Mussel as a Tool to Define Continental Watershed Quality

Bivalves appear as relevant sentinel species in aquatic ecotoxicology and water quality assessment. This is particularly true in marine ecosystems. In fact, several biomonitoring frameworks in the world used mollusks since several decades on the base of contaminant accumulation (Mussel Watch, ROCCH) and/or biological responses called biomarker (OSPAR) measurements. In freshwater systems, zebra and quagga mussels could represent alternative sentinels, which could be seen as the counterparts of mussel marine species. This chapter presents original studies and projects underlying the interest of these freshwater mussels for water quality monitoring based on contaminant accumulation and biomarker development measurements. These sentinel species could be used as a tool for chemical/biological monitoring of biota under the European water framework directive and for the development of effect-based monitoring tools

Influence of a multistress (cadmium and temperature) on the reproduction of the three-spined stickleback (Gasterosteus aculeatus)

Human activities introduce significant amounts of organic and inorganic pollutants (trace metals) into aquatic environments. However, this contamination occurs within a large context that concerns the scientific community since the last decades: global warming. The complex nature of the interactions between toxic substances and temperature presents new challenges to improve the risk assessment for aquatic environments. Thus, the study of these interactions proves an essential priority for toxicologists. This study aims to evaluate the effect of chronic exposure to both chemical (cadmium) and physical stress (temperature) on the reproduction of a river fish widely used in ecotoxicology: three-spined stickleback (Gasterosteus aculeatus). For this, juvenile sticklebacks were exposed to 1µg.L-1 of cadmium for 4 months in semi-static conditions at two different temperatures, i.e. 16°C and 21°C. Water quality and cadmium concentration in the water were monitored throughout the experiment. Parameters such as somatic indices (height, weight, GSI) were measured at 15, 60, 90 and 120 days interval after cadmium exposure. Reproductive capacity was evaluated by performing several rounds of in vitro fertilization and monitoring of the offspring. The fertilization rate, mortality and birth defects were evaluated until the end of the larval stage (21 days post fertilization “dpf”). In total, 20 in vitro fertilizations were performed during this experiment with different results for each group. A decrease in fertilization rate was observed under the effect of temperature 21°C (84.79 ± 12%), which seems to be accentuated by the presence of cadmium (77.26 ± 31%). Similarly, the rate of embryonic and larval mortality seems to follow the same trend, with a rather large effect of temperature, especially in the presence of cadmium. Temperature 21°C in presence of cadmium delays the moment of hatching about two days compared to controls (10.5 ± 0.71 dpf Vs 8.67 ± 1.15 dpf). Several malformations were observed in all groups including the control group with predominance in groups from parents exposed to cadmium at 16°C (11.79 ± 10.8%). Our results showed fairly significant and worrying effects of a very low dose of cadmium (1µg.L-1) on the parents and their offsprings. Most studies reported in the literature on the effects of cadmium were demonstrated with much higher doses than used in our study. Further experiments are needed to complete and validate these results

The three spined-stickleback's digestive enzymes as new biomarkers in environmental monitoring: effect of cadmium and temperature

The three-spined stickleback, is a freshwater, brackish, and marine fish species with large distribution throughout the northern Hemisphere. This pollution-tolerant fish is present in most European streams and small rivers but also coastal and estuarian areas, which make it a suitable candidate for environmental monitoring and risk assessment of aquatic ecosystems. Several biomarkers have been developed for this animal model. This study aims at characterizing and developing a new category of biomarkers in relation with energy acquisition, in sticklebacks. Among these parameters, digestive capacities of many invertebrates and vertebrates aquatic organisms have demonstrated a good sensitivity to contaminants. Thus, in this context, the most important digestive enzymes were firstly characterized in this sentinel species, according to it diet, in optimal living conditions. Secondly male and female juvenile sticklebacks were exposed for 3 months in semi-static conditions to cadmium at 1µg.L-1 (chemical stress), and two temperature values 16°C and 21°C (physical stress). Water quality and cadmium concentration in the water were also monitored throughout the experiment. Parameters such as somatic indexes (height, weight, fulton’s condition index) and digestive enzymes (trypsin, intestinal alkaline phosphatase and amylase) were measured at 15, 60 and 90 days interval after cadmium exposure. The results have demonstrated a significant decrease in biometric parameters, from the 3rd month, especially among groups subjected to a temperature of 21 ° C. Furthermore, we observed an important alteration of the activity of the different enzymes over time and especially for trypsin and alkaline phosphatase in individuals exposed to cadmium at 21°C suggesting interactions between chemical and physical stresses on biological responses. For the first time, the digestive enzymes of the three-spined stickleback are reported as new environmental biomarkers

Consequences of lower food intake on the digestive enzymes activities, the energy reserves and the reproductive outcome in Gammarus fossarum.

