Researchers set up quadrants in Acadia National Park’s rocky intertidal zone, some of the most popular areas of the park. Researchers hope the long-term monitoring efforts will indicate negative impacts from humans and climate change. PHOTO COURTESY OF SARAH O’MALLEY

Life in the in-between: Researchers monitor long-term changes in Acadia’s rocky intertidal coast

The intertidal areas of Acadia National Park are on the front lines of sea level rise, ocean acidification, warming temperatures. Here, researchers working with the National Park Service check out one of Acadia’s many tidepools as part of a monitoring program.

BASS HARBOR — It’s a rough life in the rocky intertidal zones of Acadia National Park. An existence between the high and low tide marks means weathering sunbaked and ice-chilled temperatures, repeated exposure to the sun and air, and a constant churning from the sea. In short, the plants and animals that make the intertidal their home are a hardy bunch.  

Sea stars, urchins, barnacles and seaweed can all be found in these in-between zones of rocky shoreline that are extremely popular with visitors. But with their popularity comes the chance of harm. 

To watch out for potential changes, the National Park Service has been monitoring several areas of the intertidal for more than a decade. The Northeast Temperate Network started the rocky intertidal monitoring to help determine the level of negative impacts on the rocky shorelines that are frequented by visitors. Intertidal ecosystems are also an ideal sampling site for indications for climate change because of the rapidly changing sea level and air and water temperatures that are critical to species that live in those areas. 

“The intertidal is probably the area of the park that is changing the most and has changed the most over the life of the park,” said Abraham Miller-Rushing, the science coordinator at Acadia National Park.  

Almost all the environmental changes happening across the park also all take place in the intertidal. Ocean acidification, warming water, invasive species and storm surges all directly affect that area.   

“A lot of things are getting thrown at the intertidal,” Miller-Rushing said. “That’s an important place for us to be monitoring.” 

Long-term monitoring of data is crucial for documenting the condition of the rocky intertidal zones so that threats can be recognized and then dealt with. The program at Acadia is one of two of the National Parks Service’s rocky intertidal monitoring programs in the Northeast. The other is the Boston Harbor islands.  

In the past, there was a lot of attention paid to forests and streams, but recently there’s been a big emphasis on understanding what’s happening on this environmental frontline.  

About a third of the park’s research now involves the intertidal areas, which are also probably the most visited part of the park, with highlights such as Thunder Hole.  

Other intertidal work has also popped up locally. The Schoodic Institute is working on starting a monitoring program in the soft-bottom intertidal mudflats of the peninsula.  

Hannah Webber, the marine ecology director at the institute, said that these intertidal zones are a “ribbon of mystery” that live in the in-between and may not show up on nautical charts. They’re home to the state’s second largest fishery, soft shell clams, and can show indications of what’s happening in the ocean at a fraction of the cost of ocean research.  

“It’s dreadfully important,” Webber said.  

For the Acadia monitoring, there are six permanent monitoring sites – four on Mount Desert Island and two on the Schoodic Peninsula. There are sites at Otter Point, Little Hunter’s Head, Little Moose Island, Schoodic Point and two in Ship Harbor. These sites largely fall into two categories: ones that are popular with visitors and ones that are relatively untouched. Some are so remote that researchers need to bushwhack to get there.  

In July, researchers head out to those locations to find pins that mark the exact spot. From there, they find plots and create quadrants. The surveyors will take overhead photos that are later analyzed. They also look for mobile invertebrates, counting and measuring the critters. Researchers will also check to see if there are changes in the ranges of species within the intertidal, such as if some are moving closer to land or water. Barnacles are looked at and water temperatures are logged. 

For the past several years, the ocean studies program at Maine Maritime Academy has been helping with the surveying, said Jessica Muhlin, an associate professor of marine biology at the school. 

“It’s a great opportunity for our students to get involved,” she said.  

Trends are starting to emerge from the monitoring. Plots that were originally designated as barnacle plots have lots of seaweed, Muhlin said. The boom-and-bust cycles of sea stars are becoming more apparent. 

These trends can also be extrapolated out to other parts of the state and serve as crucial indicators.  

“Monitoring here is going to tell us a fair bit about the rest of the region,” Miller-Rushing said. 

The rocky intertidal is resilient, but like any other environment, it can only take so much.  

“They’re used to getting hit by things,” Miller-Rushing said. “We’re just hitting them with a lot of things really fast, more than they’ve ever seen in their history.” 

Ethan Genter

Ethan Genter

Former reporter for the Ellsworth American and Mount Desert Islander, Ethan covered maritime news and the town of Bar Harbor.

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