Abstract

Salt River is a brackish water estuary in Clarendon, located on the southern coastal shelf of Jamaica. The Salt River channel acts as a nursery ground for the juveniles of the fishes that live offshore and nearby Goat Islands. The presence of Gerreidae (mojarras) is a defining aspect of tropical and subtropical estuarine fish communities globally. Fifteen families of fishes have established populations along the Salt River channel. In Jamaica, there are nine species of mojarras and five of those species have significant populations at Salt River. These secondary consumers form an important part of the food web of this ecosystem. Mojarras have a unique protrusible mouth that allows successful foraging through sediment to consume benthic organisms. Diapterus auratus, Gerres cinereus, Eucinostomus argenteus, Eucinostomus melanopterus and Diapterus rhombeus are so morphologically similar that competition for the same resources is inevitable. These five species employ numerous resource partitioning mechanisms to decrease competition. An analysis of the biology, ecology and habitat dynamics revealed that spatial, temporal, and dietary niches are a few of the measures employed to reduce competition. Stomach content analyses revealed the necessity of these measures as there is significant overlap in the food items consumed by these five species. The spatial distribution of these fishes at different sites along the channel help to limit the feeding competition. This study appraises the spatial, temporal, and dietary resource partitioning mechanisms employed by these five species of mojarras.

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