Digestive enzyme activity is often used as a sensitive response to environmental pollution. However, only little is known about the negative effects of stress on digestive capacities and their consequences on energy reserves and reproduction, although these parameters are important for the maintenance of populations. To highlight if changes in biochemical responses (digestive enzymes and reserves) led to impairments at an individual level (fertility), Gammarus fossarum were submitted to a lower food intake throughout a complete female reproductive cycle (i.e. from ovogenesis to offspring production). For both males and females, amylase activity was inhibited by the diet stress, whereas trypsin activity was not influenced. These results underline similar sensitivity of males and females concerning their digestive capacity. Energy reserves decreased with food starvation in females, and remained stable in males. The number of embryos per female decreased with food starvation. Lower digestive activity in males and females therefore appears as an early response. These results underline the ecological relevance of digestive markers, as they make it possible to anticipate upcoming consequences on reproduction in females, a key biological variable for population dynamics

Influence of molting and starvation on digestive enzyme activities and energy storage in Gammarus fossarum.

Among the many biological responses studied in ecotoxicology, energy-based biomarkers such as digestive enzyme activities and energy reserves appear to be useful predictive tools for detecting physiological disturbances in organisms. However, the use of these biological responses as biomarkers could be limited by the effects of confounding factors (biotic and abiotic) and physiological processes, such as the reproductive cycle. Thus, the optimal use of these biomarkers will be facilitated by understanding the effects of these factors on the energy metabolism of the sentinel species being studied. We considered abiotic factors (temperature and conductivity) in a previous study, whereas the present study investigated the effects of gender, the female reproductive stage, and food availability on the digestive enzyme activities and energy storage of Gammarus fossarum. The results indicated that, during the female reproductive cycle, the activities of digestive enzymes (amylase, cellulase, and trypsin) decreased significantly, whereas the levels of reserves (proteins, lipids, and sugar) increased until the last premolt stage. Restricted food diets only led to decreased amylase activities in both sexes. Food starvation also induced a decrease in the energy outcomes in females, whereas there were no effects in males. In general, the biochemical (digestive enzyme activities) and physiological (energy reserves) responses were more stable in males than in females. These results support the use of males fed ad libitum to limit the effects of confounding factors when using these energy biomarkers in Gammarus fossarum during biomonitoring programs

The three spined-stickleback's digestive enzymes as new biomarkers in environmental monitoring: effect of cadmium and temperature

The three-spined stickleback, is a freshwater, brackish, and marine fish species with large distribution throughout the northern Hemisphere. This pollution-tolerant fish is present in most European streams and small rivers but also coastal and estuarian areas, which make it a suitable candidate for environmental monitoring and risk assessment of aquatic ecosystems. Several biomarkers have been developed for this animal model. This study aims at characterizing and developing a new category of biomarkers in relation with energy acquisition, in sticklebacks. Among these parameters, digestive capacities of many invertebrates and vertebrates aquatic organisms have demonstrated a good sensitivity to contaminants. Thus, in this context, the most important digestive enzymes were firstly characterized in this sentinel species, according to it diet, in optimal living conditions. Secondly male and female juvenile sticklebacks were exposed for 3 months in semi-static conditions to cadmium at 1µg.L-1 (chemical stress), and two temperature values 16°C and 21°C (physical stress). Water quality and cadmium concentration in the water were also monitored throughout the experiment. Parameters such as somatic indexes (height, weight, fulton’s condition index) and digestive enzymes (trypsin, intestinal alkaline phosphatase and amylase) were measured at 15, 60 and 90 days interval after cadmium exposure. The results have demonstrated a significant decrease in biometric parameters, from the 3rd month, especially among groups subjected to a temperature of 21 ° C. Furthermore, we observed an important alteration of the activity of the different enzymes over time and especially for trypsin and alkaline phosphatase in individuals exposed to cadmium at 21°C suggesting interactions between chemical and physical stresses on biological responses. For the first time, the digestive enzymes of the three-spined stickleback are reported as new environmental biomarkers

Effect of ethofumesate herbicide on energy metabolism in roach (Rutilus rutilus)

International audienc

Food Deprivation and Modulation of Hemocyte Activity in the Zebra Mussel ( Dreissena polymorpha )

International audienc