Free Newsletters - Space - Defense - Environment - Energy - Solar - Nuclear
..
. 24/7 Space News .




WATER WORLD
Changing Sea Temps and Water Circulation Affecting Food Supply Of Atlantic Cod
by Staff Writers
Woods Hole MA (SPX) Jun 24, 2013


Eight boxes represent index areas for long-term sea surface temperature (SST) trends for the Northeast Shelf ecosystem; annual mean, minimum, and maximum SST for the period 1854-2011 was calculated for the index area. The grey shaded area of the Northeast Shelf was used in the calculation of thermal habitat distribution for the ecosystem. Credit: Kevin Friedland, NEFSC/NOAA.

Changing ocean water temperatures and circulation patterns have profoundly affected key Northeast U.S. Continental Shelf zooplankton species in recent decades, and may be influencing the recovery of Atlantic cod and other fish stocks in the region.

NOAA researcher Kevin Friedland and colleagues looked at the distribution and abundance of important zooplankton species, sea surface water temperatures, and cod abundance. They found that zooplankton species critical for the survival of Atlantic cod larvae have declined in abundance in the same areas where Atlantic cod stocks have struggled to rebuild after an extended period of overfishing.

"Temperature is a governing factor in the growth, reproduction and distribution of marine organisms. Shifting temperature distributions, whether triggered by natural or human factors, can cause the redistribution of plankton communities on regional and basin-wide scales," said Friedland, lead author on the study and a scientist at NOAA's Northeast Fisheries Science Center (NEFSC).

The change in thermal habitats has had biological consequences on multiple levels in the food chain, according to the study in press in the journal Progress in Oceanography (available online).

"The geographic and depth distributions of fish and shellfish populations can also change based on their preferred thermal habitats. Future changes in thermal conditions are expected to lead to further shifts in the distributional ranges of species by, in many cases, the loss and gain of local populations," said Friedland.

Friedland and his colleagues found that ocean water temperatures of the Northeast Continental Shelf have increased in recent decades, but these changes have not been uniform over the entire ecosystem. Warm water habitats (16 to 27 C, 60 to 80 F) have increased and cool water habitats (5 to 15 C, 41 to 59 F), historically the core habitats in the ecosystem, have declined; however, the coldest habitats in the ecosystem (1-4 C, 34-39 F) have either stayed the same or increased slightly during the study period 1982-2011. This discontinuity is attributed to changes in circulation in the northern Gulf of Maine associated with the Labrador Current.

Atlantic cod off the Northeast U.S. are managed as two stock units, the more northerly in the Gulf of Maine and the more southerly on and around Georges Bank. There are upward of ten known spawning populations within these two stocks, and the very young fish that they produce are found in specific larval development areas. Two zooplankton species that serve as food for Atlantic cod (Gadus morhua) larvae are Pseudocalanus spp, and Centropages typicus. The former is associated with winter-spawning cod, and the latter with spring-spawning cod.

The researchers developed indices of zooplankton and cod abundance in six index areas, relating larval feeding and development areas to associated areas where adults reside. They found that Pseudocalanus spp has declined in abundance on parts of Georges Bank and in the eastern Gulf of Maine, areas where cod have been less abundant in recent years. Centropages typicus declined in abundance in the eastern Gulf of Maine as well. The areas where these zooplankton species have declined are spatially discrete and are related to the change in core thermal habitat of the ecosystem.

The abundance of zooplankton species is measured by the NEFSC's Ecosystem Monitoring Program (EcoMon), which conducts shelf-wide bimonthly surveys of the ecosystem. Data and observations from the NEFSC's spring bottom trawl surveys were also analyzed.

Although the researchers concentrated on Atlantic cod recruitment success and population trends, many of the zooplankton species examined are important as prey for early life stages of other fish species and marine mammals. These zooplankton species are important within the Northeast Shelf ecosystem, and can serve as model organisms to test the effect of thermal habitat on changes within the food web.

An Ecosystem Advisory issued by the NEFSC on April 25, 2013 provides additional information related to the Northeast Shelf ecosystem, notably a description of the extreme warming that occurred on the Shelf during 2012 and the associated shifts in thermal habitat.

.


Related Links
Northeast Fisheries Science Center
Water News - Science, Technology and Politics






Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle




Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News





WATER WORLD
Iceland P.M. cites EU fishing dispute as case for independence
Reykjavik, Iceland (UPI) Jun 19, 2013
Iceland's new prime minister this week cited the country's mackerel fishing dispute with the European Union as a prime example of the value of sovereignty. Sigmundur David Gunnlaugsson, speaking to Reykjavik crowd Monday during the Iceland's National Day marking its birth as an independent nation in 1944, said the EU's demands that Iceland reduce its mackerel catch shows why the country ... read more


WATER WORLD
Scientists use gravity, topographic data to find unmapped moon craters

Australian team maps Moon's hidden craters

LADEE Arrives at Wallops for Moon Mission

NASA's GRAIL Mission Solves Mystery of Moon's Surface Gravity

WATER WORLD
Billion-Pixel View of Mars Comes From Curiosity Rover

Study: Mars may have had ancient oxygen-rich atmosphere

Opportunity Recovers From Another Flash-Related Reset

ExoMars 2016 Set To Complete Construction

WATER WORLD
NASA Bill Would 'End Reliance on Russia,' Nix Asteroid Capture Project

Britain shut down UFO desk after finding no threat: files

New Zealand emerges as guinea pig for global tech firms

NASA announces eight new astronauts, half are women

WATER WORLD
Chinese astronauts manually dock spacecraft

China astronaut teaches lesson from space

China's space program less costly

China seeks to boost share of satellite market

WATER WORLD
Accelerating ISS Science With Upgraded Payload Operations Integration Center

Strange Flames on the ISS

Europe's space truck docks with ISS

Russian cargo supply craft separates from International Space Station

WATER WORLD
Four O3b Network birds integrated to Arianespace Soyuz launcher

Arianespace will retain its market leadership by building on the company's flexibility and agility

Plan for modified European rocket gets backing

Peru launches first homemade rocket

WATER WORLD
NASA's Hubble Uncovers Evidence of Farthest Planet Forming From its Star

Exoplanet formation surprise

Sunny Super-Earth?

Kepler Stars and Planets are Bigger than Previously Thought

WATER WORLD
Noble gases hitch a ride on hydrous minerals

'Chemical architects' build materials with potential applications in drug delivery and gas storage

Researchers Propose New Method for Achieving Nonlinear Optical Effects

Unexpected behavior of well-known catalysts




The content herein, unless otherwise known to be public domain, are Copyright 1995-2014 - Space Media Network. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA Portal Reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement