The dynamics of leiognathidae in a tropical demersal ichthyofaunal community

Cabanban, Annadel Salvio (1991) The dynamics of leiognathidae in a tropical demersal ichthyofaunal community. PhD thesis, James Cook University.

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Abstract

Cleveland Bay (Townsville), on the tropical northeastern shoreline of Australia, is a small bay (225 km²) that historically has not been subjected to commercial trawling. However, the unexploited environment of Cleveland Bay is characterized by frequent disturbance by natural processes such as resuspension of sediments on the bottom due to currents generated by wind-waves and monsoonal trade winds, high terrigenous sedimentary input from riverine systems along the coast, and lowering of salinity due to increased flooding. This presents a rare opportunity to gain necessary biological and ecological information on the demersal ichthyofauna that may be typical of the unexploited bays in the Indo-Pacific region. The species composition and structure of the ichthyofauna of Cleveland Bay were studied using a strict sampling regime to provide a general view of the community. In addition, the distribution and abundance of leiognathids (Pisces: Leiognathidae) and their biology (growth, reproduction) were investigated. The extent of predation by synodontids (Pisces: Family Synodontidae) on leiognathids was estimated also. The ichthyofaunal community of Cleveland Bay was multispecific but consisted of only one assemblage at the scale of the whole bay (which is <20 m deep). Total biomass, leiognathid biomass, and leiognathid densities were highly variable at very small spatial and temporal scales (<20 m range of depth, < 1,000 m; daily) and these patterns persist through time (over years) in the frequently disturbed sedimentary regime of Cleveland Bay. The abundance of leiognathids persists despite high predation levels on recruits. This maintenance of high abundance may be explained by their fast growth and iteroparous reproduction. In addition, the leiognathids feed on zoobenthos and zooplankton that can respond rapidly to changes in the primary production of Cleveland Bay (due to resuspension of nutrients and recycling of nutrients by epibenthic biota). The strategy taken in studying this community (a combination of the top-down and bottom-up approaches) provided ecological bases for assessing the state of the ichthyofauna of Cleveland Bay and essential data for modelling multispecific, tropical demersal ichthyofauna and multispecies fisheries.

Item ID: 24122
Item Type: Thesis (PhD)
Keywords: Cleveland Bay; demersal fishes; distribution; Leiognathidae; leiognathids; population; predation; Synodontidae
Date Deposited: 11 Dec 2012 07:14
FoR Codes: 06 BIOLOGICAL SCIENCES > 0602 Ecology > 060205 Marine and Estuarine Ecology (incl Marine Ichthyology) @ 50%
06 BIOLOGICAL SCIENCES > 0602 Ecology > 060202 Community Ecology (excl Invasive Species Ecology) @ 50%
SEO Codes: 96 ENVIRONMENT > 9608 Flora, Fauna and Biodiversity > 960808 Marine Flora, Fauna and Biodiversity @ 100%
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