Maine study finds potentially disastrous threat to single-celled plants that support all life

Diatoms are one of the most common types of phytoplankton.
Diatoms are one of the most common types of phytoplankton.
Posted June 10, 2012, at 5:02 p.m.
Last modified June 11, 2012, at 6:18 a.m.

BOOTHBAY, Maine — Phytoplankton. If the mention of the tiny plant organisms that permeate the world’s oceans isn’t enough to pique your interest, consider this: They produce the oxygen in every other breath you take.

Still not interested? This is where it’s hard not to take notice. In 2007, the reproduction rate of phytoplankton in the Gulf of Maine decreased suddenly by a factor of five — what used to take a day now takes five — and according to a recently released study by the Bigelow Laboratory for Ocean Sciences in Boothbay, it hasn’t bounced back.

So what does it mean? According to Barney Balch, the lab’s senior research scientist and lead author of the study, such a change in organisms at the bottom of the planetary food chain and at the top of planetary oxygen production could have disastrous consequences for virtually every species on Earth, from lobsters and fish that fuel Maine’s marine industries to your grandchildren. But the 12-year Bigelow study focused only on the Gulf of Maine, which leads to the question, will it spread?

“I don’t think it takes a rocket scientist to know that if you shut down the base of the marine food web, the results won’t be positive,” said Balch.

Balch said the study, which was published recently in the Marine Ecology Progress Series, provides one of the strongest links to date between increases in rainfall and temperature over the years and the Gulf of Maine’s ecosystem. Key factors in the study’s conclusions were driven by 100 years of records on rainfall and river discharge, both of which have increased by between 13 and 20 percent over the past century.

In fact, of the eight heaviest rainfall years in the past century, four of them fell between 2005 and 2010. Balch said that increased precipitation, along with water melting from the polar ice caps, could be the reason for the problems discovered in the phytoplankton regeneration rate. The fact that Gulf of Maine’s water temperature has risen about 1.1 degrees celsius — which is on par with what is being seen around the world — could also be a factor.

“The major change that we’re seeing is that we are now able to put [precipitation and temperature data] into better context,” said Balch. “It’s so striking that the increase is so statistically significant.”

Though heavier water flows into the Gulf of Maine might be a major factor, Balch said it may actually be side-effects of that phenomenon — such as decreased salinity and increasing amounts of materials like rotting plant matter being swept up in the stronger currents — that are actually causing the problem. In other words, when the water is brown it’s bad for phytoplankton because the added material in the water starves the single-celled plants of sunlight.

During the 12-year study, which focused on the area of sea between Portland and Yarmouth, Nova Scotia, researchers noticed that plumes of material coming from Maine rivers were reaching 70-100 kilometers into the ocean — farther than had ever been seen before. The outflows also prevent nutrient-rich deep-ocean water from circulating into the Gulf of Maine.

“When you collect the amount of data that we’ve collected, it’s hard to discount the significance,” said Balch. “I know there are skeptics out there who still discount the issue of climate change, but the evidence now is just striking. We need to be thinking very carefully about trying to slow this down. It didn’t happen overnight and it’s not going to go away overnight.”

Balch said that the Gulf of Maine is small compared to the world’s oceans, but not without the capacity to have a marked effect on the overall ecosystem of the Atlantic Ocean. If the problem with the phytoplankton persists, fishermen will notice its effects long before the world’s oxygen supply suffers. Phytoplankton is a key food source for several species of larval fish and lobster populations.

“People shouldn’t freak out about this but they should think very carefully about the long-term changes that we humans are making,” he said. “This study shows the incredibly tight connection that there is between land and the ocean, especially in the coastal ocean.”

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