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  • By Mar-Vic Cagurangan

Gone fishless

Pacific Island countries could lose 50-80 percent of marine resources under climate change

Photo by Quentin Hanich

Tropical Pacific areas have been identified as one of the most vulnerable regions in the world's oceans to climate change impacts and if the ecological crisis remains unchecked, many Pacific Island nations would lose 50 to 80 percent of marine species in their waters by the end of the 21st century, according to a newly released study by the Nippon Foundation-Nereus Program.

Pacific Island nations and territories are facing a 50 percent dip in catch potential by 2100, exposing them to socio-economic vulnerability, researchers say. The projected catch decline would affect Guam, Kiribati, Tuvalu, the Cook Islands, the Marshall Islands, Micronesia, Solomon Islands, Papua New Guinea and Niue.

“These changes would be detrimental to Pacific Islanders, who are highly dependent on marine species for food, economic opportunities, and cultural heritage. Additional threats come from sea level rise and increasing major storms. Also, these are often developing countries with less resources available for societal adaptations to climate change,” says the study, published in Marine Policy in November.

The Pacific Islands region is the warmest of the global ocean. It’s also an area where there is less seasonal variability — it more or less feels like summer all year. Because there are no drastic seasons, the animals in the tropical Pacific may find changing conditions to be more of a shock.

“Under climate change, the Pacific Islands region is projected to become warmer, less oxygenated, more acidic, and have lower production of plankton that form the base of oceanic food webs,” said lead author Rebecca Asch, Nereus Program alumnus and Assistant Professor at East Carolina University. “We found that local extinction of marine species exceeded 50 percent of current biodiversity levels across many regions and at times reached levels over 80 percent.”

Under the Representative Concentration Pathways scenario, most regions of the tropical Pacific were projected to warm by 1–2 °C by 2050 and ≥ 3 °C by 2100.

Gabriel Reygondeau, co-author and Nereus Fellow at UBC, said additional warming will push ocean temperature beyond conditions that organisms have not experienced since geological time periods in this region. “Since no organisms living in the ocean today would have time to adapt to these warmer conditions, many will either go extinct or migrate away from the western Pacific, leaving this area with much lower biodiversity.”

The authors examined the effects of climate change on more than a thousand species, including those that live on reefs and those that live in open-water habitats. Both groups underwent declines in local biodiversity, but the rates of decline were higher for the open-water species.

Tropical marine species are biologically adapted to a seasonally more stable environment relative to other parts of the ocean. Scientists say tropical species generally have a narrower tolerance range for temperature, rendering them more sensitive to warming and other oceanographic changes. In addition, coral reefs, a critical habitat for many tropical species and fisheries resources, are highly sensitive to small changes in temperature resulting in coral bleaching during heat waves, physical damage from storms, and reduced calcification from ocean acidification.

The authors note that across most countries in this region, fishes contribute 20 percent of the animal protein that sustains the human population.

“From an economic perspective, this region's tuna fisheries are especially lucrative, with tuna fishing licenses sold to other countries contributing up to 60 percent of tax revenues for some Pacific Island countries and territories,” the study said. “Climate fluctuations in this region can also have economic impacts through their effect on the tourism industry, which is strongly related to iconic marine species. Overall, travel and tourism contributed 12 percent of the GDP and 13 percent of the employment in Oceania in 2016, making tourism a key sector of the regional economy.”

“One hopeful point is that the extent of these changes in biodiversity and fisheries was dramatically reduced under a climate change scenario where greenhouse gas emissions were close to what would be needed for achieving the Paris Climate Agreement” said co-author William Cheung, Nereus director of Science.

While changes in oceanic conditions are “not inevitable,” Cheung said the future of climate condition is dependent on the immediate actions of all countries to materialize their commitment to limit greenhouse gas emissions as was discussed in COP23 in Bonn, Germany last November.


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