Researchers have found that oil released into the Gulf of Mexico from the Deepwater Horizon spill has caused stressed-out phytoplankton to create massive globs of “sea-snot”.
These globules of mucus, known as marine mucilage, are large sticky masses of organic matter released by stressed-out phytoplankton — tiny ocean plants. The masses contain a variety of matter including dead shrimp, waste products and bacteria known to infect humans. The phytoplankton released this excess mucus in response to a decrease in the concentration of nitrogen and phosphorus and an increase in the concentration of carbon dioxide, which occurred as a result of the spilled oil in the Gulf of Mexico.
Marine “snowflakes” are accumulated particles held together by sugary mucus that naturally grows over time to reach only a few centimeters in diameter. Marine snow is present in all oceans of the world, but only certain conditions favor the coalescence of marine snow into marine mucilage. The oil spill in the Gulf of Mexico caused lumps of marine snow to pull together at the slightest contact and form masses of mucilage. These heavier and longer masses can then stretch for over a hundred miles. Eventually these elongated blobs of “sea-snot” sink to the ocean floor where they temporarily threaten to cover the sediments on the bottom.
Once this marine mucilage reaches the ocean floor, it forms into large blankets and can threaten to smother bottom dwellers. Uta Passow, a biological oceanographer at UCSB, said the danger of hypoxic conditions varies depending on certain conditions.
“[The danger] depends on a lot of things,” Passow said in an e-mail. “On the amount of organic bioavailable carbon the marine snow contains, the activity of organisms on the seafloor and the exchange rate.”
Marine snow falling to the ocean floor at a normal rate is the perfect vehicle for transporting organic matter — and the carbon associated with it — from the upper part of the water column to the ocean floor. The depth of the ocean in which the marine snow is converted back to carbon dioxide by bacteria affects how much nutrition is available for bottom dwelling ocean creatures.
The extra mucus that the phytoplankton produced caused the marine snow to fall at such a fast rate that scientists are using the term “marine blizzard”. While scientists did not witness the “blizzard”, it created a possible threat by producing a temporary dead zone by reducing the availability of oxygen. UCSB geochemistry and geomicrobiology professor David Valentine said he has been studying the gases released by the spilled oil in the Gulf.
According to Valentine, a very rapid consumption of hydrocarbon gasses — such as ethane, propane and butane — seemed to be the main cause of oxygen depletion. This rapid change in hydrocarbon gases only further depleted the numbers of phytoplankton — which are at the bottom of the marine food chain — as the oil is toxic enough to kill them.
While the oil well at BP’s Deepwater Horizon has been capped, the effects of the oil on marine life continue to be questioned. The sinking mucilage decayed early during its falling stage, according to Passow.
“By now the huge marine snow floc seems to be gone,” Passow said in an e-mail.
During the summer months when the oil spill was at its peak, the occurrence of marine mucilage was peaking as well. New “sea-snot” still occurs, but is not as prevalent and does not pose an immediate danger to the ocean’s water columns.
Valentine said his team expects the fresh water from moving sea currents to introduce oxygen back into the system, mitigating some concerns over long-term oxygen loss in the deep ocean from the elevated methane concentration.