NOAA documenting shift in marine species as water warms
Looking down the East Coast from Cape Cod toward Long Island from the International Space Station. Visit this NASA Earth Observatory page for more information.
By Summit Voice
FRISCO — With sea surface temperatures at a 150-year high off off the mid-Atlantic and New England coastlines, scientists are document significant shifts in the distribution of commercially important marine species, with as-yet uncertain consequences for the entire ecosystem.
Those temperatures reached a record high of 57.2 degrees in 2012, exceeding the record high set in 1951. The average sea surface temperatures in the region — extending from the Gulf of Maine to Cape Hatteras, North Carolina — has typically been lower than 54.3 degrees during the past three decades, according to a NOAA advisory.
“Changes in ocean temperatures and the timing and strength of spring and fall plankton blooms could affect the biological clocks of many marine species, which spawn at specific times of the year based on environmental cues like water temperature,” said Kevin Friedland, a federal ecosystem assessment scientist.
Friedland said the contrast between years with, and without, a fall plankton bloom is emerging as an important driver of the shelf’s ecology.
“The size of the spring plankton bloom was so large that the annual chlorophyll concentration remained high in 2012 despite low fall activity. These changes will have a profound impact throughout the ecosystem,” he said.
The NOAA report explained that the high sea surface temperatures continue a trend of above-average temperature seen during the spring and summer seasons, and part of a pattern of elevated temperatures occurring in the Northwest Atlantic, but not seen elsewhere in the ocean basin over the past century.
The record of sea surface temperatures in the region comes from satellite data and long-term measurements made from ships, dating back to 1854. The temperature increase in 2012 was the highest jump in temperature seen in the time series and one of only five times temperature has changed by more than 1 degree Celsius (1.8 degrees Fahrenheit).
Due to the continued warming, the region’s warm-water thermal habitat was at a record high level during 2012, while cold water habitat was at a record low level. Early winter mixing of the water column went to extreme depths, which will impact the spring 2013 plankton bloom. Mixing redistributes nutrients and affects stratification of the water column as the bloom develops, according to the report.
Species shifting
Species monitoring shows shifts in seven key fisheries in the region, with four southern species — black sea bass, summer flounder, longfin squid and butterfish — all showing a northeastward or upshelf shift. American lobster has shifted upshelf over time but at a slower rate than the southern species. Atlantic cod and haddock have shifted downshelf.
“Many factors are involved in these shifts, including temperature, population size, and the distributions of both prey and predators,” said Jon Hare, a scientist in NOAA’s Northeast Fisheries Science Center, where research has shown that about half of the 36 fish stocks studied in the Northwest Atlantic Ocean have been shifting northward during the past four decades.
“It isn’t always easy to understand the big picture when you are looking at one specific part of it at one specific point in time,“ said Michael Fogarty, who heads the Ecosystem Assessment Program.
The abundance of fish and shellfish is controlled by a complex set of factors, and that increasing temperatures in the ecosystem make it essential to monitor the distribution of many species, some of them migratory and others not, Fogarty said.
“We now have information on the ecosystem from a variety of sources collected over a long period of time, and are adding more data to clarify specific details. The data clearly show a relationship between all of these factors.”
“What these latest findings mean for the Northeast Shelf ecosystem and its marine life is unknown,” Fogarty said. “What is known is that the ecosystem is changing, and we need to continue monitoring and adapting to these changes.”
The Spring 2013 Ecosystem Advisory, covering the fall of 2012 with supporting information, is available online at http://www.nefsc.noaa.gov/ecosys/advisory/current/advisory.html.
