This conforms to the larger injection of warm waters into the Arctic
over the past forty years. This means a declining draw down of heat
in the near shore as the build up continues. Thus a warmer near
shore.
In the event, it is driving fish stocks northward in search of colder
waters.
At least the signal is robust and unequivocal. Of course it will be
labeled a result of global warming.
Again this all marks a shift of heat from the Southern Hemisphere
into the north Atlantic. It must be also noted that a minor
variation in the Circumpolar current is quite able to bring this all
about.
Conjecture: Is it possible that long term tidal variation drives
this cycle?
Sea Surface
Temperatures Reach Record Highs on Northeast Continental Shelf
by Staff Writers
Woods Hole MA (SPX) Sep 20, 2012
During
the first six months of 2012, sea surface temperatures in the
Northeast Shelf Large Marine Ecosystem were the highest
ever recorded, according to the latest Ecosystem Advisory issued by
NOAA's Northeast Fisheries Science Center (NEFSC).
Above-average
temperatures were found in all parts of the ecosystem, from the
ocean bottom to the sea surface and across the region, and the above
average temperatures extended beyond the shelf break front to the
Gulf Stream.
The
annual 2012 spring plankton bloom was intense, started earlier and
lasted longer than average. This has implications for marine life
from the smallest creatures to the largest marine mammals
like whales. Atlantic cod continued to shift northeastward from its
historic distribution center.
The Northeast US
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 from 1977 onward;
prior to 1977, this ecosystem was also monitored by the NEFSC through
a series of separate but coordinated programs dating back decades.
"A pronounced
warming event occurred on the Northeast Shelf this spring, and this
will have a profound impact throughout the ecosystem," said
Kevin Friedland, a scientist in the NEFSC's Ecosystem Assessment
Program.
"Changes
in ocean temperatures and the timing of the spring
plankton bloom could affect the biological clocks of many marine
species, which spawn at specific times of the year based on
environmental cues like water temperature."
Friedland said the
average sea surface temperature (SST) exceeded 10.5 degrees C (51F)
during the first half of 2012, exceeding the previous record high in
1951.
Average
SST has typically been lower than 9 degrees C (48F) over the past
three decades. Sea surface temperature in the region
is based on both contemporary satellite remote-sensing data and
long-term ship-board measurements, with historical SST conditions
based on ship-board measurements dating back to 1854.
In some nearshore
locations like Delaware and Chesapeake Bays in the Middle Atlantic
Bight region, temperatures were more than 6 degrees C (11F) above
historical average at the surface and more than 5 degrees C (9F)
above average at the bottom.
In deeper offshore
waters to the north, bottom waters were 1 degree C (2F) warmer in the
eastern Gulf of Maine and greater than 2 degrees C (3.6F) warmer in
the western Gulf of Maine.
Ocean bottom
temperature data cited in the advisory came from a variety of
sources, including eMOLT, a cooperative research program between the
Northeast Fisheries Science Center and lobstermen who deploy
temperature probes attached to lobster traps.
While some of the
temperature probes from the eMOLT program are still in the water and
have not yet been returned, those that have been returned indicate
that bottom water temperatures in 2012 were the warmest since the
eMOLT program began in 2001.
Atlantic
cod distribution in the Gulf of Maine continues a northeasterly
shift, with the spring 2012 data consistent with a response to
ecosystem warming. Warming ocean temperatures and the
resulting impact on the distribution of 36 fish stocks was reported
by the Center in a 2009 study published in Marine Ecology Progress
Series.
That study analyzed
annual NEFSC spring survey data from 1968 to 2007 and other
information and found that 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,
with some disappearing from US waters as they move farther offshore.
Friedland
notes that although cod didn't shift as much as other species like
hake in the 2009 study, the effects of warming water on ocean
currents and other ocean circulation patterns could
change that.
"Cod distribution
continues to be dynamic, with northerly shifts detected in the spring
2012 data, consistent with a response to ecosystem warming,"
Friedland said. "The big question is whether or not these
changes will continue, or are they a short-term anomaly?"
Mike Fogarty, who
heads the Ecosystem Assessment Program, says the abundance of cod and
other finfish 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.
"A
complex combination of factors influence ocean conditions,
and 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 from a variety of sources collected over a long period of
time on the ecosystem, and are continually adding more data to
clarify specific details. The data clearly show a relationship
between all of these factors."
The 2012 spring
plankton bloom, one of the longest duration and most intense in
recent history, started at the earliest date recorded since the ocean
color remote sensing data series began in 1998.
In some locations, the
spring bloom began in February, and was fully developed by March in
all areas except Georges Bank, which had an average although variable
spring bloom. The 2012 spring bloom in the Gulf of Maine began in
early March, the earliest recorded bloom in that area.
"What this early
start means for the Northeast Shelf ecosystem and its marine life is
unknown," Fogarty said. "What is known is that things are
changing, and we need to continue monitoring and adapting to these
changes."
Intensive surveys of
environmental conditions on the Northeast Shelf from Cape Hatteras,
North Carolina to Nova Scotia were conducted from 1977 to 1987 as
part of the Marine Resources Monitoring, Assessment and Prediction
(MARMAP) program. The efforts continued at reduced levels through the
1990s and are ongoing today as part of the Center's Ecosystems
Monitoring (EcoMon) program.
Plankton samples are
collected six times a year in each of the four subareas of the
Northeast Shelf: the Middle Atlantic Bight, Southern New England,
Georges Bank, and the Gulf of Maine.
EcoMon scientists also
collect water samples and other oceanographic data about conditions
during each season in each of the four areas to provide a long-term
view of changing conditions on the Shelf.
The Spring 2012
Ecosystem Advisory with supporting information is available online.
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