Publication Abstract

Effects of paint-derived tributyltin (TBT) on structure of estuarine nematode assemblages in experimental microcosms

M. Schratzberger, C.M. Wall, W.J. Reynolds, J. Reed, M.J. Waldock

A microcosm experiment was designed to evaluate the effects of different levels of TBT, and different modes of exposure, on the diversity, feeding mode and assemblage structure of estuarine nematodes. Estuarine meiofauna were exposed to two types of treatments (mixture and deposit), containing uncontaminated sediment and sediment spiked with paint-derived TBT at 1 and 10 ppm for a duration of 4 and 8 weeks. In the mixture treatments, meiofauna assemblages were incubated in clean and contaminated sediments. In the deposit treatments meiofauna assemblages were exposed to the deposition of clean and contaminated sediments simulating the disposal of TBT-contaminated dredged material at sea. Effects of TBT on nematode species are likely to occur by (a) the uptake of leached TBT from the sediment pore water through their permeable cuticle, resulting in decreased diversity and increased changes in assemblage structure with increasing levels of TBT contamination, and (b) direct ingestion of paint-particles with food, resulting in a significant decline of non-selective deposit feeders in contaminated sediments. The numbers of many species differed greatly between deposit and mixture treatments. Results from multivariate analyses showed an immediate and dominant effect of burial on most nematode species in the deposit treatments compared to the longer-term effect of TBT contamination. The survival rates of nematode species in the top layer of these sediments depended on their ability to withstand TBT contamination as well as their potential to migrate, survive and reproduce in the deposit. This study unambiguously showed that the response of nematode species depends not only on the level of TBT contamination but also on the mode of exposure to contaminated sediment which should be taken into account when assessing the effects of TBT on aquatic communities.

Reference:

M. Schratzberger, C.M. Wall, W.J. Reynolds, J. Reed, M.J. Waldock. 2002. Effects of paint-derived tributyltin (TBT) on structure of estuarine nematode assemblages in experimental microcosms. Journal of Experimental Marine Biology and Ecology, 272(2): 217-235