[Coral-List] Szmant 2002: Great review on nutrient enrichment on coral reefs (Gene Shinn)

[Eugene Shinn]

John, I agree the Szmant 2002 paper on nutrient enrichment is a classic. 
It was one of several papers consulted while we were developing our 
African dust hypothesis. At the time it was already known that African 
dust supplied the nutrients that stimulate Amazon rain forest growth. 
Thus, African dust also seemed a viable explanation for benthic turf 
algal blooms and demise of coral reefs around isolated Caribbean islands 
with small human populations. It was noted early on that the peak year 
of coral demise throughout the Caribbean was centered around 1983. That 
was also the peak year of increased dust flux in the Atlantic. During 
this period of time our USGS research revealed tidal pumping and 
offshore seepage of nutrient rich ground water. Also at that time many 
researchers were finding offshore surface waters contained insufficient 
amounts of nutrients to readily explain benthic turf algal blooms, Thus, 
seepage of nutrient rich ground water (enriched by anthropogenic sewage 
nutrients) combined with sedimentation of atmospheric dust elements 
might explain turf algal blooms and at the same time explain the 
relative lack of dissolved nutrients in the overlying water column.

So where are we now? For sure the demise of corals reefs continues 
throughout the Caribbean and especially in Florida. It seems likely 
increasing human population in the Keys and continued African dust flux 
(enhanced by climate change) is ongoing. African dust nutrients are now 
increasingly recognized as a stimulus for phytoplankton blooms in mid 
Atlantic surface waters. Many studies have also shown the dust 
transports viable bacteria and fungi along with toxic elements like 
mercury and arsenic in addition to pesticides. And now we have 
sunscreens containing Oxybenzone to contend with. It is increasingly 
difficult to remain optimistic. Gene

See: Shinn, E.A., Smith, G.W., Prospero, J.M., Betzer, P., Hayes, M.L., 
Garrison, V., Barber, R.T., 2000, African dust and the demise of 
Caribbean coral reefs: Geological Research Letters, v. 27, p. 3129-3032.

Also see https://coastal.er.usgs.gov/african_dust/gallery.html

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No Rocks, No Water, No Ecosystem (EAS)
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E. A. Shinn, Courtesy Professor
University of South Florida
College of Marine Science Room 221A
140 Seventh Avenue South
St. Petersburg, FL 33701
<eugeneshinn at mail.usf.edu>
Tel 727 553-1158
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