Plastic trash — fishing line, food containers, tampon cases, all kinds of polymer-based throw-aways — is the most abundant form of marine debris. It’s puzzling, though, that despite the glut of plastic production since World War II ( current global production is about 77 pounds of plastic a year for each of the 7 billion humans on the planet), no significant trend in plastic accumulation in the ocean has been observed since 1985. While an alarming amount of plastic washes up onshore, another chunk of it is being degraded at sea. Marine plastics are known to break down due to physical shearing and photodegradation, and MBL scientist Linda Amaral Zettler wants to know if and how microbes are involved, as well.
Amaral Zettler recently received a collaborative NSF grant to explore the “Plastisphere”–the microbial communities attached to and surrounding marine plastic debris. By determining what microbes are found in the Plastisphere and what they are doing, Amaral Zettler and her collaborators hope to determine the key biological factors that control the fate of plastic debris in the open ocean. This will open up new questions to explore, such as “How is the abundance of plastic debris affecting the health of open ocean environments and their food webs? Can a truly biodegradable plastic be formulated that can have minimal impact on marine ecosystems?”
At present, Amaral Zettler is aboard the SSV Corwith Cramer, a vessel operated by Sea Education Association (SEA) of Woods Hole. Amaral Zettler is working with the faculty at SEA to develop a new semester course in Marine Biodiversity Conservation. As part of this trip, she and SEA students are collecting marine plastic samples to begin studying The Plastisphere. Below is an update Amaral Zettler sent this week from onboard the ship.
Images from the June 2012 SS Corwith Cramer research cruise spanning over seven orders of magnitude in size (1 micrometer bacterial cell to 15 meter whale). Petri plate with marine bacterial colonies, plastic marine debris, viper fish, and humpback whale. Credit: Linda Amaral Zettler
12 June 2012
Ship Position: 42N x 69W
Weather: wind SxW, force 4. Sailing downwind under square sails
The SSV Corwith Cramer left Bermuda just over a week ago and has been sailing north of the Gulf Stream for several days now. Gone are the blue, blue, deep, deep waters of the Sargasso Sea but new discoveries await in the productive waters off Georges Bank and the Gulf of Maine as we transit back to the New England shore. This morning’s pod of humpbacks that greeted us for a pre-breakfast interlude was a nice example.
Our students aboard have logged many hours at the microscope identifying species of Sargassum hydroids, 15 species of deep-water myctophid fishes, and over 50 morphotypes of microbes belonging to the genus Vibrio. Other student projects are explorng the population genetic variability in the larvae of spiny lobsters, North-American and European eel larvae,
Sargassum shrimp, and the Sargassum macroalgae that constitute the hallmark of the Sargasso Sea. Their data will be added to the International Ocean Biogeographic Information System (iOBIS) database, the database that served the former Census of Marine Life (www.coml.org), and the Encyclopedia of Life (www.eol.org). Additional voucher samples will help promote conservation efforts via the Ocean Genome Legacy by preserving a variety of Sargasso Sea species for later downstream genetic barcoding.
Students in the microbes group are also contributing directly to an NSF-funded project examining the diversity, function and fate of microbes on plastic marine debris in the open ocean. Leading this NSF project are Amaral Zettler, Tracy Mincer of Woods Hole Oceanographic Institution [WHOI] and Erik Zettler of SEA.
In addition to traditional morphological identifications, for the first time aboard these sailing school vessels, students have extracted genomic DNA from their samples and used molecular biology techniques taught onshore to target marker genes of interest for their individual projects. Their precious samples are being sequenced this week at the W. M. Keck Sequencing Facility in the Josephine Bay Paul Center at the MBL in Woods Hole.
Upon return, students will add their new molecular findings to their existing data to prepare independent research projects that they will formally present as part of a science-policy symposium the final week of the course. Through a unique blend of hands-on research science and policy education, Marine Biodiversity Conservation students will have an opportunity to narrow the gap between science and policy makers while helping to affect change in the protection of the high seas.