Reefs at Risk

J. Charles Delbeek delbeek at
Tue Jun 30 02:52:30 EDT 1998

I seem to recall reading a recent paper on a study of nutrient levels off
of Key Largo and lower down in the keys. Although nutrient levels inshore
were found to be slightly elevated, those on the outer reef tracts were
found to be quite low. I don't see how you can make the assertion that
nutrient run-off is causing problems on these outer reefs when the levels
are so low?

However, having said that, it brings to mind the observations that many
home aquarists have made and also illustrated by the microcosm systems at
the Smithsonian Institute using algal turf scrubbers, that despite very
low levels of nitrate and phosphate in the water column algal growth can
still be quite substantial. In light of my experiences in closed systems I
would have to propose that lack of herbivores is a greater contributing
factor to algal growth on Caribbean reefs than high nutrients. I think if
coral researchers spent some time working with closed "mini-reef" 
ecosystems, they might gain a new perspective on coral reefs and how they
function in situ, as well as coral wasting diseases, which BTW are also
being encountered by home hobbyists. 

J. Charles Delbeek M.Sc.
Aquarium Biologist
Waikiki Aquarium

"The fact that my physiology differs from yours pleases me to no end." 
Mr. Spock

On Mon, 29 Jun 1998 MERPM at wrote:

> While it may not be great science to say that the leaking septic systems of
> the Keys and the nutrient addition to Florida Bay, etc., from agriculture in
> the Everglades are two of the probable major causes of reef degradation in the
> Keys it seems highly unlikely that they are not.  Human populations and
> agricultural production have expanded tremendously in all of the areas
> mentioned in the last posting about this topic....Belize, Colombia, the lesser
> and greater Antilles, Honduras, Florida, etc.  Reefs in all of these locations
> have suffered due to increases in agricultural runoff and domestic sewage, raw
> sewage in most cases, inputs.  I don't believe the science is
> lacking...fertilizer and sediments from any source harm reefs.  It is
> happening everywhere we look because human populations have expanded,
> everywhere, beyond the capacity of the land to absorb our wastes...thus the
> excess flows to the sea.  The concept is very simple and, in most areas,
> waiting for additional research to be completed is in itself a major threat to
> reefs.  We need to move from pretending that we don't know what is killing
> reefs to taking restorative measures or protective measures to prevent further
> losses.  
> Mike Marshall

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