Influence of organs, body size and growth and domoic acid depuration in the king scallop, Pecten maximus.

Abstract

Since 1995, European fisheries of Pecten maximus faced the presence of Pseudo-nitzschia species, which are able to produce the neurotoxin domoic acid responsible for Amnesic Shellfish Poisoning (ASP). As filter-feeders, scallops can accumulate and retain domoic acid much longer than most of the other bivalves, from months to years. When concentrations exceed the regulatory threshold, fisheries are closed leading to economic crisis. Inter-individual variability increases the difficulty to predict the depuration dynamics. Quantifying the correlations between domoic acid depuration in P. maximus and individual physiological traits, particularly body size, could improve the understanding of contamination and depuration. In this study, toxin dynamics in organs were analysed and the effects of body size and growth were assessed. This analysis was based on two datasets, one experimental and one in situ, of depuration monitoring of P. maximus exposed to a natural bloom of toxic P. australis. Results show that the distribuwtion of domoic acid shifted among organs between the contamination and after two months of depuration. Toxin concentrations negatively correlate with body size during contamination and after two months of depuration, but shift to a positive correlation after 7 months of depuration. This shift suggests that the smaller scallops accumulate more domoic acid and depurate it faster. Thus, dilution by growth can explain the reversal of the correlation between domoic acid and body size throughout depuration. These results yield useful information for modelling such mechanisms, providing valuable tools for scallop fishery management facing ASP. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=60 SRC="FIGDIR/small/708139v3_ufig1.gif" ALT="Figure 1"> View larger version (16K): org.highwire.dtl.DTLVardef@10e61deorg.highwire.dtl.DTLVardef@13b44b9org.highwire.dtl.DTLVardef@1cdba6org.highwire.dtl.DTLVardef@989861_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LIExperimental and in situ datasets allowed to quantify DA proportion dynamics in organs of P. maximus C_LIO_LIDA concentration and body size are negatively correlated during contamination phase, but positively correlated after a 7-month depuration C_LIO_LIConsidering dilution by growth is important for young scallops to assess DA depuration dy-namics C_LIO_LIBoth depuration rate and dilution by growth need to be considered to model DA depuration over the whole scallop size range C_LI