Open Access Publications - School of Marine Science & Policy
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Open access publications by faculty, postdocs, and graduate students in the School of Marine Science & Policy
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Item Seasonal Circulation, Transport, and Connectivity of the Gerlache and Bransfield Straits Based on 20 Years of SADCP Measurements(Journal of Geophysical Research: Oceans, 2026-02-18) Puyal‐Astals, Laia; Veny, Marta; Moffat, Carlos; Aguiar‐González, BorjaWe use shipboard ADCP data (1999–2018) and a box-integration approach to study the spatial and seasonal variability that regulates water mass exchanges between the Bellingshausen and Weddell Seas in the northwest Antarctic Peninsula. This system comprises three major currents: the Gerlache Strait Current (GSC), the Bransfield Current (BC), and the Antarctic Coastal Current (AACC). The GSC exhibits the clearest seasonality, with significant weakening in autumn (0.10 Sv; 5.2 cm s−1) relative to stronger transport in spring and winter (∼0.30 Sv; ∼19.8 cm s−1), regulated by wind-stress seasonality. Along the western Gerlache margin, flow through Croker Passage shifts southwestward from 0.13 Sv in spring to 0.23 Sv in winter. Large standard deviations indicate strong interannual variability. This pattern suggests that along-stream reversals and across-stream wind-stress intensification modulate the flow. Within the Bransfield Strait, the BC forms a robust northeastward jet year-round, peaking in summer and spring (∼37 cm s−1; ∼0.99 Sv), while the AACC flows southwestward along the Antarctic Peninsula margin (−0.45 to −0.59 Sv). High standard deviations in both indicate strong interannual variability but no significant seasonal differences. These results reveal a seasonally structured circulation rather than a simple GSC-to-BC connection, providing the first statistically supported evidence that wind forcing is a key modulator of GSC variability across the system. The present work provides a robust physical framework for interpreting oceanographic connectivity and shelf-slope exchanges across the western Antarctic Peninsula, while underscoring the need for higher-resolution and in situ observations to resolve the role of intermittent pathways and climate variability.Item Formal recognition of host-generalist species of dinoflagellate (Cladocopium, Symbiodiniaceae) mutualistic with Indo-Pacific reef corals(Journal of Phycology, 2023-05-01) Butler, Caleb C.; Turnham, Kira E.; Lewis, Allison M.; Nitschke, Matthew R.; Warner, Mark E.; Kemp, Dustin W.; Hoegh-Guldberg, Ove; Fitt, William K.; van Oppen, Madeleine J. H.; LaJeunesse, Todd C.The existence of widespread species with the capacity to endure diverse, or variable, environments are of importance to ecological and genetic research, and conservation. Such “ecological generalists” are more likely to have key adaptations that allow them to better tolerate the physiological challenges of rapid climate change. Reef-building corals are dependent on endosymbiotic dinoflagellates (Family: Symbiodiniaceae) for their survival and growth. While these symbionts are biologically diverse, certain genetic types appear to have broad geographic distributions and are mutualistic with various host species from multiple genera and families in the order Scleractinia that must acquire their symbionts through horizontal transmission. Despite the considerable ecological importance of putative host-generalist symbionts, they lack formal species descriptions. In this study, we used molecular, ecological, and morphological evidence to verify the existence of five new host-generalist species in the symbiodiniacean genus Cladocopium. Their geographic distribution and prevalence among host communities corresponds to prevailing environmental conditions at both regional and local scales. The influence that each species has on host physiology may partially explain regional differences in thermal sensitivities among coral communities. The potential increased prevalence of a generalist species that endures environmental instability is a consequential ecological response to warming oceans. Large-scale shifts in symbiont dominance could ensure reef coral persistence and productivity in the near term. Ultimately, these formal designations should advance scientific communication and generate informed research questions on the physiology and ecology of coral-dinoflagellate mutualisms.Item Widespread Phenological Shifts With Temperature in Alaska's Marine Fishes(Global Change Biology, 2026-01-16) Rogers, Lauren A.; Axler, Kelia E.; Bigman, Jennifer S.Changes in the timing of fish