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Science Wednesday: Protecting Ocean Meadows

2009 September 30

Each week we write about the science behind environmental protection. Previous Science Wednesdays.

“Amber waves of grain” conjures up images of vast expanses of grassland across middle America. In contrast, can you picture meadows of seagrasses covering broad areas of the seafloor?

image of underwater seagrassSeagrasses are underwater marine flowering plants that have long, narrow leaves. Because they photosynthesize, seagrasses must grow in shallow water where light penetrates. Most of the light required for these plants disappears below 30 feet.

Florida alone has about a half-million acres of seagrass meadow.

Seagrasses provide essential “ecological services,” such as reducing erosion, improving water quality, and supplying refuge and food for aquatic animals. They are vital to commercial and recreational fisheries that are a major part of a coastal community’s economy.

Unfortunately, the health of seagrass meadows has been compromised in many places due to pollution from land-based activities. Excess nutrients from fertilizers and wastewater cause algal blooms which deprive seagrasses and aquatic organisms of essential oxygen. In addition, over-fishing, over-crabbing, and other harvesting practices change the ecological balance within seagrass meadows, leading to shifts in both plant and animal populations.

My PhD thesis brings me to the shallow waters off Bermuda where I am measuring the simultaneous effects of heavy grazing and excess nutrients on the overall health of seagrass pastures. Seagrasses here are being eaten (grazed) by green turtles and parrotfish while fertilizer runoff is also affecting them.

My main focus is to understand how grazers with different feeding strategies—where and how they feed—control the effects of nutrient pollution. I am working in both the laboratory and the field to manipulate and measure nutrient levels.

A conservationist at heart, I constantly seek to educate others about how human actions can either positively or negatively impact the physical environment. My research looking at the indirect effects of local fishing practices and wastewater treatment on seagrass ecosystems has pressing applications for coastal conservation and management worldwide.

About the author: Kim Holzer is a Ph.D. student in the Department of Environmental Sciences at the University of Virginia. Funding for her research is provided by a 2007 EPA Science to Achieve Results (STAR) Graduate Research Fellowship. Kim expects to graduate in the spring of 2011 and continue working as a scientist in environmental protection.

Editor's Note: The opinions expressed here are those of the author. They do not reflect EPA policy, endorsement, or action, and EPA does not verify the accuracy or science of the contents of the blog.

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10 Responses leave one →
  1. Johnny R. permalink
    September 30, 2009

    Your last sentence, “My research looking at the indirect effects of local fishing practices and wastewater treatment on seagrass ecosystems has pressing applications for coastal conservation and management worldwide” is a masterpiece of bureaucratic understatement, deftly ignoring the regional and global crisis of growing human populations and growing tons of pollution dumped in the oceans. So, here you are, deliberately misinforming the public so as not to ruffle any corporate or political feathers that depend on “business as usual”. How do you sleep at night?

  2. Betty Hansen permalink
    September 30, 2009

    Unfortunately, the health of seagrass meadows has been compromised in many places due to pollution from land-based activities. Excess nutrients from fertilizers and wastewater cause algal blooms which deprive seagrasses and aquatic organisms of essential oxygen.

    These phrases are very true, but we can’t forget that each one of us are guilty of polluting our waters by our usage of toxic chemicals in and out of our homes. We use a huge amount of toxic chemicals in our everyday household cleaning products. Which a lot of this finds its way down the drains and poured into the ground. This has got to change in order for us to have cleaner waters.

  3. Steve S. permalink
    September 30, 2009

    To Johnny R.,

    I do not believe the gentlelady, you, or I have control over such things as “the regional and global crisis of growing human populations and growing tons of pollution dumped in the oceans.”

    Individual persons have the greatest control over “human populations” and individuals, individually and collectively, along with elected officials and bureaucrats have the control over “tons …dumped in the oceans.”

    She isn’t out to identify all the causes of the degradation: “where I am measuring the simultaneous effects of heavy grazing and excess nutrients on the overall health of seagrass pastures.”

    Lighten up, Johnny.

  4. Ben K. permalink
    September 30, 2009

    @ Johnny R
    I think that’s an overreaction on your part. There are certain standards of academic writing that must be maintained in order to be taken seriously. Hyperbole and – what could be considered – alarmist statements often elicit negative reactions from readers. K.H. is obviously attempting to demonstrate reasons for change to “b as u” from the inside out. Consider the substance of her work for its intention, not the way it’s presented.

  5. Michael E. Bailey permalink
    October 1, 2009

    It looks like the study you did will show how over fishing both recreational and commercial have reduced the preditory fish that feed on green sea turtles, snails, and grazing fish, leaving the grazers to proliferate to change coastal ecologies. While pollution from storm and dry weather runoff from agricultural and urban areas into rivers, lakes, and streams that empty into the ocean also plays an important role. It shows the importance of doing several things, including eliminating dry weather runoff in all but a few limited instances like fire fighting, putting tougher controls on storm water runoff, and ending gill net fishing. It also shows that development of fish farms can give wild fish some hope for recovery through providing markets and consumers farm raised ones at less cost. Best wishes, Michael E. Bailey.

  6. Edgardo Berraz permalink
    October 1, 2009

    This reply is only to alert about the extremely needness to mantain seagrass healthly,in the same with coral rifts,because they are the ultimate shelter and feedpoint for a very large number of marines species,who come here for nourishment and reproduction.Destroy that natural reserves,is an important deflect of ecological enviroment.Best wishes.

  7. Prabhat Misra permalink
    October 1, 2009

    Thanks Kim Holzer for this excellent work. It is true that eutrophication is causing algal bloom. The entry of pesticides and other pollutants in food chains and food web through seaweeds are causing diseases in higher trophic levels fauna. The sea-algae are the main source of oxygen for aquatic life so there should be effective efforts to check marine pollution. I hope that your research will provide the solution for this. You are welcome to my blog and your emails are invited. My best wishes to you for the SUCCESS.

  8. Johnny R. permalink
    October 1, 2009

    More good intentions on the road to ecocidal self-extinction. Why can’t I persuade people to think about the relentlessly growing number of people whose relentlessly growing tons of sewage and trash are killing the Earth before our eyes? We SHOULD be alarmed at the growing “garbage patch” in the Pacific, the growing tons of sludge dumped offshore by nations around the World, the growing number of coal-fired power plants spewing growing tons of toxic smoke up into the atmosphere, etc. Instead the EPA bureacracy exudes a phony confidence that everything is under control, and that is a deliberate lie.

  9. Johnny R. permalink
    October 1, 2009

    I am tempted to lighten up as you suggest, but that would mean deluding myself as to the actual events going on around me, and that would be insane. Yet, I suspect most of the so-called “environmental community” is doing exactly that, because none of them dare to expose the source of all environmental degradation — overpopulation, its industrial needs and the refusal to institute family planning in every community and to recycle 100% of all waste and garbage. How much more can the slowly shrinking Earth absorb as our population keeps on growing?

  10. Johnny R. permalink
    October 1, 2009

    The only effective way to protect the sea grass is for all nations to safely recycle 100% of all waste and garbage. Sludge and trash should NEVER be dumped in the ocean or anywhere else, but turned into fertilizesr and new products. The only reason they don’t is because neither corporate nor government agencies are willing to spend the money, so they just dump it in the ocean and into growing mountains of landfill, assuming the Earth will absorb it all and everthing will be fine. But the population keeps on growing so there is more every year.

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