5 ways that life underwater affects life on land

This year's World Wildlife Day aligns with Sustainable Development Goal 14, which focuses on life below water. Photo: Mathias Appel, Flickr
1 March 2019

The existence of terrestrial species, including humans, depends on life underwater. Yet, pollution, global warming, unsustainable fishing and degradation of natural habitats are threatening marine and coastal biodiversity – a concern that has prompted this year’s World Wildlife Day on 3 March to focus on marine species for the first time in the holiday’s history.

On this occasion, here’s a rundown on how life below the water’s surface is vital to that above.

  • Every second breath we take

Oceans comprise 99 percent of earth’s livable habitat and produce half of the oxygen in the Earth’s atmosphere – giving us, in a sense, every second breath we take. However, oceans are the least-explored ecosystems on Earth, and the fact that we know more about the moon than we do about the deep sea remains true.

  • A market worth trillions

More than 3 billion people – half of the global population – depend on marine and coastal biodiversity for their livelihoods. “The estimated market value of marine and coastal resources and industries is USD 3 trillion per year,” says head of UN Development Programme’s ecosystems and biodiversity program Midori Paxton.

  • Their growth is our growth

The majority of aquatic species have yet to be discovered. Scientists have identified some 200,000 species, but there could be millions more. In 2017, for example, researchers from Oxford University discovered more than 100 species in the Bermuda twilight zone alone, including crustaceans, algae and various corals.

The potential of such diversity is significant. “Over 18,000 natural products and 4,900 patents associated with genes of marine organisms…demonstrates that the use of marine genetic resources is no longer a vision but a growing source of biotechnological and business opportunities,” states research from the Mediterranean Institute for Advanced Studies. If species disappear, future applications in medicine and other fields will also fade.

  • A massive thermostat

Oceans absorb 90 percent of the excess heat trapped by greenhouse gases. The remainder goes into melting ice caps and warming the continents’ land mass.

“Only the smallest fraction of this thermal energy goes into warming the atmosphere,” explain scientists from the Scripps Institution of Oceanography. “Humans, living at the interface of the land, ocean and atmosphere, only feel a sliver of the true warming cost of fossil fuel emissions.”

In addition, oceans absorb 30 percent of carbon dioxide released into the atmosphere, further mitigating climate change.

  • Coastal needs

Mangrove forests, seagrass meadows and salt marshes thriving in coastal areas are among the ecosystems that absorb the most carbon dioxide. A patch of mangroves can absorb up to 10 times the amount captured by a terrestrial forest of the same size, and seagrass beds can capture up to 83 million tons of carbon each year.

Coastal ecosystems help people both adapt to and mitigate the impacts of climate change. They serve as natural buffers for storm surges; filter water; and act as nurseries for thousands of fish species, from snapper and barracudas to colorful gobies adding rainbows of color into the blue.



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