2013 Summer Research
Karina Graeter, '14
Understanding Magma Production in the Central Taupo Volcanic Zone, New Zealand, Using Quartz Crystal Clusters
Anna Hall, '15, Anna Westervelt, '14, & Cameron Adams, '14
Implications of Climate Variability on Arctic Peatland Carbon Fluxes in Eastern Hudson Bay Lowlands, Manitoba, Canada
Margaret Lindeman, '15
Analysis of extreme wave and temperature events in Moorea, French Polynesia
Stephanie Lynn, '14
The Fundy Group of Grand Manan: Sources, Relationships, and Cooling Rates
Alana Menendez, '15
NASA Three Rivers: Nutrient Flux to the Gulf of Maine
Nate Niles, '15
Studying the Passage of American Shad at the Fishway on the Brunswick Hydroelectric Dam
Ryan Peabody, '14
Coastal Current in the Gulf of Maine: A Mechanism for Algal Bloom Transport
Hugh Ratcliffe, '15
Optical and Biogeochemical Analyses of Maine's Rivers
Karl Reinhart, '15
Analyzing Algal Bloom Distribution and Modeling its Productivity in Harpswell Sound
Matt Savard, '14
Testing Mobile Computing to Enhance Student Learning in the Earth & Oceanographic Science Curriculum
Gabi Serrato Marks, '15
Trace Elements as Climate Proxies in Bamboo Coral from the Gulf of Alaska
Dana White, '15
Optical Characterization of Dissolved Organic Matter in Maine Rivers
See past years »
2011 Summer Research
Matthew Ramos, '12
Dynamics of carbon export from Maine watersheds to the Gulf of Maine
2010 Summer Research
Alexander Roberts-Pierel, '12 and Emma Beck, Colby College ‘12
Advisors: Rachel Beane and Bill Sullivan, Colby College
Quartz Crystallographic Fabrics from the Northern Mylonite Zone of the Cheyenne Belt, Se Wyoming
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The Cheyenne belt, exposed in SE Wyoming, is a system of high-strain zones interpreted as the suture zone between the 1.8 billion year old Colorado province and the 2.5 billion year old Wyoming province. Our research aimed to discover more about the tectonic history of this area, as well as to help geologists better understand deformation of Earth’s middle crust. The fault was hypothesized to be transpressional, having characteristics of horizontal simple shear as well as compression. To test this transpression hypothesis, we measured quartz CPO in quartz-rich samples to look for shallowly plunging a-axis maxima indicative of large components of horizontal simple shear during transpression. Quartz CPOs were measured in thirteen samples using Electron Backscatter Diffraction within a Scanning Electron Microscope. The consistent strong asymmetry of the quartz CPOs combined with the steeply plunging a-axis maxima argue against the transpression hypothesis, and instead indicate that this part of the northern mylonite zone records SE-side-up, oblique-slip motion with a large dip-slip component consistent with existing interpretations.
Phytoplankton are single-celled aquatic photosynthesizers, which use chlorophyll to convert light into energy. Because chlorophyll cannot absorb green underwater light, phytoplankton produce taxonomically-unique green-absorbing accessory photosynthetic pigments that can. These pigments change the absorption spectra and associated fluorescence response, allowing for taxonomic identification. My project focuses on the utility of using an instrument that measures chlorophyll fluorescence in response to excitation at three wavelengths (435nm, 470nm, 532nm, 3 wavelength eXcitation, 1 wavelength eMission). The goal is to use these observations to identify taxonomic changes in phytoplankton blooms, based upon their pigmentation and fluorescence response difference. The specific application is to identify transitions between the common, harmless diatoms and the potentially Paralytic-Shellfish-Poison-causing dinoflagellates, by looking at changes in their characteristic pigments, fucoxanthin and peridinen, respectively. Chlorophyll derived from 435nm-stimulated fluorescence and that determined analytically compared well overall, although variations due to fluorescence quenching and species composition were observed. By comparing the ratio of chlorophyll fluorescence intensity resulting from excitation at 435nm:470nm measured in Harpswell Sound to those obtained from monoculture calibrations, the ratio value distinguishing diatoms or dinoflagellates was quantified. The relationship between the fluorescence ratio 435nm:470nm and the fucoxanthin:peridinin ratio was statistically significant, confirming the relationship between fluorescence ratios and bloom composition. This capability will provide the basis for early detection of potentially toxic blooms forming in Harpswell Sound, a sentinel site for coastal bloom development this species of dinoflagellate.
