Short-term losses and long-term gains: the non-native species Austrominius modestus in Lough Hyne Marine Nature Reserve

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Gallagher, Mary C.
Culloty, Sarah C.
Davenport, John
Harman, Luke
Jessopp, Mark J.
Kerrigan, Caroline
Murray, Colette
O'Riordan, Ruth M.
McAllen, Rob
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The non-native barnacle species Austrominius modestus was first recorded in Ireland, close to Lough Hyne marine nature reserve in 1957. This species was not recorded inside the Lough until 1980, but by 2001 was the dominant intertidal barnacle within the reserve. It has been suggested that increases in the abundance of this species at other locations in Europe may be linked to increasing sea surface temperatures, and that A. modestus is an “ecological sleeper”. Despite an overall trend for increasing sea surface temperatures, this long term warming is punctuated by extreme events such as severely cold winters. A. modestus is warm water adapted, and has been recorded to decrease in abundance following cold winters. The winters of 2009/2010 and 2010/2011 were amongst the coldest recorded in Ireland in past decades. In the present study, higher levels of mortality were recorded for A. modestus than native barnacle species in Lough Hyne following these cold winters. Additionally, this species was recorded at lower abundances at the majority of sites surveyed in Lough Hyne in 2011 compared with 2009. Despite this, A. modestus remains the dominant barnacle species in the Lough and monitoring the recruitment of intertidal barnacles within Lough Hyne during 2014e2015 revealed that A. modestus was the most abundant recruit at study sites, both in removal plots and in the pre-existing community. The year-round breeding of A. modestus in addition to the closed nature of the Lough promotes A. modestus within the reserve. Despite this, native barnacle species continue to persist in Lough Hyne, though generally at low abundances, with the exception of exposed locations such as the Rapids and Bullock Island where natives outnumber A. modestus. The future intertidal barnacle community within the Lough is likely to be dominated by A. modestus with Chthamalus montagui and C. stellatus being abundant at sites which are not suitable for A. modestus. While the consequences of this are unknown, it is possible that the presence of A. modestus may alter trophic interactions and energy flow within the reserve.
Austrominius modestus , Barnacle , Climate , Invasive , Marine reserve , Long term monitoring
Gallagher, M. C., Culloty, S. C., Davenport, J., Harman, L., Jessopp, M. J., Kerrigan, C., Murray, C., O'Riordan, R. M. and McAllen, R. (2017) 'Short-term losses and long-term gains: The non-native species Austrominius modestus in Lough Hyne Marine Nature Reserve', Estuarine, Coastal and Shelf Science, 191, pp. 96-105. doi: 10.1016/j.ecss.2017.04.020
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