Esmeralda Garcia - “Gephyrocapsa Oceanica Physiological Response to Alkalinity Enhancement in Laboratory Cultures”

Mentor: Adam Subhas, Woods Hole Oceanographic Institution

Abstract: Ocean alkalinity enhancement (OAE) is a carbon dioxide (CO2) removal procedure that increases the buffering capacity of seawater by expanding the seawater’s ability to take up and neutralize atmospheric CO2. Before implementing OAE on a large scale, the impacts of modifying seawater and its effect on phytoplankton species must be studied. Coccolithophores, the most abundant calcifying phytoplankton, play a role in the carbon cycle by taking up CO2 through photosynthesis and consuming alkalinity by forming their calcium carbonate shells. Conducting laboratory OAE experiments on the coccolithophore subspecies, Gephyrocapsa oceanica, provides insight on whether amending alkalinity will impact the biological processes already managing the carbon cycle. To study the impact alkalinity had on coccolithophore growth, G. oceanica was cultured in three media treatments: a control with no alkalinity enhancement, an unequilibrated treatment, and equilibrated treatment both with an additional 500 μmol/kg NaOH. To mirror the effect of CO2 uptake following alkalinity enhancement, the equilibrated treatment was bubbled with laboratory air. The unequilibrated treatment was isolated from the atmosphere to simulate the immediate effect of OAE. The coccolithophores’ physiological responses to increased alkalinity were determined by growth rates via flow cytometry, photosynthetic efficiency via FIRe (Fv/Fm), and calcification rates via 13C tracing. Preliminary results from these assessments indicate that OAE has little to no effect on G. oceanica’s growth, calcification, and overall health. Over the course of three generations, the average growth rate for all three treatments was 0.45 per day. Future research on G. oceanica, along with other coccolithophore subspecies, should study their response to greater amounts of NaOH and over extended periods of time. 

 

Avion Brown - “Potential Methane Oxidation Rates In Howland Research Forest Soils”

Mentor: Kathleen Savage, Woodwell Climate Research Center

Abstract:Methane is an extremely potent greenhouse gas that is released into the atmosphere from wet, anaerobic soils, and oxidized (taken up) in dry, aerobic soil conditions. Within the soil horizons microbes, Methanotrophs oxidize methane under dry aerobic soil conditions, and methanogens release methane under anaerobic, wet soil conditions. Depending on the soil moisture status, oxidation and production of methane can take place simultaneously. Howland Research Forest in Maine currently oxidizes more methane than it releases making it a net sink of methane. Although Howland is currently a net sink of methane, the climate is predicted to become wetter and warmer due to climate change. This may change the current soil moisture status, and Howland forest soils may transition from a net sink, to a net source of methane. 

Howland Forest provides a unique perspective. It features soil drainage areas with dry upland (aerobic), wetland (anaerobic), and transitional soils. Samples were taken from each drainage area with the objective of finding out the methane oxidation potential of the drainage areas and depths within the soil horizons. Soil samples were incubated in a laboratory experiment to determine the potential rate at which the different drainage areas and soil horizons can oxidize methane. The samples were isolated in a closed chamber to keep environmental variance to a minimum. After isolating and aerating the samples, they received two different methane spikes. One just above ambient, and a much higher concentration. A Li-cor Infrared gas analyzer measured the spike in methane and the subsequent decrease in methane concentration over time (potential methane oxidation rate). 

Soil profile depths closest to the surface oxidized methane at faster rates than lower soil depths. This is likely due to the fact that the closer the profile is to the surface, the more favorable the conditions are for methanotrophic activity.

 

Lauren Stephenson - “Understanding the Effect of Salinity on Green Crab Biochemical Pathways”

Mentors: Carolyn Tepolt and Yaamini Venkataraman, Woods Hole Oceanographic Institution

