• Karenia mikimotoi: An Exceptional Dinoflagellate Bloom in Western Irish Waters, Summer 2005

      Silke, J.; O'Beirn, F.X.; Cronin, M. (Marine Institute, 2005)
      A protracted bloom of Karenia mikimotoi was present in summer 2005 along the northern half of the western Irish coastline. The onset of this bloom was identified in late May / early June. This event subsequently dissipated over the month of July and was succeeded by a bloom of the same species in the southwest in late July. The bloom was very intense and resulted in discolouration of seawater and foaming in coastal embayments. Major mortalities of benthic and pelagic marine organisms were observed and a complete decimation of marine faunal communities was reported and observed in several locations. Deaths of echinoderms, polychaetes and bivalve molluscs were observed in County Donegal and Mayo, while farmed shellfish and hatchery raised juvenile bivalve spat suffered significant mortalities along the Galway and Mayo coasts. Reports of dead fish and crustacea were received from Donegal, Galway, West Cork and Kerry. Karenia mikimotoi is one of the most common red tide causative dinoflagellates known in the Northeast Atlantic region, and is also common in the waters around Japan. Blooms of this species often reach concentrations of over several million cells per litre and these densities are often associated with marine fauna mortalities. Although cytotoxic polyethers have been extracted from cultures of the species, the exact mechanism of the toxic effect and resultant devastating damages yet remains unclear. It is known in the literature under several different names as the taxonomy and genetics have been studied. It is now known that previously reported names including Gyrodinium aureolum, G. cf. aureolum, G. nagasakiense and G. mikimotoi are synonymous with the current name given to the organism. The visible effects following the mortalities included noticeable quantities of dead heart urchins (Echinocardium cordata L.) and lugworms (Arenicola marina L.) deposited on beaches. Several species of wild fish were also found dead. The bloom coincided with a period of fine weather and tourists visiting the seaside were concerned about the safety of swimming in waters that were obviously harmful to marine organisms on this scale. A public awareness programme was mounted by the Marine Institute with several radio broadcasts, press releases and a website provided to give up to date pronouncements on the event. While there have been several instances of Karenia mikimotoi blooms reported in Ireland over the past 30 years, this scale of mortalities associated with the 2005 bloom were not previously observed. Recording the scale of this event was facilitated by satellite imagery while direct counts of the cells in seawater by the Marine Institute monitoring programme gave very useful information regarding the size and intensity of this event. The mortalities of marine organisms were documented from reports made by various observers and by Marine Institute field surveys.
    • Salmon Mortalities at Inver Bay and McSwyne’s Bay Finfish farms, County Donegal, Ireland, during 2003

      Cronin, M.; Cusack, C.; Geoghegan, F.; Jackson, D.; McGovern, E.; McMahon, T.; O'Beirn, F.X.; Ó Cinneide, M.; Silke, J. (Marine Institute, 2004)
      This report details the investigations into a major mortality of farmed salmon at Inver Bay and McSwyne’s Bay, Co. Donegal in July 2003. Previous reports were provided on 29th July 2003 and on 11th August 2003. The information is based upon analysis and research by MI scientists, a review of environmental data, survey reports by external consultants, inputs from veterinary practitioners who visited the site, reports from DCMNR staff in Killybegs, and site visits made by DCMNR / MI inspectors. Following a review meeting of the principal investigators on the 9th October, 2003, MI proceeded to carry out further scientific investigations. DCMNR also commissioned Kirk McClure Morton Consulting Engineers (KMM) to carry out a parallel investigation of the mortalities at Inver Bay and McSwynes Bay salmon farms. MI provided support as required to the KMM study, the report for which was furnished to DCMNR and MI on 11 February 2004. (KMM, 2004) MI wishes to acknowledge the high level of co-operation and assistance that it received from the owners and staff of Creevin Fish Farm Ltd, Eany Fish Products Ltd and Ocean Farms Ltd. It also wishes to acknowledge the assistance of veterinary practitioners, DCMNR staff and others in the course of this investigation.