Key changes in the coral reef community: Permanent photoquadrat analysis

1. The abundance of sessile marine life increased at all sites, and was most pronounced at the Reserve sites of Pain de Sucre and Ile Fregate. Gros Islets was the most dynamic site, showing both increases and decreases in individual species.

2. We recorded an overall increase in coral abundance at all sites. Increases ranged from 4% cover (Les Gros Islets) to 8% (Pain de Sucre). Changes were due to growth of existing corals and to recruitment of new species. New coral colonies established including, Eusmilia (flower coral), Montastrea, (boulder coral), Siderastrea (star coral), Porites (finger coral) Acropora prolifera (fused staghorn) Acropora crevicornis (fragile staghorn), Isophyllia/Mycetophyllia (cactus corals), Diplora (brain coral) sea rods/sea fans Plexaura, Pseudopterogorgia, Eunicea, and Briarium

3. We observed significant increases in the abundance of fused staghorn coral Acropora prolifera, especially at Ile Fregate. Here we recorded increases of over 30% cover in some quadrats. Acropora prolifera is tall, branching upright coral that forms extensive barrier reefs. However, much of the growth observed at Ile Fregate was horizontal and plate-like, probably because there is no competition for space or light, as few other corals are present. We anticipate that upright branches will form soon leading to rapid growth and recovery of the reef.

4. At all sites we observed new and recent recruitment of the fragile staghorn coral Acropora crevicornis (within and adjacent to photoquadrats).

5. Since the initial quadrat surveys there has been extensive recruitment and growth of the branching sponge Aeglis conifera. We recorded new colonies at all sites. In addition, encrusting and rope sponges increased in abundance.

6. Algal abundance remains extremely low at all sites, and has not significantly changed since the initial monitoring. Stypopodium zonale is the most common alga and covers only up to 12% at Ile Fregate. Herbivory and low nutrients probably contribute to the low algal biomass, however we do not have data on nutrient levels to support this. Low algal abundance, and absence of overgrowth of corals by algae is an indicator of a healthy reef (e.g. Hughes 1994).

7. We did record occasional reductions in the abundance of individual colonies. For instance, in quadrat 3 at Gros Islets we recorded a decrease in Porites due to overgrowth (i.e. competition) by another coral Agaricia. At Ile Fregate about 10% of a small brain coral suffered sand burial, and we also recorded loss of sponge fragments (e.g., 4% of a sponge colony lost).

8. At Gros Islets we recorded coral damage and loss. One colony of the flower coral, Eusmilia (5% cover) was completely lost and there was damage and loss to the adjacent plate-coral, Agaricia (6% cover) and to mound coral, Montastrea colonies. This loss seemed to be due to physical damage, e.g. anchor, fishtrap or diver activity rather than a natural event (examples of photoquadrat data).

9. There was no significant increase in disease at all sites. We did record one diseased gorgonian in the photoquadrats at Gros Islets, and noted signs of wasting disease and black band disease outside of quadrats and at other sites around the island, but these incidences were low and comparable to those recorded in 1996 and 1997.

click on the following thumbnail's to see full images:

Coral Families	Photoquadrats	Gros Islets , 1996	Gros Islets, 1998

Overall Conclusions

1. St Barthelemy's coral reefs suffered extensive damage from human and natural events. However, the reefs in the areas monitored are improving, and these is evidence of growth and recruitment. The next few years will be critical. There were no hurricanes during the intervening interval between setting up the photoquadrats and the most recent monitoring. This "calm" has provided an opportunity for new recruits and fragile species to establish.

2. What is the prognosis for recovery and what are the threats to recovery? We have no control over natural events, but the absence of severe hurricanes will greatly enhance reef recovery (an opinion also expressed by Dr. J. Woodley for Jamaican reefs). We do however, have some control over human activities, and it is essential that human stress on the reefs be kept to a minimum to allow for regrowth and recovery of damaged reefs. We see the main human threats to the reefs as development leading to increased runoff, sedimentation, and/or pollution (this will most likely affect nearshore reefs around St Barthelemy (e.g. Grand Cul de Sac, Baie de St Jean): reef destruction for boat channels (e.g. lle Fregate); and overfishing and/or recreational overuse. Natural ecosystems have evolved to cope with and take advantage of natural disturbances including hurricanes (e.g. Connell 1979). However, human activities can stress a system beyond its ability to cope with or recover from natural events. Careful monitoring of the new reserve and enforcement of regulations will help minimize additional stresses and sustain the reefs.

3. The Marine Reserve is a new venture, and the development of an administrative structure has yet to be completed (i.e. hiring of reserve director and guard, and establishing an office). Once this is in place, we expect that the Reserve will play a more active role in education, outreach, and the enforcing regulations. The reefs are gradually recovering, and it is essential that they receive the needed protection from human activities to grow and establish new coral and fish populations. As always, SEI gratefully acknowledges the contributions and help of individuals and organizations who have made this work possible. They include, Jean Aubin, Nicole Aussedat, Erik and Lowrance,and contributors AA, the New England Biolabs Foundation, William Lansing, and many others. Thank you.(A full list is available on our acknowledgements page)

FUTURE ACTIVITIES

Our continuing activities can be divided into two main categories;
· Continue ongoing monitoring and design additional research and monitoring activities for the Reserve and
· Expand the Knowledgeable Diver monitoring programs and activities

If you are interested in joining in any of these activities contact SEI.

	St. Barthelemy, Research and Discovery
	Montserrat, Coral Reefs under the Volcano
	Research Study - Hands Off Diving
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© 2000 Sustainable Ecosystems Institute comments: sei@sei.org