Energy and global warming news for December 24: Growing hypoxic zones reduce fish habitats; Ocean acidification may disrupt the marine nitrogen cycle

One traditional Christmas Eve dinner is fish….

NOAA, Partners: Growing Hypoxic Zones Reduce Habitat for Billfish and Tuna, which could increase vulnerability to fishing

Billfish and tuna, important commercial and recreational fish species, may be more vulnerable to fishing pressure because of shrinking habitat according to a new study published by scientists from NOAA, The Billfish Foundation, and University of Miami Rosenstiel School of Marine and Atmospheric Science.

An expanding zone of low oxygen, known as a hypoxic zone, in the Atlantic Ocean is encroaching upon these species’ preferred oxygen-abundant habitat, forcing them into shallower waters where they are more likely to be caught.

During the study, published recently in the journal Fisheries Oceanography, scientists tagged 79 sailfish and blue marlin with satellite tracking devices in the western North Atlantic, off south Florida and the Caribbean; and eastern tropical Atlantic, off the coast of West Africa. The pop off archival satellite tags monitored horizontal and vertical movement patterns. Researchers confirmed that billfish prefer oxygen rich waters closer to the surface and will actively avoid waters low in oxygen.

While these hypoxic zones occur naturally in many areas of the world’s tropical and equatorial oceans, scientists are concerned because these zones are expanding and occurring closer to the sea surface, and are expected to continue to grow as sea temperatures rise.

“The hypoxic zone off West Africa, which covers virtually all the equatorial waters in the Atlantic Ocean, is roughly the size of the continental United States, and it’s growing,” said Dr. Eric D. Prince, NOAA’s Fisheries Service research fishery biologist. “With the current cycle of climate change and accelerated global warming, we expect the size of this zone to increase, further reducing the available habitat for these fish.”

Less available habitat can lead to more fish being caught since the fish are concentrated near the surface. Higher catch rates from these areas may give the false appearance of more abundant fish stocks. The shrinking availability of habitat and resulting increases to catch rates are important factors for scientists to consider when doing population assessments.

Researchers forecast that climate change and its associated rise in ocean temperatures will further increase the expansion of hypoxic zones in the world’s oceans. As water temperature increases, the amount of oxygen dissolved in water decreases, further squeezing billfish into dwindling available habitat and exposing them to even higher levels of exploitation.

Ocean acidification may disrupt the marine nitrogen cycle

Ocean acidification, the result of roughly a third of global CO2 emissions dissolving into the seawater and lowering its pH, has complicated and poorly understood consequences for ocean ecosystems. Scientists already know that a drop in ocean pH affects the carbon cycle, reducing the carbonate ions that organisms like corals, mollusks and crustaceans use to build shells and external skeletons. Now, a new study shows that a CO2-induced increase in acidity also appears to disrupt the marine nitrogen cycle. The finding, to be published December 21 in the Proceedings of the National Academy of Sciences, could have ramifications for the entire ocean food web.

The authors of the study examined a specific step in the marine nitrogen cycle, called nitrification, in which microorganisms convert one form of nitrogen, ammonium, into nitrate, a form plants and other marine microorganisms require to survive. Previous research studies on experimentally acidified freshwater and in the laboratory have suggested that reduced pH slows nitrification, and one study in coastal ocean waters showed that large pH decreases did the same. But no one had tried to experimentally simulate the more subtle pH changes predicted to occur in oceans due to the increase in atmospheric CO2 expected over the next 20-30 years, says lead author J. Michael Beman, a professor of oceanography and biogeochemistry at the University of California Merced.

Beman and his colleagues collected samples (six in total) from four separate ocean research locations in the Atlantic and Pacific Oceans, and induced pH decreases ranging from 0.05 to 0.14 in the experimental samples””either by bubbling CO2 through the bottles or adding dilute acid. The experimental nitrification rates were then compared to those in the controls. In the bottles to which CO2 was added, explains Beman, “basically, we exposed them to the future atmosphere in terms of CO2 composition.” The group treated some samples with acid “to make sure the effect we were observing wasn’t driven by experimental approaches.”

Nitrification decreased, compared to controls, in all experimental cases, with the effect ranging from an 8 percent reduction to a 38 percent reduction. “What we saw is almost uniform across the ocean, or at least in all the experiments we conducted, which seems to suggest this is fairly consistent effect,” says Beman. Importantly, in some cases the change was quite large. “So it could have a pretty substantial effect on how nitrogen is cycled in the ocean,” he says.

One potentially positive effect would be a reduction of nitrous oxide””marine nitrification is a relatively big source of this greenhouse gas. “But the larger, much more difficult things to predict are the connections to other organisms and processes,” says Beman. Less nitrification would make fewer nitrates available to the plants and other organisms that use them to make vital proteins, making it more difficult for them to thrive. This in turn means less food would be available to the animals that eat those nitrate-using organisms, and so on up the food web. But the food web is complex, and the precise implications of the study’s results are still unclear, he says.

20 Responses to Energy and global warming news for December 24: Growing hypoxic zones reduce fish habitats; Ocean acidification may disrupt the marine nitrogen cycle

  1. Prokaryotes says:

    French flights snarled by winter weather
    Heavy snow forces evacuation of Charles de Gaulle terminal

    Californians start cleaning up mud, water, debris

    Many California residents who endured flooding, mudslides and evacuations during a weeklong onslaught of rain must now clean up or even rebuild — and some face the prospect of not being able to spend Christmas at home.

