Nearshore Accumulations of Detached Macrophytes as Nursery Areas for Fish

Abstract

he feeding ecology and seasonal pattern of occurrence of the O+ year classes of the fish Aldrichetta forsteri, Cnidoglanis macrocephalus, Sillago bassensis , and Arripis georgianus were investigated to determine relationships between these economically important species and surf-zone accumulations of detached macrophytes along the coast of Western Australia. The main prey of A. forsteri, C. macrocephalus and A. georgianus and the second most important prey of S. bassensis was the amphipod Allorchestes compressa ; the distribution of A. compressa was restricted to detached plants in the surf-zone. The arrival in winter, of 3 of the fish species on the open coast corresponded with the period of greatest deposition of detached plants in the nearshore zone, and there appeared to be sufficient plant material, and associated amphipods, to support fish during summer. The large patches of vegetation in the surf-zone of sandy beaches support densities of A. compressa up to a mean of 110 g super(-1) dry wt vegetation and provide an alternative feeding habitat for these benthic feeders, one of which is restricted to estuaries in other regions of australia. It is also likely that this vegetation provides shelter from potential predators such as diving birds and larger fish.