Oxygen levels are dropping and ocean waters are acidifying at the
fastest rate in at least 300 million years when the greatest marine
extinction in earth's history took place according to
The State of the Ocean Report 2013 written by an international panel of marine scientists.
Today's explosive increase in human CO2 emissions and warming of the
oceans are recreating the conditions of the great Permian extinction 300
million years ago when massive volcanic eruptions in Siberia triggered
the release of enormous amounts of stored carbon. A leading theory is
that
deoxygenation
and acidification of the oceans led to the bacterial production of
toxic hydrogen sulfide gas which poisoned species dependent on oxygen.
By the end of this natural catastrophe 90% to 95% of all marine species
were extinct. The biodiversity of the oceans took 30 million years for
to recover.
The next mass extinction event may have already begun.
the scale and rate of the present day carbon perturbation,
and resulting ocean acidification, is unprecedented in Earth’s known
history. Today’s rate of carbon release, at approximately 30Gt of CO2
per year, is at least 10 times faster than that which preceded the
last major species extinction (the Paleocene Eocene Thermal Maximum
extinction, or PETM, ca. 55 million years ago), while geological records
indicate that the current acidification is unparalleled in at least the
last 300 million years. We are entering an unknown territory of marine
ecosystem change, and exposing organisms to intolerable evolutionary
pressure. The next mass extinction event may have already begun.
A "deadly trio” of acidification, warming and deoxygenation
~
Human CO2 emissions directly cause both global warming and ocean
acidification. But that's just the beginning. Mixing tends to decline in
warming waters because a warm fresh surface layer is substantially
lighter than colder middle and deep water.
The surface layer tends to float and not mix.
Organic carbon is always falling from the surface to deeper waters.
Bacteria oxidize the fallen carbon to CO2. This process reduces oxygen
levels and increases the acidity of the water. When the rate of mixing
declines the residence time of water in a layer increases, so acidity
levels tend to rise and oxygen levels drop in layers below the surface
as the climate warms.
Hypoxic - low oxygen - water may be already killing keystone species in the Pacific northwest.
COOS BAY — Something is killing large numbers of a keystone
species off the Oregon Coast. Federal researchers say it could spell
danger for the region’s other marine life.
Bill Peterson, an oceanographer with the National Oceanic and
Atmospheric Administration’s Hatfield Marine Science Center in Newport,
said in the past few weeks millions of dead North Pacific krill have
washed up on beaches between Newport and Eureka, Calif.
Peterson said it’s the largest die-off he’s aware of in recent history. ...
Joe Tyburczy, a researcher with the California Sea Grant extension
office who has been looking into the dead krill with Peterson, said
oceanographic cruises along the northern California coast did find lower
oxygen levels than usually seen in Pacific Northwest waters.
“If it is hypoxia, there’s a possibility of implications for other species like crab,” he said.
Acidification of sea water in Washington State oyster hatcheries killed the developing oysters.
Please watch this outstanding video on ocean acidification.
Oysters started dying by the billions along the Northwest coast in 2005,
and have been struggling ever since. When scientists cautiously linked
the deaths to plummeting ocean pH in 2008 and 2009, few outside the West
Coast’s $110 million industry believed it.
By the time scientists confirmed it early last year, the region’s
several hundred oyster growers had become a global harbinger — the first
tangible sign anywhere in the world that ocean acidification already
was walloping marine life and hurting people.
Richard Feely and a team of scientists from Pacific Marine Environmental
Lab were stunned to discover cold, acidic, low-oxygen water welling up
to the surface along the northern California coast in 2007. Scientists
had not expected acidification to hit the west coast for 50 to 100
years. Dr. Feely published his work and word of it reached oyster
farmers who's hatcheries were failing.
The oyster farmers invited Feely to their annual conference.
Feely explained that when north winds blew, deep ocean water was
drawn right to the beach, which meant this newly corrosive water
probably got sucked into the hatchery. That same water also flowed into
the Strait of Juan de Fuca and made its way to Hood Canal.
The oyster industry pleaded with Congress, which supplied money for
new equipment. Over several years, the hatcheries tested their water
using high-tech pH sensors. When the pH was low, it was very low and
baby oysters died within two days. By drawing water only when the pH was
normal, shellfish production got back on track.
“They told us it was like turning on headlights on a car — it was so clear what was going on,” Feely said.
Moreover, because processes in the ocean are slow to change this deadly
water would continue to affect the Pacific northwest for another 50
years if all human CO2 emissions stopped today. It will take 30 to 50
years for the most acidic water already present along the west coast to
well up. This is the beginning of a disaster that we cannot stop. The
best we can do is to keep it from growing far larger and far more
deadly. The changes happening in the waters of the Pacific northwest are
the first stages of a global marine catastrophe if CO2 emissions are
not rapidly reduced.
Deadly trio will have cascading consequences for marine biology & humans
It is the simultaneous occurrence of the “deadly trio” of
acidification, warming and deoxygenation that is seriously effecting how
productive and efficient the ocean is, as temperatures, chemistry,
surface stratification, nutrient and oxygen supply are all implicated,
meaning that many organisms will find themselves in unsuitable
environments.
These
impacts will have cascading consequences for marine biology, including
altered food web dynamics and the expansion of pathogens. To make
matters even worse, this is all happening to marine ecosystems already
undermined by other human pressures such as overfishing, eutrophication
and pollution.
The adaption of species to these altered conditions is in some cases
possible – as is migration, though as warming demands a poleward
migration while acidification encourages the movement to warmer more
equatorial waters the “green pastures” will become increasingly scarce
and competition for them fierce. Mass extinctions happen in the
geological equivalent of overnight; we may already have entered into an
extinction period and not yet realized it. What is certain is that
current carbon perturbations will have huge implications for humans, and
may well be the most important challenge faced since the first hominids
evolved.
Originally posted to Ocean Advocates on Fri Oct 04, 2013 at 05:41 AM PDT.
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