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From ScienceDaily.com
Sea
surface temperatures in the Northeast Shelf Large Marine Ecosystem during 2012
were the highest recorded in 150 years, according to the latest Ecosystem
Advisory issued by NOAA's Northeast Fisheries Science Center (NEFSC).
These high sea surface temperatures (SSTs) are the latest in 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.
These high sea surface temperatures (SSTs) are the latest in 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
advisory reports on conditions in the second half of 2012.
Sea
surface temperature for the Northeast Shelf Ecosystem reached a record high of
14 degrees Celsius (57.2°F) in 2012, exceeding the previous record high in
1951. Average SST has typically been lower than 12.4 C (54.3 F) over the past
three decades.
The
Northeast Shelf's warm water thermal habitat was also 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.
Temperature
is also affecting distributions of fish and shellfish on the Northeast Shelf.
The advisory provides data on changes in distribution, or shifts in the center
of the population, of seven key fishery species over time. The four southern
species -- black sea bass, summer flounder, longfin squid and butterfish -- all
showed 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 the NEFSC's Oceanography Branch. A number of recent studies have
documented changing distributions of fish and shellfish, further supporting
NEFSC work reported in 2009 that found about half of the 36 fish stocks studied
in the Northwest Atlantic Ocean, many of them commercially valuable species,
have been shifting northward over the past four decades.
The
Northeast U.S. Continental Shelf Large Marine Ecosystem (LME) extends from the
Gulf of Maine to Cape Hatteras, North Carolina. The NEFSC has monitored this
ecosystem with comprehensive sampling programs since1977. Prior to 1977, this
ecosystem was monitored by the NEFSC through a series of separate, coordinated
programs dating back decades.
Warming
conditions on the Northeast Shelf in the spring of 2012 continued into
September, with the most consistent warming conditions seen in the Gulf of
Maine and on Georges Bank. Temperatures cooled by October and were below
average in the Middle Atlantic Bight in November, perhaps due to Superstorm
Sandy, but had returned to above average conditions by December.
"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," Kevin Friedland, a scientist in the NEFSC Ecosystem
Assessment Program, said. He noted that the contrast between years with, and
without, a fall 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."
Michael
Fogarty, who heads the Ecosystem Assessment Program, says 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.
"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," Fogarty said, a
comparison similar to not seeing the forest when looking at a single tree in
it. "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."
Ecosystem
advisories have been issued twice a year by the NEFSC's Ecosystem Assessment
Program since 2006 as a way to routinely summarize overall conditions in the
region. The reports show the effects of changing coastal and ocean temperatures
on fisheries from Cape Hatteras to the Canadian border. The advisories provide
a snapshot of the ecosystem for the fishery management councils and also a
broad range of stakeholders from fishermen to researchers.
Story Source:
The
above story is reprinted from materials provided byNOAA
Fisheries Northeast Fisheries Science Center.
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NOAA Fisheries Northeast Fisheries Science Center (2013, April
26). Sea surface temperatures reach highest level in 150 years on Northeast
continental shelf. ScienceDaily. Retrieved April 27, 2013, from
http://www.sciencedaily.com/releases/2013/04/130426115614.htm
