Report on the Reef Conservation UK (RCUK) Conference
Added to website: 18 January 2006
The Annual Reef Conservation UK Conference took place on 10 December 2005.
A number of themes were developed during the conference. The degradation of coral reefs is a symptom of the global issues of population growth and the warming of the oceans. Of the many anthropogenic threats to reefs, that of over fishing is one of the most serious. Over-fishing is often simply a result of more people becoming dependant on reefs for food and income. The causes of global warming were not discussed in any detail at the conference but whatever view is taken of the extent of the anthropogenic element, slowing, halting or reversing the current rise in sea water temperature, even if this were possible, clearly requires political actions on the world stage. Hence the conference was right to concentrate on issues related more specifically to reefs and to their biology. An additional theme was the impact of the 2004 tsunami.
Warming seas:
A report from the University of Essex highlighted the importance of adaptation mechanisms as scleractinian corals face elevated temperatures. Coral bleaching, caused by loss of endosymbiont algae due to stress factors including high temperature, can result in reduced growth and eventually coral death. Ribosomal DNA can be used to identify zooxanthellae clades from reefs over a global scale. Data from samples taken in Jamaica, Sulawesi, Indonesia, Australia and Bermuda were presented to show patterns in clade diversity. Of the Clades A, B, C and D the latter is thought to increase thermo-tolerance. An unanswered question is how the coral polyp becomes populated with Clade D. Are there low levels of D always present, albeit at sometimes undetectable levels, or does the polyp become populated by taking up Clade D from the water column?
Over-fishing:
In over 100 countries people depend on reefs for food. Over-fishing on the reef leads to an increase in coral predators such as starfish and, in the absence of a reasonable population of reef herbivores, to overgrowth with algae. Shark fishing, including the wasteful practice of ‘finning’, may sometimes take place in deeper water but the removal of such apex predators is also detrimental to the maintenance of a balanced reef ecosystem. To try and manage reefs as fisheries some knowledge of what constitutes ‘over-fishing’ is clearly important. In a collaborative study involving the Universities of East Anglia and Newcastle together with the Lowestoft Centre of the Environment, Fisheries and Aquaculture Science, data on fishery landings, national coral reef area and human population were combined. A negative relationship was demonstrated between per capita consumption of reef organisms and the number of people per km² of coral reef. In other words the greater the population pressure, the less food available per person. Presumably two effects are at work, these being the greater ‘sharing’ of what can be harvested and increasing damage caused by fishing pressure leading to a decline in catches. By extrapolating to a notional zero human population, an estimate can be obtained of the intrinsic sustainable productivity of the reef which was put at 150 kg per km² per annum. That this figure is an order of magnitude lower than previous estimates gives some idea of the difficulties faced by forecasters, fishery managers and law-making politicians.
In seeking to manage stocks, sustainable methods of fishing are needed. A poster presentation by D. Wilson, previously of the Turks and Caicos Islands, illustrated the sort of highly practical monitoring that is needed on the ground. The spiny lobster, Panulirus argus, is sometimes caught by the destructive and often illegal use of chemicals such as bleach, which can be used to drive it from its secure hiding place. The results demonstrated that a starch-iodide swab technique can be used to check the exoskeleton and detect the use of such chemicals up to 12 hours after capture.
A project in Madagascar to regenerate an octopus fishery was reported by Blue Ventures Conservation. Artisanal fishing for octopus is the primary economic and subsistence activity for indigenous Vezo coastal communities in the Andavadoaka region of Tulear. Traditionally, octopus was dried for sale in inland markets, however, the arrival in 2003 of commercial fisheries collection companies brought a readily available and higher paying market, dramatically increasing fishing intensity. In an effort to restore the local octopus population, a 200 hectare reef flat was declared an octopus no-take-zone (NTZ) for seven months from 1 November 2004. Catch data obtained since the reopening of the NTZ show a significant increase in average weight of octopus: as a result of the closure the average weight of octopus more than doubled and the average catch per unit effort increased substantially. Unfortunately the effects of the no-take period were quickly reduced as a result of elevated fishing pressure: the conserved reef had become too attractive to fishers! It was concluded that in order for this technique to work in the long term, after a closed fishing ground is reopened the intensity of fishing needs to be carefully managed.
Tsunami:
Last year the whole world was stunned by the human tragedy inflicted by the south-east Asian tsunami. Reef biology was put into perspective alongside the marathon rescue efforts of medical and assistance teams on the ground. Taking a longer term view - which is still difficult- there is a need to understand how the coral reefs of the region were affected and to assess the extent to which damage may prove a limitation on the re-development of coastal resources for food and livelihoods including reef-based tourism.
A team from Coral Cay Conservation reported on a post tsunami impact survey of the coral reefs of the Mu Ko Surin Marine National Park, Thailand, conducted seven weeks after the disaster. Data were processed to produce ‘damage contour maps’, facilitating visual interpretation of spatial damage patterns. Live hard coral cover was found to be exceptionally high on the northeast coast of the island of North Surin, with an average of 75% and a maximum of 90%. Overall, it was calculated that should all the tsunami-damaged coral subsequently die, only 8% of pre-tsunami coral coverage would be lost. Signs of coral re-growth were in fact documented, indicating that healthy reef systems such as those of Surin can regenerate rapidly in the aftermath of a tsunami.
A study by the Cambridge Coastal Research Unit, Cambridge University in the Aceh Province of North Sumatra, Indonesia, some 10 months after the event, concluded that over half of the reefs surveyed displayed no obvious tsunami damage and only 15% of the sites surveyed indicated a high level of damage. However, even in areas where severe damage was recorded, there were still large areas of intact reef present which should help re-populate the damaged reef in the future. There was evidence that the earthquake had caused both uplift and subsidence of some areas. Both uplift and subsidence have implications for reef ecosystem dynamics in the region.
Contributors:
A full list of papers and contributors is available at www.rcuk.org.uk
Simon Draper
31 December 2005
