Public Enemy #1 in SF Bay: Mercury in Fish

[caption id="attachment_4304" align="alignleft" width="300" caption="San Francisco Bay"][/caption]

GHN News —Scientists tell us that the worst contamination of San Francisco Bay is mercury in the fish.  This is, they say a major environmental disaster, and refer to it as a serious enemy to the waters of the area.

Mining in the area during the 19th and 20th centuries combined with pollution of oil refineries along with chemical and waste water treatment plants are said to be responsible for the mercury that threaten wildlife and fish consumption.

Indeed mercury is going into the food web, according to scientists.

" Joel Blum, who is the John
D. MacArthur Professor of Geological Sciences and a professor of ecology
at U-M, said "This is the first study to track mercury directly from source
to sediment to food web."

The same way the problems have been studied for San Francisco Bay can be utilized for studies elsewhere, scientists believe. Gretchen Gehrke, the paper's lead author, maintains
"Mercury contamination is a problem in areas all over the world, and
most of those places have multiple possible mercury sources. There's a
lot of interest in figuring out which sources are contributing the
mercury that most readily gets into the food web and creates
environmental and health risks."

The findings appear in two companion papers, one in the Feb. 1 issue of the journal Geochemica et Cosmochimica Acta and the other published online Jan. 21 in Environmental Science & Technology.

Health problems from too much mercury in the food supply include damage to the central nervous system, heart and
immune system, as well as infant developing brains.. The developing brains of young and unborn children are
especially vulnerable.

It is the hope of the researchers in this study that their results will help agencies determine how to protect wildlife from mercury exposure and from it therefore entering the food supply.

Reliability of research on fishing declines questioned by U of Wresearchers

GHN News Editor - How
reliable is the present research on the status of fishing and the
balance in ecosystems in the ocean relative to fish?  New science
studies tell us that half of it may be faulty.


In
1998 a landmark study was done looking at how various fish along the
food chain were dropping off in supply because of certain fish that
don't respond well to various climate conditions.  How different
predators responded was said to be affected by these ecological changes.

Scientists
tell us that conclusions made about how we are "fishing down the food
chain" is considerably different, given new information and evaluations
of organisms.  S;o the 1998 research on the health of world fisheries is
faulty given the information presently found. 

The
chief author of this new research Trevor Branch points out that
following the declines in the 1970's of the average trophic levels of
fish being caught, there has been distinct changes, with catches
actually increasing since the mid 1980's that include even the
high-tropic predadtors such as blue thing, bigeye tun, and skipjack
tuna.

"Globally
we're catching more of just about everything," Branch said. "Therefore
relying on changes in the average trophic level of fish being caught
won't tell us when fishing is sustainable or if it is leading to
collapse." That's because when harvests of everything increase about
equally, the average trophic level of what is caught remains steady. The
same is true if everything is overfished to collapse. Both scenarios
were modeled as part of the Nature analysis."


Predicting
the fishing capacity of the oceans, and the rise and fall of systems,
is a difficult process with changes made according to new information
discovered, so that what was learned in 1998, and even today, may change

with increased research.

Acidic oceans killing fish

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 Editor - Ocean creatures are  facing a crisis as temperatures rise and man continues activities that cause greenhouse emissions and pollute the waters, creating acidic conditions in the water that are killing fish.


What is happening is there are now lower oxygen and higher carbon dioxide levels in coastal water bodies.
These increased levels of carbon dioxide causes the waters to be more
acidic.  This in turn impacts the creatures that live in these waters.



Scientists say that if steps are not taken to reduce greenhouse emissions and minimize run-off from
factories, oil drilling and human waste, things will get worse.

The
ocean is filled with a soup of bacteria and viruses. The animals living
in these environments are constantly being bombarded by pathogens.
They can become infected and die.

Louis
Burnett, professor of biology and director of the Grice Marine
Laboratory of the College of Charleston, and Karen Burnett, research
associate professor at Grice Marine Laboratory of the College of
Charleston,  have been studying the rise in ocean acidity and have found
organisms in these conditions can't fight off infections as well as
animals living in oxygen rich, low carbon dixodie environments.

This study is one of a number that was scheduled at the Global Change and Global Science: Comparative Physiology in a Changing World
conference from August 4-7, 2010 in Westminster, Colorado. This
conference was in part sponsored by the 

The researchers looked specifically at fish, oysters, crabs and shrimp,
finding these animals have a decreased ability to fight off infection.
They have found it only takes about half as much bacteria to administer a
lethal dose to a creature in a low oxygen, high carbon dioxide
environmen

"Our approach is exciting because traditionally physiologists haven't
considered bacteria or disease as a natural environmental barrier, so
it's a pretty open field," says Louis Burnett.

Marine
animals have been found in research to lose blood cells within minutes
when invaded by a pathogen. The scientists see evidence that sea animals
fighting off infection lower their metabolism, which slows down other
important processes like making new proteins.

In acidic conditions it takes less time for these animals to get sick.

Burnett says, " It's alarming that
deep-water animals may be much more affected by ocean acidification,
since they are not used to the ebb and flow of oxygen and carbon dioxide
levels."

"Some
of the models for how the coastal organisms adapt may help researchers
predict how deep water organisms are going to be affected by overall
climate change too," says Louis Burnett.