Estuarine Residency and Migration of Southern Flounder Inferred from Conventional Tag Returns at Multiple Spatial Scales

An improved understanding of the spatial structure and movements of harvested populations can promote more efficient management of marine resources. Conventional tagging is a valuable approach to study the movements of marine fishes due to its relatively low expense and the typically broad spatial extent over which movements can be characterized. We present the findings of multiple tag return studies initiated in the estuaries of North Carolina during the past two decades to better understand habitat residency and migration patterns of Southern Flounder Paralichthys lethostigma, an economically important marine flatfish in the southeastern USA. Tag return data indicated large-scale (>50 km) movements of relatively large fish in the fall, which were presumably associated with offshore winter spawning migrations. Nearly all Southern Flounder that demonstrated large-scale movement were recovered to the south of the system in which they were tagged, suggesting that the spawning activity of fish using North Carolina estuaries may be concentrated mostly off the southeastern U.S. continental shelf. Tag returns from within multiple estuarine systems during the spring and summer were in close proximity to release sites (typically < 1 km), suggesting limited movement during estuarine residency. Recaptures in the spring of fish tagged the previous summer or fall were also in close proximity to release sites, in some cases within the same estuarine creek, indicating limited movement of fish overwintering in the estuary as well. Our findings reveal saltatory movement dynamics of Southern Flounder characterized by limited movement during estuarine residency and large-scale movements in the fall associated with spawning migrations. Our synthesis of several tag return studies across multiple spatial scales should contribute to a better alignment of Southern Flounder management with their spatial dynamics.

Received April 13, 2015; accepted July 20, 2015     

Two-Stage Boosted Regression Tree Model to Characterize Southern Flounder Distribution in Texas Estuaries at Varying Population Sizes

Linking trends in fish population abundance to environmental characteristics is often difficult because fish use a variety of habitats throughout their ontogeny and may exhibit large interannual fluctuations in abundance. We developed a two-stage boosted regression tree model to investigate spatiotemporal patterns of Southern Flounder Paralichthys lethostigma abundance and distribution in Texas estuaries. We used a 36-year fishery-independent data set (1977–2012) to correlate distribution with environmental conditions and seasonal or long-term changes in abundance. Adult Southern Flounder were sampled with gill nets using a random-stratified design. Predictions of abundance were made to grids of environmental data to identify “hot spots” as well as seasonal or decadal shifts in distribution. Models were fit using cross validation, and variance was estimated using nonparametric bootstrapping. Depth, temperature, distance to a tidal inlet, and salinity were the primary environmental determinants of Southern Flounder distribution and abundance. Because distribution and response to environmental conditions can depend on population abundance, we also developed a standardized index of annual abundance using the same two-stage boosted regression tree model. The index identifies a long-term decline in abundance punctuated by recent recovery (possibly in response to management actions). Mapped results identify a coastwide decline in abundance between 1980–1984 and 2005–2009 but the magnitude varied substantially, suggesting disproportionate changes in abundance across the study area.

Received April 10, 2015; accepted July 28, 2015     

Indications of Offshore Spawning by Southern Gulf of Maine Winter Flounder

This is the first study to document quantitatively that Gulf of Maine (GOM) Winter Flounder Pseudopleuronectes americanus spawn offshore. Three sites (southern Jeffreys Ledge, Bigear [an area southwest of Tillies Bank], and a portion of Stellwagen Bank National Marine Sanctuary) were sampled during spring 2016 to determine whether Winter Flounder are spawning in non-coastal, deep waters in the southern GOM. In total, 1,384 Winter Flounder were caught by trawl, measured, sexed, and assessed for reproductive stage during the peak spawning season (March–May). These fish showed clear signs that spawning was occurring either at or very near to all three sites surveyed. In all sites, a shift from prespawn to postspawn females occurred. Running ripe females were caught at both Jeffreys Ledge and Stellwagen Bank on multiple occasions, and ripe and recently spawned females were caught at Bigear. Given that these sites are over 15 km from the coast, it is not energetically likely that fish in such advanced reproductive condition are migrating to shore to spawn. Essential fish habitat (EFH) for GOM Winter Flounder is categorized as waters with depths of 5 m or less. The present study clearly shows that this depth range is incomplete and thus inaccurate for southern GOM Winter Flounder. Although it is irrefutable that GOM estuaries and shallow bays are important as nursery grounds for juvenile Winter Flounder and as postspawn feeding grounds for adults, the current GOM EFH designation warrants reclassification.

