September 8, 2013

What are these animals telling us?

Because they are sensitive to change, so-called ‘sentinel species’ can reveal a lot about the ripple effects of pollutants in our environment. And that, scientists say, serves as a warning about our own fragile future.

By North Cairn
Staff Writer

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Green crabs, like these found off Freeport, are considered a “sentinel species,” which can tell us a lot about the ripple effects of mercury, lead and other pollutants.

Gabe Souza/Staff Photographer

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Sentinel species in Maine

Explore how ocean scientists, ecologists and biologists are studying a wide range of “sentinel species” in Maine with our interactive species guide.

Plastic waste, which is virtually indestructible, has become a commonplace pollutant in oceans all over the planet.

Creatures that span the ecological chasms between very different ecosystems are in peril from human-induced climate change and its ripple effect on the water column and food web of the seas.
Nelson, the UMaine professor studying dragonflies, doesn’t need a lot of high-tech equipment to do sentinel species work. The critical tools are waders, nets, plastic sample bags, hand lenses and field guides.

Yet the findings and implications of her work are anything but simple.

Mercury is a potent neurotoxin that poses a special threat to health, especially for children, nursing mothers and pregnant women.

Dragonflies represent an intermediate step between other classes of animals, filling a gap in existing data and bridging other research on mercury contamination in birds, fish and water.

Her dragonfly studies take the monitoring of mercury to new levels, looking at forests and wetlands, both here and in areas across the country. Involving researchers, educators and citizen scientists, her work has been extended beyond Acadia National Park on Mount Desert Island to 25 national parks across the country.

She hopes her work will yield valuable information about mercury in the food chain and in watersheds.

“Mercury research is relatively new,” Nelson said. “But we’ve learned a lot already. We’re getting better at predicting mercury in the water.”

Now, the focus needs to be adjusted slightly, to see clearly how the food web has been – and is being – affected by the toxin.

Monitoring of sentinel species like the dragonfly is more complex now, because environmental, industrial and pollution factors have proliferated at an astonishing rate over the last half century, said Keenan, at the Gorham biological institute. And more intricate, complicated interactions are being uncovered all the time.

“We’ve advanced in terms of our research and ecology,” he said. That progress and sophistication are likely to yield more sentinel studies, not fewer.

As the number and complexity of sentinel studies grows, scientists are making efforts to integrate the resulting data into meaningful patterns.

One major undertaking is focused on bringing together many research efforts by creating a network to collect data and assess environmental change on a continental scale.

First approved for National Science Foundation funding in 2006, the National Ecological Observatory Network was granted $434 million to establish a network of 20 permanent monitoring stations to collect climate, environmental and biological data on a continuing basis. The network also includes 40 temporary land sites and 46 aquatic locations, said Lily Whiteman, senior public affairs officer for NSF.

A new observatory is being built as part of the network, and it will sample sentinel terrestrial and aquatic species at 106 locations across the United States, including Alaska, Hawaii and Puerto Rico.

The network’s projects will sample sentinel organisms such as microorganisms, mosquitoes, ground beetles, deer mice, fish, birds, plants, and aquatic invertebrates in an attempt to understand and forecast the impacts of climate change, land-use transitions and even invasive species, Whiteman said.

Scientists will be watching how these animals fare in and affect various ecosystems across wide geographic territories, enabling them to make comparisons from one part of the continent to another.
“It’s a very 21st century approach to ecology,” said Andrew Pershing, research scientist at the Gulf of Maine Research Institute in Portland and a professor in the School of Marine Science at the University of Maine in Orono. Without it, researchers are left to wring out every last bit of information they can find in a relatively limited ecosystem.

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