University of Maine graduate students use the DMC's facilities on a full-time, part-time or seasonal basis depending on their thesis advisor and research requirements. Most DMC graduate students are enrolled in the School of Marine Sciences Graduate Program and are pursing a M.S. or Ph.D. in Marine Biology, Oceanography or Marine Policy. Listed below are the current graduate students at the DMC and their research interests.
For more information about the SMS Graduate Programs, contact the program coordinators:
SMS Graduate Program of Oceanography
Dr. Mary Jane Perry • perrymj@maine.edu • (207) 563-3146, ext 245SMS Graduate Program of Marine Biology
Dr. Susan Brawley • brawley@maine.edu • (207) 581-2973SMS Graduate Program of Marine Policy
Dr. Yong Chen • ychen@maine.edu • (207) 581-4303SMS Marine Science and Policy Dual Degree Program
Dr. Yong Chen • ychen@maine.edu • (207) 581-4303
Skylar Bayer
Ph.D. candidate, Marine Biology
Advisor: Dr. Rick Wahle
skylar.bayer@maine.edu
Research interests: The biology, reproduction, and ecology of the sea scallop, Placopectin magellanicus, and the effects of population density on scallop fertilization success.
Nathan Briggs
Ph.D. candidate, Oceanography
Advisor: Dr. Mary Jane Perry
nathan.m.briggs@maine.edu
Research interests: factors affecting phytoplankton abundance and carbon sequestration.
Phoebe Jekielek
M.S. candidate, Dual Degree Program: Marine Biology & Marine Policy
Advisor: Dr. Jeff Runge
phoebe.jekielek@maine.edu
Research interests: Calanus copepods
Marissa McMahan
M.S. candidate, Marine Biology
Advisor: Dr. Young Chen
mmcmahan@gmri.org
Research interests: Trophic interactions, growth, and movement in juvenile and adult American lobsters (Homarus americanus). My current focus is on how environmental covariates, such as temperature, influence growth in juvenile populations. I'm also using acoustic telemetry to study how predation influences lobster movement.
Jennifer McHenry
M.S. candidate, Dual Degree Program: Marine Biology & Marine Policy
Advisor: Dr. Bob Steneck
jennifer.mchenry@umit.maine.edu
Research interests: the biological and social complexities of implementing marine spatial planning in the Gulf of Maine.
Brian Preziosi
M.S. candidate, Marine Biology
Advisor: Dr. Jeff Runge
brian.preziosi@maine.edu
Area of interest: zooplankton, ocean acidification. My current project is studying the effects of ocean acidification and rising temperature on copepod egg viability. Specifically I work with the species Calanus finmarchicus, which is a dominant member of the Gulf of Maine's zooplankton.
Anne Simpson
Ph.D. candidate, Marine Biology
Advisors: Dr. Les Watling & Dr. Kevin Eckelbarger
anne.simpson@umit.maine.edu
Watling Lab Webpage
Area of interest: Reproduction in deep & cold water octocorals
Susie Arnold,
Ph.D. Marine Biology, 2011
Spatial & Temporal Scales of Coral Recruitment & Key Ecological Processes.
Susie’s thesis research was grand in scope, focusing on the process of successful coral recruitment along the Mesoamerican barrier reef in the Caribbean Sea. On a scale of hundreds of miles, she surveyed the reef finding hotbeds of coral recruitment and regions of low recruitment. She then examined these regions more closely, on a scale of millimeters, to better understand the process of coral recruitment and survivorship in relation to other benthic organisms. She also examined the ecological role of parrotfish and herbivorous fish within the reef. Susie’s thesis advisor was Dr. Bob Steneck.
Charlene Bergeron, M.S. Marine Biology, 2010
Developing Region-specific Growth Models for the American Lobster
Charlene’s thesis focused on creating computerized growth models based on size-age relationships that will enhance lobster population studies and fishery management techniques. Following crustacean cohorts is complicated. The animals have no morphological features such as growth rings, so there is no way to tell the age of an individual. Charlene successfully combined size frequency distribution data from various sources and compared it with data from long-term monitoring and tagging programs to parameterize growth models for three regions in the Gulf of Maine. Charlene’s thesis advisor was Dr. Rick Wahle.
