Faculty Bibliography

The Hudson River (HR), New York, has been rapidly warming, with water temperatures increasing 1 °C between 1946 and 2006 and projected to rise at an even faster rate in the future. Atlantic tomcod Microgadus tomcod is a cold water, estuarine, Gadidae species whose current southern distribution along the Atlantic coast of North America is truncated by warming waters. Currently, the HR supports their southernmost spawning population whose abundance is in severe decline. We used controlled laboratory experiments to investigate the effects of projected warming HR wintertime water temperatures on a number of fitness measures in tomcod embryos and larvae. We found that higher temperatures increased hatch rate, growth rate, heart rates, mortality of larvae, and differentially expressed genes (DEGs). The number of DEGs identified by RNA-Seq analysis (≥ 2-fold change, FDR <0.1) increased when comparing the control 2.7 °C temperature group to the higher temperature exposure groups. For example, the number of DEGs was 349, 565, and 1286 when comparing the control exposure group to the groups exposed to 3.5 °C, 6.2 °C, and 8.3 °C water temperatures, respectively. DEGs genes were linked to stress response, cardiac health, and protein homeostasis. These findings indicate that Atlantic tomcod respond to temperature stress by downregulating energy-intensive processes like protein homeostasis, posing potential long-term health risks to its HR population.

Atlantic sturgeon Acipenser oxyrinchus oxyrinchus is widely distributed along the Atlantic coast of North America, with spawning populations extending from the St. Lawrence River, Quebec to the St. Marys River, Georgia-Florida. At one time, Atlantic sturgeon supported lucrative fisheries on adults within rivers where they spawned and on subadults and adults within coastal waters. Because of decimated population sizes, Atlantic sturgeon in U.S. waters are now federally protected as five Distinct Population Segments (DPS) under the U.S. Endangered Species Act. While juvenile Atlantic sturgeon are resident within their natal rivers, subadults and adults are highly migratory in coastal waters and often occur in non-natal estuaries, exposing them to a variety of anthropogenic threats outside of their natal estuaries, including bycatch. To most effectively protect the smallest and most vulnerable populations, a method is needed to accurately identify the population origin of individual specimens and their aggregations outside of their natal systems. In this study, microsatellite DNA analysis was used to identify the genetic population structure of Atlantic sturgeon across 13 reference populations. Their genetic profiles then were used to identify the population origin of individuals collected from six coastal locales and one non-natal estuary. All 13 reference collections harbored genetically distinct, and in some cases more than one, population of Atlantic sturgeon. The Hudson River was by far the largest contributor to the overall coastal and non-natal estuarine collections, at 35.3%. The contributions of the other reference populations varied considerably between < 1.0% (York, Edisto, Savannah, and Satilla rivers) to 15.6% (Saint John River) and 12.9% (James River) and appeared unrelated to their estimated population sizes. These results suggest that migratory behavior in marine waters varies greatly among Atlantic sturgeon populations, and should assist resource managers assess the effects of anthropogenic stressors on sturgeon outside of their individual natal river or DPS.

The Atlantic sturgeon Acipenser oxyrinchus oxyrinchus is an anadromous species with a wide range along the Atlantic coast of North America. Because of overharvest and a variety of other anthropogenic stressors, the numbers of estuaries that currently host successful natural reproduction and the abundances of extant populations are depressed compared to historic numbers, resulting in its listing under the US Endangered Species Act as five Distinct Population Segments (DPS). Atlantic sturgeon are vulnerable to stressors not only within their natal estuaries but also at distant locales because of the highly migratory behavior of their subadult and adult life stages. In this study, we used our previously derived microsatellite DNA catalogue of 13 reference spawning populations and Individual-Based Assignment testing to determine the origin of 202 adult Atlantic sturgeon that were collected from the lower Altamaha River during spring, several months prior to their fall upriver spawning. We found that approximately one third (37%) of these adults assigned to populations other than the Altamaha, almost all (96%) to other populations within the South Atlantic DPS, a finding consistent with our earlier acoustic telemetry results. These results have management implications, including the likelihood of recolonization of depleted populations in the South Atlantic DPS and the compilation of reference population genetic profiles used in population delineation and mixed-stock analyses.

ST and FST analyses, the extent of the pairwise genetic differentiation between the two genetic clusters in the Ogeechee River and the three in the Satilla River was greater than that between all other pairwise comparisons among rivers in the South Atlantic DPS. In contrast, we found no evidence of the genetic partitioning of juvenile sturgeon within the neighboring Savannah or Altamaha river populations. Using IBA, we found that the overall Ogeechee River population made a moderate contribution (8.3%) to the overall mixed-stock collections (n = 1512) from coastal North Carolina to the Bay of Fundy. Surprisingly, all of the Ogeechee River-assigned specimens (n = 125) in these mixed-stock aggregations were representatives of only one of the two Ogeechee River genetic clusters. These results suggest that the two Ogeechee River genetic clusters exhibit significantly different life history strategies, with one being resident and the second being highly migratory.

