Oceans and Coasts

We work in India's oceanic islands and coasts with a broad mandate to understand the basic ecology and behaviour of these systems, how human communities interact with them, and the impact of disturbances — both regional and global — on this relationship.

Coral reef responses to global change

As coral reefs across the tropics succumb to increasingly frequent ocean warming events in the wake of global climate change, documenting the consequences of these events on reef communities and their ability to resist and recover from them becomes critical.  Our investigations in the Lakshadweep Archipelago and the Andaman & Nicobar Islands attempt to understand the factors that confer resilience on these systems

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Coping with catastrophe

Documenting patterns and processes of resilience in the Lakshadweep reefs


Reef fish responses to climate change

Understanding how fish communities in the Lakshadweep cope with change 

Conflict and cooperation in the sea

Tropical coastlines are home to the highest density of people anywhere and they depend heavily on resources these waters provide.  It is not unusual then that human communities interact with wild marine species that may often compete with humans for the same precious resources. We have been working to understand the interface between fishers and wild species in Indian waters, and to unpack the ecological, socio-economic and cultural drivers of these  interactions

Boat 20and 20turtle

Turf Wars

Understanding turtle-fisher conflicts in Lakshadweep seagrass meadows

Species ecology and conservation

Understanding the basic biology and ecology necessary for their conservation and rational management

Grouper faceoff

Aggregating groupers

Documenting and protecting spawning aggregations in the Lakshadweep

Dugong 201 20neil 20island photo vardhan 20patankar

Conserving an extinct species

Tracking changes in dugong populations in the Andaman and Nicobar archipelago

Completed Projects

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Mainstreaming resilience principles

Understanding and managing the buffer capacity of the Andaman and Nicobar reefs

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Net Gains

Understanding coexistence between Irrawaddy dolphins and fishers in Chilika



Kitchen Stories

Understanding how Nicobar communities share resources in the wake of the tsunami

Traditional 20management 20project 20


Traditional management and change

Marine resource management in the Nicobar archipelago



Chickenfeed (Completed)

The economics of trawl fishing along the Coromandel coast




  • Popular Article
    Flexible Fish


  • Book Chapter
    Narrative from Indian seas: Marine resource use, Ecosystem responses, and the accidents of history.
    Pages 229-248 in G. Cederlöf and M. Rangarajan (editors), 'At Nature's Edge: The Global Present and Long-Term History,' Oxford University Press, New Delhi. 331 pp.
  • Journal Article
    Alternative reproductive tactics and inverse size-assortment in a high-density fish spawning aggregation
    BMC Ecology, 17:10, DOI 10.1186/s12898-017-0120-5

    PDF, 1.44 MB

    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.

  • Journal Article
    Coping with catastrophe: foraging plasticity enables a benthic predator to survive in rapidly degrading coral reefs
    Animal Behaviour, Vol 131: 13-22. http://dx.doi.org/10.1016/j.anbehav.2017.07.010

    PDF, 550 KB

    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 Article
    Latitude and live coral cover independently affect butterflyfish & angelfish  community distribution in the Andaman & Nicobar archipelago, India
    Vardhan Patankar, Elrika D'Souza, Aniruddha Marathe
    Marine Biodiversity. DOI 10.1007/s12526-017-0790-4

    PDF, 1.41 MB

    Latitude and live coral cover independently affect Chaetodontid and Pomacanthid fish community distribution in the Andaman and Nicobar archipelago, India

    Empirical evidence indicates that for two reef fish groups, chaetodontids and pomacanthids, live coral cover and latitude determine the local abundance and species richness patterns. Most studies have considered the influence of either live coral cover or latitude in isolation, and the interactive effects that are likely to influence the geographical distribution of species richness and diversity has not been explored. In this study we explored the relationship between (1) species richness and latitude, and (2) species richness and benthic variables, (3) species diversity and latitude and (4) species diversity and benthic variables for butterflyfish (Chaetodontidae) and angelfish (Pomacanthidae) at 75 sites across 51 islands in the Andaman and Nicobar (A & N) archipelago. A total of 30 species of chaetodontids belonging to four genera and 13 species of pomacanthids belonging to nine genera were recorded. We found that live coral cover and latitude were the best predictors for explaining variation in the distribution of these fish communities across the A & N archipelago. This is probably because of the high dependence of these two fish groups on the live coral cover and Nicobar’s geographical proximity to the Coral Triangle, which is considered to be the centre of origin of coral reefs and supports high biodiversity. Our results show that de- spite the high dependence of chaetodontids and pomacanthids on live coral cover, reduction of live coral cover due to a series of disturbance events had limited influence on species richness of these two fish groups, indicating that broad geographical trends are important in explaining variation in species richness for chaetodontid and pomacanthid fish groups.

  • Popular Article
    Fireflies in the sea
    The Hindu in School, February 8

    Link:                                                                        https://www.thehindu.com/todays-paper/tp-in-school/Fireflies-in-the-sea/article17244163.ece 

  • Popular Article
    The Bay Island Lizard: My Work Companions
    Sanctuary Asia, January. http://www.sanctuaryasia.com/magazines/features/10184-the-bay-island-lizard-my-work-companions.html
  • Popular Article
    New year on the reef
    The Hindu in School, 22 March
  • Dataset
    Long-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
  • Journal Article
    "Choice" and destiny: The substrate composition and mechanical stability of settlement structures can mediate coral recruit fate in post-bleached reefs
    Coral 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.

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