Functional Diversity of Benthic Invertebrates along an Environmental gradient induced by an Aquaculture unit: the effect of Species Rarity and Dispersal Ability
Charalampos D &
Department of Marine Sciences, University of the Aegean, 81100, Mytilene, Greece
The relation of macrobenthic species identity turn-over (beta diversity) and species plylogenetic variation with functional diversity patterns, across an environmental gradient induced by an aquaculture unit, in a coastal area of the island of Lesvos (NE Aegean) has been investigated in this study. The contribution of rare species response and species dispersal ability in the variation of functional diversity patterns along the environmental gradient, on a spatio-temporal scale, has been also examined. Our results revealed that benthic functional diversity was decreasing monotonically with increasing species turn-over rate and hence with increasing spatial variability along the environmental gradient. Increased environmental stress also resulted to low species functional redundancy, since different species didn't perform the same functional role across the gradient. Functional diversity patterns were found to be poorly correlated with species population size, whereas a strong linear relationship was detected with phylogenetic diversity patterns, thus supporting the claim that wider local taxonomic trees can support a wider range of species functions even in small spatial scales. Rare species loss seemed to be one of the dominant factors ruling functional diversity variation. Species with the minimum possible dispersal ability, which were mostly rare, tend to diminish both in species number and population size faster than species with wider dispersal ability towards the most disturbed areas. The aforementioned results indicate that rare species variation and endemic species loss are critical factors in determining functional diversity loss across an environmental gradient in soft bottom benthic communities at a small spatial scale.