SEA Semester
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Student Research

Academics

Selected Student Research Projects

Marine Debris

Atlantic Ocean Surface Circulation and the Effects on Plastic Accumulation

Student: Collin Schmitt (Roger Williams University), C-231 Ocean Exploration
Chief Scientist: Dr. Deb Goodwin

Research Abstract: Click for Details

Plastic in the Western Atlantic Ocean has been tracked and studied for numerous years. It has been possible to identify and make quantitative analyses about areas of plastic accumulation due to studies of natural weather and ocean patterns. Studies have shown that most plastic lies in convergence zones particularly the Sub Tropical Convergence Zone. This study focused on current magnitude, wind speed and fluorescence as identifiers of convergence zones at both local and large scale levels along the cruise track from Woods Hole, Massachusetts to Grenada, West Indies. More specifically, this study attempted to draw a correlation between low current and wind speeds and plastic density. Fluorescence was a subsequent source of convergence verification that was studied. Areas low in chlorophyll would potentially be nutrient depleted and high in debris. The data showed that more plastic in total was found in areas where the currents and winds were relatively low. However, the most plastic per tow was found in areas of high wind and current speed. These data sets were analyzed and graphed to provide visual evidence of the concluding research. This research provided valuable data to the continuous research of plastic in the Atlantic Ocean.

Marine Debris in the Regions of Jamaica and the Dominican Republic

Students: Aliza Goldberg (Barnard College) & Hilary Burt (St. Lawrence University), C-228 Colonization to Conservation in the Caribbean
Chief Scientist: Dr. Jeff Schell

Research Excerpt: Click for Details

The first question we addressed was: what affects the concentration of marine debris on beaches and in nearby waters, currents or littering?  Answering this question entailed performing quantitative and qualitative beach surveys in the Dominican Republic and Jamaica as well as performing Neuston net deployments and daily six-minute observations to collect data on the abundance of debris in the water around those two regions.  The second question we addressed was: how do the solid waste management plans of the Dominican Republic and Jamaica differ, and if so, how do the policies affect the abundance of marine debris on their beaches and nearby waters?  We answered this question by studying each country’s waste management plan, observing how the plans are being enforced with recycling programs, and visiting local markets to understand how Dominicans and Jamaicans use different types of materials.

A Study of Biofilm Composition and Growth on Macroplastics in the North Equatorial Pacific

Students: Christopher Klein (Colorado College), Justine Paradis (Vassar College) & Stephen Johnson (Rochester Institute of Technology), S-237 Ocean Exploration
Chief Scientist: Dr. Deb Goodwin

Research Abstract Excerpt: Click for Details

Plastics are an ever-increasing source of pollution in the world’s oceans, though there is still relatively little known about their impact and interaction with marine wildlife and environment, especially in terms of rate and extent of biodegradation.  However, it has been observed that floating plastic pieces develop biofilms, a layer of bacterial organisms that cover various surfaces. 

In this study, pieces of high density polyethylene (HDPE), polypropylene (PP), and polylactic acid (PLA) were suspended in a flow-through aquarium aboard the SSV Robert C. Seamans as she sailed from San Diego, CA to Honolulu, HI. The cruise track passed through coastal California waters, the North Pacific Subtropical Gyre and the Equatorial Current System. Seawater from the surrounding waters was constantly pumped through the tank to simulate the surrounding ocean environment.  Every three days, samples were extracted from the tank, scraped, re-suspended in sterile filtered seawater, stained with DAPI, and filtered onto individual slides.  The samples were viewed and counted on an epifluorescent microscope. Total bacteria counts were obtained under UV light and autotrophic counts were obtained under green light. Counts were reduced to concentration of cells per mm2.


Climate Change/Ocean Acidification

18˚ Mode Water Formation and Its Relationship to the North Atlantic Oscillation Cycle

Student: Tim Basarath (Fairleigh Dickinson University), C-228 Colonization to Conservation in the Caribbean
Chief Scientist: Dr. Jeff Schell

Research Introduction Abstract: Click for Details

18° Mode Water is a type of water mass that is created in the Northern Sargasso Sea (Vogels 1999). It  is defined by a temperature between 17.6°C and 18.2°C and a salinity between 36.4 ppt and 36.6 ppt (Vogels 1999), with an  isopycnal of approximately a 26.50 mg cm-3 (Morrison and Nowlin 1982).

