Coringa-Herald National Nature Reserve Marine Survey 2007

Ceccarelli, D., Choat, J.H., Ayling, A., Richards, Z.T., Van Herwerden, L., Ewel, G.D., Hobbs, J-P., and Cuff, B. (2008) Coringa-Herald National Nature Reserve Marine Survey 2007. Report. Department of the Environment, Water, Heritage and the Arts, Canberra, ACT, Australia.

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This report combines the results of two surveys of coral, macroinvertebrate and fish communities in the Coringa-Herald National Nature Reserve (CHNNR or the Reserve). The first survey, conducted by JCU in May 2007, surveyed the Herald Cays (NE and SW Herald). The C&R Consulting survey in October 2007 focused on South East Magdelaine Cay (SE Magdelaine), Chilcott Islet (Chilcott) and South West Coringa Islet (Coringa). Ecological communities were found to be in a similar condition to those described in previous surveys, with very little recovery of hard coral cover.

Reefs in the CHNNR support approximately 7.3% hard coral cover and a relatively species poor fish community. Coral cover, already historically low, has been slow to recover from disturbances in the last two decades, probably due largely to the small size of the reefs, as well as isolation and exposure. SE Magdelaine supported the highest coral cover, coral and reef fish diversity and the highest general abundance of surveyed reef species, while SW Herald had the largest populations of some large reef fish families. The presence of Pacific Ocean corals lends support to the suggestion that Coral Sea reefs provide stepping-stones for the dispersal of species between the Great Barrier Reef and Pacific Ocean reefs.

Corals of the genus Acropora were expected to be diverse and abundant on the clearwater CHNNR reefs, but very few live or dead colonies were encountered during the survey. Acropora species are the most vulnerable to disturbance and are also early colonisers of disturbed sites. Along with the small size and sexual immaturity of other hard coral, soft coral and sponge colonies, the low cover of Acropora is typical of reefs in the early phase of recovery.

Algal turf, coralline algae and Halimeda spp. were the predominant benthic taxa in the CHNNR. Algal turf is an important food source for a range of marine invertebrates and herbivorous fish, and was dominant primarily in sheltered back reef habitats, corresponding with the greatest density of large herbivorous fish. Coralline algae, often indicative of heavy grazing, was abundant on the reef front, and the low abundance of grazing herbivores in these habitats suggests that the high coralline algae cover is another historical feature of the reefs.

Densities of holothurians and tridacnid clams were similar to those found in other surveys of isolated, oceanic reefs. Some holothurians of high commercial value were more abundant in the CHNNR, suggesting successful protection from exploitation. Gastropods valuable for the ornamental shell industry were found in high densities in some areas of the Reserve, indicating that it may be important to include these species in future surveys.

Key fish species were found in low densities, potentially as a result of the low microhabitat complexity, resulting in lower food and habitat availability. Apex predators such as serranids and sharks, along with large keystone invertebrate feeders and herbivores, are economically valuable and globally vulnerable to overexploitation, highlighting the need for their protection and the careful monitoring and safeguarding of their habitat.

By nature of their isolation, oceanic reefs such as those in the CHNNR harbour unique communities. They also have few sources of propagules, and tend to recover slowly from disturbance. Many key species occur in low numbers, making them highly vulnerable to local extinction. Recommendations arising from these surveys focus on the continued protection and effective monitoring of the Reserve. The protection of the hard coral community and of key fish and invertebrate species are crucial to the safeguarding of the resilience of these reefs in the light of expected climate change.

Item ID: 28240
Item Type: Report (Report)
Additional Information:

Cover page includes 'for the Department of the Environment, Water, Heritage and the Arts by C&R Consulting and James Cook University'.

Date Deposited: 29 Jul 2013 04:01
FoR Codes: 05 ENVIRONMENTAL SCIENCES > 0502 Environmental Science and Management > 050202 Conservation and Biodiversity @ 100%
SEO Codes: 83 ANIMAL PRODUCTION AND ANIMAL PRIMARY PRODUCTS > 8302 Fisheries - Wild Caught > 830299 Fisheries- Wild Caught not elsewhere classified @ 100%
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