Ocean acidification presents challenges for marine organisms

This spring (2016), the Coastal Studies Center hosted the students of EOS2625: Ocean Acidification as they conducted semester-long acidification experiments examining both larval and adult stages of the local green sea urchin. The course was co-taught by Visiting Assistant Professor Meredith White, a researcher who also served on the Maine Ocean Acidification Commission, and marine sciences Laboratory Instructor Elizabeth Halliday Walker.

Human emissions of carbon dioxide are causing acidification of the ocean at a rate unprecedented in the geologic record, and consequently changing ocean chemistry in ways that may present challenges for many marine organisms. In addition to lowering pH, the changes in carbonate chemistry are making it more difficult for organisms to build calcium carbonate shells or skeletal structures. Because the spines, jaws, and internal skeletal structure of sea urchins are all composed of calcium carbonate, there is some concern about how these organisms will fare in the future.

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Experimental setup at the Coastal Studies Center.

To investigate the effects of ocean acidification on sea urchin growth and chemical composition, adult urchins were kept in two flow-through seawater tanks at the Coastal Studies Center for two months. In one tank, carbon dioxide was bubbled into the water to maintain a pH approximately 0.5pH units lower than the ambient seawater.

Students measured physiological stress over time by seeing how long it took for urchins to right themselves after being flipped over, and measured weight gain over the course of the experiment. To measure calcification during the experiment, Biology Professor Amy Johnson and Research Associate Olaf Ellers shared a unique method they have used in past research on sea urchins. The students injected the urchins with tetracycline at the beginning of the experiment, and because tetracycline binds to calcium, it gets incorporated into any new skeletal structures that are actively being synthesized. Tetracycline has the additional benefit of fluorescing under certain wavelengths of light, so at the end of the experiment the skeletal structures could be photographed under the epifluorescent microscope to visualize a fluorescent band of growth and measure exactly how much the jaws had grown since the beginning of the experiment.

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After the adult urchin experiment was completed, students spawned urchins to study larval development

With help from EOS Professor Emily Peterman, students were also able to assess the chemical composition of the carbonate structures using a brand new scanning electron microscope with energy-dispersive X-ray spectroscopy (EDS). In addition to changes in chemical composition, the electron microscope also revealed the beautiful complexity of the sea urchin skeletal structures, which raised many more questions about calcification!

Finally, sea urchins were spawned to conduct a similar experiment on larvae. In many organisms, larvae are more sensitive to changes in the environment. The spaceship-like sea urchin larvae grow skeletal rods as they develop, which are also calcium carbonate, and students found that larvae reared in high-CO2 conditions had shorter skeletal rods.

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Nine-day-old sea urchin larvae

The culturing techniques made possible by the facilities at the Coastal Studies Center, and the ability to conduct realistic ocean acidification experiments by manipulating pH with carbon dioxide, were essential to the success of the course and helped reveal the complexities of this growing field of research. Most of all, the interdisciplinary collaboration within the course sparked many new lines of inquiry, and revealed how big problems can be attacked in myriad complementary ways.

Story written by Lab Instructor Elizabeth Walker

Throwback: Tales from the BMSS 2015 – Hurricane Island

As dusk falls over Hurricane Sound, the yellow glow of a late September supermoon peeksIMG_8435 above the silhouetted pines of Green’s Island. The water between Green’s and Hurricane starts to shimmer in the growing moonlight. The wind picks up slightly, floating over small snippets of conversation from the canteen. I glance aside at the solar-powered aura of the central community building; a warm chocolate brownie is calling my name, but I linger another moment in the spectacle of the enormous rising moon.

We are visitors on Hurricane Island for a few autumn days as part of the Bowdoin Marine Science Semester. We, students and teachers, are here taking advantage of the unique setting and resources on this small treasure in Penobscot Bay. Although we traversed the few miles of sound between Rockland and Hurricane in beautiful sunlight and fair seas, we wake on our second day to a cool morning filled with foggy mist. We are aiming to make the low tide in the early light to collect data on intertidal transects we installed in collaboration with the Hurricane Island Foundation in 2014. These transects are marked with anchors in the form of small bolts drilled directly into the very granite so intertwined with Hurricane’s history.


Each year, we return with a new set of students to count the organisms living along these lines in low, mid, and high portions of the intertidal zone. Bowdoin Marine Science Semester students learn to identify all the usual suspects – species of macroalgae like Ascophyllum nodosum, Fucus vesiculosus and F. distichus, the periwinkle snails Littorina littorea,

L. obtusata, and L. saxatilis, the predatory dogwhelk Nucella lapillus – and rare interlopers like the arctic boring clam Hiatella arctica. Each cohort in the Bowdoin Marine Science Semester collects data for long-term monitoring of the changes in these intertidal communities as the waters of the Gulf of Maine change.

