State of the Bay Report 2011-Final.pdf - Anchor Environmental

State of Saldanha Bay & Langebaan Lagoon 2011
Birds
evident for at least 6 month after most of the dead mussel shells had been removed by SANParks in
late 2001.
11.1.2 European shore crab Carcinus maenas
Carcinus maenas is a native European crab species that has been introduced on both the Atlantic
and Pacific coasts of North America, in
Australia, Argentina, Japan and South Africa
(Carlton & Cohen 2003). It is typically is
restricted to sheltered, coastal sites and
appears thus far to have been unable to
establish on the open wave-swept coastline
in South Africa (Hampton and Griffiths 2007)
and elsewhere. In South Africa it was first
collected from Table Bay Docks in 1983 and
later in Hout Bay Harbour. It has established
dense populations in both harbours where it
has reportedly decimated shellfish
Figure 11.2
European shore crab Carcinus maenas.
Photo: C.L. Griffiths.
populations (Robinson et al. 2005). Surveys in Saldanha Bay has not turned up any live specimens of
this species to date, but a single dead specimen was picked up by Robinson et al. (2004) in Small Bay
(the Small Craft Harbour). It is not clear whether there is in fact and extant population in the Bay at
present or not.
11.1.3 Shell worm Boccardia proboscidea
Boccardia proboscidea is a small (20 mm long) tube-dwelling worm found in shallow sand-lined
burrows on the surfaces of oysters, abalone and other shellfish. It occurs naturally on the Pacific
coast of North America and Japan (Simon et al. 2009, Picker & Griffiths 2011). In South Africa it is
known to occur on a number of oyster and abalone farms and has also recently been recorded in
Saldanha Bay outside aquaculture facilities (Haupt et al. 2010).
11.1.4 Pacific South American mussel Semimytilus algosus
The Pacific South American mussel Semimytilus algosus is a small (up to 50 mm) elongated,
relatively flat and smooth brown mussel, with a shell tinged with green. This species has been long
known from Namibia (since the 1930s, Kensley & Penrith 1970) but was only recently (2010) found
in South Africa. It reportedly occurs in huge densities of thousands of individuals per square metre
low on the shore, along most of the West Coast of South Africa. It is likely that it was transported
southwards from Namibia either by shipping or under its own steam. This species show a strong
preference for wave exposed shores (C.L. Griffiths pers. comm.) and thus is unlikely it reach high
densities in Saldanha Bay. It has, however, been observed on ropes in the mussel farms in Saldanha
Bay.
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