Mainstreaming resilience principles
Understanding and managing the buffer capacity of the Andaman and Nicobar reefs
Subject to repeated disturbances, including the catastrophic tsunami of 2004 and periodic bleaching events, the resilience of the Andaman and Nicobar reefs has been severely tested. Our work attempts to understand and build support for the underlying resilience of these reefs to ensure their survival.
Enhancing natural resilience
Climate change is considered the greatest long-term threat to tropical coral reefs. The Andaman and Nicobar archipelagos in the eastern Indian Ocean are high-diversity systems that have been recently affected by a series of catastrophic disturbances including the 2004 tsunami and repeated mass bleaching events (2008 and 2010). Managing these systems in the wake of these large unpredictable events is a complex task, made all the more urgent as global climate change increasingly makes these events part of the new normality for tropical coral reefs.
The best hope for their rational conservation lies in identifying factors that could enhance the natural resilience of these systems to a suite of disturbances that currently affect them. Reef resilience is likely highly contingent on local conditions, and driven by a combination of physical, ecological and anthropogenic factors. Identifying these factors at managerially relevant scales is critical if resilience principles have to inform rational reef conservation efforts. Additionally, while there is a felt need to incorporate resilience into management, reef managers are often unclear of how to translate these principles into practical strategies. This project proposes to identify a clear set of factors that will enable a mapping of vulnerabilities and resilience across the Andaman and Nicobar Archipelagos and to translate this into a clear set of guidelines to help reef managers prioritize and evaluate their conservation action.
Conservation and planning
The factors contributing to resilience are multidimensional and contingent on local conditions. Identifying these factors at scales relevant to managers is important if resilience principles have to be included in rational reef conservation efforts.
In this study, we surveyed 49 reef sites across the Andaman archipelago to assess their responses to multiple disturbances of past years, including the tsunami. At each site, we measured a range of environmental and ecological parameters and estimated the putative resilience for each site based on an approach and methodology modified from reef resilience assessments developed by Maynard et al (2010), Obura and Grimsditch (2008) and from studies carried out by the Oceans and Coasts Programme in the Lakshadweep Archipelago.
Using this score, we identify sites based on their overall resistance relative to other sites, and determine the factors that potentially contribute to this resistance. Our findings indicate that the summer bleaching event of 2010 killed almost 60-80 %of reefs within the island chain. A regression-based approach identified that reef resistance to beaching is determined by a combination of factors i.e. the island group, current, depth and sedimentation.
This work serves as an essential baseline for the Andaman Islands from which to track patterns of recovery and further decline and we highlight the urgent need to understand more clearly the drivers of reef resilience within this group.
- Popular Article2016Living with change: local responses to global impactsCurrent Conservation, issue 10.2 http://www.currentconservation.org/?q=issue/10.2
- Journal Article2015Erosion of Traditional Marine Management Systems in the Face of Disturbances in the Nicobar ArchipelagoHuman Ecology, DOI 10.1007/s10745-015-9781-x
- Journal Article2015Synchronous Spawning of the Sea CucumberHolothuria (Lessonothuria) pardalisSelenka, 1867 in the Andaman Archipelago, IndiaJournal of Bombay Natural History Society, 112 (2) 10.17087/jbnhs/2015/v112i2/104950
- Popular Article2013A day in the life of a butterfly fishThe Hindu in School, 10 July
- Popular Article2013Securing Habitat of NemoFriday, April 12, Andaman Chronicles.
- Journal Article2012Distance-related thresholds and influence of the 2004 tsunami on damage and recovery patterns of coral reefs in the Nicobar IslandsCurrent Science 102:1199–1205
The earthquake and tsunami of 2004 resulted in the devastation of marine and coastal ecosystems across the Indian Ocean. However, without adequate baseline information it has been difficult to properly gauge its full impact. The reefs of the Nicobar Islands in the Bay of Bengal lie on a path that ranges from 190 to 500 km from Banda Aceh, the epicentre of the 2004 tsunami. In 2008, we recorded benthic damage as a result of the tsunami to reefs off 14 Nicobar Islands across a gradient of distance from the epicentre. A clear pattern was observed in the demographic structure of the most abundant coral genera, Acropora and Porites across the distance gradient. Significantly, for the largest coral individuals of both genera (> 50 cm diameter), there were distinct threshold effects – their abundance declining dramatically in reefs closer than 350 km from the epicentre. Corals between 20 and 50 cm diameter also increased with distance from the epicentre, but in a more linear fashion. Smaller size classes either showed no apparent trend (Acropora) or decreased linearly (Porites) with distance. These gen- era represent very different life-history strategies: Acropora is fast-growing and highly susceptible to a range of disturbances, while Porites typically grows slowly but is resistant to disturbance. The fact that both genera showed similar thresholds indicates that, close to the epicentre, the impact of the earthquake and tsunami was large enough to override any species- specific resistance. Also, algal cover was also much higher than at locations further north, linked to higher coral mortality at these locations. However, the fact that smaller size class coral individuals were rela- tively abundant and even increased close to the ep centre indicates possible paths of reef recovery after the catastrophe.
- Popular Article2012Expedition North AndamanThe Hindu in School, 12 September