Effects of biological disturbance on diversity and structure of meiobenthic nematode communities

Abstract

Benthic mesocosm experiments have shown that subtidal macrofauna species with contrasting feedlng behaviour and mobility can alter the structure of natural subtidal meiobenthic nematode assemblages. Test macrofauna species were the bivalves Nuculoma tenuis (subsurface-deposit feeder) and Abra alba (surface-deposiWsuspension feeder) at 3 different densities and the heart urchin Brissopsis lyrifera (subsurface burrowing deposit feeder) at a single density. a and P nematode diversity were affected by disturbance of different intensities in the bivalve treatments in a way that is consistent with the intermediate disturbance hypothesis regardless of type of disturbance. These measures of community structure did not differentiate between contrasting types of disturbance. Multivariate community analysis indicated that the species response in the assemblage was more sensitive to the type of disturbance than the intensity of disturbance. Differential responses of the nematode species did not reflect their depth distribution in natural field sediment and the likely depth at which the test macrofauna species were active. Nor was the response simply a predator-prey interaction with certain species targeted by the predator; the interactions appear to be more complex. Our experimental results suggest that patches of sediment which are dominated by hlgh abundances or biomass of one or a few species, a situat~on which is encountered in the field, are important in maintaining regional diversity. These patches will create a heterogeneous mosaic of communities with different diversities and different species compositions

Combined influence of river discharge and wind on littoral nematode communities of a river mouth area of Lake Constance

“…They stressed that high species diversity can be maintained by habitat patchiness. The results of mescosm experiments of Austen et al (1998) were consistent with Intermediate Disturbance Hypothesis (Connell 1978) and the authors suggested that dominance of few species, as it is the case in our study, is important in maintaining regional diversity. Our results agree with this study, in that species diversity (H¢) and species number (S) were reduced when wind stress and discharge stress were either both low and both high.…”

Response of intertidal macrofauna to multiple disturbance types and intensities – An experimental approach

“…Numerous studies have assessed the impacts of various types and intensities of disturbance on benthic communities (Pearson and Rosenberg, 1978;Heip, 1980;Rees, 1983;Zajac and Whitlach, 1982;Coull and Chandler, 1992;Hall, 1994;Austen et al, 1998;Schratzberger and Warwick, 1999;Cowie et al, 2000;Huxham et al, 2000;McCabe and Gotelli, 2000). These have established that benthic communities show a wide range of responses to disturbance, and that these responses can vary depending on the frequency and intensity of disturbance.…”

Benthic community response to a passive fishing gear in a coastal lagoon (South Brazil)

“…studying the response of meiofauna to different levels of trawling disturbance, showed a significant increase of Daptonema in areas subjected to medium disturbances. On other hand, meso-and microcosms experiments carried out by Austen et al (1998) and Schratzberger and Warwick (1999), respectively, showed that densities of Terschellingia may be negatively affected by low disturbance levels.…”