Monday, August 27, 2007

Take that, suckers!

Tom Goreau has submitted the following letter to Science regarding attempts to 'vacuum' algae killing coral in Hawaii (noted on Coral Bones at Believe it or not):
"Call the Hose Brigade!" (Random samples, 10 August, p. 729) describes an effort to remove a massive nuisance algae bloom killing corals in Kaneohe Bay, Hawaii, by sucking it up with huge barge-mounted vacuum cleaners. Unfortunately this will give only temporary results and will fail in the long run unless the nutrient excess that fuels the rapid growth is removed. Kaneohe Bay is a classic example of coral reef eutrophication: benthic algal blooms caused by point discharges of sewage killed the reef in the 1970s, and died back when the outfall was removed, allowing the reef to gradually recover (1). With continued suburbanization of the watershed, uncontrolled non-point nutrient discharges to the bay from golf courses, lawn fertilizers, and road runoff have again raised the nutrient concentrations (2,3) above the thresholds for nuisance algae (4-6). Besides the temporary success in Kaneohe Bay, there are very few examples of algae being successfully removed. In one bay in Jamaica where all the land-based nutrients were diverted, nuisance algae that were choking the reef began to die back in weeks, and only a few dying clumps off weedy algae remained two months later (7). If algae are starved of nutrients, they die very quickly, and will not return unless nutrient thresholds are again exceeded. But no amount of sucking them off will work when they grow right back because they are overfertilized. It is the suckers paying for this well intentioned, but ultimately futile effort, who will be hosed unless the underlying causes of eutrophication are removed.
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1. A Banner, Proc. 2nd Int. Coral Reef Symp., 2, 685 (1974)
2. E Laws, C. Allen, Pac. Sci., 50, 194-210 (1996)
3. S. Larned, J. Stimson, Mar. Ecol. Prog. Ser., 145, 95-108 (1996)
4. P. Bell, Wat. Res., 26, 553-568 (1992)
5. B. Lapointe, N. Littler, D. Littler, Proc. 7th Int. Coral Reef Symp., 1, 323-334 (1992)
6. T. Goreau, K. Thacker, Proc. Carib. Water & Wastewater Assoc., 3, 98-116 (1994)
7. T. Goreau, UN Expert Meeting on Waste Management in Small Island Developing States, 1-28 (2003)

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