Coastal “Dead Zones”: Area Affected Doubles Every 10 Years August 15, 2008

Although the Dead Zone* in the Gulf of Mexico tends to receive the most publicity in the US, there are an increasing number of dead zones around the world and the area covered by dead zones is doubling about every ten years (reported in NY Times, original study in Science).

As reported by Bina Venkataraman in the New York Times, 

“What’s happened in the last 40, 50 years is that human activity has made the water quality conditions worse,” the study’s leader author, Robert J. Diaz, said in an interview.

The trend portends nothing good for many fisheries, said Dr. Diaz, a professor at the Virginia Institute of Marine Science at the College of William and Mary. “Dead zones,” he said, “tend to occur in areas that are historically prime fishing grounds.”

Indeed, while the size of dead zones is small relative to the total surface of the oceans, scientists say they account for a significant part of ocean waters that support commercial fish and shellfish species.

The authors of the study conclude their report in Science with this observation:

Currently, hypoxia and anoxia are among the most widespread deleterious anthropogenic influences on estuarine and marine environments, and now rank with overfishing, habitat loss, and harmful algal blooms as major global environmental problems.  There is no other variable of such ecological importance to coastal marine ecosystems that has changed so drastically over such a short time as DO [dissolved oxygen].

The major cause of dead zones is the flow of too many nutrients down our rivers and out into coastal waters.  These nutrients come from agriculture (fertilizers), animal waste (from raising cows, pigs, poultry, etc.), and also from sewer overflows, air pollution, and other smaller contributors.  The entry of these nutrients into the rivers is made easier when wetlands and other riverside vegetation systems are destroyed for farmland or for other development. 

Better management of crop fertilization, manure disposal, and the requirement of ‘buffer zones’ of nutrient-absorbing vegetation and soil can all help lessen the problem of nutrient pollution (eutrophication) of our rivers and coastal zones.  Because the pollution often takes place across state and even national boundaries, this problem needs to be managed, and managed responsibly, at the highest levels.

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*A dead zone is a low-oxygen area in the ocean; the term tends to refer to areas where this low-oxygen (hypoxic) area is persistent in time, often leading to the death of sedentary and sessile organisms and attempts by mobile species to leave the area.

In the news: Baby penguins dying, Archbishop Tutu speaks on Global Warning July 20, 2008

• Baby penguins are washing up dead on the shores of Brazil.  Penguin experts interviewed feel pretty confident that somehow humans caused this.  Probably yes, but actually no one knows the reason(s) yet.  If it is climate change, and now there are dying penguins and polar bears, I predict a solution to greenhouse gas emissinos by next week.  [Washington Post]
• There is concensus that humans are messing up the salmon populations, especially in California.  The issue is complex but basically Northern California is exporting water, from rivers, where salmon reproduce.  Then lots of the young die, and the salmon populations are drastically reduced (the salmon season was cancelled this spring due to such low numbers).  There was a recent legal victory for the salmon (and their human lawyers), but no real changes will result immediately due to the decision.   [LA Times]
• High oil prices mean consumers are turning to coal.  Crap.  That is also polluting.  But cheap!  But polluting.  Also, most cars don’t run on coal.  [LA Times]
• I hate baseball.  Hold a little home-town love for the Mariners, but that is about it.  But I have to give kudos to the efforts of MLB and all others involved for taking the lead on helping sports go green.  [Washington Post]
• Police budgets are not rising as rapidly as gas prices, so more police officers are having to get out of their cars.  This actually is probably a good thing, for the most part, because if you watched The Wire you totally know that cops on the street have a much better feel for the community.  As long as they can still use the car for emergencies.  [NY Times]
• Archbishop Emeritus Desmond Tutu castigates the rich white-collar workers who fly around the world for business trips that could easily be accomplished by phone or video-conference.  Practices like these accelerate global warming and that affects the poor more than the rich.  BTW, phone calls and video-conferences also save money, so stock-holders might want to point that out at the next meeting.  [Reuters]

Enjoy the rest of your weekend.  Go outside for a while.

Sharks. Not Too Many Of ‘Em Left. July 18, 2008

In a well-researched and well-written summary of recent scientific work on shark population trends, Juliet Eilperin writes in the Washington Post about the world-wide decline of sharks.  Although the average person might think of sharks more in terms of a potential nightmare at the beach, or a mesmerizing creature to watch in an aquarium, sharks play an important role in many marine ecosystems.  However, there isn’t a lot of long-term ‘official’ data about shark populations, because in the past most people tried to avoid them rather than study them or eat them.  What is particularly interesting about the new studies coming out, on sharks and on other wildlife, is that scientists are looking for data in unexpected places, like libraries and museums and knowledge of multi-generational fishing families. 

By the way, if you want to minimize your chances of getting bitten by a shark without giving up ocean swims, one of the simplest rules is to avoid wading and swimming at dawn and at dusk.  This is when sharks tend to feed on smaller fish, often in the surf zone, and your ankles or thighs or arms could be accidentally chomped.  If you do get bitten by a shark, or see someone attacked, beat the shark on the gill openings, eyes or tip of the nose to get it to let go.

What is the Gulf “Dead Zone”? July 17, 2008

The annual forecast for the Gulf of Mexico “Dead Zone” has been released, predicting a record size disturbance this year.  So, you might ask, what is the Dead Zone?  How does it happen?

The Dead Zone in the Gulf of Mexico is an area in which the water is hypoxic or anoxic.  ‘Hypoxic’ means low-oxygen.  Water, at a given temperature, has a set limit to how saturated it can be with oxygen.  When the actual amount of oxygen dissolved in the water (known as ‘DO’, or dissolved oxygen) is below 30% of the maximum, it is considered hypoxic.  Most animals cannot survive for long in hypoxic waters.  ‘Anoxic’ means no oxygen, in which there is no dissolved oxygen in the water…for organisms that get their oxygen from the water around them, such as fish, crabs, and clams, anoxia is fatal.

