How the Gulf Spill's Devastation Works Its Way From Plankton to Pelicans
Our Link to the Marine Environment
As a wildlife biologist, I started wondering why birds, out of all of the species of wildlife being affected by the current disaster in the Gulf of Mexico, are so popular in the media. They’re such a small part of the equation. If you put all of the Gulf dwelling creatures into a pile, birds would make up a very small percentage of the biomass. Then it occurred to me that most of us just can’t relate to the rest of the ecosystem. We can grasp the lives of whales, dolphins, turtles and fish with a relative degree of attention but most of us are lost when it come to the enormous suite of crustaceans, mollusks, echinoderms, cnidarians, worms, and plankton that make up the bulk of sea life. After all, we know more about outer space than we do the deep sea.
Birds are the facet of this human created travesty that we can most easily sense. They’re cosmopolitan, and everyone knows what they are. At the very least, most people can correctly identify pigeons and chickens. Bird calls, beautiful or otherwise, filter through our soundscapes. We see them in their environments, ranging from solemnly rural to bustlingly urban. We have some insight into their lives.
Sure, we are all fond of sea turtles, dolphins, whales, and fish but most of us have no personal sensory experience with any of those creatures’ wild vitality. If we’re lucky, we get to see them in places like Marine World or the Tampa Bay Aquarium. An even smaller percentage of the US population, let alone the world, gets to view these large and charismatic creatures going about their business in their home environments. All of us have seen fish and various types of crustaceans and bi-valves either in aquariums or for sale at the market. Fewer have seen a shrimp filter feeding amongst a complex coral garden, the quietude of an oyster bed with jellyfish drifting overhead, or the single minded choreography of a school of bait fish maneuvering through the depths. An even smaller number of us have gazed in amazement at the geometry and grace of zooplankton and phytoplankton under a microscope. If a person isn’t deeply connected to these nearly invisible denizens of the deep, we just don’t think about them unless prompted.
Are we doing a disservice to the rest of the wildlife by focusing so narrowly on birds? Could conservation organizations and the media draw more understanding and support from the general public by bemoaning the plight of flatworms, brain corals, or sea anemones? I think not. We concentrate on birds because we all have personal connections with them in one way or another and more importantly, they serve as an ecological indicator for the health of the marine ecosystem. They are the link between the marine environment and us.
Weakening The Link
Birds, in addition to straddling two worlds, are among the upper echelons of the food web that is the body and soul of the Gulf of Mexico. They mainly eat fish and invertebrates that, directly or indirectly, consume the phyto- and zooplankton that are the foundation of the marine food pyramid - a foundation that is being compromised.
As we approach the eightieth day of battling Louisiana sweet crude emanating from the oil geyser known as Macondo 252, we’ve witnessed over 1.7 million gallons of oil dispersant being added the countless millions of gallons of petrol that was already weighing heavily on the health of the Gulf. Two different types of dispersant, Corexit 9527 and Corexit 9500, have been in use. First and foremost, these chemical cocktails have served to allow the oil to pollute not just the top layer of the ecosystem but the entire water column. Dispersants break the crude into tiny droplets, emulsify it and allow it to disperse – hence the name – throughout the water. They have also been instrumental in creating vast under water oil plumes at various depths. These plumes act as barriers to vertically migrating plankton. Plankton and other, slightly larger, sea life known as nekton make a daily commute from the surface to down below the photic zone in order to gather resources and avoid predators.
One of Corexit 9527’s more charming chemical characteristics is that its main ingredient, 2-butoxyethanol, is known to have a high biological oxygen demand as it breaks down in the marine environment. Plankton sustain themselves on oxygen dissolved in the water. This oxygen is greatly reduced in the presence of dispersants. Corexit 9500’s main ingredient is propylene glycol, which is the main ingredient in anti-freeze. It has a high concentration of toxic heavy metals that bioaccumulate, or become more concentrated in animals as they move up the food chain. The lack of the basic necessities of life – oxygen, food, and predator avoidance - in vast swathes of the Gulf may be a catastrophic combination for the tiny critters that constitute the foundation of an entire ecosystem.
It’s uncertain when we will begin to see the effects of dispersant chemicals play out in the bird communities of the Gulf Coast. In the meantime, plankton populations will battle to maintain their foothold in the ecosystem and toxins will bioaccumulate as they move up the food pyramid toward the top where birds exist. The only indications that most of us, as landlubbers, will have of this ecological struggle are the birds. As responsible parties to this whole disaster, our only choice is to continue to keep a close watch on our ambassadors to the sea and do all we can to stop the further purposeful poisoning of the Gulf of Mexico by oil dispersing agents and off shore drilling in general.