Assessment of the risk of introducing harmful marine organisms by shipping to Bantry Bay

Abstract

The main shipping activity in Bantry Bay is centred at Leahill, a site where there is aggregate extraction with direct transmission to bulk carriers at a dedicated pier. The size of vessels ranges from 250 to7,800mtNRT but with the majority of vessels being of 700 to l,800mtNRT. Ballast water from these vessels is required to be deposited at sea before entering the Bay should these vessels becoming from outside of Ireland. If this is done the risk of introducing dinoflagellate species present in those ports in Atlantic France and Spain will be reduced. Vessels from Irish ports are not required to discharge ballast before entering the Bay. The main risk to Bantry Bay, albeit small - because the amount of ballast discharged is small, is from inoculations of the toxic dinoflagellate Alexandrium tamarense from ships that have ballasted in Cork Harbouror Belfast Lough. It would be prudent for vessels ballasting in these sea inlets not to do so in the region and during the time of the toxic algal bloom events. Although vegetative stages of A. tamarense have been identified from the plankton of Bantry Bay and Alexandrium sp. cysts have been found in fine sediments it is not known whether further inoculations of A. tamarense either in its vegetative or cyst state could result in a PSP event within the Bay. The development of a management plan for ships' ballasting in Cork Harbour and Belfast Lough based on cyst distributions and the distribution of algal bloom events could greatly reduce the risk of a transfer. In the meantime discoloured water in Cork Harbour and Belfast Lough should not be ballasted. The Cork Harbour Commissioners will be advised when algal bloom events take place so that basic precautions.