Pollution-Induced Community Tolerance—A New Ecotoxicological Tool

Abstract

The authors hypothesize that pollution-induced community tolerance (PICT) is direct evidence that a community is disturbed by a pollutant and, furthermore, that the agent or agents causing the effects can be identified, because induced tolerance will be observed only for those compounds that have exerted selection pressure on the community. A similar concept has been formulated for population tolerance, but we suggest that the concept is more useful when applied at the community level. Our examination of some crucial points behind PICT, using arsenate and periphyton communities, demonstrates that (1) the tolerance increase can be determined in short-term photosynthesis experiments, (2) PICT correctly indicates changes in species composition and net production, and (3) the selection pressure of arsenate is specific—that is, a tolerance increase for one compound is not followed by co-tolerance to other compounds unless they are closely related chemically or in their mode of action. These results support the idea of using PICT as an ecotoxicological tool. If further corroborated, PICT can be applied in both laboratory and field studies. PICT might be used retrospecitively in the field to detect minor disturbances and to identify the causing agent. In a laboratory test system, PICT can be used to estimate the no-effect concentration for the community under study. The authors argue that test systems based on PICT will be sensitive and yield ecologically relevant information.

Analysis of Structural and Physiological Profiles To Assess the Effects of Cu on Biofilm Microbial Communities

“…These authors did not detect large differences between bacterial communities growing at Cu concentrations ranging from 3 to 87 M. Our results suggest that the complex and organized structure of the biofilm (10,18,30) would not protect the bacterial community in the same way that sediments do, even through the formation of extracellular polymeric substances was found to increase several resistance capacities of each encased organism (24) by reducing the bioavailability of heavy metals (33). Short-and long-term toxicity tests of heavy metals on aquatic biofilms have focused either on the response of the phototrophic compartment (1,2,5,17) or on that of the heterotrophic compartment (34), but toxic effect assessments based on physiological tests (3,19) or studies considering the biofilm as a whole have not investigated the effect of Cu (6,23). Possible interactions between phototrophic and heterotrophic compartments of a biofilm may be disturbed when one compartment is severely affected by a stress factor, e.g., an increase in toxicant concentration.…”

Invited Review - Fight on Plankton! or, Phytoplankton Shape and Size as Adaptive Tools to Get Ahead in the Struggle for Life

“…The first category of these hypotheses concerns community responses to stress and disturbance. Communities may build up resistance against pollution (pollution-induced community tolerance: Blanck et al, 1988) or even ÂmemoriseÊ stress they have undergone in the past (community conditioning hypothesis: Matthews et al, 1996). The community scale of research does not only reveal the direct effects of stress on the community (Brock et al, 1992a), but also about secondary effects (Brock et al, 1992b) and altered ecosystem functioning due to these changes (Brock et al, 1993).…”

Les herbicides inhibateurs du photosystème II, effets sur les communautés algales et leur dynamique

“…Les méthodologies basées sur la systématique des algues échantillonnées (microscopie et biologie moléculaire) dans les milieux naturels sont indispensables pour appréhender la biodiversité et sa variabilité dans ces milieux. En complément, l'étude de la résistance d'une communauté naturelle au polluant dans le but de caractériser une réponse à une pression de sélection par ce polluant, semble une approche prometteuse pour suivre, étudier et interpréter les effets des contaminants toxiques dans les milieux naturels (BLANCK et al, 1988 ;LUOMA, 1977 BÉRARD A., PELTE T., 1996. Effets de l'atrazine sur l'évolution des peuplements phytoplanctoniques lacustres -Étude en enceintes expérimentales in situ.…”