Eighteen Bowdoin students were awarded fellowships for coastal or marine faculty mentored summer research this summer. Two of these students traveled to Coos Bay Oregon to conduct studies on underwater locomotion at the Oregon Institute of Marine Biology with Bowdoin Professor Amy Johnson, and research associate Olaf Ellers. Another six Bowdoin students received summer fellowships to join a multi-year research collaborative with scientists and economists from Bowdoin, Bates and the University of Southern Maine who are studying past and present alewife populations in the Kennebec and Androscoggin watersheds. Jonathan Allen, Professor of Biology at William & Mary College returned for another year of research at the Coastal Studies marine lab, bringing four undergraduate research fellows from William & Mary College with him.
With the exception of our Bowdoin students working in Oregon, all the students gave Pecha Kucha presentations (20 slides/ 20 seconds per slide) on their research, or art projects over two days in late July.
Amy Anderson, ‘12
Advisor: Collin Roesler, Award: Doherty Fellowship
Investigation of Nitrate Values at the Harpswell Sound Buoy: The Sources of Nitrate and How it Affects Alexandruim fundyense Blooms (PDF)
Nutrients provide the basic building blocks for any species to live. Phytoplankton, the single-celled aquatic photosynthesizers, needs phosphate, silicate, and nitrogen compounds to meet their basic needs and function. Thus, the dynamics of phytoplankton growth in the natural environment can be controlled by nutrient availability. Nutrient dynamics are complicated, but by examining the major sources of nitrogen (in the form of nitrate, NO3, and nitrite, NO2), we are exploring the role nutrients play in the occurrences and blooms of Alexandrium fundyense, the harmful algal species that causes paralytic shellfish poisoning (PSP) in coastal Maine and is commonly known as red tide. We focused our study in Harpswell Sound, a sentinel site for A. fundyense appearance and early closures for PSP toxicity in shellfish. Research completed over the summer aimed to find a way to accurately estimate the concentration of nitrate hourly using instruments deployed on the Harpswell Sound buoy. By gaining information into an aspect of this organism, we have greater insight into its development which can led to the closure of fisheries.
Francis Armstrong, William and Mary College
Advisor: Jonathan Allen
Testing the consequenses of environmentally induced multiples in the sand dollar Echinarchnius parma
Andrew Bell '10, Henry Berghoff '11, Cory Elowe '11, Paul Hinman '12, Holly Jacobson '11, Catherine Johnston '12, and Benjamin Towne '12
Advisors: Phil Camill, John Lichter, and Guillermo Herrera, Award: Sustainability Solutions Partners
Ecological and Economic Recovery of the Kennebec and Androscoggin rivers, estuary, and nearshore marine environment (PDF)
Merrymeeting Bay is a freshwater tidal ecosystem in Midcoast Maine that supports a diverse and complex food web. Historically, migratory waterfowl and anadromous fish thrived in the bay. Human activities led to a collapse of the ecosystem in the second half of the twentieth century. Since then, water quality of the bay was able to rebound much faster than the biotic components of the bay. Improvements are still underway for populations of submerged aquatic vegetation, macroinvertebrates, and fish. Our research this summer focused on surveying populations of the bay and Lower Kennebec to begin to understand the current state of the ecosystem and the implications for human use. Although Merrymeeting Bay may never recover to the ecosystem it once was, advancements can be made through local environmental awareness and involvement and also from a continued investigation of the changes and improvements that occur in the future.
John Roger Brothers, '11
Advisor: Amy Johnson and Dan Thornhill, Award: HHMI
Effects of Climate Change on the Growth and Calcification of the Green Sea Urchin, Strongylocentrotus droebachiensis (PDF)
Increasing global atmospheric CO2 and increasing ocean temperatures have complex, and sometimes contrasting, effects on calcification and growth rates of marine calcifiers such as the sea urchin, Strongylocentrotus droebachiensis. For example, higher temperatures increase growth rates of S. droebachiensis smaller than 1 cm, but decrease growth rates of larger individuals. Increasing CO2 decreases food intake in these urchins and also induces the dissociation of CaCO3, which is needed for skeletal growth. Thus, the growth rate of small S. droebachiensis will be increased by higher temperatures, but decreased by higher CO2; the net effect is difficult to predict. We will grow small sea urchins in combinations of temperature and pH chosen based on moderate and extreme warming scenarios for 2100 predicted by the International Panel on Climate Change. Growth rates will be quantified by weighing urchins at two weeks intervals for two months. Skeletal calcification will be assessed by measuring ashed skeletal weight, the ratio of wet to ashed weight, skeletal density, calcium content and skeletal thickness. These data, in combination with data from Newcomb et al’s study on mussels and corals grown simultaneously with these urchins, will give insight into the consequences to marine calcifiers of increasing global CO2 and ocean temperatures.
Jeff Cook, ‘11
Advisor:Amy Johnson, Award: Rusack Fellowship
When to Run: The Underwater Walk-to-Run transition (PDF)
There exist differences between terrestrial and aquatic locomotion that are tractable to mathematical modeling and experimental analysis. One specific way in which terrestrial walking has been characterized is by the pendulum arc of motion (Griffin et al., 2004). What complicates this motion underwater is that higher fluid-dynamic forces and buoyancy supplement contact forces with the ground. More specifically, as Martinez (1996) suggests, fluid forces of drag and lift complicate analysis of walking underwater. The goal of this study is to determine if and when a walk-to-run transition occur for underwater walkers. The diversity of crabs available in Oregon allows a specific focus on the speeds at which crabs make a walk/run transition. To explore the potential walk-to-run transition of these crabs, we plan to design an experimental tank with an underwater treadmill (Scholnick, personal communication).
Located near the Cribstone Bridge in Harpswell, Maine is a unique array of elongated porphyroblasts within the Spring Point Formation. The mechanisms responsible for creating their unusual 3:1 length-to-width ratio is inextricably linked to the forces and processes that shaped the geology of New England, yet proposed hypothesis for their elongated form are not yet consistent with prior research on the mineral’s properties as well as the recognized history of the region. A full understanding of the garnet crystallization and transformation at this location could be extended to broader growth and deformation analysis of garnets in other locations. The goal of my research is to determine under what geological conditions these unusually elongated garnets formed by testing proposed hypothesis with the analysis of their mineral chemistry.
Maine has a significant heritage of traditional industries along its many hundreds of miles of coastline. Though the state has the postcard reputation as the “Vacationland,” what is less understood is the progressive deindustrialization and current threat to livelihoods of local coastal communities. Along with the loss of coastal job opportunities, the buildings essential to these industries are too losing their structural integrity and community importance. These buildings in themselves possess an interesting character that alludes to their functional histories. Growing up in Maine I have often been exposed to these structures having close ties to the coast as my family derives from Tremont and Southwest Harbor, Maine. My grandfather was a great craftsman, working in similar building types as a carpenter, as well as a shipbuilder. The final product of this project will ultimately be a series of paintings portraying these structures in a new light.
Connor Gallagher, '12
Advisor: Jonathan Allen and Amy Johnson, Award: HHMI
Ocean Acidifications Effect in Marine Calicifier Skeletal Structure and Predation Rates (PDF)
As global carbon dioxide levels rise (ipcc, 2007), the normal rate of ocean-air carbon cycling increases. When CO2 reacts with water, it dissolves into four species (CO2(aq)), carbonic acid H2CO3, and two other ions). Many marine organisms can tolerate the increase in acidity, but calcifiers, creatures who produce calcium carbonate skeletons, may be more or less able to sequester calcium and carbonate ions into their skeletons. At Bowdoin College’s marine lab on Orr’s Island, I will set up four tanks differing in pH. I will mark larvae with tetracycline at the start of the experiment and use distance from this mark to determine growth of the skeleton in each treatment. I will then choose appropriate predators and determine predation rate on larvae raised in the different treatments. I will measure length of larval arms, and use SEM to determine characteristics of the calcium in the skeletons. The results of my study provide insight into the consequences of ocean acidification of invertebrate calcification.
