Usually here at Xylem, I lean toward land-based ecology stories, probably since I myself spend most of my time on land. But at the AAAS conference last week, I found that many of the most interesting talks I attended dealt with ongoing research in ocean ecosystems. Here’s the three stories that really caught my eye:
1. Mussels relax their grip on coastal rocks during the summer, when the seas are typically calmer
Emily Carrington explained to a mixed audience of ecologists and materials scientists that mussels live in a dynamic environment- they have to handle varying temperatures, water chemistry, tides, currents, and wave conditions. She said that mussels are the foundation of intertidal communities, ecologically speaking. Disturbance, by waves, tides, storms, keep communities healthy, by knocking some mussels off the rocks and opening up space for other species.
Mussels hold onto the rocks, or docks or anything else really, using byssal threads. These threads are extra cellular fibers that are all embedded in one central muscle in the body of the mussel. The mussel’s foot plants thread after thread after thread to attach themselves. Carrington’s research measures the strength of the byssal threads by pulling mussels loose from rocks with a spring scale to measure the force. She found that they hold on tighter in the spring, and relax a bit in the summer. Mussels are prepared to hold on during rough spring weather and more likely to be dislodged by the occasional fall storm.
What causes the attachement strength to decrease? The mussels might make fewer threads, weaker threads, or perhaps the thread break down more quickly. The weaker attachment occurs in the summer, suggesting that warmer water might play a role. In Carrington’s lab, they are studying how the changing ocean climate- increasing temperatures and increasing acidity might affect their abilities to hang on during the increasing violent and sporadic storms that climate change drives as well.
2. Tracking toxicity in whales
Remember the gulf oil spill? The epic environmental disaster of 2010 seems to have largely slipped from the public consciousness but the toxic traces of the spill are not fading nearly as fast as our attention spans. John Wise, a toxicologist from the University of Southern Maine has been tracking the impacts of the oil, the dispersants, and oil-related metals in two whale populations that live in the Gulf. He and his research team have collected whale biopsies, samples of prey species, and environmental data for the past three summers. Wise explains that it’s hard to keep a tank of exposed whales in the lab to study, so he experiments by exposing sperm whale cell cultures to similar levels of the various chemicals that they observed in the wild populations. This allows them to study what level of exposure can kill cells or damage DNA. The whales are still swimming in the Gulf, but Wise worries about DNA impacts from the spill that could have long term effects on the population, like a killer whale pod in the pacific that has stopped reproducing since the Exxon Valdez oil spill in 1989.
3. Better food for farmed fish?
With some background interest, I went to a session on the future of fish farming. I probably arrived a bit prejudiced– my first ever science writing internship was for a marine stewardship group that gave out bumper stickers that read “Friends don’t let friends eat farmed fish.” At first glance, fish farming sounds like a great idea, if the oceans are being taxed by over-harvest, let’s grow our own. But in practice, the most valuable fish to farm, like Atlantic Salmon, are predators who eat other fish. So ocean populations of less valuable fish are still harvested to make fish food. Fishing to feed fish to feed to people– not an efficient system. Fish farming today often uses caged environments in the open ocean. Keeping fish in tight quarters requires antibiotics to keep fish healthy in close quarters and the waste can have environmental consequences. Some worry that genetically modified fish will escape from their pens, break free, and breed with wild populations.
At AAAS, I heard from several researchers trying to take a new perspective on aquaculture. There are experiments with plant based diets– yeast cultures show potential to be a large, low-impact portion of a salmon diet. New designs are keeping fish in tanks, on land, swimming in circles in highly aerated fresh water. This eliminates the risks of escaping fish, and water can be filtered and wastes treated on site. Experiments with fish vaccines may be able to replace antibiotics. A lot of these reforms are in the early stages of research, but I’m interested in learning more. There’s still the issue of a living wage for fishermen and women who harvest from sustainable wild stock, like wild Alaskan salmon. Good fish, environmentally responsible fish, isn’t always cheap. Right now, some fish are farmed with low environmental impacts meet the sustainable criteria by SeafoodWatch, others, like Atlantic salmon, don’t come close. Check out the list of fish and seafood choices you can feel good about, for now, and let’s keep an eye on the future of fish farming and its strategies to become more environmentally sustainable.