Meg Estapa, Ph.D. Oceanography, 2011
Photochemical Reactions of Particulate Organic Matte
Meg's research explored the role of sunlight in causing organic matter to dissolve from particles with the goal of predicting the “photodissolution” of particulate organic carbon (POC) in the coastal waters of Louisiana. She built a model that calculated dissolution rates from satellite data and laboratory experiments, worked out the seasonality of this reaction, and calculated its contribution to carbon cycling in the region. Her results shows that photodissolution of POC has similar importance to already established photochemical reactions of dissolved organic matter. Meg’s thesis advisors were Dr. Larry Mayer and Dr. Emmanuel Boss.
Mahima Jaini, M.S. Marine Biology, 2011
Internannual Variability in American Lobster Settlement: Correlations with Sea Surface Temperature, Wind Strees and River Discharge
Mahima examined the spatial correlation of lobster settlement with environmental variables in the Gulf of Maine and neighboring North Atlantic shelf waters. She compared 20 years of lobster settlement data with satellite derived data on sea surface temperature, wind stress and river discharge of three oceanographically distinct areas of the Gulf of Maine. The analysis revealed patterns of sea surface temperatures in the shelf waters that may be predictive of inshore lobster settlement. Mahima capped off her graduate work in June with the Best Student Paper Award at the International Conference and Workshop on Lobsters in Bergen, Norway. Her thesis advisor was Dr. Rick Wahle.
Mike Sauer, Ph.D. Oceanography, 2011
Green is the Gulf of Maine: How Have the Dynamics of CDOM ans Phytoplankton Influenced Remotely-Sensed Estimates of Chlorophyll A.
Satellite measurements of ocean color are proxies for estimating primary production and have been used with great succes the open ocean. Quantifying primary production in coastal waters from satellite data is more problematic. These waters contain colored dissolved organic material (CDOM) whose optical signals are indistinguishable from chlorophyll in the satellite data. Mike Sauer’s research focus was to tease apart these two signals and develope algorithms that when applied to satellite data provide a better estimation of coastal primary production. Dr. Collin Roesler, Bowdoin College, and Dr. Mary Jane Perry were Mike’s thesis advisors.
Nathan Briggs, M.S. Oceanography, 2010
Nathan Briggs was awarded and M.S. in Oceanography for his thesis titled: Analysis of Optical Spikes Reveals Dynamics of Aggregates in the Twilight Zone; work he did under the tutelage of Dr. Mary Jane Perry. The “biological pump,” whereby phytoplankton grow in the surface ocean, aggregate, and sink, is a critical process contributing to global atmospheric CO2 drawdown and provides the vast majority of food for deep ocean and benthic ecosystems. The phytoplankton aggregates, also called “marine snow,” are fragile and notoriously difficult to sample. In his thesis, Nathan presented a method for detecting these sinking clumps of phytoplankton and estimating their sinking speed using small optical instruments aboard automated underwater vehicles. The method revealed a large pulse of phytoplankton sinking at 75 meters per day following the North Atlantic spring phytoplankton bloom in 2008. His results confirm the value of autonomous platforms in studying biological processes in the ocean. Nathan is staying on in the Perry lab and pursuing a Ph.D.
Andrea Drzewianowski, M.S. Oceanography, 2008
Working with Dr. Mary Jane Perry, Andrea studied the diel patterns of ultraviolet absorption by phytoplankton in the Gulf of Maine. Phytoplankton need light for photosynthesis, but too much UV radiation is known to inhibit photosynthesis. MAAs (mycosporine-like amino acids) are believed to act as sunscreens, providing some protection to phytoplankton during periods of intense light. Andrea measured how much light is absorbed by MAAs and, in her thesis, reported that UV absorption was low in the morning and evening and high at midday. These data suggest that phytoplankton can respond very rapidly to changes in UV radiation.
Celeste Mosher, M.S. Oceanography, 2008
Working with Dr. Les Watling, Celeste studied the symbiotic relationship between an octocoral and a brittle star found on seamounts between 1500 and 3000 feet below sea level. On each octocoral specimen, Celeste found a solitary brittle star. She found evidence that the the brittle stars settle on the octocorals when both are young and that they continue to live together as they grow. Though the octocoral appears to neither benefit nor be disadvantaged by the brittle star, she believes the brittle star is likely obligate to the octocoral, gaining feeding and protective benefits. Celeste’s research shows that there is still much to be learned about seamount communities and reminds us that deep-sea trawling and other human impacts can cause irreparable harm, not to just one species to a host of others.