Worthington alluded to in his research that there is a connection between climate and water masses (1968). He states that climate changes affect the ocean and as climate change changes are made to the ocean as well.

I studied and examined how the creation of the 18° Mode Water is affected by regional scale, climate cycles such as the North Atlantic Oscillation. During my voyage I pinpointed exactly where the water mass was this year in the Caribbean. I determined the age of the 18° Mode Water, so that I was able to find the year of formation and connect it with the climate cycle data. I compared my data with the information on the cycle of the North Atlantic Oscillation at the time of the winter in which the 18° Mode Water I found was formed.

Comparative Carbon Flux Between Upwelling Regions of the Equatorial Pacific

Student: Karen Jackson (Macalester College), S-226 Oceans & Climate
Chief Scientist: Dr. Jan Witting

Research Abstract: Click for Details

Upwelling and outgassing in the Equatorial Pacific is the largest natural source of carbon dioxide to the atmosphere. To analyze outgassing, alkalinity and pH measurements were used to calculate pCO2 (partial pressure of CO2) and Revelle factors in each region. Outgassing rates along a North-South transect at approximately 160°W were expected to differ between the Intertropical Convergence Zone (ITCZ) and the Equator. With the onset of an El Niño cycle and deepening of the mixed layer, this study predicted outgassing would be reduced. Collection of pCO2 and Revelle factor vertical profiles revealed notable trends; however, there is no statistical difference between regions. Equatorial flux is larger at -37.5±11.73 matm, compared to ITCZ flux at -8.9±17.72 matm.  The calculated ITCZ surface Revelle Factor was 9.3±0.22, compared to 9.1±0.05 at the Equator. Circulation patterns are predicted to be the source of disparity. Studies with larger data sets are needed to solidify statistical significance and gain a better understanding of carbon transport at the global scale.

Diatom Speciation as an Indicator of Climate Change in the North Pacific

Students: John Dow (Colgate University) and Zora McGinnis (Colgate University), S-224 SEA Summer Session
Chief Scientist: Dr. Giora Proskurowski

Research Abstract: Click for Details

Sensitivity to local climate conditions and changes, and stability and frequency in the fossil record make diatoms ideal indicators of climate change. There is a forty year span between studies of diatom speciation in the North Pacific of the past and today, with the majority of studies concluding by 1972. Previously collected data from a variety of sources such as WOCE and NASA suggest that conditions in the North Pacific have changed, and this may be reflected in current diatom speciation. The four most common and easiest to identify diatoms in the North Pacific during the 1970’s were Hemiaulus hauckii, Nitzschia sicula, Rhizosolenia imbricata, and Ethmodiscus rex. We hypothesized that modern diatom speciation would differ from older data sets due to climate change factors such as temperature change and the presence of plastic waste in the North Pacific. Temperature and diatom speciation data was taken daily, and compared to each other as well as older speciation and pollution data from the same area. Our results establish definite changes in diatom speciation but statistical analysis does not identify a cause. Diatom species that thrive in degraded conditions were found in larger quantities and more sensitive species decreased in number, or were altogether nonexistent.


Marine Biodiversity

The Correlation Between Sea Surface Temperature and Leptocephali Population in the Sargasso Sea

Students: Esme Lovell-Smith (Cornell University) and Ghislaine Mareneck (St. Louis University of Madrid), C-231 Ocean Exploration
Chief Scientist: Dr. Deb Goodwin

Research Abstract: Click for Details

Eel populations are endangered and the exact cause of this decline in numbers is unknown. Their decrease affects fresh and salt-water food webs in addition to the eel fisheries which are important to the nations of Japan and China. American and European eels migrate from their fresh water habitats to the Sargasso Sea to spawn and then die between the months of October and December each year.  