William Hatleberg, '11
Advisor: Dan Thornhill, Award:Doherty Fellowship
Diversity and Phylogenetics in Marine Siboglindid Worms (PDF)
Siboglinids are a highly specialized group of annelid worms that completely lack a digestive system. Instead, siboglinids rely on symbiotic bacteria that are capable of sequestering chemical energy from the environment, much like a plant can make energy from the sun. We currently recognize four main lineages of siboglinid worms: the frenulates, the vestimentiferans, Osedax, and the moniliferans. The most well known species of siboglinid worms, the vestimentiferans, are large (1-2m long) deep-sea worms found at hydrothermal vent and hydrocarbon seep environments. In contrast, very little is known about the monoliferan, Osedax or frenulate species, even though the frenulates are the most diverse (~140 described species), widespread, and accessible group of siboglinid worms. Previous examination of siboglinid phylogeny revealed a basal polytomy among the major siboglinid lineages; however, the current study suggests two possible evolutionary scenarios for sibolginid evolution: one in which the vestimentiferans species are the ancestral group and one where the frenulates are the most ancient lineage. The newest phylogenies also indicate a complex evolutionary history among the frenulate lineage, suggesting that there is an internal evolutionary structure among frenulate taxa that is not supported by previous methods of morphological identification.
Laura Newcomb, '11
Advisor: Daniel Thornhill and Amy Johnson, Award:Doherty Fellowship
The Effects of Climate Change on the Calfification of the Temperate Coral Astrangia poculata (PDF)
Anthropogenic carbon emissions have led to global atmospheric CO2 concentrations 80 ppm greater than in the past, resulting in increased global temperatures and decreased ocean pH. For marine calcifying organisms, scientists predict decreased oceanic pH, known as ocean acidification, will slow growth and calcification because increased CO2 decelerates formation of CaCO3. However, higher temperatures increase metabolic rate leading to more rapid calcification. In the Gulf of Maine, local calcifiers that may be affected by climate change include the temperate coral, Astrangia poculata, and the blue mussel, Mytilus edulis. At Bowdoin College’s Coastal Studies Center Marine Lab, we are manipulating temperature and pH to replicate two warming scenarios, one extreme and one moderate prediction of climatic conditions in 2100, as estimated by the International Panel on Climate Change 2007 report. Calcification and growth will be measured during the experiment every four weeks through buoyant wet weight and polyp counts for corals and size measurements for mussels. After two months, we will assess density of symbionts and tissue biomass for corals and measure shell thickness, shell density, calcium content, breaking strength and the shell mass to body mass ratio for mussels. The results, along with those of Brothers et al., should illuminate how climate change will affect some marine calcifiers.
Jordan Salyers, College of William and Mary
Advisor: Jonathan Allen
Estimating Predation Rates in Juvenile Sea Urchins
Three decades ago, the urchin population in the Northern Atlantic experienced a dramatic decrease due to overfishing. In the subsequent decades, reestablishment of a successful urchin population has been difficult. To determine the causes of poor reestablishment, we performed three experiments at Bowdoin’s Coastal Studies Center Marine Lab. The study investigated potential predator-induced causes of poor reestablishment. First, we carried out a flourochrome staining protocol to determine its effects on juvenile urchin growth. Second, we studied the rate of predation of various organisms, including the American lobster and hermit crabs, on juvenile urchins. Third, we released juvenile urchins in a mesocosm, a laboratory replication of field conditions, to determine if mesocosms are a viable method for tracking juvenile survival and growth. As research continues, these data will be used to determine the predators of juvenile urchins, the effects of different juvenile backgrounds on predation, and, consequently, the possible cause of slow urchin population reestablishment.
Coral reefs are the most diverse marine ecosystem, and understanding their ecology will play a vital role in protecting them. Reef-building corals form an obligatory symbiosis with the photosynthetic dinoflagellate Symbiodinium. These endosymbionts are crucial to the survival of corals, but most corals do not pass them on to offspring, so juveniles must acquire free-living Symbiodinium. The relationship between a coral and its symbiont tends to be specific, so the dispersal of free-living Symbiodinium could theoretically determine the composition of corals on a reef. Gaining a better understanding of symbiont distribution and dispersal from a reef may help predict how corals will respond to the changing climate and how to better protect reefs. To investigate gene flow, Little Grecian Reef in the Florida Keys was sampled for the presence of free-living Symbiodinium in the water column and sediment along a transect leading off the reef. Running PCR with the 23S chloroplast gene, Symbiodinium is found as far as twenty meters off the reef. Using cultures and specific numbers of cells, the protocol used in extracting DNA detects Symbiodinium with a density as low as 1,000 cells per liter of water.