Abstract: The European green crab (Carcinus maenas) has achieved remarkable success as an invasive species, making it one of the most abundant in the world, deconstructing the new systems they settle in. Since C. maenas are euryhaline, they have the potential to achieve homeostasis in variable environments. This talk will explain the metabolic response and energy production capacity that occurred during C. maenas exposure to different salinities. In this experiment, crabs were exposed to three different salinity treatments over four days: 10 ppt, 32 ppt (control), and 47 ppt. These salinities represent diluted seawater, average seawater, and concentrated seawater respectively. During high tides or periods of heavy rainfall, green crabs may encounter diluted seawater as the influx of freshwater lowers the salinity of their surrounding environment. Conversely, during low tides or reduced freshwater input, they may experience more concentrated seawater with higher salinity levels. Before and after exposure, a citrate synthase fluorescence assay was used to measure the metabolic response. Citrate synthase is a key enzyme in the citric acid cycle (also known as the Krebs cycle or tricarboxylic acid cycle), an essential metabolic pathway involved in energy production within cells. A high value indicates that the enzyme is more rapidly catalyzing the conversion of acetyl-CoA and oxaloacetate. A lower value suggests that the citric acid cycle is functioning at a slower rate than normal. In addition to the citrate synthase assay, crab righting response and heart rates were assessed for a subset of crabs tracked throughout the experiment. By assessing variations in metabolic activity using citrate synthase measurements and observing physiological distinctions among crabs exposed to different salinities, the study revealed the boundaries of salinity tolerance in C. maenas. Due to their high tolerance to many different environments, this work provides insight into suitable habitat conditions, which will help inform invasion response.

 

Gabriella Prelosky - “It’s Electric: Understanding the development of electroreceptors in Chain Catshark (Scyliorhinus retifer)”

Mentor: Andrew Gillis, Marine Biological Laboratory

Abstract: Electroreception is an ancestral trait in fishes that has been lost in most commonly studied aquatic model organisms, such as zebrafish and Xenopus. Electroreceptors are a component of the lateral line system in cartilaginous fishes (sharks, rays, and skates), where they have an important role in predation by detecting weak bioelectric fields generated by prey. The embryonic origin of these electroreceptors in cartilaginous fishes is not fully resolved: in skates, cell labeling experiments have shown that electroreceptors derive from thickened patches of embryonic skin, called neurogenic placodes, while in sharks, gene expression suggests that electroreceptors might derive from neural crest cells (a population of migratory stem cells that forms within the developing central nervous system). In this study, we use a combination of histology and immunostaining to investigate the embryonic development of electroreceptors in the chain catshark (Scyliorhinus retifer). We find that in embryonic stage 22, the anterodorsal lateral line placode (one of the neurogenic placodes that gives rise to electroreceptors in skate) has formed behind the eye in S. retifer. By stage 27, sensory primordia are elongating above and below the eye from the anterodorsal lateral line placode, and cells from these primordia are beginning to sink beneath the surface of the skin. Finally, by stage 31, electroreceptors have formed, and possess fully differentiated sensory and support cells. These discoveries set the foundation for future cell labeling experiments in S. retifer, which will directly test the hypothesis that shark electroreceptors develop from lateral line placodes, as seen in skate.

 

Destiny Coleman - “Factors Influencing Acadian Redfish (Sebastes fasciatus) Presence in the Gulf of Maine Bottom Longline Survey ”

Mentor: Dave McElroy, National Oceanic and Atmospheric Administration, NMFS, NEFSC 

Abstract: The Gulf of Maine is an opportune commercial fishing hotspot because of high habitat diversity and biological productivity. The abundance and distribution of some species within the Gulf of Maine, however, are hard to fully characterize through trawling because of rough, structured bottom substrate. The Gulf of Maine Bottom Longline Survey was implemented in 2014 by the NOAA Northeast Fisheries Science Center in Woods Hole, MA to provide more observations in this ecosystem. This biannual survey consists of a baited bottom longline where species are captured, biologically sampled, and the data further analyzed for stock assessments. A camera system is deployed at each station to capture video of the bottom habitat. Acadian Redfish (Sebastes fasciatus) are common in deeper waters of the Gulf of Maine and favor rocky areas to serve as a refuge from predators and harsh ocean conditions. This research examines whether Acadian Redfish are captured consistently by both the survey longline and observed in habitat videos. Habitat video and longline catch data from fall 2020- spring 2022 are the focus of this study. The parameters tested to explore the differences between these sampling approaches are Terrain Ruggedness Index (TRI), bottom depth, bottom temperature, and habitat structure. It was found that there is a significant difference between Redfish presence in the two sampling approaches. Mean TRI taken at survey stations was indicative that Redfish are more likely to be present in areas with a higher TRI, according to survey catch data. When analyzing habitat video data, mean bottom depth and temperature revealed that Acadian Redfish are more likely to be present in depths <200 meters and temperatures 6-9°C. Redfish presence, using video data, was found to have a positive correlation with the presence of anemones attached to hard substrate. 