Why is the area ‘dead,’ or low in oxygen?  Understanding this concept is not too difficult, but it is easiest to go step by step.

1. Anytime something dies in the ocean (and most other places), bacteria and other decomposers start eating it, whether it is plant or animal.  This can be thought of as natural recycling.  These decomposers break down the body tissues and eventually releases a lot of the nutrients held there.  For most decomposers, this process requires oxygen (just as we require oxygen to process our food).
2. Phytoplankton are tiny little plants in the ocean, and being plants, all they need is sunlight and carbon dioxide to feed themselves, right?  Well, not quite.  They also need some other nutrients, like nitrogen and phosphorous, to make different kinds of tissues and eneymes, etc.  Anytime all the plants in an area use up all the available nitrogen, or phosphorous, or any other necessary thing, they can’t grow any more.  Whatever chemical it is that they don’t have enough of is called a ‘limiting resource’.  This same problem of limiting resources occurs for land plants, and farmers who want to grow lots of plants in one place (that is what agriculture is) use fertilizers to supplement nitrogen and phosphorous, so that they are less limiting.
3. Fertilizers used on farms all over the midwest of the US are not all used up by the plant or absorbed by the soil.  Some fertilizers run off when it rains, or when the fields are watered, and these fertilizers enter streams which flow to rivers which all flow into the Mississippi River, which empties out into the Gulf of Mexico.  So lots of nutrients from a large chunk of the US enter the Gulf of Mexico.  (The nutrients aren’t all from fertilizers; some of them come from human and animal waste, some come from industry, some come from atmospheric pollution).  Here in the Gulf, they act as ‘fertilizers’ for the phytoplankton, leading to phytoplankton blooms–or high concentrations of phytoplankton.
4. When phytoplankton bloom, there is more phytoplankton than there are phytoplankton grazers, so instead of all being eaten, some of the phytoplankton die.  Bacteria and other decomposers start eating all the phytoplankton (and these bacteria reproduce faster than phytoplankton grazers, so they do a better job of keeping up on the eating), using LOTS and LOTS of oxygen.  If there is enough phytoplankton in the area, eventually the decomposition process uses up all the oxygen in the water, leaving a dead zone.

    There is evidence of hypoxic and anoxic events in coastal waters around the US before large human impacts on the land, but as humans add more and more nutrients into the water and use coastal areas for buildings and parking lots rather than plants (which would soak up some of the nutrients before they made it to the water), hypoxia and anoxia are becoming a much larger problem.

Today in Environmental News… July 16, 2008

• Just as the people affected by the Midwest flooding still feel the effects, there will be a lasting signature of the floods in the Gulf of Mexico ecosystem.  The ‘Dead Zone,’ or the area which suffers severe hypoxic and anoxic conditions, is predicted to be larger this year than after Katrina.  (See the whole story, and how increasing use of ethanol could affect the future health of the Gulf of Mexico, at The Daily Green.)
• See?  Even small changes in the way we manage fisheries can make big changes.  Witness the changes seen off the coast of Devon, in the UK.  (BBC News)
• Seabird breeding is affected by a number of factors, including climate and food availability (read:  fish populations).  Therefore, it is just another bad sign when usually large colonies of seabirds are showing dramatically reduced breeding.  (BBC News)
• And finally, how long is it before the Bush administration craps on this step forward by the EPA in combatting our CO2 output?  (NY Times)  

Whole Foods More Blue, Less Green July 16, 2008

An article in today’s Washington Post by Ylan Q. Mui examines the trend among major grocery chains to certify as sustainable their farmed fish.  This follows an earlier trend in certifying wild fish as sustainable.  This is great; encouraging green practices among fishers and fish farmers is best accomplished with the wallet.  But, one solution for Whole Foods involves buying sustainably farmed fish from Norway.  Hmmm, has anyone at Whole Foods considered the amount of airplane fuel they are releasing, flying in their sustainably farmed salmon?  I’m going out on a limb here and assuming that the fish aren’t being driven over from Norway in a hybrid… 

Retailers need to consider the full environmental impact of the products they offer, not just whether those products fit into the latest green ‘trend’.  A truly green retailer would look at the state of the world’s fisheries right now and say, ‘Hey, people…the only way we can continue to eat salmon for the next hundred years is if we cut back a little now, stop watering our golf courses with water the salmon need for reproduction, stop warming up the globe and messing up the food supply of the salmon, and take good care of the coasts and oceans.  If you behave well for a good 20 or so years, you will have earned the right to have wild, locally caught salmon on your plates.’  Have people not figured out that we are beyond a ‘band-aid’ solution to most of our environmental problems?

What You Can Do: Choosing ‘Green’ Fish July 12, 2008

I don’t actually recommend that you eat green fish.  Green fish flesh is a sign that you in fact should avoid that delicacy.  But, a very simple way for you to encourage sustainable fisheries is to choose to buy and eat only those fish that come from such fisheries. 

Any time that you buy fish that are harvested in a way that harms the environment or the fish population over the long term, you are supporting that harmful practice.  Does this mean you have to stop eating seafood?  No.  You just need to make informed choices.  And this is particularly easy thanks to a guide from the Monterey Bay Aquarium…it can even fit in your wallet so you don’t have to memorize anything.  Simply download the seafood guide and print it out for yourself, your family and your friends.

Yup, there are probably a few of your favorites that you won’t be able to eat for a while.  But as the markets for those fish that are not sustainably harvested goes down, hopefully the fishery (the fishers and the sellers) will adjust by adopting sustainable practices.  Then they will be okay to eat again.