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Graduate students take lessons to Bay for plankton research cruise

May 9, 2017
Students in the biological oceanography and physical oceanography classes based at Horn Point Laboratory boarded the Rachel Carson Research Vessel for the lab's annual plankton research cruise.

Students threw on life jackets and met Professor Raleigh Hood starboard of the Rachel Carson research vessel as it came to a halt along the water in Chesapeake Bay.  

The Horn Point Laboratory professor and biological oceanographer introduced to the students the ship’s new CTD Rosette, an instrument that collects water samples so they could measure conductivity, temperature, and depth.

Professor Judy O'Neil shows the graduate students a net that will be used to catch plankton from the Choptank River.

Judy O’Neil, a Horn Point professor and plankton expert, was preparing another group of students to collect zooplankton or phytoplankton.

On a recent Friday morning, class was in session on the Choptank River, a major tributary of the Chesapeake Bay. The research cruise was an opportunity for the professors to breathe life into a semester of lectures.

“We need to get students out in the field to actually see what we’re talking about,” O’Neil said. “This is a lecture class, and there’s a lot of great videos and things like that, but nothing beats coming out here, taking a sample of water, and seeing what’s in a drop of water out here in the environment.”

The Rachel Carson set off from the Horn Point Laboratory pier on an early spring morning for a roughly six-hour cruise. It was one of two days about a dozen graduate students from the Marine Environmental and Estuarine Studies (MEES) program from the University of Maryland Center for Environmental Science, University of Maryland College Park, University of Maryland Eastern Shore, and George Washington University would spend on the ship.

On Saturday, April 29, the students had a second cruise along with Horn Point faculty Louis Plough and Sairah Malkin. Plough, an expert in population genetics of marine animals and larval biology of marine invertebrates, and Malkin, an expert in aquatic biogeochemistry and microbial ecology, guided the students as they trawled for fish and studied the benthic zone, home to the organisms that live at the lowest level of the Bay.

We really can take most of the concepts that we teach in class and in one cruise, we can put it all together.

Raleigh Hood
Horn Point Laboratory professor and biological oceanographer

Two students ready a CTD rosette to be lowered into the water. Its name signals what the tube-based device: It measures conductivity, temperature, and depth.

This plankton cruise is an annual tradition for the MEES biological oceanography class. This year, the trip also included physical oceanography students, Victoria Coles, a physical oceanographer and member of Horn Point’s faculty, and Carlos Lozano, a faculty research assistant from Chesapeake Biological Laboratory who operated the new CTD.

On Friday, there were three stops along the river, allowing the students to take turns collecting and analyzing samples from each of three stations. A few students steadied the CTD as the tube-based circular device Hood likened to a gatling gun was lowered into the water. Designed to collect water at various depths, the instrument would help the students study the water columns at each sampling site.

The students used two differently sized meshed nets with plastic cups (cod-ends) at their base to collect phytoplankton and zooplankton.

Phytoplankton, also called microalgae, is a type of plankton that serves as food for a wide range of marine life from jellyfish to whales. Because contains chlorophyll, it needs sunlight to live and grow. O’Neil put a glass of water pulled from the Bay under a light to try to draw out phytoplankton to view under a microscope, but had little luck, a sign there weren’t much in the water. Zooplankton are tiny animals found near the surface of a body of water, typically drifting with currents. They live near the base of the aquatic food web, serving as a meal for larger creatures, but they dine on phytoplankton.

Professor Raleigh Hood talks to one group about measuring water quality.
Split up in smaller groups, the graduate students took turns sampling the water columns and searching for plankton to view under a microscope.
Meshed nets like this one were dragged across the water from the Rachel Carson to pull in plankton for the group to observe.
Maureen Brooks and the students in her zooplankton group observe what organisms were in the water they pulled from the river.

On the research cruise, students and faculty plucked these often-microscopic organisms from the water using the meshed nets. Once the nets were cast into the water, Chief Engineer and First Mate Rob Nilsen would signal vessel Capt. Michael Hulme to push forward to gather a sample across a stretch of the water. The students used microscopes in the wet lab to better observe what they pulled in.

“Looking at some ctenophores [commonly called comb jellies] and lion’s mane jellyfish up close was pretty cool,” said Matt Damiano, a graduate student from Chesapeake Biological Laboratory. “I got to see a decomposing polychaete worm in one’s mouth. That’s another thing you get when you go on one of these cruises, an up-close-and-personal look at some of the animals we study, which is cool in its own right.”


Some of what they found held some surprises for even the professors on board.

“We saw evidence of the deterioration of the spring bloom with accumulating chlorophyll in the deep channel of the Choptank River,” Hood said. “I’ve never seen that before.”

With most chlorophyll settling to the bottom of the river where it was beyond sunlit waters, tracking sun-loving phytoplankton was made more difficult. What the group on the cruise saw instead in their water samples were several zooplankton grazers and evidence they arrived at the end of a big meal.

O’Neil said this was the first time in several years that the research cruise took place in the spring instead of the fall. While she expected seasonal differences, she was surprised to have missed the spring bloom completely.

Among the zooplankton was another new sight for Hood. He has seen barnacle in various stages of life, but never as a “cypris” larvae, the stage before it reaches adulthood, until the cruise.

“It’s a great experience not for just the students, but it’s a good experience for the instructors, as well,” Hood said. “That’s the point. We really can take most of the concepts that we teach in class and in one cruise, we can put it all together.”

Maureen Brooks, a doctoral candidate at Horn Point and teaching assistant for the biological oceanography class, echoed Hood about the value of the annual research cruise.

“A lot of these students—in their own research or own careers—they’re going to need to learn the techniques that we’re using today in terms of sampling, in terms of what this equipment is, and in terms of handling yourself on a research vessel,” she said.

Looking out over the water as the Carson cruised to the third sampling site, Nicole Basenback, a Chesapeake Biological Laboratory graduate student, said a more typical day for her is in front of a computer.

“I work with models so I use a lot of data,” she said, “but this is where data comes from.”

Hannah Morrissette, who studies with Hood at Horn Point Laboratory, appreciated the change of scenery, too.

“It’s been fantastic. I had a blast,” she said. “In class, some people don’t normally get out on a boat, they don’t have hands-on experience to come out here and get quality time with all the instruments, so it’s been really great to learn all the different things.”

Copepods, small crustaceans that play an important role in the aquatic food web, move below a microscope.
Ana Sosa, a graduate student at IMET, peers into a microscope to identify plankton pulled from the water.
Graduate student Matt Damiano holds a lion's mane jellyfish. Several small jellyfish, a type of zooplankton, were found in the sampled water.