Introduced and cryptogenic marine and estuarine species of South Africa
Author
Mead, A.
Author
Carlton, J. T.
Author
Griffiths, C. L.
Author
Rius, M.
text
Journal of Natural History
2011
2011-10-31
45
39 - 40
2463
2524
http://dx.doi.org/10.1080/00222933.2011.595836
journal article
10.1080/00222933.2011.595836
1464-5262
5204591
Class
HYDROZOA
As with other challenging groups, we can only make a first approximation of the numbers of introduced hydroids, especially as these invasions may have commenced in the 1600s. We select, as examples only, 11 species of hydroids as introduced and three species as cryptogenic. There are dozens, if not scores, of species of hydroids that could be considered for candidacy as introduced or cryptogenic in the South African fauna. For example, of the eight hydroid taxa identified to species found by
Henschel et al. (1990)
on fouling panels in Simon’s Bay (False Bay), we consider two species (
Obelia dichotoma
and
Tubularia warreni
, the latter now known as
Pinauay ralphi
). The remaining species,
Campanularia integra
,
Sertularella arbuscula
,
Plumularia setacea
,
Plumularia lagenifera
,
Nemertesia cymodocea
and
Amphisbetia operculata
, are but six examples (all of which are found elsewhere in the world) of a very large guild of species that bear careful global biogeographic, systematic and genetic study. The 11 introduced species treated here originate either from the North Atlantic, Europe, Eurasia (Ponto-Caspian) or are of unknown provenance. As a consequence, the Pacific taxa (for example, those from
Japan
or the western Americas) are missing from our assessment. Rather than Pacific hydroids not being represented as introductions in the South African biota, it is probable that species from these regions are buried in the very large “cosmopolitan” (and so cryptogenic) hydrozoan element present in
South Africa
. For all the examples presented, we consider ship fouling and ballast water the most probable vectors.