Research opportunities are increasingly offered to undergraduate students in an effort to help them understand marine and aquatic sciences and to offer them an opportunity to consider this field as a career. Undergraduates who have conducted research are invited to present their results in this general session that will highlight the wide variety of student research and provide opportunity for interested faculty to discuss your project with you. The Research Experience for Undergraduate (REU) program brings large numbers of undergraduate students to marine institutions for summer research programs, and students who have participated in REU programs are particularly invited to submit to this session. Students are not limited to this session, and we encourage any undergraduate student who wishes to submit an abstract to a specialized science session in the subject of their research to consider that option as well.
Lead Organizer: David Fields, Bigelow Labs for Ocean Sciences (dfields@bigelow.org)
Co-organizers:
Lisa Rom, NSF (elrom@nsf.gov)
Presentations
08:30 AM
Predicting Ecology and Hearing Sensitivities in Ancient 'River Dolphins' (Parpontoporia) (4687)
Primary Presenter: Joyce Sanks, Vanderbilt University (joyce.j.sanks@vanderbilt.edu)
Analyses of the cetacean (whale and dolphin) inner ear provide glimpses into the ecology and evolution of extinct and extant groups. The paleoecology of the odontocete (toothed whale) group, Parapontoporia, is primarily marine with depositional context also suggesting freshwater tolerance. As an extinct relative of the exclusively riverine Lipotes vexillifer, Parpontoporia provides insight into a transition from marine to freshwater environments. High-resolution X-ray CT scans (~3 microns or less) of three individual specimens from two species, P. sternbergi and P. pacifica, were acquired. Digital endocasts of the inner ear labyrinths were extracted non-destructively using the software VGStudioMax v. 3.5.2. Nine measurements of the cochlea including secondary bony lamina length, semicircular canal length, height, width, and fenestra cochleae surface area were added to an existing dataset covering 103 terrestrial and aquatic artiodactyls. These measurements were then subjected to a Principal Component Analysis (PCA) to interpret hearing sensitivities among other artiodactyls. From an analysis of the specimens, Parapontoporia was not likely to have been a narrow-band high frequency (NBHF) echolocator, and differences in cochlear length demonstrate intraspecific and interspecific variation. The semicircular canals were measured for comparison with previous work, highlighting a longer lateral canal, as expected compared with other odontocetes. Studying the inner ear of Parapontoporia will help inform on the ‘river dolphin’ transitions from marine to riverine environments.
08:45 AM
Influence of CO2 Exposure and Temperature on the Otolith Morphology in Hi-hat (Pareques acuminatus) (4682)
Primary Presenter: Jonathan Nash, Hampton University (jonathan.nash1234@gmail.com)
The rapid uptake of carbon dioxide (CO2) by the world’s oceans since the Industrial Revolution is causing a rapid decline in ocean pH and a rise in temperatures. This change in ocean chemistry has affected major ecophysiological mechanisms in fishes, including the development of otoliths. Changes in otolith morphology have previously been linked to decreased hearing sensitivity in fishes. To investigate the potential of CO2-induced hearing loss we assayed Hi-hat (Pareques acuminatus), a tropical soniferous sciaenid species. Sound production and reception are critical to the ecology of sciaenids, which are known model organisms for teleost bioacoustics. In this study, we compared the effects of three pH levels and two temperatures reflecting future ocean scenarios and their natural ambient conditions for two different exposure durations (19 wk and 5 wk). The sagittal otoliths were then extracted, imaged, measured, and analyzed in ImageJ. Three standardized ratios were calculated from the measurements: otolith thickness:fish length, otolith length:fish length, and otolith mass:fish mass. The 19-week otoliths from fish exposed to pH 7 had significantly higher otolith mass:fish mass ratio (ANOVA; p < 0.001), otolith length:fish length ratio (ANOVA; p < 0.01), and otolith thickness:fish length ratio (ANOVA; p < 0.01). Fish exposed to pH 7 for 19 weeks were significantly smaller than those from the control group (ANOVA; p < 0.05), however their otoliths had similar thickness:length ratio (p>0.05) to the larger higher pH fish. The relative increase in the mass, thickness, and length of Hi-hat otoliths following exposure to high levels of CO2 may affect how the otolith function. Ultimately, changes can otolith form and function may affect acoustic performance and reproductive success of soniferous species.
09:00 AM
ASSESSING THE IMPACTS OF SIMULATED OCEAN ALKALINITY ENHANCEMENT ON VIABILITY AND GROWTH OF CULTURES OF NEAR-SHORE SPECIES OF PHYTOPLANKTON (6843)
Primary Presenter: Jessica Oberlander, Dalhousie University (jessica.oberlander@dal.ca)
Over the past 250 years, atmospheric carbon dioxide concentrations have risen steadily from 277 ppm to 405 ppm, leading to the exacerbation of the effects of climate change. As a result, new technologies are being developed to remove carbon from the atmosphere, such as negative emission technologies (NETs). One proposed NET is Ocean Alkalinity Enhancement (OAE), which would mimic the ocean’s natural weathering processes and sequester carbon dioxide from the atmosphere. An analysis of published data investigating the effects of elevated pH on phytoplankton growth rate and experimental assessment of pH dependence of viability and growth rate was used to assess the potential impacts of OAE. Viability was assessed with a modified Serial Dilution Culture – Most Probable Number assay. Chlorophyll a fluorescence was used to test for changes in growth rates and photosynthetic competence. The results from this study suggest that there will be no significant impact on the viability or growth rates of Thalassiosira pseudonana or Pavlova lutheri with short-term (10 minute) exposure to elevated pH. However, when long-term (days) exposure occurs there is a significant decrease in growth rates with elevated pH. Short-term exposure is anticipated to more closely mirror the natural systems in which OAE will be implemented because of system flushing and replenishment of nutrients. These preliminary findings suggest that there will be little to no impact on a variety of taxonomic groups of phytoplankton when OAE occurs in naturally flushed systems.