The Hudson River (HR) Estuary has a long history of pollution with a variety of contaminants including PCBs, and dioxins. In fact, 200 miles of the mainstem HR is designated a U.S. federal Superfund site, the largest in the nation, because of PCB contamination. The tidal HR hosts the southernmost spawning population of Atlantic tomcod, and studies revealed a correlation between exposure of juveniles to warm water temperature during summer to abundance of spawning adults of the same cohort in the following winter. Further, a battery of mechanistically linked biomarkers, ranging from the molecular to the population levels, were significantly impacted from contaminant exposures of the HR tomcod population. In response to xenobiotic insult, the HR tomcod population developed resistance to PCB sand TCDD toxicity resulting from a deletion in the aryl hydrocarbon receptor2 (AHR2) gene. Furthermore, RNA-Seq analysis of global gene expression demonstrated that effects of the AHR2 polymorphism were far more pervasive than anticipated. The most highly PCB-contaminated sediments in the upper HR were dredged between 2009 and 2015 with the objective of lowering PCB concentrations in fishes in the lower HR. Success of the remediation project has been controversial. These observations suggest that tomcod provides an informative model to evaluate the efficacy of HR PCB remediation efforts on downriver fish populations and possible interactive effects between contaminant exposure and a warming environment.

The Atlantic Coast Migratory Stock (ACMS) of striped bass Morone saxatilis is supported by spawning populations in Chesapeake Bay and the Hudson, Delaware, and Roanoke rivers. Spawning success and recruitment differs among these populations and temporally within them and thus their relative abundances shift over time. The ACMS is subject to harvest and other sources of mortality at many Atlantic Coast locales. Effective management of these populations would benefit from knowledge of the relative contributions of these populations to the ACMS. We used microsatellite DNA analysis to measure the extent of genetic differentiation among those populations that contribute to the ACMS and to quantify their contributions to recreational harvest in 2019 at Montauk, New York. We found genetic homogeneity between the Delaware River and Chesapeake Bay populations, but significant allelic differentiation among the Hudson River, combined Delaware River-Chesapeake Bay, and Roanoke River populations. In simulations of single mixture samples, assignment accuracies for the Chesapeake-Delaware, Hudson River, and Roanoke River collections were high at 96 % (95 % CI=0.921, 0.999), 93 % (0.863, 0.979), and 81 % (0.726, 0.866), respectively. Mixture analysis and Individual Based Assignment testing were used to quantify contributions to the 2019 Montauk fishery. Mixture analysis indicated 86 %, 8.5 %, and 5.5 % contributions for the Chesapeake-Delaware, Hudson River and Roanoke River populations, respectively. Similarly, Individual Based Assignments showed the Chesapeake-Delaware population as the largest contributor (78 %), followed by the Hudson River (12 %), and the Roanoke River (10 %). Furthermore, we found no significant differences in relative contributions across the five-month recreational fishing season nor among size-classes of striped bass. Lastly, the risk of consuming a Hudson River striped bass from Montauk containing a considerably high concentration of PCBs is minimal. Future stock composition analysis of Atlantic migratory striped bass would benefit from standardization of the approach, with DNA analysis from collections made at a single strategic location offering advantages.

Although there is rising global concern over the environmental, ecological, and human health risks associated with the discharge of leachates from e-waste dumpsites into the aquatic ecosystems, little is known in this research area. Thus, for this study, we first defined the chemistry of the test leachate, followed by assessment of the leachate on the development of a model aquatic organism (Fundulus heteroclitus) used extensively as a bioassay organism in pollution studies. Chemical analyses revealed that levels of phosphate (20.03 mg/L), cadmium (Cd) (0.4 mg/L), lead (Pb) (0.2 mg/L), and chromium (Cr) (0.4 mg/L) were higher than the 2009 US EPA and the 2009 National Environmental Standards and Regulations Enforcement Agency (NESREA) permissible limits. Polycyclic aromatic hydrocarbon (PAH) burdens were dominated mainly by the high molecular weight congeners, specifically the ∑4rings (73 µg/L). Total polychlorinated biphenyls (PCB) levels ranged from 0.00 to 0.40 µg/L with the ∑deca PCBs reaching the highest concentration. For the biological studies, F. heteroclitus embryos (48-h post-fertilization) were divided randomly into groups and exposed to one of six e-waste leachate concentrations (10, 1, 0.1, 0.01, 0.001, 0.0001%). Significant differences (p ≤ 0.05) between treated and control groups were observed in standard and total length, and head size. Further analysis using Duncan"™s post-hoc test of multiple comparison also revealed specific differences within and between specific treatment groups. We conclude that e-waste leachate arising from indiscriminate dumping into aquatic ecosystems in Nigeria contains mixtures of toxic constituents that can threaten ecosystem and public health.

