Re: nudibranch extinction? (2)

May 2, 2001
From: John Hoover

Fascinating! I own that issue of National Geographic too, and have wondered about these Chromodorids. However, Zahl includes some slugs from the Great Barrier Reef in his article, so I assumed that the red spotted ones were also not from Hawaii. I certainly have never seen them.

Some random thoughts:
Zahl seems to have photographed his Hawaiian specimens in aquaria. But these two slugs are seen with an old chain in the background, so I wonder how/where they were photographed. I can't see anyone putting an old chain in an aquarium.

Cory Pittman points out that there is a colonial tunicate in the upper left. Offhand, it doesn't look like one from Hawaii, but then again who knows?

Kaneohe Bay is a unique habitat. There's no place else quite like it in the Hawaiian Islands and it's not impossible that a species could be confined to the Bay. I can think of at least one other -- a brachiopod-- whose Hawaiian population might be confined to Kaneohe, although the brachiopod is not endemic to Hawaii.

Kaneohe Bay has undergone lots of environmental changes and degradation in the past 50 years. Dredging, sewage disposal, algae blooms, exotic species, freshwater runoff, siltation, etc., so it's also not impossible that a species confined to the Bay did not survive the changes and went extinct.

Zahl writes that he got some specimens from Makua, which is a quite different habitat from Kaneohe Bay. I have dived in Makua-like environments many many times and needless to say have not seen these slugs. I have done almost no dives in Kaneohe, however, because access is difficult. Yet Kaneohe is the site of the Univ. of Hawaii marine lab, so it has been sampled extensively. University people dive there all the time so I will send this to one of them and see what he says. He's a fish person, but it would be hard not to notice these beautiful slugs if they are still there.

John Hoover

hoover@hml.org

Hoover, J., 2001 (May 2) Re: nudibranch extinction? (2). [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/4276

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