What I Did This Summer: Studying the Science of Red Tide

Sasha Kramer ’16 spent the summer at Bowdoin’s Coastal Studies Center, studying the dynamics of algal blooms that cause paralytic shellfish poisoning. Funded by a Doherty Coastal Studies Research Fellowship, she has been collaborating in the lab and on the water with Associate Professor of Earth and Oceanographic Science Collin Roesler, labmates Schuyler Nardelli ’15 and Dana White ’15, and Senior Research Associate Sue Drapeau.

Here’s Sasha:

Sasha Kramer ’16

Sasha Kramer ’16

By the third hour, Schuyler and I had our sampling routine down to a perfect twelve minutes. We felt pretty impressed with ourselves, though the only witnesses to our accomplishment were a couple of jellyfish and a swarm of gnats.

“I can’t see it!” one of us would call, lowering the black-and-white patterned Secchi disk to determine the depth where light no longer penetrated the water and the disk became instantly invisible. Next, we checked the light level at the surface and at depth with the delicate, anchor-shaped LI-COR sensor. We moved on to fill two of our many Nalgene bottles (carefully labeled the day before with depths, times, and sample numbers) to the top with seawater.

Then we lowered the heavy CTD, a profiling sensor for measurements such as depth, temperature, salinity, density, dissolved oxygen concentration, and chlorophyll fluorescence – which tells us how much phytoplankton is lurking in the water column. We towed it up slowly, our hands starting to burn from the pull of the wet rope. Finally, we filtered a fraction of each water sample to set aside for a later nutrient analysis. All of this in just twelve minutes.

Schuyler and I had been on the dock at the Bowdoin Coastal Studies Center since 5:30 a.m., the first people awake in Harpswell Sound on a sunny Wednesday in June (followed by the lobstermen, who gave us a cheery wave as they chugged by at around 7:00). Although we had complained good-naturedly to our roommates about waking up so early for a full day of sampling, we’d found ourselves wide awake as soon as we got in the van to drive out to Orr’s Island. The road was empty; arriving at the dock, we found perfect stillness. The water was calm, with a thin layer of mist hovering in the rising sunlight, and Harpswell Sound was silent.

Our purpose over the course of the twelve-hour sampling day, from 6 a.m. to 6 p.m., was to continuously collect dockside measurements that could then be compared to our observations of tidal height and sunlight level, and further linked to our data collected over the course of the summer from the Bowdoin Buoy in the middle of the Sound.

Ultimately, our goal was to discover more about the dynamics of the phytoplankton populations. Each year in the Gulf of Maine, the oceanic ecosystem is impacted by Harmful Algal Blooms – more commonly known as “red tide” – made up of phytoplankton such as Alexandrium fundyense. These toxic blooms are known to cause paralytic shellfish poisoning, and can drastically affect the health of fisheries and beaches across New England.

dock

“I’ve got the ice!” Schuyler called from the top of the dock at 8:30 a.m. We were only halfway through our third hour of sampling, but the sun was already high enough in the sky that we were worried about our water samples warming up, which could compromise our data. The giant blocks of ice from the nearby “Store on Orr’s” would not come apart very easily: we spent the time until our 9 a.m. sample picking at the ice blocks with pens and screwdrivers, hacking off small chips and throwing them into the massive coolers to insulate our samples.

At 10 a.m., we got some company when our labmates Dana, Sue, and Collin showed up. Paul Joyce, our captain, started up the engine on the R/V Laine to take us out to the Bowdoin Buoy, which continuously collects nutrient data with the help of a small sensor called an ISUS (in situ ultraviolet spectrophotometer). We completed many of the same measurements from the dock out at the buoy — checking the light level, taking water samples at depth, profiling for specific water qualities — and then headed back toward to the dock.

Later, in the lab, Schuyler would examine the biggest trends in particle size data, in hopes of finding a relationship between the species and sizes of phytoplankton in the Sound. This would allow researchers profiling the water column to more quickly identify Alexandrium, which is otherwise all but impossible to distinguish from other species in the field.

Meanwhile, I would compare the trends in nutrients to the trends in phytoplankton concentration in hopes of demonstrating a more distinct correlation between Harmful Algal Blooms and the concentration of nutrients – generally nitrate (NO3-). If a certain nitrate concentration can be matched to a peak in phytoplankton biomass in Harpswell Sound, and further correlated with historical records of Harmful Algal Blooms, then we might be able to more easily predict when these blooms will affect the Gulf of Maine.

coast

While we were out at the buoy, the wind had picked up; we could only hope that the growing swarms of black flies on the dock would disappear in the stiff breeze. On the ride back to the Coastal Studies Center, we kept an eye out for porpoises. But we seemed to see the most interesting wildlife on the rainiest days in the boat, and the blazing sun overhead proved inauspicious for marine mammal sightings.

The next six hours flew by. We ate lunch as the sun slipped over its peak in the sky. We picked at the melting ice blocks. At the top of each hour, we completed our sampling routine. Schuyler and I brought blankets to stay comfy on the dock and books to fill the time when we weren’t sampling – but as the day wore on, we found ourselves more content to watch a baby duck glide across the short expanse of ocean from the shore to the dock and back, carefully paddling around our oceanographic equipment. At 6:15 pm, we packed up our supplies and started the walk up to the vans. The sun was on the opposite side of the sky, but the peaceful beauty that had defined our day remained.

On our return to the lab, we would filter our samples and start to process the data. While we were excited to discover the results of our long day’s work, it was hard to leave this slice of Harpswell Sound – having watched the sky and sea change from dawn to dusk, we felt a sort of protective ownership over the area. But we left, with the confidence that we would return in a few days, knowing more than we had before about the marine world surrounding us.

Photographs courtesy of Sasha Kramer ’16

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