Received May 5, 2017; accepted August 2, 2017     

Genetic Structure Inferred from Mitochondrial 12S Ribosomal RNA Sequence of Oncomelania quadrasi,the Intermediate Snail Host of Schistosoma japonicum in the Philippines

Species and subspecies of the Oncomelania hupensis species complex are recognized as intermediate hosts of Schistosoma japonicum. Of these species and subspecies, O. quadrasi is distributed throughout the Philippines. This study used 12S ribosomal RNA sequences to explore the genetic structure of O. quadrasi populations in the Philippines. Three subspecies, O. h. hupensis, O. h. formosana, and O. h. chiui of this group were also examined. The phylogenetic tree and haplotypes network showed that O. quadrasi separated from the subspecies. Ten O. quadrasi haplotypes (Oq1–Oq10) clustered in relation to their geographic origin. Genetic differentiation (F_ST) and estimated gene flow (Nm) among populations showed significant differences, ranging from 0.556–1.000 to 0.00–0.74, respectively. Genetic differences among groups (F_CT = 0.466), populations within a group (F_SC = 0.727), and populations (F_ST = 0.854) were observed. These results indicate that the O. quadrasi populations in the Philippines have a substructure associated with their geographic origin.     

Genetic Variability and Population Structure of Gulf Menhaden Compared with Yellowfin Menhaden

Gulf Menhaden Brevoortia patronus is one of the most intensively fished organisms in the Gulf of Mexico. Fishery managers and industry operators have historically worked towards a sustainable fishery and have cooperated on stock assessments to estimate feasible reference points for management. These stock assessments are necessarily rooted in a strong definition of the fishery stock, including the estimation of the number of populations that are exploited. Here, genetic population structure and variability were examined in B. patronus, using genetic markers specifically designed for the species. We observed genetic variability that indicates a relatively high effective population size for a marine finfish (N_e ≥ 1,200), and two analytical approaches implied a single genetic population of B. patronus. We compared the latter finding with the population structure in the closely related Yellowfin Menhaden B. smithi, for which two distinct populations from Florida were identified using the same genetic loci (F_st = 0.015, P = 0.027). These contrasting patterns of population structure between sympatric congeneric species are likely driven by differences in distribution and census size and may relate to factors that originally drove speciation in North American Brevoortia species. The finding of a single Gulf-wide population of B. patronus suggests that there is an extensive migration throughout the species range and supports the notion of a single genetic stock.

Received February 8, 2016; accepted April 5, 2016     

Genetic Management of Black Sea Bass: Influence of Biogeographic Barriers on Population Structure

Abstract

The black sea bass Centropristis striata is a commercially important perciform fish with a general distribution along the U.S. Atlantic coast from Cape Cod, Massachusetts, to Cape Canaveral, Florida, and in the Gulf of Mexico from Mobile Bay, Alabama, to Tampa Bay, Florida. Currently, black sea bass are managed as three separate stocks: one in the Gulf of Mexico and two along the U.S. Atlantic coast. Fish from the Gulf of Mexico represent a separate subspecies, C. striata melana. The Atlantic subspecies, C. striata striata, is divided into two management units (separated at Cape Hatteras, North Carolina) based on the hypothesis that this subspecies comprises two distinct populations exhibiting life history and morphometric differences. To further investigate this differentiation, we employed mitochondrial sequence data to test whether genetic differences are observed among the three managements units. The DNA sequence analysis revealed a significant amount of genetic variability partitioned among samples from the three management areas. Similar results were observed when the analyses were confined to the two Atlantic coast management units. These results support the designation of two distinct management units for black sea bass along the U.S. Atlantic coast.

Received July 19, 2011; accepted February 17, 2012     

Detection of Borrelia burgdorferi DNA in lizards from Southern Maryland

Lizards serve as hosts for Ixodes ticks in the western and southeastern United States and may affect the transmission cycles of Borrelia burgdorferi in these regions. In Maryland, the role of lizards in the maintenance and transmission cycle of this pathogen has not been examined. We tested 29 lizards (Sceloporus undulatus and Eumeces spp.) and 21 ticks from these lizards for the presence of B. burgdorferi. Eight lizards were positive by polymerase chain reaction (PCR) for at least one B. burgdorferi-specific marker. This is the first report of B. burgdorferi sensu stricto detected in lizards in the mid-Atlantic region. Although the viability of the B. burgdorferi in these lizards was unconfirmed, recovery of bacterial DNA in a tail snip suggests that the infections in these lizards were disseminated. This study suggests that some lizards indigenous to the mid-Atlantic region may serve as alternative reservoirs for B. burgdorferi. In areas where lizard densities are high, these less efficient reservoirs may affect the enzootic cycle of this tick-borne pathogen.     

