Health indicators and contaminant levels of a critically endangered species in the Gironde estuary, the European sturgeon

Abstract

The European sturgeon, Acipenser sturio, is a highly endangered species that almost disappeared in the last decades. Thanks to yearly restocking of the population, this species is still found in the Gironde estuary (France), where juveniles grow during several years before leaving to the ocean. The aim of this study was to evaluate the pressure exerted on these fish by known organic and inorganic contaminants during their stay at the Gironde estuary, and to get information on the fish's health in this context. Monthly captures over the year 2014, provided 87 fish from the cohorts 2012 and 2013 mainly, and from cohorts 2008, 2009 and 2011, all fish born in hatchery. We report the very first analyses of contaminant levels and of biological markers measured in the blood of these fish. Low inorganic contamination was found, composed of seven metals mainly: Zn (< 5 µg.mL-1), Fe (< 1.5 µg.mL-1), Cu (< 0.8 µg.mL-1), Se (< 0.8 µg.mL-1), As (< 0.25 µg.mL-1), Co (< 0.14 µg.mL-1) and Mn (< 0.03 µg.mL-1). Concerning persistent organic contaminants, the sum of 7 PCBs varied from 1 to 10 ng.g-1 plasma, that of 8 OCPs from 0.1 to 1 ng.g-1 , and that of 8 PBDEs from 10 to 100 pg.g-1. Higher levels of contaminants were measured during spring as compared to summer. The sex steroid hormone plasma levels (estradiol, testosterone and 11ketotestosterone) were quite low, which 2 was predictable for juveniles. The transcription of reproduction-involved genes (EstR, AR, LHR, sox9) in blood cells was demonstrated for the first time. Some of them were correlated to organic contaminant levels PCBs and OCPs. Other gene transcriptions (sodCu and bax) were correlated to PCBs and OCPs. However, the DNA damage level measured here as comet tail DNA and micronuclei ratio in red blood cells, were in the very low range of the values commonly obtained in fish from pristine areas. The data presented here can serve as a reference base for future monitoring of this population of sturgeons.

The Influence of Natural and Anthropogenic Environmental Pressures on European Eel Abundances in French Estuaries

“…Eels exposed to pollutants are more susceptible to parasites such as the parasite Anguillicola crassus, a non-native species that infects eels and causes pathological damage to the swim bladder, impairing their ability to cope with hypoxic conditions [91,92]. Larger estuaries, such as the Seine and the Gironde, have higher concentrations of pollutants [93,94] and exhibit poor water quality, which we found to be associated with low eel abundances. The contaminants may affect the reproductive success of eels, exacerbating population decline.…”

Aliphatic hydrocarbons in fin spines of adult sturgeon (Acipenser stellatus) and their relationship with potentially toxic elements in the northern and southern regions of the Caspian Sea

“…Apart from the harmful effects of oil itself, the adverse effects of As on fish health include various mechanisms of acute and chronic toxicity, ranging from enzymatic, genetic, and immune system failures, which alter normal biological functions, resulting in the direct initiation of diseases or, at least, in the body’s predisposition to them (Kumari et al 2016 ). Regarding this concern, Acolas et al ( 2020 ) determined As concentrations of less than 0.25 µg/mL in European sturgeon ( Acipenser sturio ) in the Gironde estuary in France. Although it is true that they used a different biological matrix, such as blood, these are much lower concentrations than those determined in any area of this study.…”