Seychelles Introduced Species

In May, 2005 a baseline survey was undertaken by IUCN, SCMRT-MPA, Ministry of Environment, and the Coast Guard to identify native and introduced species around Port Victoria and Sainte Anne Marine National Park. Eleven sites were surveyed and species were sent to international taxonomic experts for identification. Out of 330 species identified three were found to be introduced. Although these species have not caused damage yet, their presence indicates the threat of invasive species in the Seychelles is real and must be addressed.

The introduced species found in this study the amphipods Ericthonius braziliensis and Stenothoe valida, and a sponge: Mycale cf. cecilia. These three species have never been recorded before in these locations. They were probably introduced by hull-fouling or international shipping. Finding them is an indication that species are being transported and introduced into the Seychelles, so it is essential to find and monitor any additional introduced species.



Ericthonius braziliensis is an amphipod that has been recorded in the Hawaii Islands as an aquatic invasive species. It has been found in hull fouling on vessels coming in and out of Hawaii indicating this is the most likely method of introduction and could be the way it has been introduced to the Seychelles.



Stenothoe valida is a small ‘shrimp-like’ amphipod that has been recorded as introduced in many parts of the Pacific such as the Hawaii Islands, the Western Coast of America, and Mexico. It is most likely transported through ships’ ballast water. Although it does not seem to have caused significant damage in these other locations, it must be monitored to prevent future impacts.


Mycale cf. cecilia is a sponge that is very common in shallow water locations. It has been found in Hawaii where it is believed to have been transported via ship bottoms and hull fouling. The Seychelles, like Hawaii, is vulnerable to introduced marine species due to its relative isolation and shipping traffic.

 

A fourth species not found in this study was already known to be introduced into the Seychelles. Oreochromis mossambicus, a Tilapia from Mozambique, was introduced in the 1950’s. It is a tropical freshwater food fish that has been intentionally introduced for aquaculture purposes worldwide. However, its tolerance to different environmental conditions makes it potentially highly invasive and it exists in the wild everywhere it has been introduced. Even though it is not a threat in the Seychelles yet, it must be monitored.

 

The top ten global marine invasive species in the world are:

North American Comb Jelly
North Pacific Seastar
Zebra Mussel
Asian Kelp
European Green Crab
Round Goby
Toxic Algae
Mitten Crab
Cladoceran Water Flea
Cholera

Ericthonius braziliensis
  • Ericthonius braziliensis
Stenothoe valida
  • Stenothoe valida
Mycale cf. cecilia
  • Mycale cf. cecilia
Oreochromis mossambicus
  • Oreochromis mossambicus