Arthur, Rohan (2004) Patterns and processes of reef recovery and human resource use in the Lakshadweep Islands, Indian Ocean. PhD thesis, James Cook University.

Preview	PDF Download (156kB)
Preview	PDF Download (1MB)

Abstract

Finding solutions that effectively conserve natural areas while simultaneously protecting the sustenance rights of resource stakeholders is a considerable challenge for ecosystem managers and scientists. In complex ecosystems like tropical coral reefs, the problem of management is further confounded by an inadequate understanding of how ecosystem function will respond to changes in environmental or management conditions. Given this uncertainty, managers are looking at ways to support and enhance the natural buffering capacity of ecosystems in the face of change, i.e. ecosystem resilience. Human use of natural areas can profoundly modify this resilience, particularly in the developing tropics, where a large proportion of the population depends directly on natural areas for daily sustenance. In these areas, developing and implementing effective management solutions requires a close understanding of both ecosystem processes and the factors affecting human interactions with the ecosystem. This study examined the processes of ecosystem change after a major mass mortality of coral in the Lakshadweep Islands and the consequences that changes in resource use and policy have had on the recovery potential of these reefs. The Lakshadweep Islands are a group of atolls in northern Indian Ocean. The El Niño Southern Oscillation (ENSO) of 1998 resulted in anomalous sea surface temperatures (SSTs) that caused extensive coral mortality in the reefs. I studied the patterns of recovery of coral and fish communities on outer reefs on three atolls, Agatti, Kadmat and Kavaratti from 2000 to 2003. Corals showed a mixed pattern of recovery: sites on the eastern aspects of islands showed little recovery of coral cover, while sites on the west showed a rapid increase in coral cover. This difference between aspects appears to be a function of the degree of exposure of these sites to seasonal monsoonal storms, and differences in the long-term stability of coral settlement substrate between aspects. Genera of coral that showed the most significant gains represented two very different life history strategies. Porites and Goniastrea were generally more resistant to bleaching stress. In contrast, Acropora was highly susceptible to bleaching, but recovered very quickly from disturbances by recruiting in large numbers, and sustaining high growth rates once established. Fish communities in coral reefs are naturally very variable, but there were noticeable trends in fish assemblages after bleaching in the Lakshadweep. Species richness and diversity increased from 2000 to 2003 at all sites. Herbivorous fishes such as surgeonfish and parrotfish were very abundant in post-bleached reefs, representing up to 70% of all trophic guilds in the reef in 2000. The dominance of herbivores declined with time as coral took over from algal turf in many reefs. Multidimensional scaling (MDS) analysis of fish communities indicated that fish assemblages were moving towards increasing similarity with time, possibly approaching a post-disturbance equilibrium. I interpret the recovery of Lakshadweep’s reefs to disturbance within the conceptual framework of catastrophe theory. Catastrophe theory has been effectively used in several other ecosystems as a phenomenological model of ecosystem change, and the applicability of the two-factor cusp catastrophe is a useful conceptual model of reef responses to disturbance. This theory suggests that in the face of global warming, managers and scientists many need to invest their energies in understanding uncertainty on the one hand while managing for resilience on the other. Biotic studies in the reefs of the Lakshadweep indicated that although the fine-scale patterns of recovery are variable, the reefs appear to be highly resilient after coral mortality. The current pattern of resource use practised in the Lakshadweep contributed in part to this high resilience. Despite being among the most densely populated locations in India, with over 2200 people/km2, for most of the year the human population of the Lakshadweep do not depend on the reef for food. This situation largely results from a development initiative started by the Fisheries Department in the 1960s which actively converted reef fishers to pelagic tuna fishing with a series of subsidies and training programmes. This initiative was implemented solely to enhance economic development of the islands, but it has inadvertently released reefs from a potentially large resource extraction pressure. Thus local regulations have played an important if inadvertent role in controlling marine resource use in the Lakshadweep. The Lakshadweep case study has important lessons for resource conservation in the developing tropics. The coral reefs of the Lakshadweep apparently possess considerable resilience in the face of catastrophic coral mortality. One of the major contributors to this resilience was the relatively low level of fishing pressure on these reefs, despite high human population densities. The policy change that was responsible for a shift away from reef fishing was designed primarily as a developmental activity, but it had significant, but completely unintended positive consequences for the resilience of the reef. The Marine Protected Area (MPA) is the principal tool currently used to manage the vanishing diversity of threatened ecosystems like coral reefs. While MPAs may still be the most effective solution in marine conservation, MPAs are often difficult and expensive to establish and maintain. It is even more difficult to get local communities to reconcile with a loss of access to resource areas. The Lakshadweep example suggests that there may be alternative paths to enhance ecosystem resilience that are perhaps as effective in achieving conservation goals. It is not often that ecosystem conservation and human development can pull in the same direction, but when they do, this synergy should be encouraged and supported.

Item ID:	639
Item Type:	Thesis (PhD)
Keywords:	Ecosystem resilience, Resource use and policy, Fish assemblages, Coral mortality, Lakshadweep Islands, Catastrophe theory, Species richness and diversity, Coral bleaching, Porites, Goniastrea, Acropora
Date Deposited:	04 Oct 2006
FoR Codes:	05 ENVIRONMENTAL SCIENCES > 0502 Environmental Science and Management > 050202 Conservation and Biodiversity @ 0% 05 ENVIRONMENTAL SCIENCES > 0502 Environmental Science and Management > 050209 Natural Resource Management @ 0%
Downloads:	Total: 2398 Last 12 Months: 31
	More Statistics