Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Climate events linked to reproduction of one of the most endangered marine mammals

20.11.2003


The highly endangered North Atlantic right whale population is facing a difficult journey to recovery. That recovery may become even more precarious if North Atlantic climate takes a turn for the worse, according to Cornell University ecologists.

Cornell scientists say that winter atmospheric conditions over the North Atlantic affect the abundance of zooplankton eaten by right whales, one of the most endangered species of marine mammal. New models developed by these scientists can be used to explain the relationships among climate changes, atmospheric temperatures and winds; patterns in ocean currents, water temperature and salinity; the food resources required by whales and other animals; and the reproductive success of right whales.

Details of the whale-climate studies are reported by Charles H. Greene and Andrew J. Pershing, of the Cornell Ocean Resources and Ecosystems Program, in an article entitled "Impact of Climate Variability on the Recovery of Endangered North Atlantic Right Whales" to appear in the December 2003 issue of Oceanography. Other authors of Oceanography paper are Robert D. Kenney of the University of Rhode Island and Jack W. Jossi of the National Marine Fisheries Service (NMFS). A second article, "Climate and the Conservation Biology of North Atlantic Right Whales: Being a Right Whale at the Wrong Time?" will be published in the February 2004 issue of the journal, Frontiers in Ecology and the Environment .



As Pershing explains: "Only about 300 North Atlantic right whales remain, and their reproductive health depends on finding enough food. Starting in late winter, right whales make their way to the Gulf of Maine, where they feed on high-density patches of copepods (free-floating crustaceans roughly the size of rice grains), and just like New England weather, the physical conditions in the Gulf of Maine can be highly variable." An earlier study by Pershing and Greene found that temperatures in the deep waters of the Gulf of Maine are closely linked to changes in ocean currents driven by winter atmospheric conditions in the North Atlantic during the previous year. With an additional time lag, the abundance of the common copepod species, Calanus finmarchicus , tracks these ocean temperature fluctuations. From these relationships, Pershing and Greene were able to develop a computer model to predict the number of right whale births from the observed number of Calanus and then relate these predictions to changes in North Atlantic climate.

"An important indicator of winter atmospheric conditions over the North Atlantic is the North Atlantic Oscillation (NAO), which is related to the average position of the jet stream over the Atlantic," Pershing explains. "When the NAO is in its ’positive’ state, conditions over the Labrador Sea in the northwest Atlantic are colder and stormier, while the northeast Atlantic and northern Europe experience warmer and milder weather. When the NAO is in its ’negative’ state, the conditions reverse. After a winter of positive NAO conditions, the deep waters in the Gulf of Maine typically become warmer and saltier -- leading to higher abundances of zooplankton. After negative NAO conditions, the waters become colder and fresher -- not as hospitable for the food that whales need to eat."

For example, Pershing and Greene report right whales suffered through two years of physiological stress and poor reproduction in 1999 and 2000, a setback that can be traced to a dramatic negative "flip" in the NAO in 1996 and a subsequent decline in copepod abundance in 1998. Then a sudden return of the NAO to positive conditions from 1997 to 2000 led to a 10-fold boom in copepod populations. Consequently, the northern right whales produced more calves in 2001 than at any time since records began in 1980.

During the 1980s, the NAO was predominantly positive, leading to warm conditions in the Gulf of Maine as well as plenty of Calanus and stable feeding conditions for the whales. After 1990, the NAO became more variable, causing water temperatures and Calanus populations in the Gulf of Maine to fluctuate. At the same time, the number of right whale births became highly variable, ranging from 22 births in 1996 to only a single birth in 2000, according to aerial surveys over calving grounds and feeding areas. (To determine the density of zooplankton food resources such as copepods, Greene and Pershing have relied on Continuous Plankton Recorder data collected by NMFS for nearly half a century.)

