Genetic Population Structure of Summer Flounder Paralichthys dentatus using Microsatellite DNA Analysis.

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 ST = 0.001. There was no evidence of genetic differentiation between collections from north and south of Cape Hatteras. Our microsatellite results are consistent with an earlier SNP study which failed to find significant allelic heterogeneity among coastwide collections of summer flounder. However, a subset of pairwise F ST comparisons between some collections proved statistically significant. Furthermore, in STRUCTURE analysis we found evidence of two genetic clusters within the species' northern landings area, however, this finding was not supported by DPAC analysis. We conclude that summer flounder most likely constitute a single population along their entire Atlantic Coast distribution.

Atlantic Coastwide Population Structure of Striped Bass Morone saxatilis Using Microsatellite DNA Analysis.

Striped bass Morone saxatilis support one of the most popular and important inshore recreational and commercial fisheries along the Atlantic Coast of North America. Populations at both extremes of its distribution are largely resident while those in the center of its range (Hudson River, New York, to Roanoke River, North Carolina) are seasonally migratory, ranging from the Bay of Fundy, Canada, to the Outer Banks of North Carolina. Historically, population abundances of striped bass fluctuated widely, sometimes resulting in the imposition of severe management measures to restrict their harvest. Detailed knowledge of its rangewide population structure would aid in more effective management; however, most genetic studies addressing the structure of the migratory coastal stock have largely failed to achieve this goal. To address this need, we used multi-loci microsatellite DNA analysis. We identified six genetically distinct populations across the species' distribution, including the Miramichi, Shubenacadie, Hudson, Delaware-Chesapeake, Roanoke, and Santee-Cooper rivers. We also report significant genetic differentiation between the Nanticoke and Choptank rivers along the eastern shore of the Chesapeake Bay and collections from tributaries along the western shore of the Bay. The Annapolis and Saint John rivers, tributaries of the Bay of Fundy, historically hosted striped bass aggregations that were extirpated, or nearly so, by anthropogenic stressors in the late 20th century. No specimens with unique genotypes were found in collections from either river; instead the vast majority were admixed with genotypes of Shubenacadie River, Hudson River, Chesapeake Bay, and Roanoke River lineage. Finally, we show in simulations that these genetic markers should be informative in quantifying the contributions of the Hudson River, Chesapeake Bay-Delaware, and Roanoke River to mixed-stock harvests that occur within the range of the coastal migratory stock.

Genetic variation and population structure of American mink Neovison vison from PCB-contaminated and non-contaminated locales in eastern North America.

American mink Neovison vison may be particularly vulnerable to toxicities of persistent contaminants such as PCBs because of their aquatic-based diet, position near the top of the food web, and small deme sizes. Furthermore, ranched mink are sensitive to reproductive toxicities of fish diets from PCB-polluted sites. The upper Hudson River is highly contaminated with PCBs and previous studies have shown elevated hepatic burdens of total and coplanar PCBs in mink collected near the river compared with those from more distant locales in New York and elsewhere. We hypothesized that bioaccumulation of PCBs in Hudson River mink has reduced their levels of genetic diversity or altered their genetic population structure. To address this, we conducted microsatellite DNA analysis on collections made in proximity to and from more distant locales in the Hudson River watershed, elsewhere in New York State, and at other sites in eastern North America including New Brunswick, four locales in Ontario, multiple drainages in Maine, and two ecoregions in Rhode Island. We did not find reduced genetic diversity at the individual or population levels in mink collected near (<6 km) to PCB hotspots in the Hudson River nor evidence of altered population structure. Consistent with their distribution in small localized and isolated demes, we did find significant genetic population structure among many mink collections in New York State and elsewhere. Depending on the analytical approach used, genetically distinct populations numbered between 16 when using STRUCTURE to 19-20 when using Exact G tests, F ST, or AMOVA analyses. Genetically distinct population units were found among major ecoregions and minor ecoregions in New York State, among different hydrologic subunits within the Hudson River watershed, among spatially separate locales in Ontario, and among most watersheds in Maine. However, despite this localization and potential heightened impact of stressors, genetic diversity and genetic population structure in mink does not seem to be affected by their bioaccumulation of high levels of PCBs of Hudson River origin.

