A Study of the Impact of a Pipeline Construction on Estuarine Benthic Invertebrate Communities

The effects of a pipeline construction on benthic invertebrates were investigated using a Before/After impact protocol at Clonakilty Bay, West Cork, Ireland. Benthic invertebrates were sampled once before the excavation and at one, two, three and six months after the completion of the work. Analysis was designed to compare natural variation over time within control sites with the variation that occurred in the disturbed site from before to after construction. Invertebrate samples were dominated by Hediste diversicolor, Scrobicularia plana and Tubifex spp. An impact was obvious in the construction site in that no live invertebrates were found at one month after disturbance, but there followed a gradual recolonization by Hediste diversicolor. Scrobicularia plana failed to recolonize the impacted area during the study. At six months after the disturbance there was no significant difference in the mean number of total individuals (of all species) per core sample amongst all study sites, but the apparent ‘ recovery ’ in the impacted area was due to two taxa only, namely Hediste diversicolor and Tubifex spp. The process of recovery of the benthic community within the impacted area is thus dependent on the species within the surrounding area. Their respective life cycle characteristics and mobilities will have been major factors in determining recovery