Munida rugosa (Fabricius, 1775)
Family:

A widespread and common species throughout the Northern Ireland coast, which probably holds the great majority of the Irish population.

In brief

• Throughout the Northern Ireland coast
• Low intertidal, to about 100m depth, on muddy/sandy areas with stones and rocks providing hiding places
• Can be found throughout the year
• Thought to be declining
• Main threats likely to come from disruption of seabed habitat from use of mobile fishing gear.

Species description
The rugose squat lobster grows to about 10cm in length when its abdomen is extended but this is misleading because normally it is curled up under the thorax, or central zone of the body. By flicking this abdomen sharply forward and under, it is able to dart backwards quite rapidly. It is an orange-reddish brown colour, with darker, or yellowish, striations across the carapace (upper shell) and abdomen, giving quite a distinctive pattern. The claws, spines and legs are all tipped white. The antennae are long, but not quite as long as the long thin spiny claws which are about double the length of the body.

Life cycle
Mature females carry eggs on their underside, where after mating and fertilisation, these develop into larval forms for about two weeks. They hatch into planktonic larvae, eventually settling after dispersal onto suitable habitat.

Similar species
No other Northern Irish squat lobster has such long claws or this combination of colours.

How to see this species
The species can be found throughout the year, and very widely throughout Northern Ireland coasts, in low intertidal zones through to depths of 50-100m, on sandy or soft substrata, particularly where stony crevices also offer hiding places. Key locations in Northern Ireland include Portrush Skerries, all round Rathlin, the Maidens, off Muck Island, Larne and the Gobbins, in the north end of Strangford Lough Narrows, and widely in its interior. Elsewhere in Ireland, it occurs on the south coast and is recorded off the Aran Islands, and in Britain there are numerous sites around western Scotland, north-eastern and eastern England.

Current status
Widespread in Northern Ireland. The species has no legal protection.

Why is this species a priority in Northern Ireland?
Northern Ireland seems likely to hold very much over 50 per cent of the total Ireland population. It is likely this species has declined here, due to loss of habitat.

Threats/Causes of decline
Data for the exact conservation status of this species is lacking; however, its habitat of relatively level seabeds of sand and other sediments (although it utilises shelter from any boulders or stones) implies that it may well have suffered habitat loss from the use of mobile fishing gear.

Conservation of this species

Current action
Survey work is being conducted throughout Northern Ireland waters (including the north coast) by Northern Ireland Environment Agency for this and other species and habitats generally.

Rathlin Island and its waters, and Strangford Lough have been designated Special Areas for Conservation under the EU Habitats Directive.

The UK Habitat Action Plan for Inshore Sublittoral Sediment also contains the following objectives:

• maintain the extent and quality of sublittoral sediment habitats in the UK, including the full diversity of communities.

Measures to be considered further include:

• protecting sites of conservation importance from damage through contamination and physical disturbance or excessive use (for example, nutrient enrichment, dredging and development)
• requiring EIAs for coastal developments to examine potential effects on nearshore areas
• monitoring any impact of dump sites on inshore sublittoral sediment habitats, communities and wildlife, and taking action as appropriate
• developing and implementing strategies for the conservation and management of the wider marine environment at local, regional and national levels. For example, integrated Coastal Management Plans, water quality objectives, pollution control and avoidance measures. Species recovery and habitat restoration programmes should be included.

Proposed objectives/actions

• Maintain the number of viable populations of the species
• Maintain the range of the species
• Maintain appropriate management of known sites and consider further designation, for example in the Maidens.

What you can do
Records of new sites for this species, with details of habitat and population are always valuable. Send these to CEDaR, National Museums Northern Ireland, 153 Bangor Road, Cultra, Holywood, County Down, BT18 0EU. Tel 028 9039 5257 or e-mail cedar.info [at] nmni.com. If you are a diver, and interested in becoming involved in recording marine life in Northern Ireland through the Seasearch project, contact Claire Goodwin at claire.goodwin [at] gmail.com or look at the web site www.seasearch.org.uk (Northern Ireland web pages).

Further information

Links
Encyclopedia of Marine Life

NBN Gateway

Marine Life Information Network

Literature
Bergmann, M. and Moore, P.G. (2001). Survival of decapod crustaceans discarded in the Nephrops fishery of the Clyde Sea area, Scotland. ICES Journal of Marine Science: Journal du Conseil 2001 58(1): 163-171.

Jackson, A. (2008). Munida rugosa. Rugose squat lobster. Marine Life Information Network: Biology and Sensitivity Key Information Sub-programme [on-line]. Plymouth: Marine Biological Association of the United Kingdom. [cited 13/05/2008]. http://www.marlin.ac.uk/species/Munidarugosa.htm.

Text written by:
Allen & Mellon Environmental Ltd.

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