Scientist, Oceans and Coasts
My research interests concern issues of conservation, particularly the implications of climate change for marine ecosystems, the rational management of marine systems and fisheries in India, and the interface between policy, traditional practices, and ecosystem management. I have worked in several reef systems around India, and along the Kenyan coast. My chief concerns are in furthering the fledgling tradition of good field ecological research in marine environments in India, and in helping fill some of the significant gaps in the very basic knowledge we require to manage them. A long-held fascination for their aesthetic irresponsibility, together with generous helpings of inertia and serendipity, has drawn me to marine ecosystems and their conservation. I obtained my Master's degree in Wildlife Science from the Wildlife Institute of India in 1995. For my master's research I worked on coral community composition and its response to human disturbance in the intertidal reefs of the Gulf of Kutch in Northwest India. I am one of NCF's founder-trustees, and direct its reef program. I continue to be interested in reef community dynamics and disturbance, and my doctoral research focuses on the consequences of temperature-induced mass-mortality of coral on the reef systems of the Lakshadweep atoll reefs, Western India.
- Journal Article2017Coping with catastrophe: foraging plasticity enables a benthic predator to survive in rapidly degrading coral reefsAnimal Behaviour, Vol 131: 13-22. http://dx.doi.org/10.1016/j.anbehav.2017.07.010Download
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Human-induced rapid environmental change (HIREC) disproportionately affects species with specialist traits and long generation times. By circumventing prolonged evolutionary processes, behavioural plasticity is critical in allowing species to cope with rapid environmental changes within their lifetimes. Coral reefs have faced multiple mass mortality events of corals related to climate change in the last two decades. The consequent loss of structural complexity adversely impacts long-lived, structure-dependent fish predators. We attempted to determine how well a guild of groupers (Pisces: Epinephelidae) copes with rapid structural change in the lightly fished Lakshadweep Archipelago, Indian Ocean. Of the 15 species, territorial and site-attached groupers declined exponentially with decreasing structural complexity, while widely ranging species showed no change. However, one site-attached species, the peacock grouper, Cephalopholis argus, maintained high densities across the structural gradient. We explored the mechanisms this species employs to cope with declining habitat structure. Our observations indicate that both a potential release from specialist competitors and plasticity in foraging behaviour (foraging territory size, diet and foraging mode) appeared to favour the peacock grouper's survival in sites of high and low structure. While specialist competitors dropped out of the assemblage, the foraging territory size of peacock groupers increased exponentially with structural decline, but remained constant and compact (50 m2) above a threshold of structural complexity (corresponding to a canopy height of 60 cm). Interestingly, despite significant differences in prey density in sites of high and low structure, gut content and stable isotope analyses indicated that peacock groupers maintained a specialized dietary niche. In-water behavioural observations suggested that diet specialization was maintained by switching foraging modes from a structure-dependent ‘ambush’ to a structure-independent ‘widely foraging’ mode. The remarkable foraging plasticity of species such as the peacock grouper will become increasingly critical in separating winners from losers and may help preserve specialist ecosystem functions as habitats collapse as a result of climate change.
- Journal Article2017Alternative reproductive tactics and inverse size-assortment in a high-density fish spawning aggregationBMC Ecology, 17:10, DOI 10.1186/s12898-017-0120-5Download
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Mating successfully at high densities often requires species to employ unusual reproductive tactics. We report unique courtship behaviours in an un shed, high-density spawning aggregation of squaretail groupers (Plectropomus areolatus) that are potentially associated with alternative reproductive tactics (ARTs). Aggregating males are typically known to court females in small territories (pair courtship), which is often associated with a pair-spawning tactic. However, we also observed the largest males simultaneously courting several females in mid-water shoals – a unique, high-cost-high-benefit courtship tactic which appears to result in a novel school-spawning tactic. Counter-intuitively we observed an inverse size- assortment in individuals–large males courted smaller females and vice-a-versa, likely linked to different pay- offs with competitive ability and local mate density. These unique, high-density behaviours are threatened to be lost, with increasing commercial fishing pressures on the P. areolatus aggregation.
