Oceans and Coasts

Reef accretion and island stability

Coral reefs are shaped by a various factors that affect their growth. Their health thus, has major consequences for human communities living on atolls. We aim to link ecological processes that shape reefs with the hydrology and pedology of these atolls. This will help us document how an interaction between natural forces and human decision can shape the continued habitability of the islands.

Foundation of an island

Coral reefs are structured primarily by an entire order of animals called Sclerectinians that filter out CaCO3 from the water column and use it to form skeletal structures that stand the test of time. Various biotic and abiotic processes then methodically remove calcium carbonate from the reef and eventually over time, shape various oceanic islands and atolls we see today.

However, in a world where our climate is rapidly changing, what are the current rates of accretion and erosion? Can we document the rates of growth of coral reefs by factoring in the accretion and erosion rates and thereby glean at the fragility of these islands?

To answer these questions, we systematically measure the elements that contribute to the addition of calcium carbonate in a reef and also to the removal of calcium carbonate. We therefore measure corals, coralline algae, parrotfishes, polychete worms, and other benthic organisms that have the potential to sway the growth of reefs on either direction. We then hope to understand the trajectory of this accretion budget by integrating disturbance history and information from over two decades of coral monitoring.

Myopia from a freshwater lens

Freshwater on oceanic islands is a rare resource and is probably the only immediate limiting factor to human habitation. The islands in the Lakshadweep archipelago are often elliptical in shape and thereby leave only a narrow margin for freshwater to naturally seep through the sand and accumulate in as groundwater.

The extent of groundwater available on an island is subject to rainfall intensity, land availability and human consumption. With increasing human density on the islands and the preponderance of coconuts as vegetation, does the island experience acute and chronic problems with water availability and quality? Since corals dampen the effect of strong waves and current, thereby conserving sand on the atolls and enabling steady percolation and filtration of seawater into the groundwater, can we link the health of the reefs with freshwater on the islands?

Shifting sands, shifting space

There are multitude of hydrodynamic forces shape these atolls in a seemingly unpredictable way. Certain regions of the atolls have been slowly eroding away due to strong waves; however, few regions have also apparently accreted sand. These dualities in sand accretion and erosion interplay with the rates of groundwater percolation, and would thus be crucial to understand localities of the island are under marginal or immediate threat from erosion.

Future of an atoll

Integrating the health of the reef along with the hydrology and pedology of the island, we hope to be able to form a map that highlight problematic zones for most islands and device appropriate coping strategies in conjunction with the local island administration. This, we hope will help direct limited resources to delay the onset of a possible climate catastrophe.

Coral reefs such as these are important builders that support life on remote oceanic islands by providing sand to build islands, freshwater to drink, and fish to eat, which are essential for any human settlement to survive.