A survey by hydraulic dredge of interstitial bivalves with commercial potential in Cill Chiaráin and Beirtreach buí Bays and along their connecting shoreline, Co Galway

The shellfish co-operative, Comharchuman Sliogéisc Chonamara Teó (CSC) manages oyster and scallop in Beirtreach buí and Cill Chiaráin Bays, both of which are designated aquaculture areas. Cill Chiaráin is also a candidate Special Area of Conservation (cSAC). Various traditional fishing activities are carried on in the bays and CSC has rights to exploit clam species there. The work described here is a survey of interstitial clam species by hydraulic dredge between November 2001 and January 2002. Investigations were restricted from some of the upper bay areas where surface bivalve management was in progress. Much of the remaining areas within the Bays proved unsuitable for hydraulic dredging by virtue of the nature of the substratum. The exposed parts of the lower bays and the intervening coastline where the substratum was coarse sand (maërl or shell sand) were suitable for hydraulic dredging but bedrock and loose boulders often proved obstacles to towing. There was evidence of two assemblages of bivalves in the bays: one typified by Venus verrucosa, Venerupis senegalensis and Tapes rhomboides, all large and potentially valuable, occurred within maërl mixed with fine mud, the other whose most valuable components included Ensis arcuatus and Spisula solida, occurred in disintegrating maërl and in shell sand. The bivalve fauna in the two bays appeared to be typified by relatively high diversity and low biomass – which is accentuated by recent natural mortalities of Ensis arcuatus, a dominant species - and this is likely to prove a challenge to marketing; the Irish market typically exploits small numbers of clam species simultaneously. The terms of the licence under which CSC operates may provide opportunities to exploit clams within their designated area by means other than hydraulic dredging and these should be investigated. In view of the scientific values of the area and its status as a cSAC any plan to exploit its interstitial bivalves should be discussed with the relevant state agency.Funder: Marine Institut

Current Status of Forecasting Toxic Harmful Algae for the North-East Atlantic Shellfish Aquaculture Industry

Across the European Atlantic Arc (Scotland, Ireland, England, France, Spain, and Portugal) the shellfish aquaculture industry is dominated by the production of mussels, followed by oysters and clams. A range of spatially and temporally variable harmful algal bloom species (HABs) impact the industry through their production of biotoxins that accumulate and concentrate in shellfish flesh, which negatively impact the health of consumers through consumption. Regulatory monitoring of harmful cells in the water column and toxin concentrations within shellfish flesh are currently the main means of warning of elevated toxin events in bivalves, with harvesting being suspended when toxicity is elevated above EU regulatory limits. However, while such an approach is generally successful in safeguarding human health, it does not provide the early warning that is needed to support business planning and harvesting by the aquaculture industry. To address this issue, a proliferation of web portals have been developed to make monitoring data widely accessible. These systems are now transitioning from “nowcasts” to operational Early Warning Systems (EWS) to better mitigate against HAB-generated harmful effects. To achieve this, EWS are incorporating a range of environmental data parameters and developing varied forecasting approaches. For example, EWS are increasingly utilizing satellite data and the results of oceanographic modeling to identify and predict the behavior of HABs. Modeling demonstrates that some HABs can be advected significant distances before impacting aquaculture sites. Traffic light indices are being developed to provide users with an easily interpreted assessment of HAB and biotoxin risk, and expert interpretation of these multiple data streams is being used to assess risk into the future. Proof-of-concept EWS are being developed to combine model information with in situ data, in some cases using machine learning-based approaches. This article: (1) reviews HAB and biotoxin issues relevant to shellfish aquaculture in the European Atlantic Arc (Scotland, Ireland, England, France, Spain, and Portugal; (2) evaluates the current status of HAB events and EWS in the region; and (3) evaluates the potential of further improving these EWS though multi-disciplinary approaches combining heterogeneous sources of information.Versión del edito

Dynamics of co-occurring Alexandrium minutum (Global Clade) and A. tamarense (West European) (Dinophyceae) during a summer bloom in Cork Harbour, Ireland (2006)

The dinoflagellate genus Alexandrium contains neurotoxin-producing species, which have adversely affected the aquaculture industry and fisheries worldwide. Seasonal toxic blooms of Alexandrium spp. occur on an annual basis in the North Channel area of Cork Harbour, Ireland, where resident populations of non-toxic A. tamarense (West European ribotype) and PSP toxin-producing A. minutum (Global Clade) co-occur. Field surveys were carried out throughout a bloom of Alexandrium spp. in the summer of 2006. Taxa-specific fluorescently labelled probes were used in a dual whole-cell fluorescent in situ hybridization (WC-FISH) assay for the simultaneous discrimination and quantification of A. minutum and A. tamarense in the water column. The bloom occurred following a weak spring tide in early June and Alexandrium cell concentrations exceeded 3×104 cells L-1. A. minutum dominated numerically over A. tamarense throughout the sampling period (74% on average). The maximum cell concentration was ∼3.3×105 cells L-1 at the peak of the bloom and was localized at the eastern end of the North Channel. The bloom collapse coincided with increasing tidal flushing and significantly changing meteorological conditions (wind speed increase, lesser irradiance), which led to a water temperature drop of ∼3 °C within a period of 7 days. GTX3 was the dominant PSP toxin variant and C-toxins were at times observed in samples. Assuming that A. minutum was the only microorganism synthesising PSP toxins, the internal toxin quota was on average 13.4 fmol cell-1, a value similar to that observed in laboratory experiments. Monitoring of toxic Alexandrium species in Ireland will require the use of molecular methods for reliable discrimination and quantification. © 2009 Elsevier Ltd. All rights reserved

The commonalities and complexities of the impact of life histories on the ecology of harmful algal blooms (outcomes of the SEED project)

Trabajo presentado en el 13th International Conference on Harmful Algae, celebrado en Hongkong (China), del 3 al 7 de noviembre de 200