Four coral species recorded for first time in Indian waters: Study

In Context

• Recently, four new species of corals were recorded in the Indian waters of the Andaman and Nicobar Islands.

Major Findings:

• The newly recorded species are:
  • Truncatoflabellum crassum, 
  • T. incrustatum , 
  • T. aculeatum , and 
  • T. irregulare 
    • They are a part of the family Flabellidae. 
• These species belong to the group “azooxanthellate corals”.
• These corals are a group of hard corals and the four new records are solitary and a highly compressed skeletal structures.
• The details of the new records have been published in Thalassas: An International Journal of Marine Sciences in a paper.
• More about azooxanthellate corals: 
  • Azooxanthellate corals are a group of corals that do not contain zooxanthellae.
  • They are non-reef building, unicellular, golden-brown algae. 
  • They derive nourishment not from the sun but from capturing different forms of plankton. 
  • These groups of corals are deep-sea representatives, with the majority of species reporting from between 200 m to 1000 m. 
  • Their occurrences are also reported from shallow coastal waters.

Coral Reefs:

• A coral reef is an underwater ecosystem characterized by reef-building corals. 
• Reefs are formed of colonies of coral polyps held together by calcium carbonate.
• Symbiotic Relationship:
  • Corals share a symbiotic relationship with single-celled algae called zooxanthellae. 
  • The zooxanthellae also give corals their bright colour.
  • The algae provides the coral with food and nutrients, which they make through photosynthesis, using the sun’s light. 
  • Algae provide up to 90 per cent of the coral’s energy.
  • In turn, the corals give the algae a home and key nutrients. 
• Temperature:
  • The temperature of the water should not be below 20°C. 
  • The most favourable temperature for the growth of the coral reefs is between 23°C to 25°C. 
  • The temperature should not exceed 35°C.
• Salinity: 
  • Corals can survive only under saline conditions with an average salinity between 27% to 40%. 
• Shallow Water: 
  • Coral reefs grow better in shallow water having a depth less than 50 m. The depth of the water should not exceed 200m.
• Coral reefs are divided into four classes: 
  • fringing reefs, 
  • barrier reefs, 
  • atolls, and 
  • patch reefs. 
• Coral reefs in India:
  • There are about 570 species of hard corals found in India 
  • India has four major coral reef areas: Gulf of Mannar, Andaman and Nicobar Islands, Lakshadweep islands and the Gulf of Kutch.
  • Almost 90% of corals are found in the waters surrounding Andaman and Nicobar Islands.
  • 

Significance:

• Ecosystem value:
  • Coral Reefs provide an important ecosystem for life underwater, protect coastal areas by reducing the power of waves hitting the coast, and provide a crucial source of income for millions of people.
  • The pristine and oldest ecosystem of corals share less than 1% of the earth’s surface but they provide a home to nearly 25% of marine life.
  • Thousands of species can be found living on one reef. 
• Economy:
  • Coral reefs have an estimated global value of £6 trillion each year, due in part to their contribution to the fishing and tourism industries and the coastal protection they provide.
  • More than 500 million people worldwide depend on reefs for food, jobs and coastal defence. 
• Protection from Storm: 
  • Coral reefs also provide protection from storm waves.
• Medicinal value:
  • Extracts from animals and plants living on reefs have been used to develop treatments for asthma, arthritis, cancer and heart disease.

Threats

• Global Warming:
  • Global Coral Reef Monitoring Network (GCRMN) report underlined the catastrophic consequences of global warming on coral ecosystem.
  • Rising ocean temperatures killed about 14% of the world’s coral reefs between 2009 and 2018.
• Coastal development:
  • Physical damage or destruction from coastal development, dredging, quarrying, destructive fishing practices and gear, boat anchors and groundings, and recreational misuse (touching or removing corals).
• Pollution:
  • Pollution originates on land but finds its way into coastal waters. There are many types and sources of pollution from land-based activities.
• Overfishing:
  • Overfishing can alter the food-web structure and cause cascading effects, such as reducing the numbers of grazing fish that keep corals clean of algal overgrowth. Blast fishing (i.e., using explosives to kill fish) can cause physical damage to corals as well.

Coral Bleaching

• Coral bleaching occurs when coral polyps expel algae that live inside their tissues. 
• When corals face stress by changes in conditions such as temperature, light, or nutrients, they expel the symbiotic algae zooxanthellae living in their tissues, causing them to turn completely white. 
• This phenomenon is called coral bleaching.
• Reasons:
  • The leading cause of coral bleaching is climate change. 
  • A warming planet means a warming ocean, and a change in water temperature – as little as 2 degrees Fahrenheit – can cause coral to drive out algae. 
  • Coral may bleach for other reasons, like extremely low tides, pollution, or too much sunlight.

Way Ahead

• Maintaining the integrity and resilience of coral reef ecosystems is essential for the wellbeing of tropical coastal communities worldwide, and a critical part of the solution for achieving the Sustainable Development Goals under the 2030 Agenda for Sustainable Development.
• Dead reefs can revive over time if there are enough fish species that can graze off the weeds that settle on dead corals, but it takes almost a decade for the reef to start setting up again. 
• The countries could act together to improve water quality at the reef, which would increase its resilience to climate change.

Source: TH