What happens to garbage in the ocean? Seafloor communities and Stacy’s long-term monitoring
We are really getting into the swing of things. Stacy, Kevin, Jen, and Julie take turns SCUBA diving at various spots, and Bob, DJ, and David work on SCINI and take her out for extended missions. Julie and I alternate dive tending, hole drilling, getting various supplies, and running errands. The divers sieve their samples, upload photos and videos, and analyze their data as I help or research and write my journals, correspond with my English 1A class, or find WATER DROP caretakers. Paul works on his experiments and goes through his voluminous notes from past seasons to make comparisons with today's data.
We have two major research areas that we’re focusing on this year. You have learned a bit about Paul and our retrieval of his old experiments which helps shed light on how the seafloor communities have changed over the last 50 years. That’s part one. Part two involves Stacy’s long-term monitoring of the area in front of McMurdo. Long-term monitoring involves asking questions such as these:
What has changed in the environment of the critters on the seafloor? How have the communities of animals changed in response to the environmental changes?
So how would you find answers to these questions? What would you measure and how?
Let’s start by looking at the environment. Specifically we will look at area we are focusing on which is right in front of McMurdo and is called McMurdo Sound. This sound opens to the Ross Sea to the north and to the south it connects to the Ross Ice Shelf (Do you remember what the ice shelf is made of and how thick it is?) McMurdo is on the southern end of McMurdo Sound. This body of water is covered by ice most of the year. Right about now, in the middle of October, it is the thickest. Starting soon, the ice will start to melt reaching its thinnest point around the end of February or beginning of March. Some years the ice melts all the way to McMurdo but in recent years a giant 175-miles long iceberg, Iceberg b-15, broke off from the Ross Ice Shelf and situated itself at the mouth of the sound preventing the ice from melting. In 2005, the iceberg finally drifted away and the environment is slowly recovering. The water, because it is salty, is actually not that cold - only -1.86 C (-28.5 F). (though the divers still think this is pretty cold). It doesn’t warm up from warm South Pacific or South Atlantic waters because of a strong, cold, circumpolar current that encircles the continent. The layer of ice on top makes for a dark habitat under it. The lack of light means not many plants grow in the water. If you read the blog about Paul’s talk then you’ll know that the environment is actually very predictable and stable.
However, this environment in front of McMurdo is sadly also disappointingly polluted. Remember Paul’s story of how the navy, which was running the station in the 1960’s would simply dump all trash, including human waste, into the water. It would not be cleaned or treated or flown elsewhere like it is now. In fact, DJ and Bob have seen so many empty barrels on the seafloor that they call them the “tumbleweed of Antarctica”.
In the beginning, from the early 1900s, all waste was merely thrown on the ice. Later part of it was directed by pipe to a sewage outfall area, first right at shore (from 1956-1992) and then 56 meters out and at a depth of 18 meters (after 1993). In 2003 it was finally treated with the implementation of a sewage treatment plant.
A view of the end of the sewer pipe. Under water...
During most of this time the garbage was sorted, heavy metals and junk were placed in a dump site in the ocean until that too was stopped in 1988.
Hydroids on the underwater sewer pipe.
How do you think this contamination has affected the critters and their communities? Are the communities back to normal or how long does it take for communities to recover from human pollution? Stacy’s long-term monitoring addresses just this. She is researching what happens to the animals on the seafloor in response to this contamination. How long will it take them to recover? Who recovers faster? Her various teams have focused on these two types of contamination: organic and chemical. The organic contamination is from the sewage outfall – human waste and food waste.
Bacteria are the first creatures to eat the outfall from the sewer
The sea urchins and sea stars want to come back but bacteria prevent them by using up all of the oxygen.
The chemical contamination is the pollutants like fuel, oil, solvents, hydrocarbons and heavy metals from the historic dump site in the ocean.
Can you see this car on the seafloor? How long will that take before it is gone?
Stacy has surveyed 14 different sites – some right in front of the sewage outfall area, some in the historic dumpsite and some further up current or down current. Stacy and her divers take pictures and videos, count clams, and take cores of each of these sites every year. They then analyze them by identifying and counting the organisms in the pictures or in the samples. Each year they compare the findings to previous years and to areas that are further from the contaminated sites.
This map shows some of Stacy's sites on the seafloor
The end of the line. The sewage outfall.
Her findings so far are interesting. For one, worms like the organic contamination. Stacy actually says that the worms are like weeds as there are so many in the area around the outfall. She has also found that recovery from the organic contamination is rapid and that the areas further from the outfall are back to normal though ones that are closer are still contaminated. It only took several decades for life to be almost normal! Is that a long time or a short time?
Sadly, the chemical contamination has an even slower recovery rate even though the station stopped dumping 5 years before they treated the sewage. This is shown in great part by the death of crustaceans (shrimp-like animals), which are more sensitive to the chemical changes in their environment. The chemical waste simply doesn’t decay and thus it takes decades and decades for it to return to normal.
What does this rust do to the critters?
In fact it is so bad, that 22 years later, four of the sites are still so contaminated that Stacy has to wear a special dive helmet and suit to protect herself from the waste and chemicals.
Steve lowers the core rack which Stacy will use on the seafloor to collect samples of mud
Rob and Steve help Stacy get suited up. The yellow hose sends air to Stacy from the surface
Stacy is ready! The helmet will protect her from the contaminants. The hose sends her air and she can talk to Steve and Rob on the surface.
When will life return to normal for these critters and their communities?
Stacy will keep monitoring…
Does this make you think twice about buying things like those plastic water bottles that only get used once?
What could you do to recycle and reuse more of our precious resources so they don’t end up in oceans? Though this is a really sad chapter in Antarctic environmentalism, stay tuned for the story of how the tide has turned and an explanation behind Antarctica’s complex recycling system.