Effects of Hudson River Stressors on Atlantic Tomcod: Contaminants and a Warming Environment.

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 United States dried seahorse trade: A comparison of traditional Chinese medicine and ecommerce-curio markets using molecular identification.

Tens of millions of dried seahorses (genus Hippocampus) are traded annually, and the pressure from this trade along with their life history traits (involved parental care and small migration distances and home ranges) has led to near global population declines. This and other forms of overexploitation have led to all seahorse species being listed in Appendix II under the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). The signatory nations of CITES recommended a 10-cm size limit of seahorses to ensure harvested individuals have reached reproductive maturity, and have thus had the chance to produce offspring, to maintain a more sustainable global seahorse fishery. We assessed adherence to CITES recommendations using DNA barcoding and size measurements to compare two prominent U.S. dried seahorse markets: (1) traditional Chinese medicine (TCM), and (2) non-medicinal ecommerce and coastal curio (ECC). We also estimated U.S. import abundance from CITES records. Of the nine species identified among all samples (n = 532), eight were found in the TCM trade (n = 168); composed mostly (75%) of the Indo-Pacific species Hippocampus trimaculatus, and Hippocampus spinosissimus, and the Latin American Hippocampus ingens. In contrast, ECC samples (n = 344) included 5 species, primarily juvenile Indo-Pacific Hippocampus kuda (51.5%) and the western Atlantic Hippocampus zosterae (40.7). The majority of TCM samples (85.7%) met the CITES size recommendation, in contrast to 4.8% of ECC samples. These results suggest non-size discriminatory bycatch is the most likely source of imported ECC specimens. In addition, CITES records indicate that approximately 602,275 dried specimens were imported into the U.S. from 2004-2020, but the exact species composition remains unknown as many U.S. imports records list one species or Hippocampus spp. from confiscated shipments due to difficulties in morphological identification and large numbers of individuals per shipment. Molecular identification was used to identify the species composition of confiscated shipment imports containing undesignated species, and similar to TCM, found H. trimaculatus and H. spinosissimus the most abundant. By combining DNA barcoding, size comparisons, and CITES database records, these results provide an important glimpse into the two primary dried U.S. seahorse end-markets, and may further inform the conservation status of several Hippocampus species.

North American diadromous fishes: Drivers of decline and potential for recovery in the Anthropocene.

Diadromous fishes migrate between freshwater and marine habitats to complete their life cycle, a complexity that makes them vulnerable to the adverse effects of current and past human activities on land and in the oceans. Many North American species are critically endangered, and entire populations have been lost. Major factors driving declines include overfishing, pollution, water withdrawals, aquaculture, non-native species, habitat degradation, over-zealous application of hatcheries designed to mitigate effects of other factors, and effects of climate change. Perhaps, the most broadly tractable and effective factors affecting diadromous fishes are removals of the dams that prevent or hinder their migrations, alter their environment, and often favor non-native biotic communities. Future survival of many diadromous fish populations may depend on this.

Population genomics reveals seahorses (Hippocampus erectus) of the western mid-Atlantic coast to be residents rather than vagrants.

Understanding population structure and areas of demographic persistence and transients is critical for effective species management. However, direct observational evidence to address the geographic scale and delineation of ephemeral or persistent populations for many marine fishes is limited. The Lined seahorse (Hippocampus erectus) can be commonly found in three western Atlantic zoogeographic provinces, though inhabitants of the temperate northern Virginia Province are often considered tropical vagrants that only arrive during warm seasons from the southern provinces and perish as temperatures decline. Although genetics can locate regions of historical population persistence and isolation, previous evidence of Virginia Province persistence is only provisional due to limited genetic sampling (i.e., mitochondrial DNA and five nuclear loci). To test alternative hypotheses of historical persistence versus the ephemerality of a northern Virginia Province population we used a RADseq generated dataset consisting of 11,708 single nucleotide polymorphisms (SNP) sampled from individuals collected from the eastern Gulf of Mexico to Long Island, NY. Concordant results from genomic analyses all infer three genetically divergent subpopulations, and strongly support Virginia Province inhabitants as a genetically diverged and a historically persistent ancestral gene pool. These results suggest that individuals that emerge in coastal areas during the warm season can be considered "local" and supports offshore migration during the colder months. This research demonstrates how a large number of genes sampled across a geographical range can capture the diversity of coalescent histories (across loci) while inferring population history. Moreover, these results clearly demonstrate the utility of population genomic data to infer peripheral subpopulation persistence in difficult-to-observe species.