Due to climate change and a shift in monsoon weather patterns over India, the phytoplankter Noctiluca scintillans has been overtaking phytoplankton blooms in the Arabian Sea and producing massive subsurface low dissolved oxygen zones when it dies that can lead to wide spread fish kills. Identifying N. scintillans distributions and natural abundances during these blooms will provide a better indication of the environmental conditions that favor this species. This in turn may provide insight into its recent appearance in the Arabian Sea. One way to assess phytoplankton composition in the ocean is through pigment-based taxonomic differences. These pigment differences can be quantified using either High Pressure Liquid Chromatography, spectral absorption or multi-excitation chlorophyll fluorescence. The latter approach, while still in exploratory stages provides a means for realtime quantification of taxonomy in situ, without time intensive laboratory analyses. The multi-excitation chlorophyll fluorescence is measured with the custom designed, now commercially available ECO 3X1M sensor (3 wavelength eXcitation, 1 wavelength eMission, WETLabs Inc.). The absence of factory calibrations requires (1) routine calibrations of each sensor with a standard culture to quantify fluorescence to chlorophyll a response; (2) calibration with multiple species of diverse pigmentation to define species-specific pigment-based taxonomic response; (3) a means to quantify a transfer function in order to calculate the species-specific fluorescence response between sensors. Fluorescence ratios among the three emitted wavelengths can then be computed and used to assess pigment ratios as a taxonomic tool. Following this approach, fluorescence profiles from three stations in the Arabian Sea from 2010 were analyzed. By isolating zones of uniform fluorescence ratios, seven different phytoplankton populations of different pigmentation have been identified. These populations will be evaluated for specific pigment analysis and the taxonomic composition identified.
Nutrients provide the basic building blocks for any living organisms. Phytoplankton, the single-celled aquatic photosynthesizers, specifically require nitrogen compounds to meet their basic needs and functions. The dynamics of phytoplankton growth in the marine environment can be controlled by nitrogen availability. While nutrient dynamics are complicated, a first step is to explore the roles that nitrogen in the forms of nitrate, NO3, and nitrite, NO2, play in the occurrences and composition of blooms in a dynamic estuary in Casco Bay. Harpswell Sound, is a retentive basin and appears to be a sentinel site for the formation of blooms of Alexandrium fundyense, the causative species for paralytic shellfish poisoning (PSP) in coastal Maine.
A realtime reporting oceanographic buoy in Harpswell Sound is equipped with a suite of hydrographic and optical sensors, including an optical nitrate sensor (Satlantic ISUS). The sensor makes use of the specific absorption coefficients of nitrate and nitrite in the ultraviolet range, a portion of the spectrum for which dissolved organic matter, which is plentiful in this region, also absorbs. Research completed over the summer aimed to investigate the accuracy and precision of optically-based nitrate concentrations compared to standard analytic methods. In the laboratory, we developed standard curves relating nitrate concentration to absorption peak height by chemically reconstructing seawater from its constituent parts to understand its complexities. This allowed for the determination of in situ nutrient concentrations and shed light on nutrient dynamics.
2009 Summer Research
Whitney Grass, '10
Advisor: Peter Lea, Award: Kibbe Fellowship
Exploring nutrient dynamics in the Androscoggin Lake watershed: Bioavailable phosphorus in agricultural runoff
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Androscoggin Lake discharges into the Androscoggin River under normal flow conditions. During high runoff events, however, flow direction within the Dead River reverses, and Androscoggin River water surges into the lake. Since the early 1900's the Androscoggin River has been heavily polluted and conventional thought ascribed poor water quality in the lake to periodic back-flooding of the polluted Androscoggin River. Much of the concern with the lake water quality centers upon nutrients, particularly high levels of phosphorus, which stimulates algal growth which reduces water clarity, depletes the water oxygen level and hinders aquatic life. Research conducted by Peter Lea's Watershed Hydrology course found that sites with the highest phosphorus concentrations are located along the Dead River and not in the Androscoggin River. This pattern suggests that farmland bordering the Dead River, with its runoff of manure, fertilizer and exacerbation of soil erosion by plowing and tilling could be responsible for the poor water quality. Whitney's research analyzed non-point sources of nutrient loading along the Dead River, particularly in regard to agricultural influences.