Jennifer Wenz, '12
Advisor: Amy Johnson, Award: Doherty Fellowship
The Divesity of Underwater Locomotion in Coos Bay, Oregon (PDF)
Terrestrial walking has been very well studied and mathematically modeled. However, underwater locomotion has received little attention by researchers. The mathematical equation derived for terrestrial locomotion cannot be applied to aquatic locomotion because underwater buoyancy and positive lift effectively decrease gravitational force on the animal and fluid forces increase 800-fold. The goal of this study is to fit crab gaits, using Mathematica, to the theoretical predictions derived from Ellers et al.’s (2009) models of an inverted pendulum swinging underwater. Using the motion analysis software ProAnalyst, I will map x,y coordinates and velocity of the crab’s movement at multiple points on its body. Working as a team with Jeff Cook (see above) we will be able to videotape and analyzes the motion for a broader species range of crabs. We will measure species and size specific buoyancy, leg length, and carapace length and width, thereby enabling broader insight into which aspects of morphology best enable underwater walking.
Connor White, College of William and Mary
Advisor: Jonathan Allen
The effect of egg capsule clustering on embryonic survival in the dogwhelk Nucella lapillus
Observations of several species from a taxonomically diverse group of amphibians, reptiles, arachnids, coleopterans, lepidopterans and molluscs have suggested that clustering of eggs is a survival strategy through which rates of predation or desiccation are decreased. The dogwhelk Nucella lapillus is an intertidal predatory snail that deposits egg capsules under intertidal rocks in clusters of up to 1000 capsules. These benthic egg capsules are then left to develop undefended for up to four months. This study investigated the adaptive significance of clustering eggs capsules by manipulating cluster size in the field over a five week span. In this study and previous work it was found that capsules themselves provide little direct protection against predators. However, it was found that clustering of egg capsules is beneficial and significantly reduces predation relative to uniformly spaced egg capsules. Similarly, it appears that encapsulation alone is an ineffective means to prevent desiccation induced mortality in the embryos. However, this study found that clustering of capsules significantly reduced mortality due to desiccation. Overall, clustering increased survival among egg capsules and the increase in survival was roughly proportional to cluster size. In addition we conducted laboratory predation trials to identify potential predators on N. lapillus egg capsules. We found that lobsters, green crabs and rock crabs all consumed N. lapillus capsules in the lab but hermit crabs did not.
Teerawit Wiwatpanit, '10
Advisor: Patsy Dickinson, Award: Doherty Fellowship
Possible Effcts of the Molting Hormone 20-hydroxyecdysone on Cardiomodulation by C-type Allatostatins in the American Lobster (PDF)
The American lobster is one of the many marine organisms that have to cope with periodic physiological changes due to molting behavior. Throughout the molting cycle, there are differential releases of hormones into the hemolymph which essentially flows through the heart. Thus, the cardiac function must vary in order for lobsters to cope with change in the internal environment and the changing demands for blood supply. The different physiological needs can also be a result of changes of external influences, such as temperature and level of oxygenation. By examining how the molting behavior alters the control of physiological system, we would be able to better understand the fundamental role of biological modulation in the lobster. Previous studies have shown that molting behavior in lobsters involves various endocrine mechanisms that can alter physiological conditions within the lobster. Moreover, there is significant water uptake during lobster molting behavior, suggesting the demand for a regulation of the cardiac output and the rate of hemolymph flow to accommodate such changes. Thus, we hypothesized that the variability of the change in contraction amplitude due to C-ASTS might be due to interactions of the peptides or their receptors and the crustacean molt cycle.
The compounds 20-hydroxyecdysone and hemocyanin in the lobster hemolymph have been shown to vary during different stages of the crustacean molt cycle. Because 20-HE is a steroid hormone, the surge of this hormone could alter the transcription of receptor proteins in certain tissues, in our case, the heart. It is possible that 20-HE bind to the putative steroid receptor, forming a complex that serves as a transcription factor, activating the expression of the C-AST receptors in the cardiac neuromuscular system. With different expression level of C-AST receptors, the heart as a whole is likely to respond differently to the presence of C-ASTS released into the lobster hemolymph.