Resistance to contaminants in North American fish populations.

Fish from urban and industrialized estuaries are exposed among the highest levels of contaminants of any vertebrate populations. As a result, they serve as especially relevant models for determining the toxic effects and mechanisms through which environmental toxicants work. In controlled laboratory experiments, fish from highly contaminated locales sometimes exhibit resistance to contaminant-induced toxicity. Resistance may be due to genetic adaptation or physiological acclimations. Distinguishing between these possibilities is important in predicting the persistence of resistance and its potential costs to affected populations and communities. Along the Atlantic coast of North America, populations of two estuarine species, Atlantic killifish (mummichog) Fundulus heteroclitus and Atlantic tomcod Microgadus tomcod, exhibit phenotypes that are resistant to aromatic hydrocarbon (AH) contaminants, including polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs), and polycyclic aromatic hydrocarbons (PAHs). Populations of these species exhibit resistance to AH-induced lethality, early life-stage toxicities, and expression of cytochrome P4501A (CYP1A). However, some differences among populations in the occurrence and type (genetic or physiological) of AH-resistant phenotypes have been observed. In some instances, resistance was obviously genetic and resulted in its transmission to at least the F2 generation, in others, resistance had a physiological or yet to be identified epigenetic basis. In some cases, resistance was observed for all AH compounds tested, in others, it was seen only for halogenated AHs. As toxic responses to AHs are believed to be mediated by the aryl hydrocarbon receptor pathway (AHR), several studies compared the structure and expression of AHR pathway molecules between resistant and sensitive fish populations. However, no obvious differences in these molecular parameters were observed between resistant and sensitive populations at the transcriptional level. Further studies at the protein level are recommended to further evaluate the role of the AHR pathway in conferring resistance. Open-ended microarray and proteomic approaches may provide additional resolution in determining the molecular mechanisms of resistance. Also, studies that evaluate the prevalence and ecosystem cost of resistance are needed.

Factors affecting profitability for craniotomy.

OBJECT: The authors studied factors influencing hospital profitability after craniotomy in patients who underwent craniotomy coded as diagnosis-related group (DRG) 1 (17 years of age with nontraumatic disease without complication) and who met their hospital's craniotomy pathway criteria and had a hospital length of stay 4 days or less during a 20-month period. METHODS: Data in all patients meeting these criteria (76 cases) were collected and collated from various hospital databases. Twenty-one cases were profitable and 55 were not. Variables traditionally influencing cost of care, such as surgeon, procedure, length of operation, and pharmacy use had no significant effect on whether a patient was profitable. The most important influence on profitability was the individual payor. Cases in which care was reimbursed under the prospective payment system based on DRGs were nearly always profitable whereas those covered by per diem plans were nearly always nonprofitable. CONCLUSIONS: 1) Hospital information systems should be customized to deliver consolidated data for timely analysis of cost of care for individual patients. This information may be useful in negotiating profitable contracts. 2) A clinical pathway was successful in reducing the difference in cost of care between profitable and nonprofitable postcraniotomy cases. 3) In today's health care environment both cost containment and revenue assume importance in determining profitability.

Conservative management of ventriculoperitoneal shunts in the setting of abdominal and pelvic infections.

