Our post today is from Chelsea Rochman. This is her third post.
The array of emotions this cruise has brought to us all is indescribable. It started off with such excitement and anticipation of what we may find and the journey ahead. That was followed by amazement and awe of the odd animals we were pulling up in the tows in the California Current. Then we began to find what we came here to see and emotions varied by person. For me, the reality of the plastic soup hit hard. The sight is overwhelming and the sadness for this mess in the ocean rained over me. Like a train wreck you cannot look away. As we continue on in the gyre thoughts about what we can do surround us. How can we truly make a difference? In my opinion there are two really important things we can do right now. One: educate others about the issue so that we can attempt to cut it off at the source. Prevention is important. Two: further our understanding of the effects on the oceans and its inhabitants. Amazing research is being conducted as we speak from all over the world. Each issue must first be understood in order to attack it properly. On this specific cruise we all may have a common interest, yet we each have our own specific niches. My niche happens to lie in the field of ecotoxicology.
The issue of marine debris is not new. Scientists and environmentalists have been shining light on this issue for years. In terms of adverse effects on marine life, information has been mostly mechanical. Mechanical aspects are those involving animals entangled in debris or ingesting it and either choking or satiating them so they starve. It has become apparent that these issues may not be the only ones. Lately we hear about the “other” plastic problem. This “other” problem deals with chemistry.
There are two issues we are dealing with here. One, the plastic leaches chemicals used in manufacturing that can be toxic to organisms at certain concentrations. And, the issue that worries me most, plastics are like magnets to pollutants already present in seawater and these adhere to their surfaces at magnified concentrations. The ocean is the ultimate sink for many industrial and agricultural pollutants. It is a known fact that pesticides, fuel residue, flame retardants, etc… are in the oceans. These are a few of what we refer to as a suite of chemicals called persistent organic pollutants, or POPs. Many POPs are known to be harmful to marine organisms. Animals will bioconcentrate (take up directly) these pollutants from water or sediments, or bioaccumulate them (through ingestion from other contaminated organisms). Rachel Carson told the story of how DDT, a pesticide, brought the brown pelicans down to crippling numbers. POPs are persistent and not very soluble and thus can concentrate in the water, sediments and the food chain… and now plastic.
These pollutants are hydrophobic, meaning they do not like water and thus stick to other particles in the water. Plastic has become a new material for them to leach onto. Now, don’t let this fool you into sounding like a good thing because it removes the pollutants from the water. Some organisms ingest plastic, mistaking it for food. Once this plastic is introduced into their system the POPs have the ability to leach off and grab onto the tissue of the organism. As the animal eats more and more plastic it has the ability to accumulate more pollutants. Plastics have been documented to attract magnified amounts of POPs from the water. Now, lets say ten krill eat a plastic pellet and accumulate a certain amount of a pollutant. Then, two fish eat five of the krill each and now each have five times as much pollutant as the krill. Then a tuna comes along and eats the two fish and has ten times as much pollutant as the krill. Then the tuna is caught in a net, sold at the grocery store, and sold to you at the store to put on your dinner plate. After dinner, you have now accumulated the magnified concentration of pollutant. This is termed biomagnification. Now the issue involves more than just the ocean, but us. What are the adverse effects of some of these pollutants you may wonder? At certain levels some are carcinogens, may harm the reproductive system, disrupt the endocrine system, and some can lead to death.
As we begin to understand this issue better there is hope that we can make a change. While the ocean may be the ultimate sink for many pollutants, it does not have to be. If we can understand the adverse affects of our run-off, policy can be implemented to create cleaner and safer oceans for both marine life and other critters, including ourselves, that use the ocean for sustenance.