Pollution-induced community tolerance (PICT) in periphyton communities established under tri- n-butyltin (TBT) stress in marine microcosms

Abstract

The environmental problem of the antifouling agent tri- n-butyltin (TBT) was recognized during the 1980's and the use of TBT on pleasure crafts was banned in several countries. Marine periphyton were established in a flow-through aquaria system under TBT stress. Pollution-induced community tolerance (PICT) was quantified, in a short-term test for inhibition of photosynthesis, and compared to effects on biomass and community structure. Community structure was measured by diatom species richness, Jaccard similarity index, Bray-Curtis dissimilarity index and evaluated by linear regression and multidimensional scaling (MDS) techniques. The aim was to (1) determine a no effect level for marine periphyton communities under ecologically realistic conditions (2) validate PICT against other long-term effect indicators (3) confirm, with a controlled experiment, the TBT effect thresholds indicated by PICT studies in the field. We found that TBT alone indeed was able to cause the same kind of effects on periphyton that earlier have been detected in periphyton from contaminated ecosystems and that the effects occur at concentrations in water higher than 0.5 nM TBT. The agreement between TBT effects in field and in the microcosm system implies that the system is sufficiently realistic in yielding ecologically relevant information. Effect indicators such as periphyton photosynthesis and net production were found to be less sensitive than PICT and community structure.