OBJECT: The optimal management of a ventriculoperitoneal shunt in the setting of acute, non-shunt related abdominal and pelvic infections is unknown. In the literature, distal shunt catheter reimplantation with or without a variable period of externalization has been recommended to prevent ascending ventriculitis. While this strategy is effective, there is little to almost no published data suggesting that it is necessary in all cases. Furthermore, it is not clear that shunt externalization to an external drainage bag during the treatment of non-shunt related peritonitis is any less likely to lead to ventriculitis than leaving the catheter in place. In the authors' experience, shunt externalization or revision during an episode of acute, non-shunt related peritonitis is unnecessary to prevent ventriculitis or chronic peritonitis. METHODS: In the present case series, the authors report on 7 patients whose shunts were left in the abdomen while they were treated for acute peritonitis. The patients were followed clinically for up to 21 months after the diagnosis to assess for evidence of recurrent abdominal infections, shunt infections, or shunt failure. RESULTS: In a follow-up period ranging from 13 to 22 months, no patient developed ventriculitis, required a shunt revision, or was unable to clear the peritoneal infection. CONCLUSIONS: The results of this small series suggest that leaving the distal end of a shunt catheter in place in a patient with acute peritonitis is a reasonably safe choice in specific patients, provided the source of infection is aggressively treated with systemic antibiotics and local debridement when necessary.

Decompressive craniectomy and postoperative complication management in infants and toddlers with severe traumatic brain injuries.

OBJECT: Infants with severe traumatic brain injury represent a therapeutic challenge. The internal absence of open space within the infant cranial vault makes volume increases poorly tolerated. This report presents 7 cases of decompressive craniectomy in infants with cerebral edema. METHODS: The authors reviewed the medical charts of infants with brain injuries who presented to Albany Medical Center Hospital between January 2004 and July 2007. Variables that were examined included patient age, physical examination results at admission, positive imaging findings, surgery performed, complications, requirement of permanent CSF diversion, and physical examination results at discharge and outpatient follow-up using the King's Outcome Scale for Childhood Head Injury. Seven infants met the inclusion criteria for the study. Six infants experienced nonaccidental trauma, and 1 had a large infarction of the middle cerebral artery territory secondary to a carotid dissection. At admission, all patients were minimally responsive, 4 had equal and minimally reactive pupils, 3 had anisocoria with the enlarged pupil on the same side as the brain lesion, and all had right-sided hemiparesis. Six patients received a left hemicraniectomy, whereas 1 received a left frontal craniectomy. In all cases, bone was cultured and stored at the bone bank. RESULTS: Postoperatively, 3 patients who developed draining CSF fistulas needed insertions of external ventricular drains, with incisions oversewn using nylon sutures and a liquid bonding agent. After prolonged CSF drainage and wound care, these patients all developed epidural and subdural empyemas necessitating surgical drainage and debridement. Methicillin-resistant Staphylococcus aureus was found in 2 patients and Enterococcus in the third. All patients developed hydrocephalus necessitating the insertion of a ventriculoperitoneal shunt, and all had bone replaced within 1-6 months from the time of the original operation. Two patients required reoperation due to bone resorption. At outpatient follow-up visits, all had scores of 3 or 4 on the King's Outcome Scale for Childhood Head Injury. Each patient was awake, interactive, and could sit, as well as either crawl or walk with assistance. All had persistent, improving right-sided hemiparesis and spasticity. CONCLUSIONS: Despite poor initial examination results, infants with severe traumatic brain injury can safely undergo decompressive craniectomy with reasonable neurological recovery. Postoperative complications must be anticipated and treated appropriately. Due to the high rate of CSF fistulas encountered in this study, it appears reasonable to recommend both the suturing in of a dural augmentation graft and the placement of either a subdural drain or a ventriculostomy catheter to relieve pressure on the healing surgical incision. Also, one might want to consider using a T-shaped incision as opposed to the traditional reverse question mark-shaped incision because wound healing may be compromised due to the potential interruption of the circulation to the posterior and inferior limb with this latter incision.

Comparison of accidental and nonaccidental traumatic brain injuries in infants and toddlers: demographics, neurosurgical interventions, and outcomes.

