In-situ microcosms, a tool for assessment of pesticide impacts on oyster spat (Crassostrea gigas)

Abstract

Effects of the herbicide Basamaïs (bentazon) and the fungicide Opus (epoxiconazole) on oyster spat (Crassostrea gigas) were assessed using in-situ microcosms in a field experiment lasting 13 days. Six-week-old hatchery spat (mean size 1.1 mm), previously collected on PVC plates, was immersed in glass bottles filled with 200 mum filtered seawater. Bottles were maintained underwater at 6 m depth and their water content changed every other day. Growth, measured as shell area index increase, was 126 +/- 4% in the control bottles. While no growth differences were observed between control and individual pesticide treatments at 10 microg l(-1), oysters treated with a mix of 10 microg l(-1) Opus and 10 microg l(-1) Basamaïs showed a 50% growth reduction compared with the control (P < 0.0001), suggesting a synergistic effect of these contaminants. Laboratory controls in microcosms maintained in a water bath with filtered natural light, were not significantly different from in-situ microcosm controls in the field, for organic weight content or growth. This in-situ experiment in microcosms allowed us to conclude that: (1) oyster spat can achieve significant growth in bottles immersed in situ without supplementary food; (2) this microcosm system is reliable and easy to use for environmental toxicity tests with C. gigas spat; (3) such microcosm systems can also be run in a laboratory water bath instead of more technically difficult immersed field experiments; (4) the synergistic effect observed here, at a concentration simulating a peak agricultural runoff event, suggests that the impacts of pesticides could be a real threat for oysters in estuarine areas.

Scientific Opinion on the increased mortality events in Pacific oysters,Crassostrea gigas

“…In the Ebro delta a study was published where the authors found a correlation between pesticides concentration in water and shellfish and episodes of mortality in shellfish (Kock et al 2010). A laboratory experiment showed a synergistic effect between the herbicide bentazone and the fungicide epoxiconazole on C. gigas spat at concentrations simulating a peak agricultural runoff event (Stachowski-Haberkorn et al, 2008).…”

Ecotoxicological evaluation of Glyphosate use in controlling E. crassipes e Salvinia sp. macrophytes

“…According to Haberkorn et al (2008), the surfactant may retain the herbicide on the water surface of the aquarium and on the surface of the plant, being the main pathway for its disappearance in the water.…”

EMBRYOLOGICAL AND MICROMANIPULATION TECHNIQUES IN ZEBRAFISH (Danio rerio) AND PACIFIC OYSTER (Crassostrea gigas)

“…For example: cryopreservation of sperm, oocytes and embryos (Chao et al, 1997;Dong et al, 2005;Tervit et al, 2005), embryo/larvae obtaining for toxicologic assays (da Cruz et al, 2007;Stachowski-Haberkorn et al, 2008) or embryo electrofusion, transfection and poliploidy induction studies (Buchanan et al, 2001;Cadoret et al, 1992;Guo et al, 1993;Guo and Allen, 1994) among others. To this respect, in Table 3 the obtaining of both gametes could only be achieved in only 16 sessions from 29.…”

“…The oyster biological interactions with toxic agents can be measured at different stages of their live: in embryos (Beiras and His, 1995;Calabrese et al, 1973), spat (Stachowski-Haberkorn et al, 2008) and adult (Bolognesi et al, 2006). Moreover, of much importance is also the development of chronic or sub-chronic tests, due they may have a higher ecological relevance when dealing with the embryonic development of a key species for the ecosystem at risk (da Cruz et al, 2007;Muller et al, 2009).…”

“…In spat, the assessment of growth differences due to pesticide impacts can be measured by the shell area index increasment (Stachowski-Haberkorn et al, 2008). In adult oysters, there can be evaluated concentrations of selected elements (Schuhmacher and Domingo, 1996), thus allowing the assessment of human health risks from exposure to toxic compounds (ie.…”