Induced Community Tolerance in Marine Periphyton established under Arsenate Stress

Abstract

Pollution-induced community tolerance (PICT) may be used to assess impact of pollutants in the environment and to identify the agents causing the impact. We have examined this possibility using marine periphyton communities. These were established under arsenate stress in indoor aquaria and their community tolerance to arsenate estimated with a short-term photosynthesis test. Arsenate concentrations above 0.1–0.3 μM induced an increased tolerance to arsenate; at severe arsenate stress the increase in tolerance was more than 17 000-fold. Our interpretation is that arsenate exerted a selection pressure on the community, leading to the replacement of sensitive species by tolerant ones which caused the overall arsenate tolerance of the community to increase. Arsenate concentrations that induced the tolerance also affected species composition and biomass accrual, suggesting that community tolerance can be used to properly indicate a disturbed community. Hence the basic requirements are met for the use of PICT as an ecotoxicological tool.