Patterns of recruitment and resource use in a shallow-water fish assemblage in Moreton Bay, Queensland

Abstract

The most abundant fish species was cardinal fish Apogon fasciatus, followed by fan-bellied leatherjacket Monacanthus chinensis, leatherjacket Paramonacanthus otisensis, trumpeter Pelates quadrilineatus and pony fish Leiognathus moretoniensis. Small juveniles of these species recruited to the area, with all except L. moretoniensis being most abundant at the most vegetated site. Mean catch rates differed significantly between sites, and patterns of habitat use, seasonality and diel behaviour varied between species. There was evidences of ontogenetic migration into deeper water in all species, although this was weakest for A. fasciatus. P. quadrilineatus and L. moretoniensis took large amounts of polychaetes and copepods, M. chinensis and P. otisensis consumed more amphipods, molluscs and vegetation, and A. fasciatus exploited a wide size range of prey, including crabs, fish and small crustacenas. Interspecific diet overlap was greater in larger fish, but was less than intraspecific overlap between size classes. Daytime feeders dominated the assemblage, but catch rates were higher at night. Overall patterns of resource use suggested species partitioning, but strong evidence of niche separation was obtained only for L. moretoniensis, which was distinct on all three major resource axes (food, habitat, time). Scope thus existed for interspecific competition between members of the assemblage. -from Authors