Lisa Pickell, Ph.D. Oceanography, 2008
Lisa completed her Ph.D. in September. Her advisor was Dr. Mark Wells. Using a novel continuous culture system at sea, Lisa exposed coastal and offshore phytoplankton populations to different forms of naturally occurring ligand-bound iron and copper. She found different algal assemblages in the different treatments suggesting that phytoplankton species have evolved various systems to maximize their uptake of these micronutrients. Pseudo-nitzschia, appears to have evolved a highly specialized iron uptake system powered by copper and domoic acid. In the presence of these compounds, the uptake of ligand-bound iron increases and Pseudo-nitzschia thrives, out competing other phytoplankton species in coastal environments.
Susie Arnold, M.S. Marine Policy & Marine Biology, 2007
Working with Dr. Bob Steneck, Susie Arnold studied the processes of coral recruitment on the reefs of Bonaire. Parrotfish and other herbivorous reef fish keep algal abundance low. Damselfish, however, ward off such grazing fish from their territories, creating areas of increased algal biomass. Focusing on the role of algal biomass on potential coral nursery habitats, Susie placed standardized terra-cotta coral settlement plates inside and outside of Damselfish territories. After 27 months, baby coral densities were 73% higher in well-grazed treatments. This suggests that herbivory, or a lack thereof, explains a considerable portion of the variance associated with coral recruitment at a very local scale. Thus, careful management and monitoring of herbivores could improve the potential for coral reefs to recover from disturbances.
Curt Brown, M.S. Marine Policy & Marine Biology, 2007
Curt Brown worked with Dr. Rick Wahle, Bigelow Laboratory for Ocean Sciences and Graduate Faculty in the School of Marine Sciences, studying predation pressure on juvenile lobsters from Rhode Island to Maine. He used video monitoring as well as diver and ROV surveys to determine abundance and diversity of lobster predators, and tethering experiments to determine relative predation rates. Curt’s findings confirm that predation pressure increases from north to south, as does the diversity and abundance of predatory fish. The interesting twist to his story is that a recent episode of very high recruitment of crabs has made life more risky for newly settled lobsters in the Gulf of Maine.For the Marine Policy portion of his degree, Curt looked at lobster fishery regulations which were largely initiated and enforced by lobstermen; exploring the history behind this unique conservation ethic and why it persists today.
Kelly Dorgan, Ph.D. Oceanography, 2007
Working with Dr. Pete Jumars, Kelly Dorgan studied the biomechanics of worm burrowing and discovered that a worm functions more like a wedge than a backhoe, using crack propagation rather than excavation, to tunnel though muddy sediments.
Gelatin is a suitable analog for mud, having many of the same mechanical properties. Like mud, it is a cohesive, elastic solid. Unlike mud, however, gelatin is translucent and birefringent. Using a video camera and polarized light Kelly was able to not only see crack propagation, but also quantify the stresses necessary for the sandworm, Nereis virens, to propagate cracks in the gelatin. The implications of Kelly’s findings may be far-reaching. In addition to “rewriting” textbooks on worm locomotion, her findings may also hold for other mud-inhabiting marine fauna including clams, small crustaceans and anemones, and may impact bioturbation models.
Elizabeth Stephenson, M.S. Marine Policy & Marine Biology, 2007
Elizabeth Stephenson began her graduate studies in 2002, barely a year after the invasive Asian shore crab (Hemigrapsus sanguineus) was first detected in Maine waters. She was thus presented with the unique opportunity to study a bioinvasion from its beginning stages. Working with advisor Dr. Bob Steneck and Robin Hadlock Seeley of Cornell University, Elizabeth explored whether temperature may limit range expansion by this species.
Elizabeth’s results suggest that the invasion is progressing much more slowly in Maine than in the southern New England and Mid-Atlantic states. The crab’s range seems to be stalled at the terminus of the cold Eastern Maine Coastal Current, and rates of population growth have been slow even in the warmest, most southern locations of the state. She speculates that the summer temperatures of Maine waters are too low to allow for regular successful recruitment, but notes that a warming ocean may create a more hospitable environment for the Asian shore crab as well as other future invaders.