Samuel Hankinson, '10
Advisor: Ed Laine, Award: Rusack Fellowship
The influence of oceanographic and hydrological factors on blooms of the harmful phytoplankton Alexandrium fundyesnes in Harpswell Sound
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Harpswell Sound is the home of recurring blooms of the harmful phytoplankton Alexandrium fundyense, with the largest bloom occurring during the spring season. However in 2008 the ‘spring bloom’ occurred long before it was expected. Various explanations have been considered – the current one points to a large influx of fresh water from the Kennebec River – but the picture is far from complete. By examining the record of river discharge for the Kennebec, the three year-long hourly time series of temperature from the buoy in Harpswell Sound, similar temperature time series from nearby GoMOOS buoys, and from two years of twice weekly discrete sampling in Harpswell Sound, this investigation focused on determining whether the freshwater input was sufficiently large enough to influence water temperatures enough to create a suitable environment for a bloom of A. fundyense, or perhaps if there were other factors involved in warming the water such as currents from shallower regions of Casco Bay.
Jane Koopman, '10
Advisor: Peter Lea, Award: Doherty Fellowship
Dynamics of Estuarine Sand Dunes in Merrymeeting Bay
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Merrymeeting Bay is a large tidal, freshwater bay that feeds Maine’s coastal beaches with sand. With rising global sea levels however, there is concern that much of this key sediment supply could be trapped in the bay and estuary, depriving Maine’s coast of its lifeblood.
By observing the sand dunes of the bay over a period of time and correlating this data with flow data obtained through the department’s Acoustic Doppler Current Profiler (ADCP) and side-scan sonar, I will look at the relationship between dune characteristics and flow variations (high and low tides, spring and neep cycles). The outcome will be a better understanding of both the spatial and temporal variation of how sand moves within these dunes in response to changing currents.
2007 Summer Research
Millan AbiNader, '10
Developing Protocols for Quantifying Alexandrium cysts in Casco Bay Water and Sediments
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This past summer I studied Alexandrium cysts in Harpswell Sound. For unknown reasons, Harpswell Sound blooms earlier than other parts of Casco Bay, making it an indicator site for Harmful Algal Blooms. Researchers postulate that there is a cyst bed in Harpswell that contributes to the early blooms. I took bottom samples and counted the cysts present in the mud using epifluorescent microscopy. This research will help us gain an idea of the number and location of Alexandrium cysts in the sound. I also compared current data from the Bowdoin College buoy with the PSP score in Harpswell Sound, to see if the current had any impact on blooms. This research will add to our understanding of the bloom dynamics in Harpswell Sound.
2006 Summer Research
Eric Hawes, '09
Strain Partitioning in Anorthosite
Thomas Duffy, '07
As a recepient of a fellowship from the Gibbons Summer Research Program, I used Google Earth to assist in developing teaching materials for Sedimentary and Glacial Geology.
Astrid Rodriguez, '07
Microstructural Investigation of Martian Meteorite EETA79001
Astrid's summer was spent using the EBSD system to examine pigeonite microstructures in two lithologies that are separated by a linear contact.
Owen McKenna, '07
Geology of the Vinalhaven Magmatic Complex, Coastal Maine
Owen focused his research on the Vinalhaven Intrusive Complex on Vinalhaven Island off of mid-coast Maine. By taking thin sections of rock samples and using Bowdoin's EBSD system, he hoped to shed some light on the flow and compressive events that helped shape this complex.
Greg Wyka, '08
Mapping Harpswell Sound
Greg spent his days out on the 21' Seaway surveying the floor of Harpswell Sound with a Knudsen Echosounder. He found sediment waves that were discovered by a student in a prior year and compared the findings. He also made a bathymetric map of Harpswell Sound using a multibeam sonar system.