Three oceanographers from Duke studied two decades of NASA satellite photos of the ocean to see how the water’s color has changed. Dr. Susan Lozier says large portions are becoming more blue — and other parts becoming more green — though it’s hard to see with the naked eye.
“It's not like the average person is going to go to the beach in Wilmington and say, 'I think I can see a bluer ocean out there.' This is something that we see from space.”
The color shifts they saw are due to the abundance of tiny algae, called phytoplankton. These microorganisms are green because they are full of the chemical chlorophyll, which they use to photosynthesize. Greener water comes from heavier concentrations of algae.
The researchers found that algae populations are declining in tropical regions around the equator. Algae support the food chain for a lot of sea life, so scientists worry that these losses could hurt many species, as well as fishing industries.
“I would say if the trends continue and we think definitely that will impact the ecosystem, especially for the local ecosystem where the countries or people heavily rely on those fisheries and those mammals and animals. So because phytoplankton is the bottom of the food chain and any change in their population that will affect the the population of fish or other animals from the trophic levels," Dr. Haiping Zhao said.
The research team was careful not to draw conclusions yet as more research was needed on both the cause and consequences.
“We would say it's a little bit difficult for us to establish a confidence causation between the temperature and the chlorophyll, because we have relatively short satellite records.” Lozier said. “If we can get a longer record of observation. We will be more confident to say whether this weather we observe is attributed to the climate or the rising temperature.”
Still, they say identifying the color changes was an important step.
