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Final Report Presentations of the 2020 Tibor T. Polgar Fellows

2020 Polgar Fellows

Sarah Trabue, Columbia University: Photo-Identification and Skin Lesion Prevalence of Bottlenose Dolphins in the New York-New Jersey Harbor Estuary. Supervisors: Howard Rosenbaum, Director, Ocean Giants Program, Wildlife Conservation Society and Melinda Rekdahl, Ocean Giants Program, Wildlife Conservation Society


For the past two decades, skin lesions have been documented on bottlenose dolphins (Tursiops truncatus) across the globe. Lesion presence indicates underlying disease or diminished health, and can be used to infer the presence of environmental stressors and ultimately population health. In some populations, lesion development has been associated with environmental variables, including sea surface temperature and salinity, as well as anthropogenic factors, such as pollutants. Photo-ID has been an increasingly used method for documenting skin lesion prevalence (P). Here, photo-ID was used to monitor and infer the health of the migratory population of bottlenose dolphins in the New York-New Jersey Harbor Estuary during their seasonal residency by investigating patterns of skin lesion prevalence. Bottlenose dolphins were sighted and photographed from May to October 2017-2020. Photographs of distinct individuals were compiled into a photo-ID catalog and subsequently screened for skin lesions. Skin lesions were categorized and the overall, annual and monthly prevalence were calculated and compared to other populations along the Atlantic coast. The relationship between environmental variables and lesion prevalence was investigated using generalized linear models. Prevalence varied annually, with the highest in 2017 (P = 0.48) and lowest the following year (P = 0.28). By month, lesion prevalence was highest in June and decreased into the summer and fall. Overall lesion prevalence in the Harbor Estuary (P = 0.41) was lower than reported prevalence estimates in North Carolina, South Carolina, and Georgia, and roughly equivalent with Florida. The most common lesion types in this population have been associated with viral infections, namely herpesvirus and poxvirus. The only significant environmental variable was salinity, which was negatively correlated with lesion prevalence. This research helps to establish baselines for monitoring bottlenose dolphin population health in the New York-New Jersey Harbor Estuary and surrounding waters, which are particularly relevant given the extent and expansion of anthropogenic activities, including those related to forthcoming offshore wind development.

Emma Garrison, Queens College, CUNY: Exploring the Influence of Urban Sewage Pollution on Fish Microbiomes in New York Harbor. Supervisor: Gregory O’Mullan, Professor, School of Earth and Environmental Sciences, Queens College, City University of New York


New York Harbor waterways experience contamination through a variety of pathways including persistent historic industrial pollution and modern pollution primarily associated with sewage infrastructure and stormwater runoff. This results in poor water quality conditions which are spatially heterogeneous and can be highly localized within the harbor. Despite poor water quality conditions, New York Harbor hosts a wide variety of fish species, many of which are on high priority lists for conservation. While many direct pathways of impact on these species are well studied, one potential pathway may be through fish gut microbiomes which play critical roles in fish health but are not well understood in the context of urban pollution. In order to address this gap, the gut microbiomes of mummichogs (Fundulus heteroclitus) were compared with environmental water samples along a gradient of urban sewage influence using cultivation based enumeration of antibiotic resistant bacteria as a metric of impact. Antibiotic resistant bacteria in guts were found to be positively correlated with those in water samples, suggesting that sewage exposure may impact fish microbiomes.

Azlan Maqbool, Queens College: Investigating the Distribution of Legionella in a Freshwater Hudson River Watershed. Gregory O’Mullan, Professor, School of Earth and Environmental Sciences, Queens College, City University of New York and Elias Dueker, Associate Professor of Environmental and Urban Studies; Director, Bard Center for the Study of Land, Air, and Water, Bard College


Bacteria in the genus Legionella are known to have a widespread occurrence in the environment, including prior literature demonstrating presence in soils, lakes, river systems, the coastal ocean and man-made water systems. Legionnaires Disease, caused by pathogenic strains of Legionella pnuemophila, is thought to be primarily associated with commonly known aerosolization sources in built environment infrastructure, such as cooling towers. In urban centers where there are an abundance of cooling towers and man-made water systems, there is little known about other potential reservoirs of Legionella. In the summer of 2019, we investigated western Long Island Sound and East River tributaries of New York City to determine if Legionella pneumophila was detectable and if it increased in sewage impacted waterways following rainfall. We found that 51% of estuarine samples were positive for Legionella pneumophila, most with low concentrations, and the levels increased following rainfall. In contrast, 95% of streetwater samples were found to contain detectable levels. This presented a strong initial indication of wet weather contamination from the street water input into the estuarine environment. The current study expanded on these initial results to explore if the pattern of stormwater from streets surfaces acts as a source to waterways in less densely populated areas and in freshwater areas of the Hudson River watershed. These data suggest that street water in both urban and suburban areas harbor similar concentrations of Legionella pneumophila enough to be considered a significant source to surrounding waterways. These results reinforce stormwater as of microbial concern and reinforces the need for management of aerosolization sources from water containing elevated bacterial concentrations.

Eva Hasegawa, New York University: Contribution of the Hudson River Striped Bass Population to the Mixed Coastal Recreational Harvest at Montauk Point, NY. Supervisor: Isaac Wirgin, Associate Professor, Department of Environmental Medicine, NYU Grossman School of Medicine


Striped bass, Morone saxatilis, support one of the most lucrative recreational and commercial fisheries along the Atlantic Coast of the U.S. In New York alone, $1.165 billion was added to the state’s gross GDP by the recreational fishery in 2016 (Southwick Associates 2019). Yet, today striped bass numbers are down significantly along the Atlantic Coast and new management initiatives have been implemented in 2020 to reduce the catch coastwide. In the middle of its range along the Atlantic coast of the U.S., striped bass are seasonally migratory, ranging from the Bay of Fundy, Canada, to the Outer Banks of North Carolina. This coastal migratory stock of striped bass is primarily supported by spawning populations in the Hudson River and Chesapeake Bay with smaller contributions from the Delaware River and Roanoke River, North Carolina populations. Spawning success and recruitment within these populations vary temporally and is often asynchronous suggesting that they likely require differing levels of protection over time. Therefore, an important prerequisite to effective management of these populations is a quantitative estimate of their relative contributions to these coastal landings. Montauk Point is probably the site within New York state that hosts the largest striped bass recreational fishery and is geographically sited to host migrant striped bass from all possible populations that contribute to the coastal migratory stock. Therefore, we evaluated the stability of the Hudson River contributions to the recreational harvest of striped bass at Montauk Point in 2019. We used Mixed Stock Analysis (MSA) and Individual Based Assignment (IBA) testing with microsatellite DNA data. In the Montauk mixed-stock fishery, we found that Chesapeake fish are the largest contributors (88%), followed by Hudson River fish (8.5%), and, lastly, Roanoke River fish (3.6%). Our data from this study will be useful for NOAA managers in their stock assessment modeling for striped bass since variations in recruitment of contributing stocks vary over time, which reflects their differing population abundances.

On January 21st, 2021, the 2020 Tibor T. Polgar Fellows presented final reports on their research via live webinar.

The Tibor T. Polgar fellowship program provides support for a summer of research to graduate and undergraduate students focusing on the physical, chemical, biological, and public policy realms of the Hudson River Estuary. Click here to learn more about the fellowship program.

Presentation Slides