Benthic Ecosystems and Coastal Acidification

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The Project

The phenomenon of the unprecedented increase in H+ ion concentration and changes in the aquatic carbonate chemistry (pCO2, pH, alkalinity, and calcium carbonate saturation state) primarily due to the rapid uptake of atmospheric CO2 in the seawater is known as Ocean Acidification. At present, the ocean is 30% more acidic than it was 200 years ago, and the rate of acidification is faster than ever. Compared to the oceanic waters, coastal waters are subjected to higher anthropogenic pressure largely due to its proximity to the terrestrial environment. The decrease in pH of the coastal waters ‘Coastal Acidification’ is emerging as an additional global threat to the health of coastal ecosystems. Ecosystem responses to environmental changes has poorly been studied particularly with reference to continuous, long term monitoring of coastal ecosystems. The key issues are

  • Decrease in oceanic pH
  • El Nino and La Nina – sea surface temperature anomalies
  • Eutrophication –nutrient enrichment from land-based sources
  • Change in sea water carbonate chemistry

The combination of eutrophication and coastal acidification is likely to have greater adverse effects on coastal ecosystems. Therefore, optimal management of coastal eutrophication suggests controlling both N and P, in part because P can limit primary production in some systems.

Selected coral reef ecosystems (Gulf of Mannar in the east coast of India, Lakshadweep Island) and lagoon ecosystems (Chilika and Pulicat) are been studied to depict future responses to nutrient enrichment, coastal acidification and formation of oxygen minimum zones (OMZ).

Benthic Ecosystems and Coastal Acidification


Observe trends in oceanic pH and to determine the causes of change to sustainably manage and protect marine and coastal ecosystems. Selected sites are been studied to depict future responses to nutrient enrichment, coastal acidification and formation of oxygen minimum zones.


  • Creation of long-term database for identification of mitigation strategies for coastal acidification

  • Coral reef ecosystem health in connection with changes in biological and physical indicators

  • Assessment of past climate by studying Foraminifera/ Radiolarians/ Coccoliths in sediments

  • Local/ regional hotspot of coastal acidification will be recognized to identify the sources of pollution that causes stress on the reef.

Expected Outcome

  • Estimation of primary productivity and calcification rates in coral ecosystems and coastal lagoons and, their dependency on the environmental parameters
  • Comprehensive nutrient management plan for minimizing eutrophication and OMZ in coastal waters
  • Scenario building on ecosystem responses to nutrient enrichment and coastal acidification through microcosm/ mesocosm and modelling
  • Mitigation strategies for coastal acidification
  • Site-specific appropriate interventions and alternative management options