An investigation into the influence of marine pipelines and cables on benthic ecology and biodiversity

Installation of bottom-founded marine pipelines and cables involves an initial disturbance usually resulting in the creation of a new linear substrate. The effect of these two elements on the ecology of benthic organisms and marine biodiversity depends on facility siting, design characteristics of the facility construction methods and the receiving environment. While consideration is given to direct construction-related impacts, the biological consequence of the creation of new linear substrate on feeding, reproduction, predation, distribution and dispersal of benthic organisms has for the most part received little attention. This paper explores the potential for marine pipelines and cables to impact species movement and dispersal, habitat availability, boundary layer ecology, predation and the marine acoustic environment. Data are analyzed based on available literature, laboratory simulation, in situ field measurements and field inspection. Data from laboratory study suggests pipelines can act as barriers to the movement of some benthic species (e.g., crabs), an effect likely mediated by several biological and physical factors. The extent to which other residual ecological or hydrological barriers may occur is unclear. As a source of new hard substrate, pipelines are readily colonized by a variety of sessile marine organisms and so act as artificial reefs. During a reconnaissance of an exposed marine pipeline in temperate coastal waters of British Columbia, a minimum of 24 species of encrusting organisms and associated fish species were recorded. A case can be made that pipelines affect benthic communities through alteration of boundary layer processes, near bottom current dynamics and induced scour. Data obtained on pipeline noise and observed pipeline colonization by numerous benthic organisms suggest pipeline noise per se, is not a deterrent to certain invertebrate communities. The effect of electro magnetic radiation from cables is unresolved. Recommendations are made concerning facility siting, construction procedures and future research.