09:15 AM
ASSESSING THE IMPACT OF SIMULATED OCEAN ALKALINITY ENHANCEMENT ON PHYTOPLANKTON IN A MESOCOSM STUDY IN BEDFORD BASIN, NOVA SCOTIA (6719)
Primary Presenter: Mikaela Ermanovics, Dalhousie University (mk667000@dal.ca)
I tested the potential impacts of Ocean Alkalinity Enhancement (OAE) on phytoplankton in a mesocosm study. To restrict warming to the 1.5-degree target, we must now rely on carbon dioxide removal strategies (IPCC 2022) such as OAE. I deployed six mesocosms in the Bedford Basin, the pilot site for this technology, with three duplicated treatments: a control, and alkaline treatments with 50 uM and 500 uM magnesium hydroxide additions. These correspond to target and 10x target concentrations for OAE and resulted in changes of 0.3 and 0.8 pH units, respectively. Incubations lasted 24 hours to represent the effect of alkalization before dilution by water flow. Mesocosms were sampled before and after the addition of alkalinity and again on harvest. Physicochemical parameters, including particulate and dissolved carbon pools, were measured; phytoplankton community composition and abundance were assessed by flow cytometry and chlorophyll-a content. Statistical tests for treatment effects on population structure and chlorophyll-specific growth rates were tested using analysis of similarity (ANOSIM) and analysis of variance (ANOVA), respectively. At harvest, there was no significant difference in community composition between treatments (p=0.13) nor between chlorophyll-specific growth rates (p=0.26). There were significant differences (p<0.05) in both community composition between the start and end of the experiment. This study is an important first step in assessing the potential impact of OAE and demonstrates that it can be undetectable.
09:30 AM
Exploring Marine Heatwave Impacts on Early Development & Larval Thermotolerance in K. kelletii Larvae in Santa Barbara, California (4810)
Primary Presenter: Kyaralind Vasquez Liriano, Wellesley College (kyaralind2@gmail.com)
Marine heatwave (MHW) events are periods of anomalously high temperatures relative to long-term average sea surface temperatures. In the last decade, MHWs have increased in frequency globally, causing devastating impacts on critical coastal marine ecosystems, such as kelp forests on the California coast (e.g., the 2014-2016 “Blob”). Due to their seasonal timing, MHWs pose a major threat to reproduction and early stage life history events for many benthic marine invertebrates. This study investigated the effects of MHWs on the Kellet’s whelk (Kelletia kelletii), an emerging kelp forest fishery species in the Santa Barbara region in the southern California Current System. In this study, we sought to determine if trochophores (2-week-old larvae) of adult whelks exposed to a MHW simulation would show greater larval thermotolerance. Adult whelks collected from Carpinteria Reef, California, were held under ambient conditions in the laboratory and were allowed to mate and lay egg capsules (March - July 2022). Trochophores were exposed to a “ramp-up-ramp-down” MHW simulation: 15°C ramped up to 23°C and back down to 15°C over the course of 14 days. After a MHW simulation, larvae were challenged in 1-hour thermotolerance trials via an aluminum heat block and then scored for abnormal morphology following the acute thermal stress. We observed that at 25.6°C, 72% of the trochophores were normal. However, at 29°C or higher, the majority of trochophores (78-100%) displayed abnormal morphology, and exhibited slower mobility compared to unaffected larvae. These results indicated that K. kelletii trochophore larvae were moderately affected by high MHW temperatures. Future studies on the effects of MHW temperatures on larval development will provide further insight into the extent of larval thermotolerance under extreme MHW events and inform the next steps for sustainable fisheries management of this species.
09:45 AM
Strong vertical zonation of epibenthic megafauna abundance and biomass of a deep and large seamount west of Cape Verde islands (southern North Atlantic) (5475)
Primary Presenter: Dominik Scepanski, University of Cologne (dscepan1@uni-koeln.de)
Seamounts are often thought to function as a major hotspot for megafauna accumulation due to their unique topology and environmental characteristics. However, comprehensive assessments of megafauna communities inhabiting seamounts, including diversity, abundance and biomass are seldom available. We investigated the vertical distribution of epibenthic megafauna over a newly discovered seamount region West of Cape Verde. Utilizing OFOS-dives, calibrated videos were taken as a horizontal transect from the northeastern flank of the seamount, distinguishing between the upper (-1354/-2358m) and deeper section (-2358/-3218m). Taxa were morphologically distinguished, their diversity, abundances and biomasses estimated and related to habitat parameters. Both the upper and lower seamount region hosted unique communities with significantly higher megafauna richness at the seamount’s top. While megafauna abundances differed significantly between the upper and deeper community, no significant differences were detected concerning the estimated biomass. The complete seamount showed a vertical zonation with dense aggregations of cold-water corals dominating the seamount’s upper and colonies of the glass sponge Poliopogon amadou dominating the lower region. Special for our study is that abundance and biomass data are provided for a continuous survey of a seamount down to 3,200m. The results are discussed in light of detected substrate preferences, co-existence of species and comparisons with literature data on comparable seamounts.
SS002A Undergraduate Research in Marine and Aquatic Sciences
Description
Time: 8:30 AM
Date: 9/6/2023
Room: Sala Ibiza A