    The storm’s push across the West left a muddy mess Thursday across Southern California and the threat of avalanches in Nevada, where Clark County officials urged residents of Mount Charleston, near Las Vegas, to leave after snow slides near two mountain hamlets.

    Preliminary damage estimates throughout California were already in the tens of millions of dollars and expected to rise. A state of emergency was declared in a total of nine counties, including Los Angeles, Orange and Santa Barbara.

    The inland region of Southern California east of Los Angeles emerged as among the hardest hit, especially San Bernardino County.

  2. Paulm says:

    Great quote…for many this year was utter devastation.

    Snow paralyses transport in parts of Western Europe

    “Professionally speaking, the airport should be prepared for this. It’s not the Second Coming.”

  3. fj3 says:

    Not being known the complete life-giving environmental services that the world’s oceans provide it is imperative that immediate restoration has the highest priority; i.e., along with dramatic reductions in emissions; also, since the oceans are great natural sequestering systems which now require some sort of human intervention for maintenance and regeneration.

  4. Prokaryotes says:

    Scientists say extreme winter a result of climate change

  5. Prokaryotes says:

    New research digs beneath Dead Sea for climate change history

    In an unprecedented research, an international team of scientists has been digging deep beneath the Dead Sea to collect a record of climate change and earthquake history stretching back half a million years. Under this unique project, led by Prof Zvi Ben-Avraham of Tel Aviv University’s (TAU)
    Minerva Dead Sea Research Center, the team will dig deep beneath the Dead Sea, 500 meters down under 300 meters of water. At 423 meters below sea level, the Dead Sea is the lowest place on earth which attracts millions of tourists from around the world to enjoy its legendary healing properties.

    “The study aims to get a complete record in unprecedented resolution — at one year intervals — of the last five hundred thousand years,” said Prof Ben-Avraham. Looking at the core sample to be dug about five miles offshore near Ein Gedi, the researchers hope to pinpoint particular years in Earth history to discover the planet’s condition. They will be able to see what the climate was like 365,250 years ago, for instance, or determine the year of a catastrophic earthquake, a TAU release said, describing the 40 day project as the largest ever Earth sciences study of its kind in Israel.

    The evidence, according to the university, will help the world’s climatologists calibrate what they know about climate change from other geological samples and may lead to better predictions of what’s in store for Middle East weather.

  6. Prokaryotes says:

    Hundreds of Christmas flights canceled, as storm threatens East Coast

    Big freeze strands travellers across Europe
    Heavy snowfalls and freezing temperatures across Europe and the United Kingdom are causing Christmas heartache for thousands of stranded travellers.

  7. Esop says:

    To illustrate how warm parts of the Arctic is right now, here is the 8 day forecast for Bjørnøya (Spitsbergen), at 74.5 deg latitude:
    Forecast for December 29th is +2C and rain. No wonder the sea ice is melting up there.
    Again, that is at 74.5 degrees latitude and we are in late December. The sun does not rise above the horizon up there now, darkness 24-7.
    I’m curious if sun spotters like Piers Corbyn have any comments or forecasts for the high Arctic.

  8. Paulm says:

    Papers coming round???

    Global warming ‘will give Britain longer, colder winters’ as melting sea ice plays havoc with weather patterns

  9. Paulm says:

    Snow closes ski resort…..

    Meanwhile, heavy precipitation at Mount Washington proved more than the resort could handle.

    The resort is digging out from the 2.5 metres of snow it has received since Monday has broken a record for a four-day snowfall.

    That meant delays with all lifts on Friday. “It is unbelievable — I’ve never seen anything like it,” said resort spokesman Brent Curtain.

  10. Rabid Doomsayer says:
    How Hard Are We Pushing The Land?

    Just another clue that we could be in more than a little trouble this century

  11. PAUL DONOHUE says:

    I wonder why NOAA’s global November report is so late? My suspicious mind wonders what would they say if they found evidence for the Gulf Stream slowing? It would cause panic.

  12. Wyoming says:

    Paul (#11)

    DO you mean this? ( Dec 8th.

    Or do you mean this? ( from Dec 12th.


  13. PAUL DONOHUE says:

    I mean the first one. Normally the NCDC.NOAA global analysis come out on about the 14th. I have seen the National for November and the NASA global data but not the NOAA global report.

  14. Anonymous says:

    Christmas weekend storm could dump 5 inches on Baltimore region

    Last-minute shift in weather models means more than we thought,0,1878736.story

  15. Colorado Bob says:

    PAUL –
    I was wondering the same thing.

  16. Edward says:

    14 Paulm: That link leads to Al Gore which lead to gets re-directed to
    How do I get to

  17. gallopingcamel says:

    Every year there is a hypoxic zone in the Gulf of Mexico and it is growing year on year.

    Apparently the growing of corn for ethanol requires more fertilizer than the crops replaced and the increasing run off is depleting the dissolved oxygen in the Gulf.

  18. Prokaryotes says:

    November 2010 1st or 2nd warmest on record; ZombieSat saga ends
    November 2010 Arctic sea ice extent 2nd lowest on record
    Major atmospheric pattern shift coming