 

Aaron Edley - “Salt Marsh Restoration: Soil Shear Strength”

Mentor: Hillary Sullivan, Woodwell Climate Research Center

Abstract: Salt Marshes are one of the most important ecosystems in the world because they store large quantities of atmospheric carbon, protect the coastline from storms, and are nutrient buffers from runoff pollution. However, salt marshes are currently threatened by climate change and human activities. For example, in Waquoit Bay, Massachusetts, we have seen an increase in flooding and vegetation dieback, which results in lower elevation and further vegetation loss. This habitat loss causes alterations to sediment structure, therefore, we aim to understand how sediment characteristics such as shear strength, organic matter, and bulk density differ between areas of healthy marsh and areas of shallow standing water with vegetation loss. We found that in healthy marshes, the shear strength is slightly higher than in areas with dieback. We also found that generally, as bulk density increases, shear strength also increases.  Conversely, as organic matter increases, shear strength decreases. This relationship is strongest in the dieback areas. Our findings suggest that shear strength is influenced by organic matter and bulk density. However, there is only a treatment effect in dieback areas. These areas have little to no vegetation and therefore less belowground organic matter. We hypothesized that this would decrease the integrity of the sediment, thus reducing shear strength. However, in our dieback areas, the opposite is true. This is a result of higher bulk density, which has a stronger influence on soil shear strength. As the marsh loses vegetation and elevation, bulk density increases, which actually increases sediment shear strength, however, this is at the expense of organic matter composition. Thus, introducing remediation strategies that encourage revegetation and elevation gain could restore the balance between bulk density and organic matter. 

 

Isis Kees - “Hydrothermal Vent Communities in Late-Stage Succession along the East Pacific Rise”

Mentors: Lauren Mullineaux and Susan Mills, Woods Hole Oceanographic Institution

Abstract: Hydrothermal vents are volcanic structures that emit heated, chemical-rich fluids formed through the percolation of seawater into the seafloor near spreading centers. We know that eruptions at these vents can destroy the unique communities that are fueled by chemosynthetic production. It has also been demonstrated that the communities are patchy, and can only recover through larval dispersal from undisturbed vents elsewhere. Ecological succession is known to occur at vents. Early studies at East Pacific Rise vents suggested that communities could return to their pre-eruption state within 4 to 10 years of an eruption. However, we have found that more recent observations that include smaller species suggest that communities may continue to change if further eruptions do not occur. Our hypothesis is that species composition and diversity have continued to change over 15 years following a

2006 eruption at 9°N on the East Pacific Rise. We tested this hypothesis with a novel method involving the deployment of colonization ‘sandwiches’, which consist of six plates stacked together, and were used to collect samples every 10 years before an anticipated eruption. The samples were collected from the Tica vent in 2021 aboard the research vessel Roger Revelle (RR21-02). We then organized the specimens that settled onto the sandwich plates and identified them enabling detailed analysis of community composition. My contribution for this project will be to continue to count these specimens on the most recent sandwich retrieved from the cruise. I will also be analyzing the 2021 dataset using a coding program called R to plot. Over the summer, we have found at least one species not found before at the Tica site. Which suggests that late-stage succession is important in vent community structure and function and that recovery from disturbance, both natural and anthropogenic, is likely to take longer than predicted from early studies.

 

Samuel Barrett -

Mentor: Jesús Pineda, Woods Hole Oceanographic Institution/WHOI Sea Grant

Abstract: Biofouling, the covering of objects by unwanted organisms, is a problem for oyster farms and it is headed by barnacles, which cut off waterflow to cages. Understanding barnacle reproduction habits would be useful for the farmers and marine enterprises to have, however barnacle settlement periods are largely unknown. To discover the times of settlement we placed PCV plates with grooves all around Cape Cod and collected them once a week, replacing the plates each time. The barnacle settlement on the plates were then counted, recorded, and collected. This gives an accurate timeline of when barnacles settle in addition to DNA samples to test from; which we then extracted DNA from, ran a polymerase chain reaction (PCR), and used agarose gel to confirm success, where the PCRed DNA was then sent out for testing. We found that the main species were Chthamalus fragilis(little brown barnacle) and Semibalanus balanoides(northern acorn barnacle), and were able to obtain enough data to create meaning full settlement graphs.

 

11:15-11:30: BREAK

 

Emily Orozco - “Comparing Growth Between Two Year Old Hatchery and Wild Origin Atlantic Salmon in the Narraguagus, Little Falls River”

Mentor: Ruth Haas-Castro, National Oceanic and Atmospheric Administration, NMFS, NEFSC 

Abstract: Atlantic Salmon have been on the endangered species list since 2000. In North America, they can now only be found in rivers in Maine, with only about 1,000 fish returning every year. One of the main ongoing conservation efforts is breeding fish in hatcheries to later place them back into rivers. The hatchery reared fish are clipped before being put into rivers so that they are distinguishable from wild fish during yearly stock assessments. 