OBJECT: Nonaccidental trauma has become a leading cause of death in infants and toddlers. Compared with children suffering from accidental trauma, many children with nonaccidental trauma present with injuries requiring neurosurgical management and operative interventions. METHODS: A retrospective review was performed concerning the clinical and radiological findings, need for neurosurgical intervention, and outcomes in infants and toddlers with head injuries who presented to Albany Medical Center between 1999 and 2007. The Fisher exact probability test and ORs were computed for Glasgow Coma Scale (GCS) scores, hyperdense versus hypodense subdural collections, and discharge and follow-up King's Outcome Scale for Childhood Head Injury (KOSCHI) scores. RESULTS: There were 218 patients, among whom 164 had sustained accidental trauma, and 54 had sustained nonaccidental trauma (NAT). The patients with accidental traumatic injuries were more likely to present with GCS scores of 13-15 (OR 6.95), and the patients with NATs with of GCS scores 9-12 (OR 6.83) and 3-8 (OR 2.99). Skull fractures were present in 57.2% of accidentally injured patients at presentation, and 15% had subdural collections. Skull fractures were present in 30% of nonaccidentally injured patients, and subdural collections in 52%. Patients with evidence of hypodense subdural collections were significantly more likely to be in the NAT group (OR 20.56). Patients with NAT injuries were also much more likely to require neurosurgical operative intervention. Patients with accidental trauma were more likely to have a KOSCHI score of 5 at discharge and follow-up (ORs 6.48 and 4.58), while patients with NAT had KOSCHI scores of 3a, 3b, 4a, and 4b at discharge (ORs 6.48, 5.47, 2.44, and 3.62, respectively), and 3b and 4a at follow-up. CONCLUSIONS: Infant and toddler victims of NAT have significantly worse injuries and outcomes than those whose trauma was accidental. In the authors' experience, however, with aggressive intervention, many of these patients can make significant neurological improvements at subsequent follow-up visits.

Onyx embolization of a thoracolumbar perimedullary spinal arteriovenous fistula in an infant presenting with subarachnoid and intraventricular hemorrhage.

Identifying a source of spontaneous subarachnoid hemorrhage (SAH) or intraventricular hemorrhage (IVH) in patients with negative results on cranial angiographic imaging can be a diagnostic challenge. The authors present the case of a 14-month-old girl who presented with lethargy and spontaneous SAH and IVH, and later became acutely paraplegic. Except for the SAH and IVH, findings on neuroimages of the brain were normal. Magnetic resonance imaging revealed an intramedullary thoracolumbar spinal cord hemorrhage that was found to be associated with arterialized veins intraoperatively. Catheter-based diagnostic angiography identified a spinal perimedullary macroarteriovenous fistula (macro-AVF) that was completely embolized with Onyx, negating the need for further surgical intervention. The authors believe this to be the first reported case of a thoracolumbar perimedullary macro-AVF presenting with SAH and IVH. In addition, descriptions of Onyx embolization of a spinal AVF in the literature are rare, especially in pediatric patients.

Sea lamprey Petromyzon marinus: an exception to the rule of homing in anadromous fishes.

Anadromous fishes are believed to make regular circuits of migration in the sea before homing to their natal rivers. Sea lamprey Petromyzon marinus is an anadromous fish that is an exception to this life-history pattern. It also differs from other anadromous fishes in that its adult phase is parasitic, a feeding strategy that should make homing problematic for lamprey cohorts that become widely dispersed through transport by the diverse hosts they parasitize. We sequenced a portion of the mitochondrial DNA control region from sea lampreys collected from 11 North American east coast rivers to test for genetic evidence of homing. There were no significant differences (chi2=235.1, p=0.401) in haplotype frequencies among them, with almost 99 per cent of haplotypic diversity occurring within populations. These findings, together with concordant genetic results from other geographical regions and ancillary information on pheromonal communication, suggest that sea lamprey does not home but rather exhibits regional panmixia while using a novel 'suitable river' strategy to complete its life cycle.

When the American sea sturgeon swam east.

The two species of Atlantic sea sturgeon on either shore of the North Atlantic, Acipenser sturio in Europe and A. oxyrinchus in North America, probably diverged with the closure of the Tethys Sea and the onset of the North Atlantic Gyre 15-20 million years ago, and contact between them was then presumably precluded by geographic distance. Here we present genetic, morphological and archaeological evidence indicating that the North American sturgeon colonized the Baltic during the Middle Ages and replaced the native sturgeon there, before recently becoming extinct itself in Europe as a result of human activities. In addition to representing a unique transatlantic colonization event by a fish that swims upriver to spawn, our findings have important implications for projects aimed at restocking Baltic waters with the European sturgeon.