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Marine Surveys undertaken in the Lihou Reef National Nature Reserve, March 2004
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- Author / Creator
- Oxley, W G; Emslie, M; Muir, P; Thompson, A A
- Copyright
- The Australian Institute of Marine Science 2004
- Full Abstract
- The Lihou Reef National Nature Reserve (Reserve) is one of two protected areas in the Coral Sea region. The Reserve is located some 400 kilometres east of Townsville, Queensland. The Australian Institute of Marine Science (AIMS) conducted fish, benthic and bêche-de-mer surveys in the Reserve, 15-18 March 2004. One hundred species of hard coral were recorded in the Reserve compared to 99 at the Coringa-Herald Reserve in 2003. Coral cover was low (7.9%) and consistent with a reef recovering from a disturbance. At the time of the surveys, a severe bleaching event was in progress. Bleaching of hard corals was observed at all sites and at the Reserve level it was estimated that 65% of the hard coral cover was bleached. Bleaching was uneven among coral families with the Acroporidae most affected, followed by the Pocilloporidae. Faviidae and Poritidae were least affected. The high levels of bleaching in the Acroporidae were consistent across all reefs. A few hard coral species did not appear to be affected by the bleaching, including Coscinarea columna and Porites lichen, while some species showed a low level of bleaching including Pocillopora edyouxi, Leptastrea inequalis, Turbinaria spp., Goniopora spp. and Astreopora spp. The majority of hard coral species had unusually small colony sizes. There were few hard coral colonies greater than 50cm diameter. The small size of coral colonies and low overall coral cover is interpreted as an indication of a recent large-scale disturbance event. The occurrence of another large-scale disturbance raises serious concerns that some coral species will become severely depleted. There is evidence that this has already occurred as a result of the previous disturbance event. No crown-of-thorns starfish (COTS) were observed during the surveys and there was no sign of damage to corals from COTS activity. There were no signs of damage to corals from coral disease. Multivariate analysis has revealed that the fish community at Lihou Reef Reserve was very similar to that encountered at the Coringa-Herald Reserve in 2003. However, this ‘Coral Sea’ community was quite distinct from the community encountered at Elizabeth Reef in 2003. This separation was largely driven by the presence of several temperate water species at Elizabeth Reef, most notably Prionurus maculatus, Chromis hypsilepis and Chrysiptera notialis. Three species of coral trout (Plectropomus laevis, P. leopardus and Variola louti) were recorded during the surveys at Lihou Reef Reserve. Plectropomus laevis dominated the upper size class frequency distribution to the exclusion of P. leopardus. The only previous survey of Lihou Reef was conducted in 1984. A comparison between the 1984 data and this survey provides some evidence for a decline in cover of hard coral, soft coral and sponges. In contrast, numbers of the commercially valuable coral trout species appear to have increased slightly between 1984 and 2004. This report represents the first published surveys of bêche-de-mer in the Reserve. Only four bêche-de-mer species were observed. They were the commercially important Holothuria whitmaei (nobilis), along with Holothuria atra, Bohadschia argus and Thelenota ananus. The densities of H. whitmaei observed in the Reserve was similar to those observed in the Coringa-Herald Reserve in 2003. They were clearly lower than the densities observed at Elizabeth Reef in 2003. It is clear that the reefs of the Lihou Reef National Nature Reserve are under significant pressure, especially from the effects of coral bleaching and cyclones. The bêche-de-mer populations in the Coral Sea are also under heavy pressure as evidenced by the decline in catch rates in the local fishery. This highlights the importance of maintaining a proportion of the reefs in the region as strict nature reserves (at present: Coringa-Herald NNR and Lihou Reef NNR) in an attempt to maintain the long-term viability of these habitats, ecosystems and native species, by preventing additional human impacts. This is a key objective of the management plan for both the Lihou Reef NNR and the Coringa-Herald NNR.
- Issued / Published
- 2004
- Publisher
- Australian Institute of Marine Science, Townsville, Queensland
- ISBN
- 0-642-32296-1
- Subject (AGROVOC)
- Nature reserves; surveys; surveying; species (taxa); Marinating; Reefs; Species; Coral reefs; Corals; Bleaching
- Subject (GEMET)
- reef; survey; fish; fishing; coral; species; sampling; indicator; science; tropics
- Subject (Author)
- Marine parks and reserves; Lihou Reef National Nature Reserve; fish surveys; benthic animals; coral; coral bleaching
- Region
- Australia; Queensland; Lihou Reef
- Repository ID
- mql:584