Do Temporal and Spatial Parameters or Lifestyle of the Pacific Oyster Crasssostrea gigas Affect Pollutant Bioaccumulation, Offspring Development, and Tolerance to Pollutants?

Perrine Gamain,Pierre-Yves Gourves,Patrice Gonzalez,Hélène Budzinski,Bénédicte Morin,Jérôme Cachot

doi:10.3389/fmars.2017.00058

Abstract

This study evaluated the vulnerability of early life stages of native oysters (Crassostrea gigas) from the Arcachon Bay (SW, France) to pollutants at risk in the lagoon in particular copper and S-metolachlor. Developmental abnormalities in wild and cultivated oyster D-larvae were investigated during 2 breeding-seasons (2013 and 2014) at different sampling sites and dates. In addition, copper and metolachlor concentrations were determined both in seawater and in mature oysters. Bioaccumulation of Cu was observed at higher levels in wild than in farmed specimens. Metolachlor was accumulated at much lower levels. After 24h exposure, significant increases of the percentage of abnormal D-larvae were observed when exposed at 1 µg L-1 of copper or 10 ng L-1 of metolachlor in comparison with the controls whatever the date, the site and rearing conditions of the genitors. The current study demonstrates that environmental concentrations of copper and metolachlor can induce a significant increase of developmental abnormalities in farmed and wild populations of oysters. However, no significant differences of sensitivity were observed according to temporal, spatial parameters and lifestyle of genitors. In addition, oyster larvae obtained from the hatchery displayed the same sensitivity to pollutants as larvae from the field, demonstrating their suitability for toxicity assays and water quality monitoring.

Highlights

Bivalve mollusks such as oysters, mussels, and clams contribute significantly to world aquaculture and the Pacific oyster Crassostrea gigas (Thunberg) is ranked number one in terms of world aquaculture production with 555,913 tons estimated in 2013 (FAO, 2010)
For seawater spiked with 10 ng L−1 metolachlor, the measured concentrations varied between 14 and 44 ng L−1 depending on the background levels of the reference Filtered seawater (FSW)
The larval abnormalities obtained for all control conditions did not show significant differences (14 ± 4.8 and 13 ± 5.2% for oysters from the Arcachon bay or oyster from hatchery respectively), the reference seawaters sampled at different dates and locations were differently contaminated with copper and oysters were from different origins

Summary

Introduction

Bivalve mollusks such as oysters, mussels, and clams contribute significantly to world aquaculture and the Pacific oyster Crassostrea gigas (Thunberg) is ranked number one in terms of world aquaculture production with 555,913 tons estimated in 2013 (FAO, 2010). The mass mortality phenomenon encountered in recent years is often associated with infectious agents, it is often related to environmental changes and highlights the delicate balance that governs an ecosystem Coastal ecosystems such as Arcachon Bay, are under constant increase of anthropic pressure. The quality of coastal waters has been deteriorated in recent years as the population and human activities have increased (Newton et al, 2003) These areas have become over the years the recipient of many contaminants generated by human activities and are exposed to a wide variety of natural and anthropogenic stressors (Adams, 2005). Our objectives here were 2-fold (1) determine if the temporal and spatial parameters or lifestyle of the broodstock oyster of the Arcachon Bay affect the sensitivity of the D-larvae to pollutants and (2) assess if offsprings from adult oysters from the Arcachon Bay which have been living all their life in a Cu and S-metolachlor contaminated area, were more tolerant or not than those from hatchery

Methods

Results

Discussion

Conclusion