spawning and early life stage development can affect the temporal match or mismatch of larvae with production of preferred prey as well as their availability to predators, with potential consequences for recruitment success, food- web dynamics, and fisheries. Using > 370,000 observations from over four decades of spring ichthyoplankton surveys in the Gulf of Alaska and Bering Sea, we investigated long- term changes in the phenology of 29 fish species, including commercially important taxa such as Pacific cod, walleye pollock, and Pacific halibut. Larval size on a standardized date (size- at- date) was used as a proxy for larval developmental timing in spring, and reflects a combination of hatch timing (larval age), growth, and mortality. Spatiotemporal generalized linear mixed models were used to account for variable sampling effort in space and time in order to isolate long- term trends and thermal effects on larval size. For a majority of species, interannual variation in mean size- at- date was significantly and positively related to temperature, demonstrating widespread thermal effects on the phenology of fish early life stages. Despite the wide diversity of life history traits exhibited by the 29 species examined, patterns in size- at- date over time were similar across most species within each ecosystem, reflecting the common effect of temperature on phenology. While temperature affected size- at- date, there was little evidence of long- term trends, likely due to the lack of a linear trend in winter–spring temperatures observed in recent decades. We demonstrate a novel analytical method to assess changes in phenology from larval size observations sampled at variable locations and times, and detect phenological shifts that were not necessarily identifiable from larval abundance data alone. Our results suggest that earlier spring phenology due to warming will be a common response among fishes to projected future climate change in high- latitude ecosystems.Item Ventilation and buffering capacity effects on ocean acidification in low oxygen environments(Nature Communications, 2025-12-19) Xue, Liang; Sabine, Christopher; Chen, Jianfang; Lauvset, Siv K.; Wei, Qinsheng; Li, Kuiping; Cai, Wei-JunOcean acidification results from oceanic uptake of anthropogenic CO2 (ΔCant). Weak carbonate buffering capacity (high Revelle factor, RF) amplifies acidification, but its role in persistently low-oxygen, poorly ventilated regions is unclear. Here we compare preindustrial to present changes in partial pressure of CO2 (pCO2), hydrogen ion concentration ([H+]), pH, aragonite saturation state (Ωara), and RF within permanent oxygen minimum zones (OMZs) versus well-ventilated regions. We find that acidification is negligible in the least-ventilated, poorly buffered lower OMZs, but detectable in moderately ventilated upper OMZs. In upper OMZs, pCO2 and [H+] increase faster while Ωara, pH, and RF change more slowly than in adjacent well-ventilated regions. Our analysis reveals that limited ΔCant delivery by ventilation ultimately constrain acidification in low-oxygen regions. Accordingly, low-oxygen regions with poor ventilation will experience less acidification than well-ventilated regions, and different metrics (notably [H+] versus Ωara) respond distinctly due to their different definitions and sensitivities.Item DATA FROM: MICROPLASTIC ACCUMULATION AND VERTICAL DISTRIBUTION IN THE DELAWARE ESTUARY ESTUARINE TURBIDITY MAXIMUM(2026-01-06) Fontana, Julia M.; Mason, R. Alan; Kukulka, Tobias; Cohen, Jonathan H.We sampled microplastics at three depths in the estuarine turbidity maximum region of the Delaware Estuary using an open/close Tucker Trawl net system. Microparticles were isolated and confirmed as microplastic by micro-FTIR spectroscopy. For more details on sampling and instrumentation, see the paper associated with this dataset: Fontana et al. (2026) Marine Pollution Bulletin ##:###-###.Item Tellurite and selenite processing by tellurite resistant marine microbes(Applied and Environmental Microbiology, 2025-10-01) Ollivier, Patrick; Hanson, Thomas; Tessier, Emmanuel; Amouroux, David; Church, ThomasUnderstanding microbial transformations of the group VIa/16 metalloids tellurium and selenium is important for the remediation of contaminated environments and has been proposed as a green route for Se/Te nanoparticle synthesis. We previously isolated several strains of aerobic tellurite resistant marine yeast and bacteria. Here, we explored the capability of these strains to metabolize selenite and mixtures of tellurite and selenite to quantify fate and identify volatile metabolic products. The experimental results indicate that