PERU fishing with guts to report…
94% of marine dead zones in the world are in regions where it is expected that the temperature increase to minus 2 degrees Celsius by the end of the century, according to a recent report by the Smithsonian Tropical Research Institute and the Center for Environmental Research Smithsonian in Panama
Dead zones are formed in waters where oxygen falls to too low for fish, crabs and other animals to survive levels. The largest dead zone in the Gulf of Mexico and the Baltic Sea can cover more than 20,000 square kilometers of seabed. The number of dead zones worldwide is growing exponentially, doubling every decade since the 60s.
The main culprit is the massive proliferation of algae, which extract oxygen from the water when they breathe or decompose. The algal blooms are formed from excess runoff of nutrients such as nitrogen and phosphorus, widely used as fertilizer. But climate change could exacerbate the problem.
"Our study is the first to consider more than a dozen direct and indirect effects of climate change in the dead zones, and suggests that we have underestimated its contribution to the growing problem of these and the effects on Marine Life"Said Andrew Altieri, lead author of the study and ecologist at the Smithsonian Tropical Research Institute.
"Dead zones have a major impact on life in coastal areas around the world"Said Keryn Gedan, Co-author and marine ecologist at the Smithsonian Center for Environmental Research and the University of Maryland. "A lot of people live on the coast and are experiencing more deaths Fish and outbreaks of harmful algae.
Altieri and Gedan analyzed a database of more than 400 dead zones around the world that then superimposed on a map of annual temperature anomalies is expected to happen in each region.
The warm waters are less oxygen, say the authors of the paper, allowing the dead zones are more easily formed. When temperatures rise, marine animals need more oxygen, which the ocean is less able to provide.
Furthermore, the increased temperatures prevent water mixture which can keep in check the dead zones. Dead zones in the bottom of the sea may vanish if the surface waters sink, injecting fresh oxygen from above. But since the warmer water float, this conveyor belt that gives life stops.
The Sea level rise leads to the expansion of the Bays and Estuaries, bringing the total volume of water susceptible to low oxygen levels and may also destroy wetlands. Wetlands are one of the best defenses against dead zones, and that filter excess nutrient pollution that feeds the massive proliferation of algae.
Altieri and Gedan found only one possible positive impact of rising temperatures: Due to the metabolism of animals excels under higher temperatures, small crustaceans such as copepods and other zooplankton can eat sprouts algae that create dead zones in First. "We see some cases where the proliferation of algae is lower than in warmer years because herbivores are better able to control algae"Said Gedan. However, he added, it is not clear how it will interact with the other effects of climate change they have witnessed.
Altieri suggests that there is an important lesson to learn from their study: "There are a lot of inertia when it comes to global climate change, but we can counter the effects of climate dead zones through local control of nutrient pollution."
SOURCE: Larazon.es