The Cornell scientists are still pondering all of the interacting factors in whale reproduction. Right whale physiology requires at least three years between births (a full year of lactation after the previous birth, another year to eat heartily -- if they can -- and amass fat stores for the next pregnancy, then a yearlong gestation), Pershing observes. "We think we’re seeing a one- to two-year time lag until poor feeding conditions take effect, as well as a slightly longer time lag from when changes in the NAO occur to when they have their effect on copepod abundance," Green says, "and that gives us some confidence in predicting whale births a year or more in advance."

Longer-term predictions of the right whales’ fate would be easier in an era of unchanging climate -- which is rarely the case, especially in recent years. "Rather, we could be heading into a period of increased climate variability as a result of continually rising greenhouse gas concentrations," Greene says. And 1996, when the NAO flipped even as right whales were enjoying a banner birth year, "could have been an unusual event -- or a sign of the larger swings in climate that we might expect in the future."

Development of the computer model by the Cornell ecologists was funded by the Northeast Consortium’s Right Whale Program. Right whales were so named by 18th and 19th century whalers because they were the "correct species" to hunt for their monetary value, slow swimming speed, and tendency to float after being harpooned. Nearly exterminated by uncontrolled hunting, right whales have been protected by international treaties since 1946.

Roger Segelken | Cornell News
Further information:
http://www.news.cornell.edu/releases/Nov03/whale_weather2.hrs.html
http://www.osp.cornell.edu/VPR/CenterDir/OREP.html
http://www.NortheastConsortium.org/

More articles from Ecology, The Environment and Conservation:

nachricht Dispersal of Fish Eggs by Water Birds – Just a Myth?
19.02.2018 | Universität Basel

nachricht Removing fossil fuel subsidies will not reduce CO2 emissions as much as hoped
08.02.2018 | International Institute for Applied Systems Analysis (IIASA)

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Writing and deleting magnets with lasers

Study published in the journal ACS Applied Materials & Interfaces is the outcome of an international effort that included teams from Dresden and Berlin in Germany, and the US.

Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia...

Im Focus: Gamma-ray flashes from plasma filaments

Novel highly efficient and brilliant gamma-ray source: Based on model calculations, physicists of the Max PIanck Institute for Nuclear Physics in Heidelberg propose a novel method for an efficient high-brilliance gamma-ray source. A giant collimated gamma-ray pulse is generated from the interaction of a dense ultra-relativistic electron beam with a thin solid conductor. Energetic gamma-rays are copiously produced as the electron beam splits into filaments while propagating across the conductor. The resulting gamma-ray energy and flux enable novel experiments in nuclear and fundamental physics.

The typical wavelength of light interacting with an object of the microcosm scales with the size of this object. For atoms, this ranges from visible light to...

Im Focus: Basel researchers succeed in cultivating cartilage from stem cells

Stable joint cartilage can be produced from adult stem cells originating from bone marrow. This is made possible by inducing specific molecular processes occurring during embryonic cartilage formation, as researchers from the University and University Hospital of Basel report in the scientific journal PNAS.

Certain mesenchymal stem/stromal cells from the bone marrow of adults are considered extremely promising for skeletal tissue regeneration. These adult stem...

Im Focus: Like a wedge in a hinge

Researchers lay groundwork to tailor drugs for new targets in cancer therapy

In the fight against cancer, scientists are developing new drugs to hit tumor cells at so far unused weak points. Such a “sore spot” is the protein complex...

Im Focus: The Future of Ultrafast Solid-State Physics

In an article that appears in the journal “Review of Modern Physics”, researchers at the Laboratory for Attosecond Physics (LAP) assess the current state of the field of ultrafast physics and consider its implications for future technologies.

Physicists can now control light in both time and space with hitherto unimagined precision. This is particularly true for the ability to generate ultrashort...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

IWOLIA: A conference bringing together German Industrie 4.0 and French Industrie du Futur

09.04.2018 | Event News

 
Latest News

Diamond-like carbon is formed differently to what was believed -- machine learning enables development of new model

19.04.2018 | Materials Sciences

Electromagnetic wizardry: Wireless power transfer enhanced by backward signal

19.04.2018 | Physics and Astronomy

Ultrafast electron oscillation and dephasing monitored by attosecond light source

19.04.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>