selenite is metabolized differently than tellurite by the yeast Rhodotorula mucilaginosa and bacteria Bacillus spp. and Virgibacillus halodenitrificans. The production of volatile Se compounds appears to be positively correlated with selenite resistance. However, selenite fate, e.g., the proportion of volatilized or precipitated Se, was not predictable from tellurite resistance or fate of the same strain. Under non-aerated conditions, when cultures were provided mixtures of selenite and tellurite, tellurite strongly influenced the fate of selenite and the types of volatile products made. Tellurite in oxyanion mixtures appears to strongly inhibit Se volatilization and drive speciation to less complex Se volatiles. Mixtures boosted the production of Te and Se precipitates by Bacillus sp. strain 6A and the production of Te precipitates by Rhodotorula mucilaginosa strains 13B and decreased the production of both volatile Te and Se compounds. Dimethylselenide and dimethyltelluride are acutely toxic by inhalation and oral exposure, so understanding their production is a key consideration in any biologically based manufacture of Se/Te containing nanoparticles.Item Hydrographic and Activity Data From: Light Sensitivity of the Arctic Copepod Metridia Longa During Midnight Sun and Polar Night(2025-09-18) Lightfoot, Meaghan; Last, Kim S.; Cohen, Jonathan H.We sampled the water column hydrography at three locations in the Barents Sea and Kongsfjorden, Svalbard during May 2022 (Midnight Sun) and January 2023 (Polar Night), then collected the copepod Metridia longa for behavioral experiments. Sampling took place in May 2022 (Midnight Sun) and January 2023 (Polar Night) in the Barents Sea at two locations: 74.597 N, 29.057 E (Midnight Sun-shelf; MS-S) and 75.007 N, 15.117 E (Polar Night-shelf; PN-S). Further Polar Night sampling was conducted in Kongsfjorden, Svalbard at 78.967 N, 11.967 E (Polar Night-fjord; PN-F). For more details on sampling and instrumentation, see the paper associated with this dataset: Lightfoot et al. (2025) 247:118-133. Collections of the copepod Metridia longa were used to measure irradiance and spectral activity responses of copepods in a novel laboratory locomotor activity apparatus. For more details on sampling, instrumentation, and experimental protocols see the paper associated with this dataset: Lightfoot et al. (2025) 247:118-133.Item SOURCES OF DIC AND δ13C-DIC IN THE ROOSEVELT INLET(2025-01) Jordan A. WatsonThis study investigates biogeochemical variability in Roosevelt Inlet (Lewes, DE), where mixing between four water sources—Broadkill River (freshwater), Canary Creek (marsh), Lewes-Rehoboth Canal (brackish), and Delaware Bay (seawater)—shapes marine carbonate chemistry. The goal of this work is to use discrete endmember tide cycle sampling with continuous data logging to identify contributions of dissolved inorganic carbon (DIC) and δ¹³C-DIC from marshes and Delaware Bay to the Broadkill Estuary. Previous studies of DIC in coastal systems have rarely incorporated δ¹³C data, thereby limiting insight into carbon source attribution. To address this, we conducted five seasonal samplings at each water source where we combined discrete endmember high/low tide and high-resolution tide cycle sampling surveys on separate days and weeks within the same months. Measured pH, pCO₂, total alkalinity (TA), DIC, and δ¹³C-DIC identified physical and biological controls on marine carbonate chemistry. Isotopic signatures revealed the influence of organic matter decomposition, with δ¹³C values consistent with inputs from Spartina alterniflora (–13‰) and freshwater endmembers (–10‰). A two-endmember mixing model demonstrated seasonal effects on DIC and δ¹³C, where August and October values were driven by marsh-derived aerobic respiration rather than sulfate reduction. August and October low tides were dominated by marshland, producing high pCO₂ and low pH and dissolved oxygen (DO) values. December and February were influenced by the Delaware Bay endmember (–10‰), and reflected carbonate precipitation and cumulative aerobic processes, whereas April conditions indicated enhanced photosynthesis. Here, the mixing model effectively traced organic carbon sources and may be applicable to similar estuarine systems.Item Decadal Variability in the Core Strength of the South Pacific Convergence Zone(Geophysical Research Letters, 2025-08-25) Wang, Handa; Zhuang, Wei; Yan, Xiao-HaiThe South Pacific Convergence Zone (SPCZ), the primary rainfall source for South Pacific islands, exhibits decadal variability in its core region that remains insufficiently studied. Isolating sea surface temperature internal variability (SSTIV) from external forcing (1940–2013) reveals SSTIV is the dominant driver of SPCZ core strength variability (CSV), quantified via 10‐m wind convergence. Local SSTIV modulates CSV through thermodynamic feedbacks, whereas equatorial Pacific sea surface temperature (SST) anomalies exert limited remote influence. Regression analysis shows a 9.1 × 10 6 s 1 increase in CSV and a 1.7 mm day 1 increase in precipitation per 1°C SSTIV rise on decadal scales. Although external forcing significantly shapes SPCZ SST, its direct impact on CSV is counteracted by the tropical Pacific SST gradient. The strong sensitivity of CSV to internal SST variability, compared to its muted response to external forcing, underscores the pivotal role of internal climate variability in shaping SPCZ dynamics.Item Glacial-Interglacial Climate Cycles of Atmospheric Hg Deposition: Insights From Hg Isotopes in Loess-Paleosol Sequences on the Chinese Loess Plateau(Geophysical Research Letters, 2025-04-09) Xue, Wen; Xu, Zhidong; Cheng, Xing; Gou, Longfei; He, Maoyong; Jin, Zhangdong; Li, Miling; Fang, Linchuan; Yin, RunshengAs a highly volatile heavy metal, Hg is transported over long distances in the atmosphere and enters global ecosystems via Hg(II) wet deposition and Hg(0) dry deposition. The Chinese Loess Plateau develops loess-paleosol sequences (eolian deposits) reflecting glacial-interglacial cycles. Here, we investigate the Hg concentration and isotopic composition of loess-paleosol sequences covering three glacial-interglacial cycles (spanning 350–80 ka). Paleosol layers display higher THg, Δ199Hg, and Δ200Hg values than loess layers, meaning enhanced Hg(II) wet deposition during interglacials. Based on a Δ200Hg-based mixing model, Hg(II) wet and Hg(0) dry depositions account for 42% and 58% of Hg input into the Chinese Loess Plateau during interglacials but 21% and 79% during glacials, respectively. This work highlights a strong climatic control on atmospheric Hg deposition at glacial-interglacial time scales, and suggests that atmospheric Hg deposition will likely increase in middle latitudes without considering perturbations of anthropogenic emissions. Key Points - The atmospheric Hg deposition history was reconstructed using loess-paleosol sequences on the Chinese Loess Plateau - Glacial-interglacial cycles of atmospheric Hg deposition were reported for the first time in eolian deposits - Variations in summer and winter monsoons during glacial-interglacial cycles control atmospheric Hg deposition Plain Language Summary Mercury is a heavy metal pollutant that undergoes global transport in the atmosphere and enters global ecosystems via atmospheric deposition. This work for the first time observes glacial-interglacial cycles of Hg concentration and Hg isotopic ratios in loess-paleosol sequences on the Chinese Loess Plateau. The results provide strong evidence of climatic control on atmospheric Hg deposition. Variations in summer and winter monsoons during glacial-interglacial cycles regulate the intensity of atmospheric Hg deposition on the Chinese Loess Plateau. This work predicts that atmospheric Hg deposition will likely increase in middle latitudes without considering perturbations of anthropogenic emissions.Item Social Perceptions of Offshore Wind Energy through the Lens of Acceptance and Justice(Mainsheet, 2024-12-20) Howley, Shannon; Korein, EmmaThe offshore wind industry is rapidly expanding across the globe as countries aim to meet ambitious renewable energy targets and provide renewable energy to coastal population hubs. Offshore wind represents not only a transformation of energy markets but also ocean spaces with which individuals and communities have economic, personal, and cultural ties. Social science research can help understand the complexity of this human-technology interaction by exploring individuals’ perceptions of offshore wind projects and their effect on sociocultural systems. In this article, we review two theories that examine the social dimensions of offshore wind: social acceptance and energy justice. We then conduct a literature review of offshore wind research using these social acceptance and energy justice frameworks, with a focus on three groups of affected communities (coastal residents, tourists and recreationists, and commercial and recreational fishers) and compensation measures. We finish with a discussion of what the current literature reveals about the complex and diverse responses people have to offshore wind development in their community and the implications for future research.Item An approach to predicting linear trends in tagging-related mortality and tag loss during mark-recapture studies(Frontiers