James M. Cervino
cnidaria at earthlink.net
Thu Jul 2 11:04:15 EDT 1998
Reefs At Risk
My students and myself have been reading the debate on the coral list
server regarding the problems reefs are facing, and we had some questions:
1) I have been diving the Caribbean since 1979, and the Pacific since 1990.
We have seen the exponentially expanding human populations and tourist
hotels grow in numbers in the past 15 years, and along with this growth we
have seen the steady growth of macro-algae smothering the corals leading to
coastal eutrophication . None of these islands have sewage treatment
plants, and the islands that don't have septic tank overflows, dump sewage
directly into the water. I don't even think there is a debate as to whether
this direct dumping of sewage is causing such high nutrient loads along
these coasts and shallow lagoons, or is there?
2) Are we saying in situations such as this, up-welling of nutrients from
the deep oceans, and sewage from anthropogenic sources are equally causing
the demise of coral cover?
3)Can someone honestly say that fertilizers and anthropogenic waste,
whether it be direct or from leaky septic is not part of the major problem
on these islands and southern Florida??
4) Regarding Fl. : What about the river of sand, a geological formation
called the Long Key Formation, that was deposited along the Florida
peninsula 3-5 million yrs ago. Larry Brand has claimed that this is an
ideal way for phosphate laden water to move through unchanged, thus leaking
under the Florida Bay, is this not true?? It makes sense! Is this not
causing the demise of coral cover from coastal eutrophication??
5)Studies by Lapointe and Tomasko have shown that increased water column
nutrient availability typically results in greater epiphyte levels on
seagrass blades. Nutrient-induced increases in epiphyte coverage decrease
the amount of light that seagrass blades and corals tissue receives. Is
this not a stress causing a major problem??
6) CAN WE ALL AGREE THAT NUTRIENTS FROM ANTHROPOGENIC SOURCES ARE CAUSING
THE DEMISE IN CORAL AND SEA GRASS COVER IN FL. AND CARIBBEAN ISLANDS?
WILL THIS NOT LOWER THE METABOLIC ACTIVITY OF THE CORALS THUS MAKING THEM
MORE SUSCEPTIBLE TO DISEASES?
Excess nutrients can cause the proliferation of macro-algal blooms, and
cyanobacteria in and around these oligotrophic systems. Example: Sipadan
Island, Indo-Pacific. In 1988 Sipadan Island had 15 rooms (huts on stilts,)
on this 600 yard circle coral cay. In 1990 there were 2 more dive operators
on this cay adding 30 more rooms. In 1992 another 2 dive operators added 30
more rooms, and as of 1998 I heard there were 7 dive operators on this tiny
coral cay. So this small island now has 200 to 300 humans whose waste is
deposited in the porous limestone substrate each day. We have photo graphed
the decline in corals due to excess sediment, and proliferation of
macrophytes growing all over the Acroporids and soft coral species. Gardens
of hard and soft corals that once thrived on this 400meter wall in front of
the island, are now 80% gone. The corals 1/2 km. out from shore are
smothered with bluegreens and weedy types. The nutrient thresholds noted by
Bell PRF (1992) Water Research 26:553-560, for inorganic nitrogen and
soluble reactive phosphorus must be at level. This is a protected reserve,
with no HCN or dynamite fishing. Therefore herbivores should be controlling
the macrophytes. AND THIS IS NOT SO!
7)There are plenty of sea urchins and parrotfish, and yet still we see the
smothering of algae on corals?? Why is this so??
8) LAST QUESTION: LETS SAY WE SEE AN INCREASE HUMAN GROWTH AND IN DIADEMA
ANTILLARUM IN THE NEXT 10 YEARS. WILL THE URCHINS START TAKING CARE OF THE
MACROPHYTES THAT ARE SMOTHERING THE CORALS? AND WHAT ABOUT THE GREEN PEA
SOUP ON THE SURFACE WATERS COMING FROM PLANKTON BLOOMS? I GUESS THE WATER
BELOW WILL BE CLEAR, HOWEVER, WE STILL HAVE A PHOTOSYNTHESIS PROBLEM. WILL
THIS NOT SLOW THE GROWTH RATE IN CORALS?
I GUESS WITH THE GROWING CHLOROPHYLL CONCENTRATIONS WE MIGHT HAVE ANOTHER
PROBLEM, INCREASE TEMPS. AND BLEACHING, I DON'T THINK THESE LITTLE CRITTERS
CAN SOLVE THIS PROBLEM!
THANKS, JAMES AND STUDENTS FROM AP SCIENCE AT ST. FRANCIS IN NY.
James M. Cervino
Global Coral Reef Alliance
124-19 9th ave. College Point
New York, N.Y. 11356
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