Eel larvae are clear flat creatures known as leptocephali. Little is known about their migration but it is speculated that factors during either their journey to the Sargasso or during the leptocephali’s period of maturation in the Sargasso are contributing to the eels population decrease. One suggested cause of their fall in numbers is the increase in surface water temperatures in the Sargasso Sea. The leptocephali are unable to reach maturation in higher water temperatures due to it having a negative effect on their bodily developments. Warmer waters also diminish nutrient levels, leaving the leptocephalis with reduced food supplies.

This project focuses on the effect of sea surface temperature on the number of leptocephali found in the Sargasso Sea. It also examines the number of samples caught in the North versus South Sargasso. The results showed an obvious increase in leptocephali caught between 24.5 and 25.5 Celsius and a sharp decrease in the number of leptocephali caught above 25.5C.  There was also a significant increase in the number of leptocephali caught in the cooler waters of the North Sargasso then the Warmer waters of the South Sargasso. The data collected supports our hypothesis. 

The Effects of Temperature, Salinity and Nutrient Concentrations on the Horizontal Distribution of Zooplankton Communities

Student: Kat Conway (Trinity College), C-228 Colonization to Conservation in the Caribbean
Chief Scientist: Dr. Jeff Schell

Research Introduction Excerpt: Click for Details

In this study potential relationships between the horizontal distribution of zooplankton communities and surface properties like temperature, salinity, and nutrient concentration, as well as their proximity to land were examined. The sample regions; Caribbean Sea, Sargasso Sea, Greater Antilles, and Windward Passage (see Figure 1) are all in a similar geographic region, however they are characterized by differing properties. There are a number of physical, biological, and spatial differences, such as varying temperature, salinity, and nutrients that affect the abundance, diversity, and horizontal distribution of zooplankton communities in fluid water (Sabates, et al 1989). Data for biomass and bio-diversity along our cruise track and differentiated between gelatinous communities and crustacean zooplankton, in order to analyze the different population concentrations. The final data can be compared to existing data, patterns, and baseline conditions to further the understanding of horizontal distribution.


Ocean Conservation

Assessing Possible Inhibitors to Seasonal Migration of Commercial Tuna Stocks

Student: Sanya Compton (Savannah State University), S-226 Oceans & Climate
Chief Scientist: Dr. Jan Witting

Research Abstract: Click for Details

Reduced oxygen levels and increased ocean temperatures both occur in the upper 700 m of the equatorial Pacific, especially during El Niño years. Tuna, an economically important species, vary in sensitivity to changes in temperature and oxygen. In order to assess possible barriers to tuna migration along the selected cruise track - 20°N to 0°, 43 hydrocast-CTD deployments were completed. Temperature and oxygen data from the surface to 600 m were analyzed.

The major finding of this study was that low oxygen concentrations ranged from 34.5 µmol/kg to 9.8 µmol/kg between 15°-5°N, at these latitudes sea surface temperatures steadily increased from 26.8°C to 29.5°C. The relationship between temperature and oxygen from 120 – 300 m water depths falls within the physiological limits for skipjack tuna. Changes in temperature and oxygen may directly affect tuna abundance and distribution, creating challenges for fisheries management in countries such as Kiribati.

The Environmental Impact of the SSV Corwith Cramer Along the C-233 Cruise Track

Student: Morgan Barrios (Florida State University), C-233 Ocean Exploration
Chief Scientist: Dr. Heather Schrum

Research Abstract: Click for Details

Environmental impact on the ocean is an issue that has become more pertinent in the media around the world in the past few decades. The impacts of fresh water consumption, biodegradable waste, chemical and detergent runoff, and macro plastic waste were documented to determine the environmental impact of the SSV. Corwith Cramer. Fresh water consumption and the production of biodegradable waste and macro plastic waste were logged daily.  Sargasso shrimp and crabs were collected in a Neuston Tow to test the impact of chemicals and detergents.  Cramer held up well in comparison to The Schooner Mary Day and UNOLS Oceanus. Cramer also showed improvement against past research on her own environmental impact.