Inter-period comparisons of the ichthyofaunas of two nearby, modified estuaries and the biology of Pelates octolineatus (Terapontidae)

摘要: The nearby Leschenault and Peel-Harvey estuaries, on the lower west coast of Australia, have undergone radical “engineering” changes. This applies particularly to Estuary, in which a second artificial entrance channel was constructed 1994 increase tidal exchange thereby reduce massive eutrophication that afflicted system. number species, densities species compositions ichthyofaunas these two systems between winter 2008 autumn 2010 were determined using data derived from seasonal seine netting. results compared with those obtained Estuary 1996-97 1980-81 Estuary. Sampling throughout 2008-10 21.5 m net yielded 27,044 fish, representing 43 75 % catch comprising atherinids Atherinosoma elongata, Craterocephalus mugiloides Leptatherina presbyteroides, clupeid Hyperlophus vittatus mugilid Aldrichetta forsteri. Species richness greatest middle regions, due high abundance marine whereas C. A. elongata only consistently abundant upper apex are influenced far less by undergo more pronounced changes salinity temperature. contrast large numbers Atherinomorus vaigiensis caught their absence earlier period represents southwards extension tropical presumably response increasing water temperatures recent years. 58,980 46 when net, 107,670 56 employing 102.5 net. While H. vittatus, L. Ostorhinchus rueppellii catches both nets, samples contained greater Torquigener pleurogramma. Favonigobius lateralis, T. pleurogramma generally found reaches south-western Australian system, reflecting maintenance salinities for much year. Following introduction Dawesville Channel subsequent increases exchange, ichthyofaunal composition changed being related mainly region becoming season (Young & Potter, 2003a, b). Since late 1990s, there has been an teleosts, fish especially “plant” associated species. is attributable seagrass macroalgal biomass certain regions reduced freshwater flows reflected similarly region. While geomorphology estuaries differ, underwent similar cycling 2000s. However, faunas sequentially distance thus along gradient salinity, basin varied less, similar. influence movement ocean provides effective mechanism transporting into out this A concomitant study biology Pelates octolineatus coastal emabyments. terapontid settles shallow beds bays, where they remain about year, before moving deeper waters can live up 10 maturity at end its year life spawns spring summer. Growth highly seasonal, occurring warmer months. also acts as important nursery area P. octolineatus, young juveniles recruiting summer emigrating decline, trend repeated some 1+ 2+ fish. Instantaneous growth rates than embayments, productivity estuary. This thesis demonstrates markedly environmental, anthropogenic climatic effects. It valuable insight biological ecological characteristics estuarine-opportunist complete cycle embayments but use during years cycle.