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German wasp | Vespula germanica

German wasp

Vespula germanica

Coral bush | Ardisia crenata

Coral bush

Ardisia crenata

Purple loosestrife | Lythrum salicaria

Purple loosestrife

Lythrum salicaria

Pom pom weed | Campuloclinium macrocephalum

Pom pom weed

Campuloclinium macrocephalum

Canarybird bush | Crotalaria agatiflora

Canarybird bush

Crotalaria agatiflora

Peanut butter cassia | Senna didymobotrya

Peanut butter cassia

Senna didymobotrya

Rubber vine | Cryptostegia grandiflora

Rubber vine

Cryptostegia grandiflora

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Environmental Programmes

In order to tackle our country’s socio-economic challenges, the government adopted the Outcomes based approach to improve government performance and providing focus on service delivery. find out more

Pacific mussel

Semimytilus algosus

Common name:

Pacific mussel

Scientific name:

Semimytilus algosus

Alternative common names:

Bisexual mussel

Pacific mussel is a marine mussel that has invaded South Africa’s west coast. The present geographic range of pacific mussel in South Africa extends some 500 km, from Groenriviersmond in the north to Bloubergstrand in the south. It has become a dominant intertidal organism on wave-exposed rocky shores across this region.

Additional Info

  • Where does this species come from?


    What is its invasive status in South Africa?

    NEMBA category 1b

    Where in South Africa is it a problem?

    Western Cape

    How does it spread?

    Spread by ballast water.

    Why is it a problem?

    It’s an invasive mussel that has become a dominant intertidal organism on wave-exposed rocky shores across the region of West coast (Western Cape Province). It’s much more abundant intertidally than either of the indigenous mussels Aulacomya ater and Choromytilus meridionalis, which have become largely confined to sublittoral and sand-inundated habitats respectively.

    What does it look like?

    Description: Pacific mussel exists as 2 morphotypes: a thick, smooth shell and a thinner, ringed shell. Habitat: The thick-shell morphotype is mostly found on compact, rocky platforms, whereas the thin one is found on emergent rocks. Breeding: The pacific mussel attaches eggs to rocks or substrate or bear live young, the distance between adult population and juveniles will be small and thus determine the population size of embryos and larvae.

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General News Updates

2019 National Symposium on Biological Invasio…


This is your invitation to South Africa's 2019 National Symposium on Biological Invasions. The convention is hosted by the Centre for Invasion Biology (CIB), University of Stellenbosch, and the Biolo... Read more

2019 Invasive Species Training


During the past five years (2014-2018), ISSA invasive species trainers have trained 4 000 in the identification of invasive species and laws pertaining to invasive species across South Africa.  ... Read more

Alien Grass Working Group


Who are we? The South African National Alien Grass Working Group was jointly initiated by the South African Biodiversity Institute (SANBI) and the Centre for Excellence in Invasion Biology (C·I·B) in... Read more

Permits for planting indigenous Cynodon?


On 16 February, 2018, South Africa's Department of Environmental Affairs issued amendments to the regulations and lists relating to the National List of Invasive Species.  Updates to the draft&n... Read more

Invasive species training 2018 dates released


Interested in invasive species?  How much do you know about NEMBA invasive species compliance for landowners and organs of state? The South African Green Industries Council (SAGIC) have released... Read more

Communications post for Africa advertised


The Nature Conservancy has advertised a brand new post:  Communications Manager, Africa Region. Knowledge of invasive species and water would be an asset in this post. See details below:    Job Titl... Read more