Can mysid shrimp help us unravel possible endocrine disruption in marine environments?

Changes in the hormone regulation in animals due to environmental contaminants (endocrine disruptors) has recently become a widely investigated and politically charged issue. Invertebrates account for 95% of the known species of animals on earth, yet surprisingly little effort has been made to understand their value in signaling potential environmental endocrine disruption. A few reports, however, do suggest that endocrine disruptive effects also affect invertebrates. Due to the high pollutant load of the Scheldt estuary and North Sea, effects on resident populations may occur. A recent database published by our laboratory summarizes the possible effects of potential endocrine disruptive compounds for the North Sea ecosystem. Mysids are used frequently in toxicity studies and there is growing interest in developing toxicity tests with mysids that are indigenous to local ecosystems. Furthermore, United States Environmental Protection Agency (USEPA) has included mysid shrimp as part of a tiered approach in its Endocrine Disruptor Screening Program. In this context, we are examining the potential use of Neomysis integer as a test organism for determining the effects of endocrine disruptors on northern European estuarine communities. The hyperbenthic N. integer dominates the upper regions of European estuaries and are thought to provide a significant link in the exchange of organic matter between the benthic and pelagic systems of estuaries. Cellular and physiological biomarkers for endocrine disruption related to the energy and steroid metabolism of N. integer have been developed and are currently being evaluated in an inter-laboratory validation study. The results obtained with these biomarkers are linked to ecological field observations and measured concentrations of selected endocrine disruptors in the Scheldt estuary (Netherlands). Results of the biomarker studies and field samplings will be highlighted and suggestions on the use of this invertebrate model to test possible endocrine disruptive effects in estuarine environments will be discussed

Endocrine disruptors in the Scheldt estuary (2)

The Scheldt Estuary is known as one of the more polluted estuaries in Europe (OSPAR, 2000). All major compartments of the estuary, i.e. water, suspended matter, sediments and biota, may be contaminated with chemicals such as polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs) and organotin compounds. In the framework of the ENDIS-RISKS project, the different compartments of the estuary were sampled during the last 2 years and the concentration levels of 22 different polycyclic aromatic hydrocarbons (PAHs), 18 polybrominated diphenylethers (PBDEs), 5 OCPs, 16 PCBs and 6 organotin compounds were determined. For the biota, mysids were selected as indicator organism for this particular ecosystem. In this group of organisms, the highest contaminant levels were found for TBT with concentrations of up to 2500µg/kg on a dry weight basis (or approx. 100µg/kg on a wet weight basis). With an ecotoxicological assessment criterium (EAC) - as established by OSPAR - of 2.4µg/kg on wet weight basis, the EAC is exceeded by a factor of 50 at some sampling stations. For the same species, the body concentrations of SPCB7 varyied from 200 to 1400µg/kg (dry weight), again exceeding the OSPAR-EAC by a factor of more than 100. OCPs and PAHs are found in quantities varying from 5 to 100µg/kg (dry weight) which is below the EAC, except for lindane (EAC 0.29µg/kg on wet weight basis)

Endocrine disruptors in the Scheldt estuary: distribution exposure and effects

The Scheldt Estuary is known as one of the more polluted estuaries in Europe (OSPAR, 2000). The major compartments of the estuary, i.e. water, suspended solids, sediments and biota, are all affected by common POPs (persistent organic pollutants). In the framework of the ENDIS-RISKS project these compartments were frequently sampled during the last four years and analysed for these POPs indicated as possible endocrine disruptors. As such, the concentration levels of 22 different polycyclic aromatic hydrocarbons (PAHs), 18 polybrominated diphenylethers (PBDEs), 5 organochlorine pesticides (OCPs), 16 polychlorinated biphenyls (PCBs) and 6 organotin compounds e.g. TBT were determined by the MUMM laboratory. Their distribution (speciation within different compartments), concentration and geographic distribution are assessed. For the biota compartment, mysids were selected as an indicator organism for this particular ecosystem. In these invertebrates, the highest levels ever found for TBT were noted, with concentrations of up to 2500µg.kg-1 on a dry weight basis (or approx. 100µg.kg-1 on a wet weight basis). In the same species, SPCB7 levels varying from 200 to 1400 µg.kg-1 on dry weight were noted. OCPs and PAHs concentrations varied from 5 to 100µg.kg-1dw. The geographic distribution - along the salinity gradient of the Scheldt Estuary - of the body burdens of these compounds in mysids are discussed. Finally, the observations were compared to internationally accepted ‘Ecotoxicological Assessment Criteria’ used to assess the potential adverse effects on the ecosystem