Trididemnum solidum

[Paul Hoetjes]

Dear all,

Does anyone know whether *Trididemnum solidum*, a compound encrusting
ascidian, is native to the Caribbean or whether it is an exotic species
brought in accidentally from the Pacific? *Trididemnum* is very common
on the island of Curacao which is a major port (in the sixties and
seventies it was in a league with New York and Rotterdam) just north of
the coast of Venezuela, but I understand it is not very common elsewhere
in the Caribbean.

Because it can overgrow and kill corals it is a source of some concern
here on the island. A survey on the island in 1993 by Reef Care Curacao
(a non-profit volunteer organisation striving to protect the reefs)
found an increase in number of *Trididemnum* colonies of up to 725 %
compared to a survey done in 1978 in the same localities (631 colonies
along one of the 45 line transects from 10-120 ft, a distance of about
100 meters). In our quarterly reef monitoring program we find 1 % cover
for *Trididemnum* in some localities.

I'd appreciate any information about this organism, please e-mail me
direct at
reefcare at cura.net

Paul C. Hoetjes
Scientific Coordinator, Reef Care Curacao