Participatory habitat characterization and GIS database development for the conservation and management of sea turtles in south coast kenya

Abstract

Three sites in south coast Kenya i.e. Msambweni, Funzi and Bodo were studied with an overall objective of characterizing the existing sea turtle nesting and foraging habitats. Nesting beach stretches in Msambweni and Funzi were evaluated based on human and natural predation indices and environmental factors which considered temperature measurements. The targeted foraging grounds consisted of seagrass beds and associated food items which included sponges and mollusks. Participatory approaches as well as a stratified sampling design were used in studying both habitats. A total of 10 beach stretches measuring 5.84km were identified in both Funzi and Msambweni. Msambweni beaches had a higher index of human pressure than Funzi beaches although the later had a higher natural predation index in relation to clutch and nesting females' survival. The mean temperature range at a depth of 10-30cm was higher for the Funzi hatchery when compared with samples from Funzi beaches (t= 2.7, p<0.05) but was not significant when compared with measurements from Bodo beach stretches (t= 0.05, p>0.05). However there were significant differences in temperature range reported within sites i.e. Funzi (t= 1.73, p< 0.05) and Msambweni beaches (t= 4.00, p<0.05) at depths of 10-30cm. Funzi had the highest mean temperature range at all depth measurements. Seagrass cover ranged from 1.3-44.23% but there was no significant differences (p>0.5) between sites. Most of the sampling stations were dominated by Thelassodendron ciliatum, Thalassia hemprichii, Siringodium isoetifolium, and Halodule uninervis. A two-factor ranking exercise identified fisheries, sea urchins and pollution as the most immediate threats to sea turtle habitats within the study sites. The overall mean densities of sponges were higher in Msambweni than in Funzi - Bodo sites pooled (p<0.001) while there were more mollusks within the Funzi-Bodo channels compared to Msambweni (p<0.001). The distribution of gelatins was not significant between the two sites (p>0.05). Interviews with fishermen and observations suggest a spatial coincidence between specific seagrass pastures and green turtle sightings. During the survey period 67 green turtle nests were sighted in Funzi and Msambweni beaches and a total of 32 mortality cases reported.