| dc.description.abstract | Most studies along the Kenyan coast have concentrated on coral
reefs and mangrove swamps. Limited studies have been carried out on
seagrasses though they provide an important link between the
mangroves and the coral reefs. Seagrass beds are located in
intertidal lagoons which lie directly in front of coastal hotels,
hence they are thought to be affected by hotel sewage through
underground seepage particularly where the sewage disposal systems
are located close to the shore.
The aim of this study was to ascertain the effects of this on the
marine life sustained by the seagrass community. The flora, fauna
and physico-chemical parameters of the littoral seagrass community
in Diani Beach, a tour i st resort located in the south coast of
Kenya, was compared to the one in Galu Beach, a relatively
unexploited area in terms of beach hotel development.
The mean biomass of seagrass was significantly higher in Diani
Beach (H = 6.96, p ~ 0.05). Though the algal biomass was higher in
Diani Beach, a comparison between the two areas revealed that the
difference was not statistically significant. The epiphytic load on
the stems of the seagrass Thalassodendron ciliatum (Forssk.) den
Hartog was significantly different (H = 18.13, p ~ 0.05). However,
the abundance of the epiphytes was governed by the availability of
T. ciliatum stems in both Diani and Galu Beaches. The mean number
of epibenthic fauna and infauna were higher in Diani Beach though
it was not statistically significant when the two areas were
compared. The fauna, unlike the flora, experienced significant
seasonal fluctuations attributed to the seasonal environmental
changes particularly in the sediment characteristics.
Detectable nutrient levels in the water column in both Diani and
Galu Beaches indicated the presence of nutrient seepage into the
seagrass ecosystem. The overall levels of nitrates were
significantly different (H = 4.57, p ~ 0.05) when the two areas
were compared with higher levels recorded in Diani Beach. However
the levels of ammonium and phosphate were similar in the two areas.
Nutrient levels in the two areas appeared to be related to the
maximum spring tidal heights and the tidal pumping of groundwaters
as well as rainfall levels.
The levels of biochemical oxygen demand were less than the critical
level of 10 mg °2/1 in.both Diani and-Galu Beaches. In spite of the
high concentration of beach hotels in Diani, tidal out-flushing and
strong circulation patterns prevent the eutrophic accumulation of
nutrients in this lagoon. | en |
