produced by 5 young (0+) and 5 old (I+) Palaemon serratus females. We prepared 3 diets based on Artemia, in decreasing order of total fatty acid content: freshly hatched nauplii (N), unenriched metanauplii (M) and metanauplii enriched with a mixture of microalgae (ME). At hatching, the larvae produced by I+ females had a higher biomass but a similar fatty acid concentration to those produced by 0+ females. Larvae survived better and developed relatively faster as temperature increased, and the longer they waited to metamorphose, the greater their weight at metamorphosis. These performances were diet-dependent, with more survival and more growth in less time with diet N than with the other two. Larvae from I+ females performed better than those from 0+ females, especially under the most stressful conditions. The greater biomass of the larvae of I+ females seems to have enabled them to follow a shorter, and therefore faster, development path than those of 0+ females. The larvae's diet also had an impact on post-metamorphic composition: larvae eating a diet richer in fatty acids produced richer juveniles and those eating a poorer diet produced juveniles with slightly more essential fatty acids. This study supports the high plasticity of caridean shrimp larval development and the importance of maternal effects on the fitness of offspring.

Larval feeding activity and use of embryonic resources determine juvenile performance of the common prawn Palaemonserratus.

Phenotypic links are the potential for "carryover" of effects of experience during one life history stage into performance and selection at subsequent stages. They reflect plastic responses to the environment experienced during an early phase on the phenotype of subsequent phases. We are studying these effects by following individuals of the shrimp Palaemon serratus from the embryonic (eggs carried by females) through the larval phase (pelagic) to the juvenile phase (benthic). In experiment 1, we investigated the effects of larval prey concentration (10, 4 and 2 Artemia/mL) and larval incubation temperature (16 and 22 °C) on larval performance (metamorphosis rate, developmental duration and growth) and then on juvenile performance (survival and Specific Growth Rate, SGR, at 18 and 24 °C in 14 days). In experiment 2, we investigated the effects of embryonic incubation temperature (larval biomass and lipid content of newly hatched larvae from embryos incubated at 12 and 18 °C) and larval prey concentration on larval performance and then on juvenile performance. In both experiments, the larvae plastically increased their development time in response to the reduction in temperature and prey concentration, whereas their survival decreased with temperature and prey concentration. The quantity of lipids available at hatching decreased with decreasing embryonic incubation temperature, which reduced the larval performance, particularly with a low concentration of prey. Survival at 14 days post-metamorphosis was significantly reduced when the embryos were incubated at 12 °C compared with those incubated at 18 °C, regardless of the subsequent larval incubation conditions, revealing phenotypic links between overconsumption of embryonic yolk reserves and post-metamorphic fitness. Overall, juveniles had a better SGR at 24 than at 18 °C, and even better when incubated under stressful embryo-larval conditions (temperature and prey concentration). This study highlighted phenotypic links between developmental stages and over developmental periods of several months.

Advancing environmental monitoring across the water continuum combining biomarker analysis in multiple sentinel species: A case study in the Seine-Normandie Basin (France).

Nowadays, biomarkers are recognized as valuable tools to complement chemical and ecological assessments in biomonitoring programs. They provide insights into the effects of contaminant exposures on individuals and establish connections between environmental pressure and biological response at higher levels. In the last decade, strong improvements in the design of experimental protocols and the result interpretation facilitated the use of biomarker across wide geographical areas, including aquatic continua. Notably, the statistical establishment of reference values and thresholds enabled the discrimination of contamination effects in environmental conditions, allowed interspecies comparisons, and eliminated the need of a reference site. The aim of this work was to study freshwater-estuarine-coastal water continua by applying biomarker measurements in multi-species caged organisms. During two campaigns, eight sentinel species, encompassing fish, mollusks, and crustaceans, were deployed to cover 25 sites from rivers to the sea. As much as possible, a common methodology was employed for biomarker measurements (DNA damage and phagocytosis efficiency) and data interpretation based on guidelines established using reference values and induction/inhibition thresholds (establishment of three effect levels). The methodology was successfully implemented and allowed us to assess the environmental quality. Employing multiple species per site enhances confidence in observed trends. The results highlight the feasibility of integrating biomarker-based environmental monitoring programs across a continuum scale. Biomarker results align with Water Framework Directive indicators in cases of poor site quality. Additionally, when discrepancies arise between chemical and ecological statuses, biomarker findings offer a comprehensive perspective to elucidate the disparities. Presented as a pilot project, this work contributes to gain insights into current biomonitoring needs, providing new questions and perspectives.