TOXIC EFFECTS OF THE ANTIFOULING AGENT IRGAROL-1051 ON PERIPHYTON COMMUNITIES IN COASTAL WATER MICROCOSMS

In the late 1980s, a number of countries restricted the use of tri-n-b utyltin (TBT) as an active ingredient in antifouling paint for small b oats, including pleasure craft, Irgarol -(cyclopropylamino)-6-(methylt hio)-1,3,5-triazine, belonging to the s-triazine group of herbicides-i s now used in combination with copper in several antifouling products, Irgarol 1051 contamination of the marine environment was studied clos e to a marina on the west coast of Sweden, Highest concentrations (1.6 nM, 0.4 mu g l(-1)) were observed during the peak of the boating seas on, To investigate the potential for toxic effects, marine periphyton communities were established on artificial substrata in 22-litre flow- through aquaria and exposed to Irgarol 1051 during a 3-week period in April 1994, The algicide was continuously added at concentrations rang ing from 0.06 to 260 nM, Irgarol 1051 was found to significantly (p<0. 05) inhibit periphyton photosynthetic activity at 3.2 nM in short-term (hour) tests, Long-term (weeks) exposure produced effects at even low er concentrations, A significant change in community structure was fou nd at 1 nM, which produced a shift towards tolerant species, Photosynt hetic activity and algal biomass (chlorophyll a content) was significa ntly lowered at concentrations of 1 and 4 nM, respectively, indicating only minor functional redundancy in the communities, The most sensiti ve long-term effects were detected at 0.25-1 nM (0.063-0.25 mu g l(-1) ) of Irgarol 1051, which is within the concentration range detected in the contaminated areas around the marina, It can be concluded that th e present use of Irgarol 1051 is likely to damage microalgal communiti es in contaminated coastal waters. Copyright (C) 1996 Elsevier Science Ltd