in Ecology and Evolution, 2025-04-30) McCutcheon, Jasper; Campbell, Brendan; Hudock, Rileigh E.; Motz, Noah; Windsor, Madison; Carlisle, Aaron; Hale, EdwardUsing tags within a mark-recapture framework allows researchers to assess population size and connectivity. Such methods have been applied in coastal zone habitats to monitor salt marsh restoration success by comparing the movement patterns of Mummichogs (Fundulus heteroclitus) between restored and natural marshes. Visible Implant Elastomer (VIE) tags are commonly used to tag small fish like Mummichogs, though the retention and survival of small fish using this method varies between studies, producing uncertainty during mark-recapture-based approaches. To address this, we conducted a laboratory experiment to determine the rate of tag loss and mortality of VIE tags on Mummichogs of two size classes (greater or less than 61 mm) and across different taggers. Tag loss and mortality increased over time, and the latter significantly varied between taggers. We then developed a predictive model, R package ‘retmort’, to account for the effect of this increase on mark-recapture studies. When adapted to a series of published works, our model provided rational estimates of tagging error for multiple species and tagging methods. Of the case studies the model was applied to (n = 26), 15 resulted in a percent standard error greater than 5%, signaling a significant percent of error due to uncounted, tagged animals. By not accounting for these individuals, recapture studies, particularly those that assess restoration efforts and coastal resilience, could underestimate the effects of those projects, leading to superfluous restoration efforts and erroneous recapture data for species with low tag retention and high mortality rates.Item Assessing Deep and Abyssal Ocean Heat Content Changes With a Dynamically Consistent Ocean State Estimate(Journal of Geophysical Research: Oceans, 2025-03-20) Zhang, Yang; Liang, Xinfeng; Chambers, Don P.; Huang, MinghaiBecause of the sparseness of existing observations, our understanding of deep (2,000–4,000 m) and abyssal (>4,000 m) ocean heat content (OHC) changes remains limited. Previous studies utilizing repeated hydrographic section measurements identified a global warming trend in these layers. However, studies based on a widely used ocean state estimate ECCO v4 (Estimating the Circulation and Climate of the Ocean, version 4) show a contradictory cooling trend in the deep and abyssal Pacific and Indian Oceans. To examine if the sparseness of hydrographic measurements results in this contrasting conclusion, we conducted a sampling experiment with ECCO v4. Our results show that the signs of the OHC trends in the deep and abyssal oceans from the full spatial-temporal data and the sampled data are generally consistent. The largest uncertainties mainly occur in regions where the deep ocean is dominated by newly formed deep-water masses or where hydrographic sections are extremely sparse, such as the Northwest Atlantic Ocean and the Southern Ocean. Our findings also indicate that the discrepancies between ECCO v4 and observations in deep and abyssal OHC changes are not likely a sampling issue, and further studies are needed to determine the reasons. Key Points - A sampling experiment was conducted to assess possible biases of deep and abyssal ocean heat content changes due to under-sampling - Deep and abyssal ocean heat content trends from sampled data are generally consistent with those from full spatial-temporal data - Under-sampling does not explain the differences between ECCO and observations in the deep and abyssal ocean heat content changes Plain Language Summary Deep and abyssal oceans are key heat reservoirs in the Earth System. However, the limited number of available observations constrains our understanding of changes in deep and abyssal ocean heat content (OHC). In addition, studies based on limited observations and a widely used ocean state estimate display contrasting trends in deep and abyssal OHC changes in the Pacific and Indian Oceans. Here, we conduct a sampling experiment with a state-of-the-art ocean synthesis product to explore if under-sampling is the reason for the contrasting results. We found that the OHC changes estimated from the repeated hydrographic sections are generally reliable, suggesting that the current sampling framework is not likely the cause of the opposite OHC trends in studies based on observational data and the ocean state estimate. Significant uncertainties do exist and primarily appear in regions such as the Northwest Atlantic and Southern Ocean. Our findings provide a valuable reference for