EXPERIMENTAL EFFECTS OF TRIBUTYLTIN (TBT) CONTAMINATED SEDIMENT ON A RANGE OF MEIOBENTHIC COMMUNITIES

Microcosm experiments have been carried out with whole natural meioben thic communities to look at the effects of TBT sediment contamination on the community structure of the dominant nematode component of the m eiobenthos. TBT has a high affinity for aquatic sediments, yet this is the first study of the effects of this contaminant in sediment on nat ural benthic communities. Three communities were studied from contrast ing locations in south-west England: the intertidal of the Lynher estu ary (muddy sediment) and the Exe estuary (sandy sediment) and the subt idal (50 m depth) at Rame Head off Plymouth (muddy, sand), Fresh sedim ent with natural meiobenthic communities was incubated for 2 months wi th TBT-contaminated sediment (three dose levels) in bottles. Nematodes were identified and enumerated and subjected to multivariate data ana lysis. The sandy Exe estuary fauna was significantly affected by TBT-c ontaminated sediment at all three doses (0.3, 0.6 and 0.9 mu g g(-1) d ry wt (as Sn) sediment), whereas the offshore fauna from Rame Head was significantly affected only at the highest dose. The muddy Lynher est uary meiofauna was affected (somewhat peculiarly) at the medium dose l evel only. Meiobenthic nematodes may not be as sensitive to TBT-contam inated sediment as other infaunal benthos but exhibited responses to l evels of contamination still persisting in some UK estuaries and harbo urs. Comparing the effects of TBT with those of copper and zinc in the same laboratory experiments, our observations suggest that the relati ve impact of TBT on meiobenthic community structure is not as great as these contaminants in marine sediments, Although there are very few o bservations of TBT toxicity in sediment, it appears that TBT is toxic at much lower concentrations in seawater (ppb) than it is in sediment (ppm). (C) 1997 Elsevier Science Ltd.