The larval fish assemblage of the Nornalup-Walpole Estuary, a permanently open estuary on the southern coast of Western Australia

Abstract

Fish larvae were sampled in the entrance channel and in the two basins of the permanently open Nornalup-Walpole Estuary, on the southern coast of Western Australia, in each month between October 1989 and September 1990. Sampling yielded a total of 39 068 larvae belonging to 36 species and 23 families, with the engraulidid Engraulis australis (56.7%) and the gobies Pseudogobius olorum (24.4%) and Favonigobius lateralis (15.0%) being the most abundant species. Most of the larvae were caught between November and March, with the concentrations of the most abundant species reaching peaks between January and March, when water temperatures had reached 21-24�C. In terms of number of larvae, the larval fish assemblage in the basins was dominated by species that spawn within the estuary, with the larvae of these species contributing ≥98.7% to the totals at the basin sites. Although the larvae of 26 marine species were caught in the entrance channel, these were either rare or absent in the basins, except for those of the terapontid Pelates sexlineatus, which were moderately abundant in the outer basin. The fact that the larvae of most of these marine species were at the preflexion stage, and that all but three of those species had never been previously recorded as either juveniles or adults within the system, indicates that they were passively transported from outside the estuary. The absence of larvae of most of the marine teleosts that are abundant in the basins of the Nornalup-Walpole Estuary parallels the situation in the nearby and seasonally closed Wilson Inlet.

Estuarine Ichthyoplankton Ecology in Relation to Hydrology and Zooplankton Dynamics in salt-wedge Estuary

“…Springlsummer and autumn peaks in the concentration of fish larvae have been reported from other Australian estuaries (e.g. Kott 1955;Hodgson 1979;Miskiewicz 1987;Gaughan et al 1990;Neira and Potter 1994).…”

“…In contrast, species richness of fish larvae is generally highest in the lower regions of estuaries close to the sea, as occurs in Lake Macquarie (Miskiewicz 1987) and the Swan River estuary (Gaughan et al 1990;). This is due to the higher incidence of marine species that enter the lower reaches of estuaries (Lenanton and Potter 1987;Gaughan et al 1990;Neira and Potter 1994). The mid to upper reaches of estuaries are generally dominated by estuarine-spawned larvae (e.g.…”

Diversity, abundance and seasonal variation of the ichthyofauna associated with shrimp farming in a tropical estuary in northeastern Brazil

“…Collectively, fish assemblages during both seasons were comprised of many rare species and a few species in large numbers, a frequent characteristic for estuarine fish populations (Whitfield 1989(Whitfield , 1999Tzeng and Wang 1992;Neira and Potter 1994;Barletta-Bergan et al 2002. Fish fauna peaked in abundance in the wet period.…”

Spatial and temporal patterns in the distribution of large bivalves in a permanently open temperate estuary: implications for management

“…Alternatively, the distributions of adult bivalves across shallow sand habitats in the estuary may be influenced by patterns of water circulation and tidal flow which transport pelagic early life stages. Such processes have been shown to influence the distribution of pelagic fish larvae in this system (Neira and Potter 1994), and differences in water movement may partly explain, for example, why the widespread S. alba tended to be more abundant at sites on the entrance channel sandbars compared to those at the northern side of the estuary where coarser sediments were present.…”