Climate Change Already Causing Fisheries Collapse
Climate change is causing sardine populations near Venezuela to plummet. Photo credit: SWFSC/NOAA.
A new study determined that climate change caused the collapse of a fishery in Venezuela, showing that even small increases in temperature are harming ocean life.
This study was conducted over a 15-year period, during which researchers from University of Southern California, Stony Brook University, University of South Florida and several Venezuelan institutions collected data regarding nutrient and chlorophyll concentrations, meteorological readings, and many other variables at a single point off the coast of Venezuela.
Throughout this period, the temperature only increased about 1 degree Celsius, but the population of many microscopic organisms, and the local sardine harvest plummeted consistently, beginning in 2006.
Robert Thunell, co-author from USC, explained the reason for the decline:
- The “thermal equator” is the area just north of the geographic equator where the northeast and southeast trade winds meet
- The location of the thermal equator causes the northern hemisphere to heat faster than the southern hemisphere
- This uneven heating due to global warming causes the thermal equator to shift farther northward
- The shift causes the trade winds to decrease in the southern Caribbean, where Thunell and colleagues have been collecting data for over a decade
- Less wind means less mixing of the oceans
- Less mixing means a diminished food supply for phytoplankton
- Decrease in phytoplankton causes a decrease in fish populations
“That’s a big deal. The plankton near the surface of the ocean are the base of the food chain,” said Thunell. “This climatological change is driving a change in the food web structure, which we’re now seeing affect the fisheries.”
Islas Los Roques, a Venezuelan National Park known for its beautiful reefs and marine diversity, located in the Caribbean Sea. Photo credit Juan Valero.
To learn more:
- Read the full press release from USC, here: Venezuelan fishery collapse linked to climate change
- Find the results, published in the Proceedings of the National Academy of Sciences, here: Ecosystem responses in the southern Caribbean Sea to global climate change
Copyright © 2012 by Marine Science Today, a publication of Marine Science Today LLC.
