First published in Landings, February, 2013.
You and I and the guy down the street typically like to be warm. After all, Homo sapiens lack a nice covering of fur or a robust layer of blubber to keep ourselves warm in a cool environment. Warmth is critical for our survival. But this is not so for many of the species in the Gulf of Maine. Creatures from the tiny Pandulis borealis (northern shrimp) to the mighty Eubalaena glacialis (North Atlantic right whale) prosper in its cold, nutrient-rich waters. Researchers, however, are finding that Gulf of Maine water temperatures are going up, both at the surface and in the deeper waters, and that may mean fundamental shifts in the Gulf’s ecology.
A recent paper titled “Rapid Detection of Climate Scale Environmental Variability in the Gulf of Maine” laid out an unsettling future for the Gulf of Maine. Co-authored by Ru Morrison, Northeastern Regional Association of Coastal and Ocean Observing Systems (NERACOOS); Neil Pettigrew, University of Maine; James O’Donnell, University of Connecticut; and Jeffrey Runge, University of Maine, the paper draws on continuous data compiled during the past decade from the Gulf of Maine Ocean Observing System buoy array, now part of NERACOOS and the Gulf of Maine Research Institute. The seven buoys spread across the Gulf measure many environmental conditions at different depths, including current speed, direction, salinity and density, as well as wave heights, speed and direction. Most of the buoys record water temperature at one, two, 20 and 50 meters while the Northeast Channel buoy measures at 100, 150 and 180 meters.
The authors found that during the past decade, the water temperature at depth has increased steadily. “Analysis of this large time series … shows statistically significant warming trends at all depths for all locations” according to the paper.
Of course, the Gulf of Maine has warmed up at various times in the past. The most recent was during the decade between 1940 and 1950, when water temperatures rose by approximately 0.25o C per year. Then the Gulf’s temperature took a dip, cooling at a similar rate during the next decade. Overall, however, the Gulf warmed by about 0.01o C per year during the past seventy years. As the authors note, “The period of rapid warming recorded by the NERACOOS buoys since 2004, of similar magnitude to the 1940-50 warming trend, may represent another cycle of decadal variability or perhaps indicate a warming trend.”
Whatever the cause, many Gulf of Maine marine species will not thrive in these warming waters. Adapted to a specific range of temperatures, the animals may simply move on to cooler regions. The paper states, “… at a sustained bottom temperature increase of >2-3o C, Gulf of Maine cod stocks are anticipated to decline or collapse (Drinkwater 2005, Fogarty et al. 2008). Bottom temperature increases also affect reproductive cycles of Northern shrimp, with the likelihood of hatching dates in winter in advance of the phytoplankton blooms upon which the pelagic shrimp larvae depend (Koeller et al. 2009).”
The North Atlantic right whale might not have any place to move to, however. The endangered whales recently were found to overwinter in the Gulf, snacking on their favorite high fat food, Calanus finmarchicus, a small copepod. Others return every summer to the Gulf to graze on huge schools of the copepods, court and mate. But Calanus finmarchicus likes cold water. In a paper published in February, 2011, in the Global Change Biology journal, Gabriel Reygondeau and Gregory Beaugrand predicted that, due to warmer waters, the range of Calanus finmarchicus will shrink, particularly on Georges Bank and the Scotian Shelf, while it will be found in greater abundance to the north, especially in the Barents Sea. That’s bad news for just about everything that swims in the Gulf of Maine. In dry scientific language, the authors note, “Since the lipid-rich Calanus is a key prey for forage species such as herring, sand lance, mackerel, as well as for the northern right whale, regional shifts in feeding distributions and abundance of these planktivorous predators may be anticipated.”
Human beings want and need to be warm. Numerous valuable marine species in the Gulf of Maine do not. As their environment continues to warm up, those creatures may become notable not because of their abundance, but because of their absence.
For the past decade a system of buoys throughout the Northeast have been collecting hourly ocean and weather information. NERACOOS, the Northeastern Regional Association of Coastal and Ocean Observing Systems, support many of these buoys and are often asked how the current conditions compare to previous years or the average conditions. In order to help answer some of these questions, NERACOOS has developed a new display of ocean and weather climate information. This display delivers information about the average weather and ocean conditions between 2001 and 2012. The data in the display comes from NERACOOS supported buoys that are deployed throughout the northeast and have been collecting hourly weather and ocean data for the past 10+ years. The display also includes information about recent and past years ocean and weather conditions so that users can compare them to the average conditions from the past decade. The NERACOOS ocean and weather climate display will be available on the NERACOOS website (www.neracoos.org) in February.Category: Science