The Gulf of Mannar and Palk Bay, biodiversity hotspots along India’s southeastern coastline, play a pivotal role in sustaining marine ecosystems and supporting the livelihoods of coastal communities. Amid growing concerns about climate change and human-induced pressures, a comprehensive study, titled Marine Ecosystem Status and Health Monitoring 2023-24, has brought much-needed attention to these vital regions.
Edited by Dr. Terney Pradeep Kumara of the University of Ruhuna, Sri Lanka, along with Dr. Jayanthi M. of the Tamil Nadu Pollution Control Board and Dr. J. K. Patterson Edward from the Suganthi Devadason Marine Research Institute, this publication focuses the importance of regular ecosystem monitoring.
Speaking to The Island, Dr. Kumara, Professor in Oceanography, Department of Oceanography and Marine Geology, University of Ruhuna/ Director of the Centre for International Affairs (CINTA), told The Island: “Marine ecosystems are the lifelines of coastal economies. Their degradation not only impacts biodiversity but also the communities that depend on them. Our study aims to provide actionable insights for sustainable management.” With over 4,000 species reported in the Gulf of Mannar alone, these ecosystems are treasures of marine biodiversity.
The report, authored by V. Naganathan, Deepak S. Bilgi, A. S. Marimuthu, T. K. Ashok Kumar, and Bakan Jagdish Sudhakar, highlights several key findings:
Coral Reefs: Live coral cover has seen a slight recovery in the Gulf of Mannar, increasing from 23.3% in 2022 to 23.5% in 2023. However, the Palk Bay’s coral cover remains precariously low at 18.4%.
Seagrass and Mangroves: Seagrass beds, critical for carbon sequestration, exhibit varying health across regions, while mangroves, vital for coastal protection, remain under threat from anthropogenic activities.
Pollution: While physico-chemical parameters are largely within safe limits, seasonal fluctuations and marine debris continue to pose significant challenges.
Dr. Kumara emphasizes the global significance of these findings: “As part of the Indo-Pacific realm, the Gulf of Mannar and Palk Bay hold a unique place in global marine conservation efforts. Collaborative actions between India and Sri Lanka are crucial.”
The report, backed by the Tamil Nadu Forest Department, and other key stakeholders, provides a framework for future conservation efforts. Dr. Kumara and his co-editors, Dr. Jayanthi and Dr. Patterson Edward, hope the findings will catalyze policy changes and foster stronger community involvement.
“This decade is critical,” Dr. Kumara concludes. “We must act now to ensure that future generations inherit thriving oceans.”
For conservationists, policymakers, and researchers alike, this report is a clarion call to protect the invaluable marine ecosystems of the Gulf of Mannar and Palk Bay.
Marine Ecosystem Monitoring: Gulf of Mannar and Palk Bay (2023-2024)
The Gulf of Mannar and Palk Bay, located along the southeastern coast of India, are biodiversity hotspots with immense ecological and economic significance. These marine ecosystems encompass coral reefs, seagrass meadows, and mangrove forests, supporting a vast array of flora and fauna while providing livelihoods to coastal communities. This article explores the findings of the 2023-24 monitoring report, highlighting the status and health of these ecosystems, the threats they face, and recommendations for their conservation.
The Gulf of Mannar and Palk Bay fall within the Indo-Pacific realm, known as the world’s richest region for marine biodiversity. With over 4,000 species reported in the Gulf of Mannar and nearly 3,300 species in Palk Bay, these ecosystems are critical for sustaining marine life. The Gulf of Mannar is India’s first marine biosphere reserve and was designated as a Ramsar site in 2022.
However, these ecosystems are vulnerable to both climatic and non-climatic factors, including coral bleaching, pollution, overfishing, and habitat destruction. Recognizing this, the Tamil Nadu Forest Department has established permanent monitoring sites to assess and manage the health of these vital habitats.
Coral reefs are among the most biologically diverse ecosystems on Earth. The monitoring data for 2023-24 revealed a slight improvement in coral health in the Gulf of Mannar compared to previous years:
The live coral cover averaged 23.5% in the Gulf of Mannar and 18.4% in Palk Bay. However, these figures are significantly lower than the baseline of 37% recorded in 2005 due to multiple bleaching events and human-induced stressors.
Some 70 coral species were identified in the Gulf of Mannar and 36 in Palk Bay. Massive corals dominated, followed by branching and table forms.
Juvenile Coral Density: This metric, indicative of reproductive success, averaged 9.0 m2 in the Gulf of Mannar and 5.8 m2 in Palk Bay.
Coral reefs are threatened by invasive species like Kappaphycus alvarezii, marine debris, and rising sea temperatures, which have consistently exceeded the bleaching threshold during summers.
Seagrass Meadows
Seagrass beds are crucial for nutrient cycling, coastal protection, and as habitats for species like dugongs and sea turtles. The study recorded:
Seagrass Cover: The Gulf of Mannar showed seagrass coverage ranging between 27.9% and 67.8%, while Palk Bay ranged between 19.5% and 60.9%.
Species Diversity:
Nine seagrass species were identified, with Cymodocea serrulata, Syringodium isoetifolium, and Thalassia hemprichii being the most common.
Shoot Density: Higher in regions with greater seagrass cover, showcasing a healthy ecosystem.
Mangrove Forests
Mangroves are natural buffers against coastal erosion and provide critical habitats for marine organisms. The study recorded:
Gulf of Mannar: The largest mangrove cover was in the Tamiraparani river estuary, spanning 172 hectares. Four mangrove species were identified, including Avicennia marina and Rhizophora mucronata.
Palk Bay: The Karankadu region had the highest mangrove cover of 250 hectares, with three dominant species.
Challenges: Mangroves face threats from habitat destruction, pollution, and encroachment.
Coastal Pollution
Physico-chemical parameters indicated that water and sediment quality were generally within acceptable levels. However, seasonal fluctuations caused by strong winds and water currents led to elevated turbidity and suspended solid levels. Heat stress during summer also exacerbated coral bleaching.
Marine Debris: Significant debris was observed, affecting 838 m2 of reef area in the Gulf of Mannar and 90 m2 in Palk Bay.
Conservation Efforts and Recommendations
The Tamil Nadu Forest Department has taken steps to mitigate threats and improve the health of these ecosystems:
Invasive Species Control: Manual removal of Kappaphycus alvarezii has significantly reduced its spread.
Community Involvement: Programmes, like eco-development committees and self-help groups, empower local communities to engage in conservation.
Regular Monitoring: Permanent monitoring sites provide long-term data critical for effective management.
Recommendations:
The Gulf of Mannar and Palk Bay are ecological treasures that require vigilant protection. While the current state of these ecosystems is fair, ongoing threats necessitate robust conservation efforts. By fostering a balance between biodiversity conservation and sustainable livelihoods, these marine ecosystems can thrive for generations to come.