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The Hindu
29-04-2025
- Science
- The Hindu
Changes in monsoon affect marine productivity in Bay of Bengal: study
Strong and weak monsoons can influence marine productivity in the Bay of Bengal, a study exploring fluctuations in the Indian Summer Monsoon (ISM) over the past 22,000 years has found. Marine productivity is a proxy for plankton growth – the main source of nourishment for aquatic life. The study is significant given that several climate models warn of significant disruption to the monsoon, under the impact of human-caused warming. The study, which appears in the peer-reviewed, Nature Geoscience, brought together scientists from India, China, Europe and the United States. 'By analysing their chemistry and tracking the abundance of certain types that thrive in productive waters, we reconstructed long-term changes in rainfall, ocean temperatures and marine life in the Bay of Bengal,' said Kaustubh Thirumalai, of the University of Austin and lead author of the study. 'Together, these chemical signals helped us understand how the monsoon and ocean conditions responded to global climate changes over the past 22,000 years.' Despite covering less than 1% of the world's ocean area, the Bay of Bengal provides nearly 8% of global fishery production. Its nutrient-rich coastal waters are vital to the densely populated communities along its shores, many of whom rely heavily on fisheries for food and income. 'Millions of people living along the Bay of Bengal rely on the sea for protein, particularly from fisheries,' said Yair Rosenthal, of the Rutgers University and a co-author. 'The productivity of these waters – the ability of the ocean to support plankton growth – is the foundation of the marine food web. If ocean productivity declines, it will powerfully affect the ecosystem, ultimately reducing fish stocks and threatening food security for coastal communities.' The study found that both abnormally strong and weak monsoons throughout history caused major disruptions in ocean mixing, leading to a 50% reduction in food for marine life in the surface waters. This occurs because extreme monsoon conditions interfere with the vertical movement of nutrient-rich waters from the deep ocean to the surface, where plankton—the base of the food chain—flourish. To reconstruct past ocean conditions, scientists analysed fossilised shells of foraminifera, tiny single-celled marine organisms that record environmental data in their calcium carbonate shells. These microfossils were retrieved from seafloor sediments by scientists aboard the JOIDES Resolution, a research ship operating under the International Ocean Discovery Program. The researchers found that marine productivity declined sharply during periods like Heinrich Stadial 1 (a cold phase between 17,500 and 15,500 years ago) and the early Holocene (about 10,500 to 9,500 years ago), when monsoons were either unusually weak or strong. Monsoon rainfall directly affects river run-off into the Bay of Bengal, altering ocean salinity and circulation. When too much freshwater builds up at the surface, it prevents nutrient mixing. Conversely, weak monsoons reduce wind-driven mixing, also starving surface waters of nutrients. 'Both extremes threaten marine resource availability,' Mr. Thirumalai said. By comparing ancient patterns with modern ocean data and climate model projections, researchers identified 'worrying' similarities, the authors said in a statement. Future scenarios suggest warmer surface waters and stronger freshwater run-off—conditions linked to past drops in marine productivity. Additionally, weaker future winds may fail to break through ocean stratification and restore nutrient cycling.
India Today
29-04-2025
- Science
- India Today
Monsoon changes threaten Bay of Bengal: Your favourite fish curry is at risk
A new study published in Nature Geoscience reveals that climate-driven extreme weather events in India's summer monsoon could permanently disrupt the Bay of Bengal's marine productivity, jeopardising food security for by researchers from Rutgers University, the University of Arizona, and international collaborators, the analysis of 22,000 years of monsoon and ocean data warns of a 50% decline in surface food availability during intense rainfall or drought periods - a pattern poised to repeat as global warming intensifies monsoon Bay of Bengal, covering less than 1% of the global ocean, supplies nearly 8% of the world's fishery production, including critical species like hilsa, a dietary staple for coastal communities. By studying fossilised shells of foraminifera-microscopic plankton that record environmental conditions - the team reconstructed historical monsoon impacts. Stronger monsoons will increase freshwater runoff, while weaker winds fail to counteract stratification. (Photo: Getty) They found that both abnormally strong and weak monsoons stifled ocean mixing, blocking nutrient flow from deeper waters to surface Heinrich Stadial 1 (17,500–15,500 years ago), weak monsoons reduced wind-driven nutrient circulation. Conversely, early Holocene-era heavy rains (10,500–9,500 years ago) created a freshwater 'cap' on the ocean surface, starving plankton of nutrients. These extremes led to collapses in marine productivity, a scenario now projected to recur as climate models predict warmer surface waters and intensified monsoon 150 million people rely on the Bay's fisheries for protein and livelihoods. 'The ocean's ability to support plankton growth is the foundation of the marine food web. Its decline would reduce fish stocks catastrophically,' said Yair Rosenthal, a Rutgers climate scientist and study the crisis, artisanal fisheries-which constitute 80% of Bangladesh's marine catch-already face overfishing pressures, pushing stocks below sustainable levels. Modern ocean data and climate models align with past collapses: stronger monsoons will increase freshwater runoff, while weaker winds fail to counteract stratification. 'Both extremes threaten marine resource availability,' emphasized Kaustubh Thirumalai, the study's lead author. For example, the hilsa fishery, vital for regional protein needs, could collapse under repeated productivity study points to the urgency of refining climate models and implementing sustainable fisheries Rosenthal noted, 'These insights can inform strategies to protect coastal resources as climate impacts accelerate'. With the Bay's marine ecosystems at a tipping point, mitigating overfishing and curbing greenhouse emissions are critical to safeguarding this lifeline for future findings highlight a stark reality: the Bay of Bengal's role as a global food source hangs in the balance, demanding immediate action to avert a climate-driven crisis.
News18
29-04-2025
- Science
- News18
India's Changing Monsoon Patterns, Warmer Climate Threaten Bay of Bengal's Marine Life: Study
Future projections show climate change-induced warmer surface waters, strong freshwater run-off and weaker winds could lead to sharp fall in marine productivity in Bay of Bengal India's changing monsoon patterns and continuously warming climate could drastically weaken the Bay of Bengal's ability to support marine life – a crucial part of the region's food supply. The latest study has long-term consequences for fisheries and coastal livelihoods. Flanking India's vast east coast, the Bay of Bengal supports densely populated regions that rely heavily on marine resources for food and livelihoods. Even though it covers just 1% of the global ocean, the Bay of Bengal supplies nearly 8% of the world's fishery production. 'Millions of people living along the Bay of Bengal rely on the sea for protein, particularly from fisheries. The productivity of these waters – the ability of the ocean to support plankton growth – is the foundation of the marine food web. If ocean productivity declines, it will powerfully affect the ecosystem, ultimately reducing fish stocks and threatening food security for coastal communities," said author Professor Yair Rosenthal from the Department of Marine and Coastal Sciences at Rutgers University. The team from Rutgers University, the University of Arizona, and collaborators from India, China and Europe found that both extremely strong and extremely weak monsoon periods over the past 22,000 years caused a nearly 50% reduction in food available from marine life at the surface. They published their findings in the peer-reviewed Nature Geoscience. This may occur because the monsoon, which provides over 75% of the annual rainfall over the country during four months from June to September, is also essential for providing freshwater to the region. However, due to global warming and rising temperatures, this is changing because the southwest monsoon is becoming more erratic and extreme over the years. INDIA'S MONSOON TURNING MORE ERRATIC According to researchers, the extreme conditions in the past stopped the deep and surface waters from mixing, blocking nutrients from reaching the upper layers where marine life depends on them. With climate change expected to make the monsoon more intense and erratic, those extremes provoking stratification of the ocean layers, the food supply produced by the Bay of Bengal may be threatened, they said. This is likely because the monsoon rainfall controls the volume of river discharge into the Bay of Bengal. The freshwater significantly changes oceanographic conditions and affects the feeding cycle of fish and plankton. When monsoon rains are too intense, a freshwater layer can cap the ocean surface, blocking nutrients from below. Without nutrients, plankton growth drops – and with it, the entire food chain, including fish. Weaker monsoons also suppress nutrient delivery by reducing ocean circulation and wind-driven mixing. The study showed that the productivity of the Bay of Bengal's waters collapsed during periods of very weak monsoons – a period between 17,500 and 15,500 years ago, and very strong monsoons, such as those in the early Holocene, a time marked by rapid warming and sea level rise because of melting glaciers, occurred between about 10,500 and 9,500 years ago. The team's future projections showed that warmer surface waters, strong freshwater run-off and weaker winds could create conditions for a sharp fall in marine productivity in the Bay of Bengal. 