Two students are busy leaning over a small, white, PVC square calledIMG_8507 a quadrat which they use to count critters along the transect. They discuss what species of algae they think they have found before confirming with one of the instructors. Lobster boats blink in and out of the ephemeral fog like diesel powered ghosts. Our small army of green muck boots splashes in and out of the waves as we hop from point to point along our transects.

“Have you counted at the 60 foot mark yet? There is a huge crevice full of dogwhelks.”

“Yes, there are so many in there! An array of stripes and colors. . .”


The students chatter back and forth about the unique assemblages they are observing, and how they change from the point nearest the water to the more exposed areas.

As the sun climbs from the horizon, the fog patches dwindle and the air begins to warm. We finish our data collecting, reorganize our gear, admire the wind bent trees of Two Bush Island now fully awash in golden fall sunlight, and head back to warm up with tea, conversation, and some dry socks.

–Sarah Kingston, Doherty Marine Biology Postdoctoral Scholar


Coastal Studies Center gets a new weather station

Carter Newell and I installed a new Rainwise weather station at the Coastal Studies Center on Friday. It is now streaming data to the web at https://rainwise.net/weather/BowdoinCoastalStudiesCenter04079. The data is being used by the new NSF EPSCOR Seanet, which is “gathering inshore environmental data of value through a buoy-based sensor system in three bioregions and in six bays to understand Maine’s dynamic coastal ecology” https://umaine.edu/epscor/seanet/. Bowdoin College is a partner in this large multi-institution effort, and Collin Roesler’s Buoy in Harpswell Sound will be part of a larger Buoy array in the Casco Bay Area.

Bowdoin College is hosting the 2016 Benthic Ecology Meeting in Portland, Maine

Dave Carlon is serviing as President of the Benthic Ecology Meeting Society this year, accepted at last years  BEM in Quebec with encouragement from Ladd Johnson and one too many merlots! The president gets to run the meeting, and this year we are happy to host at the Westin Harborview in lively downtown Portland, Maine. I’m lucky to have Steve Allen as the meeting organizer; and Sarah Kingston (Bowdoin), Bob Steneck (U. Maine), and Graham Sherwood (GMRI) on the scientific committee. We have some great activities planned, including a plenary by Boris Worm of Dalhousie and a fun Friday tour of the Coastal Studies Center with libations donated by Oxbow Brewery. Check out the BEM website: http://www.bemsociety.org, and see the story Bowdoin ran last week: http://community.bowdoin.edu/news/2016/01/bowdoin-to-host-big-marine-science-conference-in-portland/

A post from the Bowdoin Marine Science Semester- fieldtrip to Baja California Sur!

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The echo of scales slapping still water en mass reverberates between steep rock walls, jolting me awake. The school of jack responsible for the dawn racket darts out of the cove toward deeper water. I sit up, squinting in the new day’s sunlight. I wiggle my legs out of my sleeping bag and swing my toes down into the cool sand. It takes me a minute to register the reality that I’m on a literal desert island in the middle of the Sea of Cortez: Isla Partida. Isla Partida is separated from her larger sister, Espiritu Santo, by a narrow sliver of the sea. Both are situated in Baja California Sur, Mexico. We, a group of students and scientists from Bowdoin College and Universidad Autónoma de Baja California Sur, are camping in this amazing and intimidating place to experience Marine Science in a truly unique way. Scientists, students to professors, from Maine and La Paz are coming together to exchange ideas, observe an extraordinary ecosystem, and experience all the Gulf of California has to offer.

Two pangas, longboats common in Baja, bob expectantly on the moorings in the cove. Fire-warmed coffee, chorizo, and eggs provide much needed sustenance and set us on course for the day. We wrangle snorkel gear, wetsuits, ripening salt-soaked clothing, and bathing suits from their overnight drying spots. Students and professors alike are eager for the surprises of the day.

We head for another adjacent island to the north, a rocky outcrop host to thriving sea lion and frigate bird colonies – Los Islotes. The guano-stained shell visible protruding out of the ocean tells only a fraction of the story; under surface of the sea, the wall of rock drops off precipitously. A coral reef, teeming with diversity, clings to the side of the drop-off, fed by the nutrient rich waters coming up from the deep. It is an El Nino year, so the waters are unusually warm. We observe some coral bleaching, as well as crown-of-thorns starfish preying on the vulnerable colonies. Students add to their species list with each glance, king angelfish, a variety of parrotfish, skipjack tuna and grouper darting briefly out of the deep blue depths. Coral polyps dangle their tiny tentacles into the water column to catch a passing meal.

The windward side of Los Islotes is connected to her leeward side through a spectacular archway. The reef wall extends from the precipitous deep water, through the arch, to the calmer, shallower waters. Swimming toward the safety of calmer waters, we are greeted with playful sea lion pups, eager to tug on fins, hands, or even a lock of hair or two.


Pruned hands and a chill through the wetsuit, even in the El Nino warm waters, signals it is time to lug ourselves back on board the pangas and head for the next chapter of our day’s adventure. Post written by Sarah Kingston, Doherty Marine Biology Postdoctoral Scholar, and faculty member in the Marine Science Semester.

