Keeping population of larger fish intact is critical to carbon accumulation and long-term storage in vegetated coastal habitats such as saltmarsh, mangroves and seagrass
Culling sharks like those in the recent fatal attacks in Australia can disturb the carbon stocks present in the environment. A recent research has pointed out the need of further research on the influence of predators on carbon cycling. The study was published in the journal Nature Climate Change, titled "Predators help protect carbon stocks in blue carbon ecosystems”.
The paper also highlighted the need for an improved policy and management for blue carbon - the carbon which is captured by world’s ocean and coastal ecosystems. According to the research, keeping population of larger fish intact is critical to carbonaccumulation and long-term storage in vegetated coastal habitats such as saltmarsh, mangroves and seagrass. Rod Conolly, a marine scientist from Griffith University's Australian Rivers Institute and co-author of this research, has warned that loss of top order predators through excessive culling or over-fishing has serious environmental upshots. He also adds "Altering the numbers of top ocean predators has major consequences for the way we tackle climate change. These predators have a cascading effect on the food web and the ecosystem generally that ultimately changes the amount of carbon captured and locked up in the seabed."
Coastal wetlands play a crucial role in this process, extracting carbon from the atmosphere and burying it in the mud for hundreds and even thousands of years.
"When we change the abundance of higher order predators, this affects the number of smaller animals living in the mud, and that has flow-on effects for carbon storage in coastal wetlands," adds the expert. Therefore,“continued unsustainable harvesting of large predatory fish”, including the culling of sharks, can have far-reaching consequences for the way we tackle climate change.
An earlier research, titled “The Impact of Whaling on the Ocean Carbon Cycle: Why Bigger Was Better”, was conducted by the researchers from University of Maine, Gulf of Maine Research Institute and the University of British Columbia. The study found that about 160,000 tonnes of carbon per year could be removed from the atmosphere if whale populations were restored to pre-industrial levels. This amount is equivalent to adding 843 hectares of forest. Restoring the whale populations compares favorably with unproven schemes such as iron fertilization in removing carbon from the ocean surface. Iron fertilization is an intentional introduction of iron to the upper ocean to stimulate a phytoplankton bloom which can probably help in carbon dioxide removal from the atmosphere benefitting the marine food chain as well.
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