'The relationship between monsoons and ocean biology we have uncovered in the Bay of Bengal gives us real-world evidence of how marine ecosystems have reacted to warming and monsoon shifts and may do so in the future," said Rosenthal highlighting the need for sustainable management of fisheries and coastal resources as the impacts of climate change accelerate. ADAPTING TO CLIMATE CHANGE IMPACT ON OCEANS The team studied the fossil shells of foraminifera – tiny single-celled plankton that live in the ocean and build calcium carbonate shells, since they preserve information about the environment they grew in, acting like natural recorders of past ocean and climate conditions. top videos View all By analysing their chemistry and tracking the abundance of certain types that thrive in productive waters, they reconstructed long-term changes in rainfall, ocean temperatures and marine life in the Bay of Bengal. 'Together, these chemical signals helped us understand how the monsoon and ocean conditions responded to global climate changes over the past 22,000 years," said lead author geoscientist Kaustubh Thirumalai from the University of Arizona. The sediments analysed were recovered from the seafloor by scientists aboard the research vessel JOIDES Resolution, funded by the National Science Foundation-funded as part of the International Ocean Discovery Program. tags : news18 specials Location : New Delhi, India, India First Published: April 29, 2025, 12:47 IST News india India's Changing Monsoon Patterns, Warmer Climate Threaten Bay of Bengal's Marine Life: Study
The Hindu
29-04-2025
- Science
- The Hindu
Changes in monsoon strength affects marine productivity in Bay of Bengal
Strong and weak monsoons can influence marine productivity in the Bay of Bengal, a study exploring fluctuations in the Indian Summer Monsoon (ISM) over the past 22,000 years has found. Marine productivity is a proxy for plankton growth – the main source of nourishment for aquatic life. The study is significant given that several climate models warn of significant disruption to the monsoon, under the impact of human-caused warming. The study, which appears in the peer-reviewed, Nature Geoscience, brought together scientists from India, China, Europe and the United States. 'By analysing their chemistry and tracking the abundance of certain types that thrive in productive waters, we reconstructed long-term changes in rainfall, ocean temperatures and marine life in the Bay of Bengal,' said Kaustubh Thirumalai, of the University of Austin and lead author of the study. 'Together, these chemical signals helped us understand how the monsoon and ocean conditions responded to global climate changes over the past 22,000 years.' Despite covering less than 1% of the world's ocean area, the Bay of Bengal provides nearly 8% of global fishery production. Its nutrient-rich coastal waters are vital to the densely populated communities along its shores, many of whom rely heavily on fisheries for food and income. 'Millions of people living along the Bay of Bengal rely on the sea for protein, particularly from fisheries,' said Yair Rosenthal, of the Rutgers University and a co-author. 'The productivity of these waters – the ability of the ocean to support plankton growth – is the foundation of the marine food web. If ocean productivity declines, it will powerfully affect the ecosystem, ultimately reducing fish stocks and threatening food security for coastal communities.' The study found that both abnormally strong and weak monsoons throughout history caused major disruptions in ocean mixing, leading to a 50% reduction in food for marine life in the surface waters. This occurs because extreme monsoon conditions interfere with the vertical movement of nutrient-rich waters from the deep ocean to the surface, where plankton—the base of the food chain—flourish. To reconstruct past ocean conditions, scientists analysed fossilised shells of foraminifera, tiny single-celled marine organisms that record environmental data in their calcium carbonate shells. These microfossils were retrieved from seafloor sediments by scientists aboard the JOIDES Resolution, a research ship operating under the International Ocean Discovery Program. The researchers found that marine productivity declined sharply during periods like Heinrich Stadial 1 (a cold phase between 17,500 and 15,500 years ago) and the early Holocene (about 10,500 to 9,500 years ago), when monsoons were either unusually weak or strong. Monsoon rainfall directly affects river run-off into the Bay of Bengal, altering ocean salinity and circulation. When too much freshwater builds up at the surface, it prevents nutrient mixing. Conversely, weak monsoons reduce wind-driven mixing, also starving surface waters of nutrients. 'Both extremes threaten marine resource availability,' Mr. Thirumalai said. By comparing ancient patterns with modern ocean data and climate model projections, researchers identified 'worrying' similarities, the authors said in a statement. Future scenarios suggest warmer surface waters and stronger freshwater run-off—conditions linked to past drops in marine productivity. Additionally, weaker future winds may fail to break through ocean stratification and restore nutrient cycling.
