Macrofaunal recovery following the intertidal recharge of dredged material: a comparison of structural and functional approaches

Abstract

There is a growing need to understand the functional implications of anthropogenic pressures, such as those following coastal disposal of dredged material. Current assessments, based on taxonomic structure of benthic organisms, only provide a limited capacity to determine functional impacts or recovery. This study assesses recovery of two intertidal dredged material recharge schemes, comparing results obtained based on taxonomic structure (univariate and multivariate approaches) and function (biological trait composition, functional diversity, secondary production) of the benthic assemblages. The assemblages recolonising both schemes were consistently less speciose, less densely-populated and exhibited multivariate community structures that differed from those of the reference areas. However, for both schemes metrics of functionality converged to those of reference areas, although some differences in trait composition persisted for up to 3 years. These data support the proposition that impacts of, and recovery from, anthropogenic disturbance should be assessed using a combination of both functional and taxonomic structural approaches.

Keywords: Function; Intertidal; Macrofauna; Sediment recharge; Structure; Traits.