Snorkeling for Sea Stars and Urchins

A few months ago, researchers from the Coastal Studies Center traveled up the coast to Rockland, a scenic, artsy fishing town with some fantastic marine life. Students and professors from the College of William and Mary, Stony Brook University, and Bowdoin College donned their snorkel gear  and wet suits before they walked down the nearly mile long interconnected slabs of granite known as the Rockland Breakwater.

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Koko Novak ’16 collecting sea stars for her lab.

The goal for the day was to collect sea stars and sea urchins for various projects at the college. Amy Johnson’s lab is working with the biomechanics of the various species—how their size affects how they move. Jon Allen’s lab (from William and Mary) is studying elements of sea star reproduction through experimentation.
Sea stars of all sizes were easily found in cracks and behind some of the larger rocks, out of the way of direct wave exposure. Sea urchins were grouped in colonies, and could be particularly difficult to pry off of the rock surface, not only because of their spines, but because when you removed one, all of the others in the area would cling tighter to the rock.

Researchers from three colleges at the Rockland Breakwater.

There were occasional hazards, primarily slippery rock, sharp barnacles, and very, very cold water. Despite the 80 degree day, the water was in the low 50s and researchers needed frequent breaks to warm up.

At the end, researchers sorted out the findings into what they needed–sea stars and urchins that would live in the marine lab for the remainder of the summer, throwing back all those that would not be used for research.

Interested in how sea stars move? Check out this underwater video filmed in the Marine Lab from David Conover’s Sea Shore Digital Diaries course from last year.

Summer Wrap Up

Horseshoe CrabAs the summer draws to a close, we would like to share some of the goings-on in and around the Coastal Studies Center. Most researchers at the Marine lab have ended the research portion of their projects, or are finishing up this week. Bowdoin Students are now beginning prep work for the President’s Science Symposium, that will take place this fall. Check out some of the happenings from this summer!

Snorkeling for Sea Stars and Urchins
HHLT Nature Camp
Coastal Studies Center Symposium

New Semester offers Old Opportunities

As professors prepare and plan for the autumn debut of the Bowdoin Marine Science Semester (BMSS) at the Coastal Studies Center, it is a nice time to reflect on some invaluable historic resources that the college has to offer.

The Schooner Bowdoin was a sailing vessel built in the early 1920s intended and designed for Arctic exploration. After being stranded for several years on an expedition to Crocker Land, Bowdoin alumnus Donald B. Macmillan decided to commission a ship that could withstand such conditions. The Schooner Bowdoin is 88 ft long, 21 ft wide, and equipped with a thick, sturdy frame and a large rudder to protect against ice. Throughout many exploratory expeditions to the arctic, this ship and its captain cultivated Bowdoin’s arctic legacy, placing itself at the forefront of polar research.

Now, the Schooner Bowdoin is in use at the Marine Maritime Academy as a training vessel for northward sailing. Last year, Bowdoin’s growing marine science program allowed for a weekend sailing expedition for biology students to gain a small taste of what living and working on a boat is like as a scientist. After a successful weekend, BMSS plans on making this an annual excursion.

The Bowdoin Marine Science Semester is a small, tight-knit program where students take all of their classes at the Coastal Studies Center, utilizing the opportunity to fully immerse themselves in their coursework and special projects. This semester is designed to give students incredible research tools, knowledge and experiences that will draw from Bowdoin’s previously underused resources.

BMSS also plans to offer a trip to Hurricane Island and a 10 day research expedition to Baja, California.

Students Communicate Science Through Film

Science to Story, the second of Professor David Conover’s two courses offered this academic year, examines the translation of science into stories and digital media that successfully engage public attention.

This semester, students began the immersion into science communication by analyzing psychological and behavioral studies relating people to climate change. Early research included an introduction to Dan Kahan’s study on the Cultural Cognition of Scientific Consensus and Anthony Lieserowitz’s work on the public’s perception of climate change. Furthermore, the class had the opportunity to speak with MIT’s Professor of Atmospheric Science, Kerry Emanuel, as well as with Discovery Channel’s executive producer, Paul Gasek, in order to get a better sense for what real-world challenges arise when communicating science to the public. Students have viewed various films and television shows such as The Day After Tomorrow, Earth Underwater, and the 2014 Emmy Award winning television series Years of Living Dangerously, analyzing these productions for their accuracy and effectiveness in conveying climate science.

Throughout the course of the semester, students have taken a creative approach to filming and editing and will continue to practice setting up green screen shoots and interviews as they prepare for a major final production. The class has spent time filming at the Coastal Studies Center working with Marine Biology Professors David Carlon and Sarah Kingston. While scientific accuracy and creativity are paramount, students are encouraged to take strong consideration of who their audience is and how the tones and undertones of their productions shape the way viewers connect with the scientific concepts being presented.

Perspectives on Climate Change is an early semester submission by Emi Gaal ‘15.