Sturgeon populations worldwide are threatened with extirpation but little is known about their tendency to bioaccumulate contaminants and their sensitivities to environmental burdens of these contaminants. Shortnose sturgeon and Atlantic sturgeon, two species that are federally endangered in the USA, co-occur in the Hudson River (HR) where high sediment levels of polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzo-p-furans (PCDFs) occur. Previous controlled laboratory studies showed that young life-stages of both species are sensitive to toxicities at low levels of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and PCB126 exposure. The objective here was to measure congener-specific hepatic levels of PCBs and PCDD/Fs in HR specimens in order to determine if in situ bioaccumulation of these compounds is sufficiently high to have caused the early life-stage toxicities previously observed. Estimates of hepatic burdens of PCBs and PCDD/Fs were obtained from a small number of specimens of each species collected between 2014 and 2016 and specimens of shortnose sturgeon collected over 30 years earlier and archived in a museum collection. Several significant patterns emerged. Hepatic levels of legacy PCBs and PCDDs were low in specimens of both species but typically higher in shortnose than Atlantic sturgeon, a pattern consistent with their habitat use in the HR. Hepatic burdens in shortnose sturgeon tended to be higher in archived specimens than in more recently collected ones despite expected reduction in archived specimens due to preservation methods. Several inadvertent PCBs congeners were detected at high levels, including PCB11, but their toxicity to natural populations remains unknown. Levels of select PCDFs congeners, 2,3,7,8-TCDF and 2,3,4,7,8 PeCDF, were elevated in some shortnose sturgeon individuals from the HR. Using Relative Potency (ReP) factors derived from white sturgeon, the observed levels of some hepatic PCDFs in HR shortnose sturgeon may have been sufficiently high to impair recruitment of young life-stages in this ecosystem.

Summer flounder Paralichthys dentatus supports one of the most valuable commercial and recreational fisheries along the Atlantic Coast of the U.S. However, in recent decades the management of this species has proven to be one of the most contentious for any exploited marine resource in the region. A coastwide catch quota is imposed annually for summer flounder of which 60% is allocated to the commercial fishery and 40% to the recreational fishery. The allocation is further divided among the individual coastal states from North Carolina to Massachusetts based on their landings in the 1980s. This process, based on political jurisdictions, does not consider the species' biological stock structure. Previous genetic studies (allozyme, mtDNA, and SNPs) provided contradictory results regarding the possible population structure of summer. To address this issue, we used DNA microsatellite analysis at 9 loci to define the coastwide population structure of summer flounder. In total, 1,182 specimens were analyzed from 18 collection sites. Most collections were from the continental shelf during the fall-winter spawning season. These were supplemented with additional samples from inshore waters from North Carolina to Florida, and inshore sites which support significant recreational fisheries at Nantucket Shoals, Massachusetts and Fire Island, New York. The overall level of genetic differentiation in pairwise comparison between collections was very low, mean F

Atlantic sturgeon (Acipenser oxyrinchus oxyrinchus) is a long-lived, anadromous species that is broadly distributed along the Atlantic coast of North America. Historic overharvest and habitat degradation resulted in significant declines to Atlantic sturgeon populations and, following decades of limited recovery, the species was listed under the Endangered Species Act of the United States in 2012. Given continued threats to recovery and limited information about population demography, there is a need for new tools to assist in Atlantic sturgeon conservation. Here, we present a range-wide microsatellite genetic baseline for North American Atlantic sturgeon that is comprised of 2510 individuals from 18 genetically distinct groups collected in 13 rivers and one estuary. Analysis of this baseline suggested that populations from the northern range of Atlantic sturgeon were more highly differentiated than those from the southern extent, where patterns of differentiation were complicated by rivers with genetically distinct spring and fall spawning runs and less geographic distance separating populations. Despite significant demographic bottleneck events, all populations showed at least moderate levels of genetic diversity across a suite of metrics. Additionally, individual-based assignment tests had over 80% accuracy for assigning individuals to their river of origin, highlighting the utility of this baseline for characterizing the composition of mixed-stock aggregations and understanding stock-specific vulnerability and recovery. The expanded spatial coverage of this baseline dataset enabled novel inferences about patterns of genetic differentiation and spawning phenology in Atlantic sturgeon which can be used to support conservation and management efforts.