Study: Climate change causes 4 degree rise in Buzzards Bay
A sailboat on Buzzards Bay passes between pedestrians June 4 at Fort Tabor. Michael Smith/Standard-Times FilePosted Jan. 22, 2016 at 7:29 PM
Climate change has caused a four-degree rise in water temperature and a decline in water quality over the past two decades in Buzzards Bay, according to a study by the Woods Hole Oceanographic Institution and the Buzzards Bay Coalition.
"We have seen a widespread and rapid increase in water temperature from 1992 to 2013 and this agrees with other regional studies so we are fairly confident that this is related to climate change," said Jenny Rheuban, a research associate at WHOI and lead author of the study.
The study — which involved data collected by more than 1,000 trained citizen scientists involved with the coalition over 22 years — also revealed an increase in algae growth, a cause of poor water quality.
"Algae like phytoplankton are the reason that when you go to the beach the water is murkier and not as clear as you'd like," said Rachel Jakuba, science director for the Buzzards Bay Coalition and co-author of the study.
The levels of chlorophyll, an indicator of phytoplankton or algae, in the water nearly doubled, according to the study, despite the fact that nitrogen levels remained relatively constant.
Algae forms the base of the marine food chain and is essential for a healthy ecosystem but too much can have consequences — including reducing sunlight and oxygen levels and making it harder for certain species to survive.
"It's harder for eelgrass to grow, and eelgrass is important for species like shellfish and others. Scallops need it for their lifecycles, and species like stripers use it in their juvenile stages," Jakuba said.
The most extreme consequence of low levels of oxygen in the water is what scientists call a "fish-kill," or the dying off of fish populations in a certain area.
And this is something that has happened periodically in Buzzards Bay and as recently as last fall with fish-kills occurring in the Acushnet River and Nasketucket Bay, according to Jakuba.
The increase in algae growth means that water quality is worse with nearly the same nitrogen concentration, the study said, which will have serious implications for cleanup plans.
"Much of what we do is try to reduce the nitrogen levels and work with towns to ensure septic systems and wastewater treatment sites are upgraded to limit nitrogen pollution, but the results suggest we'll have more of a challenge improving water quality," Jakuba said.
Though the data shows a significant warming of the water in recent decades, it is unclear if the trend will continue.
"We wouldn't necessarily want to take these trends and project them for the future because this is based off of historical data, so I wouldn't expect a rapid increase like this going forward," Rheuban said.
But the effects of the warming and increasing algae levels will take a toll on the marine ecosystem.
"In areas with less oxygen and higher levels of nitrogen, there are fewer, less diverse species and more murky, muddy waters," Rheuban said.
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