In this study we will be comparing growth between two year old hatchery raised fish and wild fish from the 2023 smolt survey in the Narraguagus river - Little Falls location. Scales from individual fish were collected and mounted between two glass microscope slides. We imaged each scale and came to a consensus on the age based on up to four scales for each fish. After age was determined, we measured scale features from a subset of 30 fish from both hatchery and wild origins. We compared growth in the scale (which corresponds with fish size) from the first to second year for the smolts from different rearing origins using ImagePro software. We also used length, weight, and water temperature data to compute our results. 

Preliminary data suggests that hatchery origin fish are growing at increased rates when compared to wild origin fish. Differences in fish size can also be due to rising water temperatures.  

 

Cameron Johnson - “Assessing spatial and temporal variation in copepod reproduction in the Gulf of Maine”

Mentors: Ann Tarrant and Rebecca Gast, Woods Hole Oceanographic Institution

Abstract: This study is a part of a broader investigation into the extent to which mixotrophic protists may serve as a food source for copepods in the Gulf of Maine. Within this project, my specific aim was to investigate spatial and temporal variation in the size and reproductive output of two copepod species, Calanus finmarchicus and Centropages typicus. These are two dominant mesozooplankton species in the region, and they serve as an important food source for fish, whales and other predators. This research was conducted throughout the spring/summer of 2023, with cruises taking place in April, June, and July. Experiments were conducted to assess copepod reproductive traits, and the methods were adjusted for each species. To date, we have determined that during April C. finmarchicus egg production was high overall (eggs/female/day: 0-149, x̅ = 50). but did not vary spatially. During the same period, C. typicus produced an average of 21 eggs/female/day. During two subsequent experiments, we did not observe egg production by either species, and further studies will assess whether this may have been an artifact of stressful laboratory conditions. We also examined copepod size (prosome length) because warm conditions are known to correlate with smaller body size and may affect reproductive output. Of the data analyzed to date, we have not observed significant variation among sites (3 sites in April), and did not observe a reduction in size over time that would have been consistent with seasonal warming. There was no clear association between prosome length and egg production. We are continuing to analyze samples from our experiments to more fully characterize the spatial and temporal patterns. When complete, these data will provide important context for ongoing studies of copepod physiology. Next steps will be to identify the dietary sources of these copepods through metabarcoding of their gut contents, compare the gut contents with the composition of the surrounding protist community, and assess the extent to which copepods are feeding on any available mixotrophs. 

 

Julia Hill - “Measuring coastal change through photogrammetry at Head of the Meadow Beach in Truro, Massachusetts.”

Mentor: Chris Sherwood, United States Geological Survey

Abstract: Sandy ocean-facing shorelines are constantly changing from processes such as wind- and wave-driven currents, wave breaking, overwash, and aeolian transport. Vegetation contributes to dune growth by trapping sand. Satellite images of Head of the Meadow beach (Cape Cod National Seashore, Massachusetts) suggest that vegetation has been expanding over the last decade. In March of 2020, 2022, and 2023 and February of 2021, we collected an average of 1000 overlapping images along a ~250-m long section of the beach using a camera attached to a helium-filled kite. We used Agisoft Metashape software to perform structure-from-motion photogrammetry with ground control points to create precise digital elevation maps (DEMs) for each year. We calculated erosion and deposition rates by differencing the DEMs and found that the small dunes at the landward edge of the beach were growing. Parts of Head of the Meadow beach gained as much as 1.7 m of sand, and the vegetated band at the base of the bluff  averaged about 0.30 m of deposition. In a world with rising sea levels where many beaches are eroding, these measurements provide an example of coastal accretion.

 

Blaze Miles - “Decarbonization of The Shipping Industry”

Mentor: Hauke Kite-Powell, Woods Hole Oceanographic Institution - Marine Policy Center

Abstract: Cargo vessels play a substantial role in the generation of worldwide carbon emissions, accounting fsor approximately 3% of human-induced greenhouse gas emissions. This study seeks to determine the ideal fuel tax rate that would encourage shipowners to make investments in enhancing efficiency. The research primarily concentrates on the economic aspects of ship operation, examining potential options like wind sails and wake flow improvement devices to reduce the carbon footprint. In order to assess the viability of these alternatives, a profit model was created to estimate how varying fuel tax rates would impact the profitability of efficiency-improvement initiatives. The findings indicate that implementing higher tax rates per tonne of fuel would incentivize shipowners to adopt fuel-efficient modifications. The fuel tax rates vary between 200 and 400 per tonne, contingent on the specific type of modification being applied.

