13th International Conference on Aquatic Invasive Species

The Irish Seweed Centre attended the International Aquatic Invasive species conference in Ennis in September 2004. The introduction of nonindigenous aquatic species is an ongoing problem that is increasing in frequency. Although the zebra mussel is perhaps the most widely known aquatic invader, there are numerous invertebrates, fish and marine plants that are causing significant damage to freshwater and coastal ecosystems, and to the economies that depend upon them.This annual conference series is widely considered the most comprehensive international forum for the review of accumulated scientific knowledge on the impacts of aquatic invasive species, presentation of the latest field research and related data, introduction of new technologies and advancements in control and mitigation, and discussion of policy and approaches to effective public education and outreach initiatives to prevent new introductions.

Two poster were presented of which the pdf can be downloaded. For abstracts see below.

Commercial seaweed farming of Asparagopsis armata at the west coast of Ireland, impact and distribution ( pdf)

Robert Wilkes, Kelly Barrington and Stefan Kraan Irish Seaweed Centre, Martin Ryan Institute, National University of Ireland, Galway, Ireland

The gametophytes of Asparagopsis armata growing in Ireland presently exist in a 75 km radius of a seaweed farm that commercially cultivates A. armata for the cosmetics industry.  It is believed that this farm acts as a source pool for the Irish population of A. armata. Fragmentation of the algae, to seed the ropes of the commercial seaweed farm, also maintains the population in Ard Bay, without this farm this rhodophyte would probably not flourish at the Irish west coast.  The population of A. armata that does exist in Ard Bay may have an epiphytic relationship with Ulva sp. The optimum growth conditions for the gametophyte of A. armata was observed to be 15°C, 8:16 (l:d), 10 mE.  The sea surface temperature of Irish waters is suitable for growth and survival of the tetrasporophyte and gametophyte, however, it may not be warm enough for sexual reproduction.  That is probably the reason it is not present outside the radius of the farm.  Although there is plenty of suitable habitat, and little, if any, herbivory, A. armata does not appear to be flourishing in Ireland.

Sargassum muticum at the west and south coast of Ireland: an invasive species on the move? ( pdf)

Stefan Kraan
Irish Seaweed Centre,
Martin Ryan Institute,
National University of Ireland,
Galway, 
Ireland

The alien invasive seaweed species Sargassum muticum was recorded from Kilmore Quay for the first time in Ireland by the Irish Seaweed Centre in 2001. After this record, it has been found at Rath strand Kenmare River (Co. Kerry), Cashel Bay (Co. Galway) and Drum Cliff Bay (Co. Sligo) in the following years. It is important to note that these specimens were attached, indicating the presence of established populations. As shown in other studies of the invasion of Sargassum muticum in the U.K., Denmark, and Portugal, this species may have an impact on tourism, biodiversity and the aquaculture industry. In Ireland a study was carried out form April 2003 to November 2003 to map the geographical distribution and spread of the invasive brown macroalgae Sargassum muticum.  The overall objective of the study is to determine the present status, distribution and invasive capability of Sargassum muticum at the west and south coast of Ireland.The areas where Sargassum muticum were reordered for the first time in the past were surveyed in this study including neighbouring areas. Furthermore, bays and inlets in close proximity of the original survey area were also examined. The extent of the population and spreading ratio was measured if Sargassum muticum was encountered. Detailed maps with distribution, spreading and extend of the beds are produced from the survey records. This study showed that Sargassum muticum most probably arrived in the mid nineties and is spreading along the coast of Ireland. The results indicate that spreading is facilitated by Yachting and perhaps via Oyster transport. Spreading rates are difficult to calculate due to the nature of the introduction and late discovery in Ireland, nevertheless, with some uncertainty a rate of spreading of 2-3 km year ^-1 has been calculated for two bays. Furthermore, this study showed that S.muticum has been found growing in Seagrass beds and in rock pools, which might have serious consequences for the biodiversity in rock pools and protective status of seagrass habitats.

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