Long before crowd-sourcing and citizen science were buzzwords, volunteers for Buzzards Bay Coalition were monitoring water quality along the estuary's edges, from Westport to the Elizabeth Islands. The resulting data set spans twenty four years, and includes information about nutrients, temperatures, oxygen levels, and algral growth at two hundred locations. It's a scientific treasure-trove, but one which has gone relatively un-mined ... until now.
Scientists at Woods Hole Oceanographic Institution have partnered with the Buzzards Bay Coalition to analyze long-term trends, with a particular eye toward signatures of climate change. Research associate Jennie Rheuban says figuring out how to work with a large body of data she had no hand in designing has presented challenges, but it's reaping rewards.
In particular, she's identified a major effect from rising water temperatures. Rheuban says that looking through the data, it's clear that the same amount of nitrogen today results in a lot more algal growth than it did two decades ago. She points the finger at warmer waters, which accelerate algal growth.
Algae, of course, are essential to a healthy ecosystem. They're the microscopic plants at the very base of the entire food chain. But when waters become supercharged with excess nitrogen (a.k.a. fertilizer), algae can bloom out of control. Water can become so clouded it blocks sunlight from reaching eel grass, which then dies. The microbes that eat the algae suck the oxygen out of the water, killing fish and other animals. They also release carbon dioxide, which can make the water so acidic it's harmful to shellfish.
Rachel Jakuba, science director for Buzzards Bay Coalition, says nitrogen, or nutrient, pollution remains the single greatest threat to the long-term health of Buzzards Bay. Rising temperatures are adding to the existing problems, and may have rendered obsolete the nutrient pollution limits imposed on many of the region's coastal waters.
Still, Jakuba sees reason to be optimistic - and to work harder. Rising water temperatures are beyond local control, but nutrients are not. And while this new work suggests the problem is worse than previously thought, knowing is half the battle.