Status of Malindi Marine Park: Study of the 1991 and 1992 Sabaki River Sediment Discharge on the Park's Coral Community. Report to Kenya Wildlife Service, Kenya Marine & Fisheries Research Institute. and Kenya's Fisheries Department.
Increased discharge of terrigenous sediments, due to changing land use practices in the Sabaki River catchment basin, has resulted in concern about the ecological health of coral reefs in the Malindi Marine National Park. A comparison of sediment influences (low, intermediate, high) and time (1980's versos the 1990's) was carried out to determine whether degradation of shallow « 5 meters at low tide) coral communities has resulted from sedimentation. Reef substrate data collected from 284 10m line transects over an eight year period (1985 to 1993) were used to test 6 commonly stated ecological predictions of sediment influence. The predictions are that under increased sedimentation or eutrophication coral reefs should be characterized by 1) increased algal cover, 2) increased soft coral and sponge cover, 3) decreased hard coral cover, 4) decreased coral richness, 5) decreased coral diversity and increased dominance, and 6) either a) decreased mean colony size due to greater sediment clearing efficiency of small corals, or b)increased mean colony size due to lower recruitment success. None of these predictions were unequivocally accepted with the exception of increased soft coral cover. Algal cover remained the same, increasing only in the control reef. Soft coral and sponge cover were higher in high-sediment reefs but only increased over time in the intermediate reef. Coral cover was similar in all reefs except at the intermediate reef, where it increased overtime in direct opposition to the prediction. Coral genera richness, diversity and dominance were predominantly similar overall reefs. Differences in genus abundances between reefs suggest a suite of sediment tolerant genera: Echinopora, Galaxea, Hydnophora, Millepora, Platygra and a suite of 'sediment-intolerant'genera: Acropora, Astreopora, Favia, Favites, Montipora, and Pocillopora. Mean coral colony size increased under higher sediment influence for 'sediment-tolerant' genera and decreased for 'sediment-intolerant' genera. Overall, though there were changes in some of the parameters listed above, no evidence for decreased diversity and hea1th of shallow sediment influenced reefs could be found for Outset of measurements. Evidence for change in the bottom dwelling community in the intermediate reef (Malindi Coral Gardens)was found, with sediment tolerant hard corals gaining in dominance and increases in soft coral cover. The lack of a strong effect is very likely due to the active protection of the Malindi reefs over the last 30years. From an ecological perspective, protection preserves the full suite of natural factors that help maintain reef productivity and diversity. The prevention of fishing has allowed normal herbivore populations to persist, actively preventing the predicted increase in algae. Increasing exploitation of reef resources in the future will necessitate management of other factors that may add further stresses-tourist damage, pollution, and varied extractive uses in the Marine Parks and Reserves reef system.
| Main Authors: | , , , |
|---|---|
| Format: | Report biblioteca |
| Language: | English |
| Published: |
NYZS - The Wildlife Conservation Society, Coral Reef Conservation Project
1994
|
| Subjects: | Marine parks, Protected areas, Protected resources, Sediments, Coral reefs, Abundance, |
| Online Access: | http://hdl.handle.net/1834/7146 |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|