 

Autumn Johnson - “The effects of endolithic community on coral calcification of Astrangia poculata”

Mentors: Loretta Roberson and Mayra Sanchez-Garcia, Marine Biological Laboratory

Abstract: Corals acquire their nourishment from symbiotic algae, although they may also get it from endoliths. Endosymbiont research has been conducted, but little is known about the endolithic community. Astrangia poculata, commonly known as the northern star coral, is found along the western Atlantic and Gulf of Mexico coastlines of the United States. Astrangia is a good model organism for studying symbiosis and the impact on calcification as they naturally occur as symbiotic and aposymbiotic (without algal symbionts). In this experiment, we quantified calcification and endolith growth in symbiotic and aposymbiotic colonies to characterize the role of symbionts and the endolithic community on coral growth. In addition, we collected weekly photosynthetic yield data and monthly whole-colony calcification using the buoyant weight technique. To measure endolith growth, we cut colonies into individual polyps and placed them in glass-bottom dishes. Once the polyps began to calcify on the glass, we imaged calcification over the course of 9 hours, and endolith growth weekly. The calcification and weekly growth rates were calculated using Fiji software. Calcification rates exhibited a pattern of higher growth in coral colonies without endoliths. The data also indicated that symbiotic corals had the highest rate of photosynthesis, reflected in their higher growth. Understanding the dynamics between corals, symbionts, and endolithic communities is crucial for coral reef conservation and management.

 

Jonathan Kopeliovich - “The Value of Science Communication to the Partnership Education Program”

Mentor: Heather Goldstone, Woodwell Climate Research Center

Abstract: The Woods Hole Partnership Education Program, or PEP, has been ongoing for fifteen years, and has been a beacon of diversity and representation in STEM. The program has typically been focused on science research experiences, but there is an increasing awareness of the necessity of science communication in public and policy engagement. This project was the first science communication project at PEP and focused on telling the stories of PEP students and their research according to evidence-based storytelling best practices. At the same time, a deeper look into the lives of PEP students and the diverse research they participate in would be valuable for both prospective students taking an interest in PEP and to stakeholders for continued opportunities. My research project involved creating multimedia pieces called StoryMaps, multimedia web pieces that integrate maps, photos, text, and more, on two students’ research projects. To create the first StoryMap, I accompanied Avion Brown to Maine to see him collect soil samples and to learn about methane cycles in a transitional boreal forest. For the second StoryMap, I documented Sam Barrett while he collected barnacles and replaced settlement plates. I then wrote about his laboratory work on barnacle ecology and its applications in helping oyster farmers. StoryMap creation involved interviewing the mentors, students, and researchers in the lab on camera and with external mics as well as taking photos of their field work. This presentation will showcase these two StoryMaps, their role in raising awareness about the research areas and their broader applications in encouraging broader participation in STEM.

 

Taina Sanchez - “Patterns at the Edge: Ocean Biogeochemistry at the Edge of the Northeast U.S. Shelf Revealed by Autonomous Underwater Vehicles (AUVs)”

Mentor: Stace Beaulieu, Woods Hole Oceanographic Institution

Abstract: There is a dynamic ecosystem at the edge of the Northeast U.S. continental shelf where inshore shelf water and offshore slope water interact. Productivity here is essential to understand as interactions at the planktonic level significantly affect higher trophic levels. As climate change will impact sea water temperatures, we may expect changes including seasonal patterns in ocean biogeochemistry affecting the base of the food web. Collaboration of the Northeast U.S. Shelf Long-Term Ecological Research (NES-LTER) and Ocean Observatories Initiative (OOI) allowed us to examine data from 2016 to 2022 for seasonal patterns in nitrate and chlorophyll distribution in across-shelf transects. In this study, we examine nitrate and chlorophyll data collected from autonomous underwater vehicles (AUVs) deployed by OOI in spring, summer, and fall. Using salinity to represent the shelf break front and chlorophyll as an indicator of phytoplankton biomass, we focused on understanding the relationship between phytoplankton distribution and the position of the nitracline in the water column, in which the nitrate concentration changes rapidly with depth. Our assessments showed seasonal variabilities among all parameters, with the most consistent patterns in the summer months into early fall. Summer patterns appeared controlled by biological factors in that there was a greater association between phytoplankton distribution and the position of the nitracline. These patterns held into early fall. Spring patterns showed more variabilities, with signatures of physical processes playing a more important role. These findings are significant in better understanding the biogeochemistry patterns and potential impacts on ecosystem dynamics and fisheries dependent on the productivity of lower trophic levels.