understanding deep and abyssal ocean changes as well as for designing and implementing future global ocean observational systems.Item Considerations for using sharks as ocean observing platforms(ICES Journal of Marine Science, 2025-02-07) Wiernicki, Caroline J.; Curtis, Tobey H.; Block, Barbara A.; Shivji, Mahmood S.; Vaudo, Jeremy J.; Wetherbee, Bradley M.; Holland, Kim N.; Pinti, Jérôme; Oliver, Matthew J.; Carlisle, Aaron B.The combination of animal-borne telemetry and oceanographic sensor technologies creates an opportunity for marine animals to serve as ocean observing platforms (OOPs), carrying tags that record in situ oceanographic data as they naturally move. In this study, we create a blueprint of shark OOP species selection, quantifying and comparing the potential for species to transmit collected data, the environmental ranges various candidates are expected to encounter, and the oceanographic features they may be expected to resolve. Metrics of data satellite transmission probability, movement behaviors, and environmental sampling ranges are calculated combining historically collected satellite tag data for 11 shark species tagged in the Atlantic and Pacific Ocean basins. Species with the highest satellite data transmission potential include shortfin mako (Atlantic and Pacific) and blue (Pacific) sharks. These species also demonstrated overlap in time and length scales for area-restricted search-like movement behaviors with several mesoscale ocean features, including hurricanes and upwelling events. Additional comparisons of decorrelation time scales between theoretical shark versus glider sampling platforms suggest that shark OOPs have the ability to provide three times more uncorrelated water column temperature and conductivity profiles than gliders at 15% of the operational cost.Item A global dataset of nitrogen fixation rates across inland and coastal waters(Limnology and Oceanography Letters, 2025-01-23) Fulweiler, Robinson W.; Berberich, Megan E.; Rinehart, Shelby A.; Taylor, Jason M.; Kelly, Michelle C.; Ray, Nicholas E.; Oczkowski, Autumn; Balint, Sawyer J.; Geisser, Alexandra H.; Mahoney, Catherine R.; Benavides, Mar; Church, Matthew J.; Loeks, Brianna; Newell, Silvia E.; Olofsson, Malin; Oppong, Jimmy C.; Roley, Sarah S.; Vizza, Carmella; Wilson, Samuel T.; Groffman, Peter M.; Scott, J. Thad; Marcarelli, Amy M.Biological nitrogen fixation is the conversion of dinitrogen (N2) gas into bioavailable nitrogen by microorganisms with consequences for primary production, ecosystem function, and global climate. Here we present a compiled dataset of 4793 nitrogen fixation (N2-fixation) rates measured in the water column and benthos of inland and coastal systems via the acetylene reduction assay, 15N2 labeling, or N2/Ar technique. While the data are distributed across seven continents, most observations (88%) are from the northern hemisphere. 15N2 labeling accounted for 67% of water column measurements, while the acetylene reduction assay accounted for 81% of benthic N2-fixation observations. Dataset median area-, volume-, and mass-normalized N2-fixation rates are 7.1 μmol N2-N m−2 h−1, 2.3 × 10−4 μmol N2-N L−1 h−1, and 4.8 × 10−4 μmol N2-N g−1 h−1, respectively. This dataset will facilitate future efforts to study and scale N2-fixation contributions across inland and coastal aquatic environments. Scientific Significance Statement Here we provide and describe a dataset of global nitrogen fixation rates for the water column and benthos of inland and coastal waters. This dataset is useful for understanding how nitrogen fixation varies across these ecosystems and is a resource for focusing future research questions. We anticipate this is the first version of this dataset that will continue to develop with newly published rates and expanded data on environmental drivers.Item Characterizing Storm-Induced Coastal Flooding Using SAR Imagery and Deep Learning(IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, 2025-01-21) Edwing, Deanna; Meng, Lingsheng; Lv, Suna; Yan, Xiao-HaiFlooding is among the most common yet costly worldwide annual disasters. Previous studies have proven that synthetic aperture radar (SAR) is an effective tool for flooding observation due to its high-resolution and timely observations, and deep learning-based models can accurately extract water bodies from SAR imagery. However, many previous flood analyses do not account for influences of tides and permanent water bodies, and the comprehensive characteristics of coastal storm flooding are still not fully understood. This study therefore presents a novel approach for isolating storm-induced flood waters in coastal regions from