Mediterranean Mussel

Mytilus galloprovincialis

Overview

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Mytilus galloprovincialis

Habitat

Usually found living on rocky intertidal coastlines
Prefers habitats with fast water flow
Thrives in areas where nutrient upwelling occurs
Can sometimes be found growing in sheltered habitats such as sandy bottomed harbours and estuaries

Description

A marine bivalve mollusc comprising of two dark blue or brown-black shells
The shell halves are equal in size
Tends to grow larger than other Mytilus species, up to 15cm but typically only grows 5-8cm
The size of this mussel depends on the area it inhabits; intertidal shells tend to remain smaller than those growing subtidally
Very similar in appearance to other Mytilus species, including the native blue mussel, Mytilus edulis
Accurate identification can sometimes require genetic analysis
Internal shell features can be used for identification
Readily hybridises with other Mytilus species
The mussel feeds by filtering plankton and detritus from seawater
The larval phase of the lifecycle is planktonic
Larvae settle onto rocks, and attach using byssal threads

Download N.I.E.A. ID guide

Origin and Worldwide Distribution

Native to the Mediterranean and eastern Atlantic
M. galloprovincialis has been introduced widely across the globe, including into the United Kingdom and Ireland

Potential or Known Impacts

It can outcompete and displace native mussel species, becoming the dominant species on the rocky shore
Readily hybridises with other Mytilus species, such as the native mussel blue mussel M. edulis; reducing genetic diversity of the native mussel
Biofouling of pipes and water systems can have a negative economic impact

How did it get here?

It was likely introduced via ship hull fouling and through transport in ballast water
It may be transferred via the aquaculture pathway, where it has been misidentified as the native blue mussel, M. edulis

Is it found in Northern Ireland?

There is currently one record in Northern Ireland, near Portaferry

The species may be under-recorded due to its similar appearance to the native blue mussel, M.edulis

You can help by reporting any sightings: @ the Centre for Environmental Data & Recording (CEDaR) - Or via the iRecord App. DAERA staff will verify your record and provide further advice. If possible, when submitting your record please include photos of key identification features.

Methods For Prevention

Follow Check Clean Dry to prevent spreading this mussel
Avoid hull fouling on boats
Report all sightings

Species Related Files:

NIEA-ID-Guide-ISNI-website-Mytilus galloprovincialis-Mediterranean mussel