Effects of Netting and Other Structures on Benthic Fauna
Michel Kaiser, School of Ocean Sciences, Bangor University, UK
Abstract
The use of netting or other structures in the cultivation of marine molluscs inevitably introduces an artificial substratum into the marine environment. Empirical studies of clam netting and oyster trestles both lead to similar outcomes. Both of these structures reduce water flow in the vicinity of the structure, and in the case of oyster trestles can lead to static water masses beneath the structure. Reduced flow and increased drag and turbulence increases the advection of particulate material to the seabed. This leads to a build-up of sediment beneath netting that further increases the topographic complexity of the seabed, which further increases turbulence and advection. The increased supply of organic matter and the protection from predators lead to an increase in invertebrate biomass beneath the netting relative to adjacent uncultivated areas. Excessive sedimentation can lead to high (total) mortality of all fauna, including the cultivated species.