wrecks as natural laboratorium

[Mark Vermeij]

Aloha- For the past few days I have been swimming over the reefs on the
Florida Keys to look for areas with high coral recruitment. On average
you'll find between 8-15 juveniles (<1cm diameter) within a square meter.
Surprisingly,  the number of recruits  increases enormously on wrecks (as it
does in other regions in the Caribbean) and up to 100 juvenile  individuals
can easily be found per m^2. Although the composition of such communities is
biased towards "opportunistic" species (i.e. Siderastrea, Porites, Madracis,
Agaricids, Dichocoenia),  there is still a lot of potential to use such
communities in life history analyses since signs of reduced growth or
increased (partial) mortality resulting from their position on a "unnatural
substratum" seem absent. Adult colonies are also more abundant and also do
well. Despite these promising characteristics (high density, survival and
low "stress") I wonder whether anybody can explain why coral recruits do so
well on these structures that have been submerged for >30 years? Is it
because of an  settlement preference for metal structures, a large reduction
of in the competition for space with macro algae (these are nearly absent on
the wrecks I saw) or something else?
I look forward to your suggestions/ hypotheses to clarify this phenomenon.
Best regards,
Mark


--
Dr. Mark Vermeij
Post Doctoral Associate
Cooperative Institute for Marine and Atmospheric Studies
NOAA Fisheries, Southeast Science Center
75 Virginia Beach Dr, Miami, FL 33149 USA
Tel: +1 305-361-4230,
Fax: +1 305-361-4562
E-mail: Mark.Vermeij at noaa.gov

http://www.rsmas.miami.edu/groups/cimas/
http://www.noaa.gov