[Truncated abstract] Aspects of the biology of the commercial sea cucumber Holothuria whitmaei were investigated at Coral Bay, Ningaloo Reef, Western Australia. The study was partitioned into several components: i) spatial distribution, ii) temporal changes in behaviour and iii) reproduction biology. The spatial distribution of H. whitmaei at Coral Bay was typical of that reported in the literature. H. whitmaei had distinct preferences for outer reef habitats, including the outer reef flat and reef slope. However, the distribution of H. whitmaei within these habitats was heterogeneous, or, aggregated within certain micro-habitat zones - predominantly at the leading edge of the reef flat, perpendicular to the prevailing current. Two potential biological advantages of this distribution were hypothesised: i), that species aggregation enhances prospects for gamete fertilisation, a process which may be impeded under typical densities, and ii), large deposits of detrital matter, an important food source for holothurians, may accumulate within these zones. ... A striking feature of the reproduction biology of this species was the potential for specimens to mature asynchronously. It was hypothesised that this phenomenon may be a reflection of isolated individuals located too far from conspecifics to receive pheromone signals; cues which are known to entrain synchronous gonad development in some holothurians. Hence, it was proposed that aggregations of H. whitmaei may be important to the maintenance of population recruitment, given that animals at the periphery of species concentrations may have relatively little chance of achieving fertilisation. ... Given that H. whitmaei were observed to maintain highly specific patterns of distribution, this may have significant ramifications for trophic level cascades in the outer reef zone, particularly where this species is present in higher densities (i.e. >100 ind. ha-1). The findings of this study, apart from highlighting the spatial and temporal biological attributes which may facilitate feeding and reproductive success, also emphasised the importance of biological knowledge to the management of sea cucumber fisheries. The study highlighted the need for further research to ascertain both the importance of species aggregations to population recruitment, and of the actual densities required to achieve high rates of gamete fertilisation. Such knowledge may help ultimately to identify suitable habitats for inclusion in marine protected areas.
| Identifer | oai:union.ndltd.org:ADTP/221244 |
| Date | January 2006 |
| Creators | Shiell, Glenn Raymond |
| Publisher | University of Western Australia. School of Animal Biology |
| Source Sets | Australiasian Digital Theses Program |
| Language | English |
| Detected Language | English |
| Rights | Copyright Glenn Raymond Shiell, http://www.itpo.uwa.edu.au/UWA-Computer-And-Software-Use-Regulations.html |
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