Subject: Red tides, kelp and whales

Phil Colla (
Mon, 16 Feb 1998 17:13:16 -0800

>Could a red  tide occur  in or around  Kelp beds?
>Do red tides affect the  migration  of  sea  mammals, especially whales?

Yes, I think that red tides can occur near kelp beds.
I live in Southern California, where kelp grows.  We occasionally
have red tides occur.  While the red tide is mostly offshore,
it does extend inshore close enough to cloud the water amid the kelp
beds.  The surf will turn brown and smell.  If the red tide comes
this close to shore, it is definitely mixing in to the kelp bed.

Your second question is a good one, and I don't know the answer.
I suspect that migratory or travelling marine mammals might avoid
red tide areas, once they sense the difference in taste, salinity,
smell or lack of prey in a red tide area.  Also, red tide aggregations
can contain toxins that might prove harmful to sea mammals -- it is
possible that some mammals have evolved an inate avoidance reaction
to red tides because of this.  I do not know of any studies done about
red tides and migration.

You might search the web for information about the recent (1996,1997)
die offs of manatees in Florida -- I believe that it was related to
a toxin or biological agent correlated with a type of red tide (but I
could be mistaken, check it out yourself).

Phil Colla

Phil Colla,
Humpback Whales: