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Abstract-The sea cucumber Holothuria fuscogilva is currently one of the most commercially valuable species of sea cucumber worldwide. This study investigated reproduction of this species in order to characterize the reproductive pattern and evaluate the relationship with temperature, light and lunar periodicity. Individuals were collected monthly, between 1998 and 2007, at Shimoni, Kenya and processed using standard gonad index methods and macroscopic and microscopic observations of the gonads. Gametogenesis commenced from May and spawning occurred from December to April of each year and there was close synchrony between the sexes, contrary to the hypothesis that breeding patterns on the equator will be continuous and less synchronized between sexes. Peak spawning occurred during the last quarter of the moon. The gonad index of individuals correlated significantly with gonad tubule length and fecundity indicating that it was a good predictor of sexual maturity and reproductive output. The gonad index showed a significant correlation with temperature but not light, suggesting that temperature may play a role in controlling reproduction. The life history strategy of this sea cucumber included a higher energetic investment in the reproductive output of females and spawning at a time favorable for larval development. There was a shift in sex ratio from unity to significantly more males over the sampling period, as well as a significant reduction in mean sizes (body wall weight) and reproductive output (gonad index) suggesting that the reproductive success of this species was potentially negatively affected by fishing.

Summary A comparison of Echinometra mathaei densities and sizes was undertaken on an inner reef lagoon and an outer reef edge on a densely populated tourist beach at Diani, Kenya. Echinometra mathaei densities and average lengths were significantly higher (t‐test, P <0.001) in the inner reef lagoon (density = 14.2±1.7 no. m‐2, n= 90; lengths = 40.8 ±0.6 mm, n= 144) than on the outer reef edge (density = 1.7 ± 0.13 no. m‐2, n= 60; lengths = 31.2 ± 0.8 mm, n= 68). A comparison with density and length data collected 15 years previously (Khamala, 1971), showed increases in the numbers and average lengths (t‐test; P < 0.05) in the inner reef and a decrease in the average lengths (t‐test; P < 0.05) on the outer reef edge. Using a correlation of the length and average weight of individual urchins (weight = 0.0021 length2.64, r= 0.96, n= 144) and the average length and density measurements (no. m‐2), an increase of 424 g m‐2 on the inner reef and a decrease of 81 g m‐2 on the outer reef edge was found over the past 15 years. Quantities of sediment found in the gut contents of the sea urchins (69.5% by weight) were positively correlated with the weight of the sea urchins (F=67.5, P<0.001, r= 0.73), which suggests that reef substrate degradation rates are proportional to the urchin biomass. Therefore, we suggest that there has been an increase in reef substrate degradation rates on the inner reef lagoon but not on the outer reef edge. The distribution of E. mathaei on the inner reef was positively correlated (F= 82.2, P < 0.001, r= 0.69) with the percentage of hard substrate (dead coral and coral rubble) but not on the outer reef, where the availability of shelter appears to be of greater importance. We suggest that the population increase in the inner reef is due to ecological release of E. mathaei from competitors and predators due to increased fishing and shelling activities. On the outer reef the stressful physical environment may limit both the sea urchin populations and man's ability to fish and collect shells. RÉSUMEÉ On a réalisé une comparaison des densités et des tailles de Echinometra mathaei si les cǒtés interne et externe de la barrière récifale le long d'une plage touristiqi densément peuplée à Diani, au Kenya. Les densités et longueurs moyennes de E. mathaei sont significativement supérieures (test de t P < 0001) du cǒté interne de barrière (densité= 14.2±1.7 ind./m2, n = 90; longueur = 40.8±0.6mm, n = 144) que du cǒté externe (densité=1.7 ± 0.13 ind./m2, n = 60; longueur = 31.2±0.8 mm n = 68). Une comparaison avec les données de densité et de longueur récoltées 15 ans auparavant (Khamala, 1971) montrent une augmentation des nombres et des longueurs moyennes (test de t; P < 0.05) due cǒté interne et une diminution des longueurs moyennes (test de t; P < 005) du cǒté externe. En correlant la longueur et le poids moyen des oursins (poids = 0.0021.longueur2.64, r = 0.96, n= 144) avec la longueur moyenne et les mesures de densités (en ind....

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