Comparative evidence for harvesting-driven enhancement of clam beds in northeastern New Brunswick, Canada

Abstract

Populations of infaunal clams can be affected by natural and anthropogenic factors. Two such factors include sediment porewater pH and clam harvesting. To date, however, the potential effects of clam harvesting on sediment pH conditions and corresponding clam densities remain understudied. To fill this knowledge gap, we sampled sediment pH conditions and the densities of three clam species (Mya arenaria spat, and all life stages of Macoma balthica and Gemma gemma) in harvested and non-harvested areas at two sites (Miramichi and Point aux Carr) in eastern New Brunswick, Canada. Within sites, sediment pH conditions were higher within harvested areas and correlated with significantly higher clam densities compared to non-harvested areas. Between sites, clam abundances were significantly higher at the site with lower pH conditions, suggesting that reduced clam densities associated with low sediment pH may be restricted to small spatial scales in this region. These results add to a growing body of literature suggesting that, under certain contexts, commercial clam harvesting may enhance habitat suitability and benefit some clam populations. The ways in which commercial clam harvesting affects habitat suitability and clam densities under a wide range of ecological and anthropogenic conditions warrant future investigation.