SAR imagery through the identification and removal of permanent water bodies and tidal inundation. This methodology is applied to the Delaware Bay region, with ancillary geospatial data used to determine resulting landcover impacts. Results indicate that flooding primarily impacts agricultural and marsh regions, as well as urban areas like airports and road systems adjacent to rivers or large inland bays. The sensitivity impacts of tides on flood estimates reveals that estimates significantly increase if included in analysis, highlighting the importance of their removal prior to flood identification. Finally, exploration into intense coastal storm events in the Delaware Bay region reveal the importance of storm characteristics like high water levels, wind, and precipitation in generating extreme flooding conditions. The case study presented here has important implications for other coastal regions and provides an innovative and comprehensive approach to coastal storm flood identification and characterization which can benefit coastal managers, emergency responders, coastal communities, and researchers interested in coastal flood hazards.Item Bacteria-Produced Algicide for Field Control of Toxic Dinoflagellates Does Not Cause a Cortisol Stress Response in Two Estuarine Fish Species(Marine Biotechnology, 2025-01-14) Simons, Victoria E.; Targett, Timothy E.; Gaffney, Patrick M.; Coyne, Kathryn J.Application of algicides produced by naturally occurring bacteria is considered an environmentally friendly approach to control harmful algal blooms. However, few studies assess the effects of bacterial algicides on non-target species, either independently or with other stressors. Here, we measured sub-lethal effects of dinoflagellate-specific algicide IRI-160AA on the estuarine fish Fundulus heteroclitus and Menidia menidia in laboratory experiments. Plasma cortisol levels were measured to test whether a neuroendocrine stress response was induced in these fish following exposure to the algicide alone, and in combination with diel-cycling hypoxia and/or pH, at 25 and 30 °C. Results show that exposure to IRI-160AA does not significantly affect cortisol levels in either species, at either temperature tested, whether exposure occurs independently or with co-occurring hypoxia and/or pH cycles as potential multiple stressors. These results support the application of IRI-160AA as an environmentally friendly approach to control harmful algal blooms in estuarine environments.Item Private versus Public Flood Insurance: Differences in Premiums and Uptake Observed in Two Coastal Housing Markets Using Survey Data(Marine Resource Economics, 2025-01-01) Fielding, Samuel; Parsons, GeorgeUsing a natural experiment created by the 1982 Coastal Barrier Resources Act (CBRA), we measure the extent to which insurance premiums vary between private and publicly backed flood insurance policies. The CBRA resulted in homeowners living in neighboring housing markets in which some have access to the federally backed National Flood Insurance Program (NFIP) and others do not. Flood risks and other features of the neighborhoods are otherwise indistinguishable. Those without access to publicly backed insurance must purchase private insurance if they desire coverage. We compare insurance premiums and uptake in the two markets and find that premiums for private coverage are significantly higher than public rates (after controlling for other factors in a reduced-form regression), implying a subsidy by NFIP. We also find a much lower uptake of insurance in the areas without federally backed insurance. Our results are based on a mail survey of residents in two US coastal communities with a 50% response rate: North Bethany Beach, Delaware, and North Topsail Beach, North Carolina. We also present results related to perceptions of flood hazards, of being under- or overinsured, and measures taken to mitigate flood damage.Item Comparative metagenomics of tropical reef fishes show conserved core gut functions across hosts and diets with diet-related functional gene enrichments(Applied and Environmental Microbiology, 2025-01-22) Wu, Derek G.; Harris, Cassandra R.; Kalis, Katie M.; Bowen, Malique; Biddle, Jennifer F.; Farag, Ibrahim F.Fish gut microbial communities are important for the breakdown and energy harvesting of the host diet. Microbes within the fish gut are selected by environmental and evolutionary factors. To understand how fish gut microbial communities are shaped by diet, three tropical fish species (hawkfish, Paracirrhites arcatus; yellow tang, Zebrasoma flavescens; and triggerfish, Rhinecanthus aculeatus) were fed piscivorous (fish meal pellets), herbivorous (seaweed), and invertivorous (shrimp) diets, respectively. From fecal samples, a total of 43 metagenome assembled genomes (MAGs) were recovered from all fish diet treatments. Each host-diet treatment harbored distinct microbial communities based on taxonomy, with Proteobacteria, Bacteroidota, and Firmicutes being the most represented. Based on their metagenomes, MAGs from all three host-diet treatments demonstrated a baseline ability to degrade proteinaceous, fatty acid, and simple carbohydrate inputs and carry out central carbon metabolism, lactate and formate fermentation, acetogenesis, nitrate respiration, and B vitamin synthesis. The herbivorous yellow tang harbored more functionally diverse MAGs with some complex polysaccharide degradation specialists, while the piscivorous hawkfish’s MAGs were more specialized for the degradation of proteins. The invertivorous triggerfish’s gut MAGs lacked many carbohydrate-degrading capabilities, resulting in them being more specialized and functionally uniform. Across all treatments, several MAGs were able to participate in only individual steps of the degradation of complex polysaccharides, suggestive of microbial community networks that degrade complex inputs. IMPORTANCE The benefits of healthy microbiomes for vertebrate hosts include the breakdown of food into more readily usable forms and production of essential vitamins from their host's diet. Compositions of microbial communities in the guts of fish in response to diet have been studied, but there is a lack of a comprehensive understanding of the genome-based metabolic capabilities of specific microbes and how they support their hosts. Therefore, we assembled genomes of several gut microbes collected from the feces of three fish species that were being fed different diets to illustrate how individual microbes can carry out specific steps in the degradation and energy utilization of various food inputs and support their host. We found evidence that fish gut microbial communities share several core functions despite differences in microbial taxonomy. Herbivorous fish harbored a functionally diverse microbial community with plant matter degraders, while the piscivorous and invertivorous fish had microbiomes more specialized in protein degradation.Item Identifying potential introduced and natural sources of pollution in Delaware watersheds(Applied and Environmental Microbiology, 2024-12-17) Bowen, Malique; Main, Christopher R.; Farag, Ibrahim F.; Biddle, Jennifer F.Managing water quality with microbial impairment caused by Enterococcus poses unique challenges regarding the determination of fecal host origin. Most water monitoring is performed based on Enterococcus counts that neither detect the location of the introduction of pollution nor identify the type of contaminating Enterococcus. The use of sequenced-based microbial source tracking could allow for identification of fecal origin and potential remediation of pollution. The state of Delaware has numerous waterways with high microbial impairment from unknown sources, so we used sequence-based microbial source tracking to investigate potential microbial pollution in three watersheds with significant variation in land use and population density. In this study, we use a 16S rRNA sequence reference library of microbial communities from relevant fecal sources (wild animal, domestic animal, sediment, and septic/wastewater) to determine the most likely sources of microbial impairment in three Delaware watersheds. This study assigned sources of microbial contamination to mostly human-related sources (septic and wastewater) or unknown sources indicating that waste infrastructure may have a larger influence on microbial community structure in Delaware watersheds than previously considered. Our results suggest that long-term source tracking is valuable for ruling out native or domesticated animals as contributors to water pollution. IMPORTANCE Traditional microbial pollution monitoring utilizes specific fecal indicator bacteria that need to grow in the laboratory for detection. Here, we show the use of sequence information from whole microbial communities and an expanded reference library in microbial source tracking. Expanding the host detection range by including the whole microbial community may allow for a wider range of potential fecal origin identification even when specific fecal indicators are absent or in low concentration. We show that many Delaware waterways bear the signature of human influence compared to natural sources. In addition, the robust reference library built in this study can be used to conduct source tracking studies in the mid-Atlantic USA.