A model of the structure and dynamics of benthic marine invertebrate communities

Abstract

The species abundance distributions of many benthic marine invertebrate communities may not satisfactorily conform to either the log-normal or log-series models that are central to theories of community structure. Benthic communities usually have dominance-diversity curves that are concave, rather than linear (log-series) or sinusoidal (log-normal), with a progressive increase in the number of rare species; singleton species outnumber doubletons and so on. There is no mode in the species abundance distributions An alternative theory is presented here to offer an explanation for these observed species abundance distributions. The theory is explained by use of a model of benthic marine community dynamics based upon established principles of population regulation, notably recruitment behaviour, competition and mortality. The model sinlulates several previously recognised features of community development. A 'non-interactive' stage of colonisation is followed by a n 'interactive' stage where, because of competitive interactions, environmental stab~lity leads to a n increase in dominance which depresses the diversity of the community and the number of species. Intermediate levels of disturbance maintain a n increased divers~ty and a larger number of specles by ensuring that dominance by any one species is only temporary and a stable 'climax' is never reached. The model consistently predicts the products of the interactions between population growth, competitlon and mortality to be communitites with dominance-divers~ty curves similar in shape to those of natural communities. The model also suggests that while many species have the potential for geometric population growth some species do not achieve this because of mortality and competitive exclusion and, within an area of study, some specles may have only an anthmetic potential for population growth.

Species abundance patterns of benthic macroinvertebrate communities in polluted streams

“…In addition a similar trend in SAD was reported in plant community recovery on Mount St. Helens after its eruption (del Moral 1999). Although Patrick (1975) reported SAD in algal communities, not much research has been carried out on communities collected in freshwater aquatic ecosystems, while studies on SAD have been extensively conducted on terrestrial (Whittaker 1965, MacArthur 1972 and marine (Hughes 1984, Gray & Mirza 1979, Gray 1981, Magurran & Henderson 2003 communities.…”

The macrofauna associated with the bryozoan <i>Schizoporella unicornis</i> in southeastern Brazil

“…Theory predicts that few factors determine community structure, and species colonization at random intervals along time results in many rare species (May, 1975;Magurran, 1988). However, Hughes (1984) noted that the number of rare species in marine benthic communities may accumulate faster than predicted by the logseries distribution. Species recruiting to the substrate could eventually displace competitively inferior species, but dominance patterns should be dynamic, as mortality events, density-dependent reduction of recruitment, and variable population growth rates would prevent the same species from dominating these communities for long time intervals (Hughes, 1984).…”

“…The assemblages associated with these substrata generally have high species diversity, and adjust to common species abundance models characterized by many rare species and few dominant ones, as a result of recruitment patterns and interspecific interactions (Hughes, 1984). Increasing introduction of exotic species can also influence local community dynamics, through additional habitat alteration (Crooks and Khim, 1999).…”

Community-level analysis of anthropogenic impacts on rocky shore communities in Sri Lanka

“…This distribution pattern can be explaining, due to, differences in species abundances in terms of variation in recruitment and mortality rate. The typical community, in this case Rumassala, contains a few very abundant species and many rare species (Hughes, 1984). With increased disturbance from Galle to Unawatuna, dominant conservative species have been affected first and their abundance become low.…”