SPECIES-SPECIFIC RELATIONSHIPS OF INVERTEBRATES TO VEGETATION IN A SEAGRASS BED .1. CORRELATIONAL STUDIES

The relationship between abundances of small epifaunal invertebrates and biomass of several macrophyte species was examined within a seagrass bed in Pomquet Harbour, Nova Scotia, Canada. Vegetation cover was markedly heterogeneous due to variations in seagrass biomass density and the presence of several kinds of macroalgae which were classified as: coarsely branched, finely branched and filamentous. The sampler simultaneously collected vegetation and associated epifauna. The data were analysed to determine the relative influence of each vegetation type on the faunal assemblage. Abundances of individual species were examined by an analysis of covariance. Of seven common epifaunal species, one was associated with eelgrass, four with coarsely branched algae (which tended to be freely drifting), and two showed no consistent affinity. Principal components analysis showed that a major part of the variance in the faunal assemblage could be attributed to variations in the amount of drifting, coarsely branched algae. The variable response to vegatation types was interpreted in terms of the biology of individual species, with respect to suitability of macrophytes as a food source and as living space, especially as a refuge from predators.