- Popular Article2016Living with change: local responses to global impactsCurrent Conservation, issue 10.2 http://www.currentconservation.org/?q=issue/10.2
- Journal Article2016"Choice" and destiny: The substrate composition and mechanical stability of settlement structures can mediate coral recruit fate in post-bleached reefsCoral Reefs. 35: 211-222
Increasingly frequent and intense ocean warming events seriously test the buffer and recovery capacities of tropical coral reefs. Post-disturbance, available settlement structures on a reef (often dead coral skeletons) vary considerably in their mechanical stability and substrate composition, critically influencing coral recruit settlement choice and fate. In the wake of a coral mass mortality in the Lakshadweep archipelago, we examine (1) the relative availability of recruit settlement structures (from stable to unstable: reef platform, dead massive coral, consolidated rubble, dead corymbose coral, dead tabular coral, and unconsolidated rubble) in 12 recovering reefs across three atolls in the archipelago, (2) the substrate composition [crustose coralline algae (CCA), mixed turf, macroalgae] of these structural forms, and (3) whether the choice and fate of young coral are mediated by the substrate and stability of different structural forms. For this, we measured the abundance and distribution of recruit (<1cm), juvenile (1–5 cm), and young adult (5–10) corals of 24 common coral genera. Four years after the mass mortality, reefs differed considerably in composition of settlement structures. The structures themselves varied significantly in substrate cover with dead tables largely covered in CCA [60 ± 6.05 % (SE)] and dead corymbose coral dominated by mixed turf (61.83 ± 3.8 %). The youngest visible recruits (<1 cm) clearly preferred CCA-rich structures such as dead massives and tables. However, older size classes were rarely found on unstable structures (strongly ‘‘avoiding’’ tables, Ivlev’s electivity index, E = -0.5). Our results indicate that while substrate cover might mediate coral choice, the mechanical stability of settlement structures is critical in determining post-settlement coral survival. The composition and availability of settlement structures on a reef may serve as a characteristic signature of its recovery potential, aiding in assessments of reef resilience.
- Journal Article2016For traditional island communities in the Nicobar archipelago, complete no-go areas are the most effective form of marine managementFor traditional island communities, no-go areas are the most effective form of managementOcean & Coastal Management 133, 53-63 http://dx.doi.org/10.1016/j.ocecoaman.2016.09.003Download
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For traditional island communities in the Nicobar archipelago, complete no-go areas are the most effective form of marine management
The ability of local communities to sustainably manage natural resource harvests in coral reefs ecosystem depends heavily on the strength of traditional institutions. Coastal communities have evolved a suite of restrictive practices to control marine offtake and there is considerable recent evidence of their effec- tiveness in protecting and enhancing resource stocks. However, traditionally imposed restrictions can vary considerably in their complexity and in their functional effectiveness. The indigenous communities of the Nicobar Islands are dependent on marine resources for sustenance, managing them with a range of traditionally imposed restrictions. These include limited entry to certain locations, closed seasons and areas, and restrictions on species, size-classes of fish and fishing methods. We tested the relative effectiveness of protection in areas managed under different traditional control regimes by comparing the abundance and biomass of targeted fish groups in managed and unmanaged areas. Our results indicate that reef sites with the strictest form of restriction e essentially no-go areas e had significantly higher abundance and biomass values of most functional groups of fishes compared with partially protected and control locations. In contrast, targeted food fish stocks did not differ from control locations in partially protected sites managed with even complex forms of traditional management. Ensuring that traditional harvest rules are complied is critical to the success of any management system, and our re- sults suggest that they can be most strictly enforced in traditional no-go areas. Our work highlights the importance of critically evaluating the factors influencing traditional management systems to strengthen their ability to protect these reefs from unsustainable overharvest.
- Dataset2016Long-lived groupers require structurally stable reefs in the face of repeated climate change disturbances.Karkarey R, Kelkar N, Lobo AS, Alcoverro T, Arthur R (2014) Data from: Long-lived groupers require structurally stable reefs in the face of repeated climate change disturbances. Dryad Digital Repository. http://dx.doi.org/10.5061/dryad.d7j02
- Poster2015What makes a healthy reef?
- Poster2015What are coral reefs?
- Popular Article2015Eats shoots and doesn't leave: Dugong herbivory and movement patterns in the seagrasses of the Andaman and Nicobar IslandsEcoLogic: The NCF Blog
- Journal Article2015Sharing mechanisms in corporate groups may be more resilient to natural disasters than kin groups in the Nicobar IslandsHuman Ecology. 43:709-720
It has been suggested that kin groups are better predisposed to cooperatively manage essential natural resources than non-kin groups because of inclusive fitness gains. Whether these long-term genetic pay-offs sufficiently offset the immediate costs of cooperation in periods of scarcity is uncertain. We compared patterns of resource sharing across three island communities in the Nicobar Archipelago affected by the 2004 tsunami. While sharing mechanisms were similar across regions, group composition varied: Central and Southern Nicobar were organised along kinship lines, while Chowra was organised as corporate alliances of unrelated households. We documented post-tsunami losses and conflicts emerging in resource sharing after the event. While kin groups showed considerable breakdown in resource sharing arrangements, corporate communities in Chowra were much more resilient to change. Our results suggest that the more immediate reciprocity of corporate alliances may outweigh the potential benefits of inclusive fitness when faced with conditions of extreme resource scarcity.