Changes in rainfall affect more than just land-based ecosystems. New research shows that increased rainfall in Maine led to the decline of ocean dwelling plant-like organisms called phytoplankton, which make up the base of the oceanic food web.
Researchers led by William Balch, of Bigelow Laboratory for Ocean Sciences in East Boothbay, Maine, found that more rainfall translates into more river runoff flowing into the Gulf of Maine. The runoff, in turn, prevents phytoplankton from receiving the nutrients and light they need to thrive, researchers reported March 29 in Marine Ecology Progress Series. Read the study here, and Bigelow Laboratory’s story here.
“We demonstrated a massive, five-fold drop in primary production in this region — along with other big changes — associated with the record-breaking precipitation events that started in the mid-2000’s,” Balch said.
The researchers combined climate and river flow data with the results from a 12-year time series collected during the NASA-funded Gulf of Maine North Atlantic Time Series (GNATS) project. Between 1998 and 2010, GNATS documented changes in nutrient concentrations, phytoplankton biomass, and carbon fixation between Portland, Maine and Yarmouth, Nova Scotia (see map, below).
“We combined climate data from over a century, river run-off data and the coastal time series to show how intimately the coastal ecosystem is connected to hydrological processes on land,” Balch said.
It remains to be seen how the shift in the base of the food web will trickle up to impact the Gulf of Maine’s fish, lobster, and the endangered North Atlantic right whale, which has been known to feed in the Gulf.
Text by Kathryn Hansen. Top image: William Balch collects temperature measurements from the Gulf of Maine. Credit: Globe Staff / Dina Rudick. For related images, check out The Boston Globe’s “Climate Change in the Ocean” gallery.
Bottom image: Data from NASA’s Sea-viewing Wide Field-of-view Sensor shows areas in the Gulf of Maine that on May 11, 2002, exhibited the high chlorophyll concentrations (red and orange) that mark thriving phytoplankton populations. New research shows that increased rainfall and river runoff caused phytoplankton to decrease five-fold since the mid-2000s. Credit: NASA