MEPS prepress abstract  -  DOI:

Intertidal invertebrate harvesting: a meta-analysis of impacts and recovery in an important waterbird prey resource

Leo. J. Clarke*, Kathryn M. Hughes, Luciana S. Esteves, Roger. J. Herbert, Richard A. Stillman


ABSTRACT: Harvesting of marine invertebrates in intertidal areas often comes into conflict with conservation objectives for waterbird populations (orders Anseriformes, Charadriiformes). We present a meta-analysis of the relationships between benthic invertebrate communities and various sources of intertidal harvesting disturbance to investigate impacts and recovery in bird prey resources. The effect size (Hedges’ d) of harvesting on benthic species abundance, diversity and biomass was calculated for 38 studies in various locations globally, derived from 16 publications captured through a systematic review process that met the meta-analysis inclusion criteria. A negative response to harvesting disturbance was found for all taxa, including both target and non-target species, that represent important types of waterbird prey. Impacts appear most severe from hand-gathering; significantly reducing the abundance of target polychaete species, a key prey group for many bird species. Across all gear types, non-target species demonstrate a larger reduction in abundance compared to target species. Recovery trends vary, with differences observed between taxonomic groups and gear/habitat combinations. Abundance of bivalve molluscs, a potentially highly profitable bird prey item, is suppressed for > 60 days by mechanical dredging in intertidal mud, while annelid and crustacean abundances demonstrate near recovery over the same period. Data suggest that recovery following harvesting in sandier habitats may in some cases take as long as or longer than in muddy sediments. We recommend management measures to minimise disturbance to benthic prey resources and support conservation objectives for waterbird populations to meet international legal requirements.