Brandon Sackmann, Ph.D. Oceanography, 2006
Brandon Sackmann was awarded a Ph.D. in Oceanography for his dissertation “Remote Assessment of 4-D Phytoplankton Distributions off the Washington Coast.” For nearly three decades oceanographers have had access to sea surface data (including ocean color and temperature) collected by satellites. More recently oceanographers have come to use a variety of autonomous underwater vehicles to provide in-water measurements of chlorophyll-a fluorescence, optical backscattering, temperature, oxygen concentrations and more. Using data from Seaglider (an autonomous underwater glider) and from satellites for waters off the coast of Washington state, Brandon developed methods to combine the two data sets into a 4-dimensional model of the water column. The result offers a clear look at water column characteristics below the sea surface and improves regional estimates of phytoplankton biomass.
Mei Sato, M.S. Oceanography, 2006
Mei received a M.S. in Oceanography for her thesis titled “Diel and Tidal Rhythms of Emergence Events Based on Acoustic Observations in a Shallow Estuary." Her advisor was Dr. Pete Jumars. Emergence events were believed to be nighttime affairs, where under the cover of darkness, epibenthic organisms could safely swim up into the water column to feed and reproduce. Using acoustic profiling, Mei Sato found that diel migration was only part of the emergence story–tidal periods also played a role. Mei collected acoustic data over a longer time frame than previous researchers and was thereby able to track seasonal patterns of emergence and to differentiate between diel and tidal migrations. Mei’s data suggests that the mysid, Neomysis americana, has a diel pattern of emergence during the summer and a semidiurnal tidal rhythm in the fall. Such patterns reveal a more complex life history pattern of mysids as well as a greater degree of benthic-pelagic coupling.
Brian Thompson, M.S. Oceanography 2006
Brian Thompson received a Master’s degree in Oceanography for his thesis research titled “Phytoplankton Carrying Capacity in the Damariscotta River Estuary.” Working with Dr. MaryJane Perry, Brian investigated the variability of phytoplankton biomass in the Damariscotta River Estuary, as well as environmental factors, such as nutrients, light, and physical conditions, in order to assess the estuary's ability to sustain shellfish aquaculture farms. He found highest chlorophyll-a concentrations in the upper reaches of the estuary, above Glidden Ledge. Brian concluded that environmental conditions favoring phytoplankton production, and a longer residence time for water north of this constriction promoted these higher concentrations. Throughout the study Brian posted his chlorophyll-a data on the web. These continued postings have been a useful resource for local aquaculturists who need to make informed decisions about the management of their sea farms.
Jeanne Brown, M.S. Marine Biology & M.S. Marine Policy, 2006
“Save the Parrotfish!” was the take home message of Jeanne Brown’s Master’s thesis “Multi-scale and Multi-species Interaction Strength of Damselfishes on Coral Reef Ecosystems.” Working with advisor Dr. Bob Steneck, Jeanne spent hours underwater scouring the coral reefs of Bonaire to study the damselfish in reef ecosystems.
Protected as national parks with only a limited hook-and-line fishery, Bonaire’s reefs are the healthiest on the planet and have significant herbivorous fish populations, including damselfish and parrotfish of all sizes. These herbivores eat the macroscopic algae that would otherwise overrun the corals.
Jeanne’s research showed that damselfish eat some of the algae, but their territorial nature actually keep other smaller herbivorous fish at bay. Large parrotfish, however, were not deterred by the damselfish, grazing voraciously on macroalgae when and where they like.
Lisa Nigro, M.S. Microbiology, 2006
Lisa Nigro successfully defended her Master’s thesis titled “Distribution and Diversity of Bacterial Chemolithotrophs in Marine and Freshwater Sediments”, a topic not previously explored by scientists. Her advisor was Dr. Gary King. Chemolithotrophs can fix CO2 and use inorganic compounds as a food source. Lisa hypothesized that chemolithotrophs in sediments would differ based on the relative availability of sulfide. Using molecular techniques to look at RuBisCO, a CO2 fixation enzyme, she found that bacteria in sulfide-rich intertidal marine sediment mainly contained a RuBisCO gene type similar to that found in known sulfur-oxidizing bacteria. Sulfide-poor Damariscotta Lake sediment, however, largely contained a RuBisCO gene type mainly seen in carbon monoxide and hydrogen-oxidizing bacteria.