Ecological Significance of Endocrine Disruption in Marine Invertebrates

Abstract

Anthropogenic chemicals which can disrupt the hormonal (endocrine) systems of wildlife species are currently a major cause for concern. Reproductive hormone-receptor systems appear to be especially vulnerable. In the past few years, numerous effects of endocrine disrupting chemicals on wildlife have emerged including changes in the sex of riverine fish, reproductive failure in birds and abnormalities in the reproductive organs of alligators and polar bears. Much less is known regarding endocrine disruption in marine invertebrates, the key structural and functional components of marine ecosystems. In this paper, potential effects of different classes of endocrine disrupting chemicals are reviewed. The endocrinology of several major invertebrate groups is briefly examined to identify which phyla are most likely to be at risk. Gaps in our knowledge concerning the availability and uptake of endocrine disruptors are identified. For example, the relative importance of different routes of chemical uptake (from seawater vs food) is considered. Feeding strategies (herbivores, carnivores, deposit feeders, suspension feeders) in relation to uptake of endocrine disruptors are also discussed. Examples of endocrine disruption in marine invertebrates in situ are provided, including imposex in gastropod molluscs exposed to organotin compounds and intersex in crustaceans exposed to sewage discharges. Laboratory data are presented concerning the effects of endocrine disruptors on the growth and reproductive output of the deposit feeding amphipod Corophium volutator and the polychaete worm Dinophilus gyrociliatus. Recent findings are reported which demonstrate reductions in settlement following exposure of barnacle larvae to the xeno-estrogen, 4 nonyl phenol. The potential use of cyprid major protein as a biomarker of oestrogenicity is explored. The ecological significance of endocrine disruption in marine invertebrates is discussed. With regard to environmental management action, an evidence-based approach is advocated. A protocol for collecting evidence of ecologically significant endocrine disruption is outlined.