Fishing Mortality in North Carolina's Southern Flounder Fishery: Direct Estimates of Instantaneous Fishing Mortality from a Tag Return Experiment

Abstract

Estimation of harvest rates is often a critical component of fishery stock assessment and management. These assessments are often based on catch-at-age data sets generated over many years, but estimates of instantaneous fishing mortality (F) can also be obtained from a shorter-term tag return study. We conducted a 2-year tag return experiment to generate direct estimates of F for southern flounder Paralichthys lethostigma in a North Carolina estuary. The southern flounder supports lucrative commercial and recreational fisheries within the state and has experienced heavy fishing pressure for more than a decade. During 2005 and 2006, fish were captured and tagged with the assistance of commercial harvesters in the New River estuary. Tag returns were used to generate monthly estimates of F, which demonstrated a clear seasonal pattern that was consistent between years. Several important assumptions of the tag return model were accounted for through the use of double-tagged individuals, the distribution of both high- and standard-reward tags, and the completion of an independent controlled experiment to evaluate mortality related to tagging. Annual estimates of F exceeded the short-term management target in both years. Residual patterns suggest that the estimates may actually have been biased low, possibly due to delayed mixing of tagged fish. Thus, despite recently amended fishery regulations, F in the North Carolina southern flounder gill-net fishery still has the potential to greatly exceed targeted levels, which may delay stock recovery. Tag return studies can provide reliable (and nearly real-time) information about F and natural mortality as long as the experimental design addresses specific assumptions related to tagging-induced mortality, tag shedding, and nonreporting of tags.     

Familial B-cell Chronic Lymphocytic Leukemia in a Population of Patients from Southern Italy

We investigated the prevalence of chronic lymphocytic leukemia (CLL) in 9650 relatives of 510 CLL patients from 5 different regions (Apulia, Basilicata, Campania, Calabria, and Sicily) of Southern Italy. Data collection included a family history questionnaire. In our series of 510 CLL patients, 53 families with 2 or more individuals who had chronic lymphoproliferative disease (CLD) or other hematological malignancies were identified. In these families, 27 cases of CLL, 10 of indolent non-Hodgkin's lymphoma, and 7 of multiple myeloma were identified in relatives of CLL probands. Twenty-two relatives developed hematological malignancies other than CLD (19, acute leukemia; 3, chronic myeloid leukemia). In this study the prevalence of CLD in relatives of 510 CLL patients was 8.6% (44/510), and the prevalence of CLL in the same series was 5.2% (27/ 510). Considering the presence of clusters of individuals with hematological malignancies, overall our series contained 4 families showing a cluster with more than 2 cases. The most frequent pattern of affected family members was represented by 39 families (39/53 [73%]) with affected siblings or cousins only. Twenty siblings had CLL. The other families showed a multigenerational pattern with an affected parent-offspring relationship in only 11 (21%) of the cases and with a combination of the first 2 categories in 3 (6%) of the families. In 8 families belonging to both the last 2 mentioned groups, the affected offspring had an earlier disease onset than their parents, suggesting anticipation. We estimated the size and examined the pattern of familial aggregation of hematological malignancies, in particular CLL/CLD, in a specific geographical area. CLL was the most frequent disease in relatives, mainly siblings, of our CLL patients. Our results may be a contribution to the characterization of the epidemiological distribution pattern of CLL.     

CCL22 16C/A Genetic Variation is not Associated with Breast Carcinoma in Southern Iranian Population

Background: CCL22/MDC is a CC chemokine with a critical role in regulation of the immune balance in physiological condition. CCL22/CCR-4 ligation has been documented to participate in the migration of regulatory T (Treg) cells and Th2 lymphocytes to the site of breast tumors; circumstances that are known to be associated with poor prognosis. Objective: To investigate the association of a single nucleotide polymorphism (SNP) in CCL22 gene; 16C/A (rs4359426; Asp2Ala), with susceptibility to breast cancer in a sample of Iranian population. Methods: 161 patients with pathologically confirmed breast carcinoma (mean age 49.3 ± 11.5 yrs) and 178 agematched healthy women (mean age: 49.3 ± 12.9 yrs) were studied. CCL22 genotypes were investigated by the Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) method. Data was verified by direct automated sequencing. Arlequin analysis showed no deviation from Hardy-Weinberg equilibrium. Results: The most frequent genotype in both patient and control groups was wild type CC genotype with frequency of 146 out of 161 (90.7%) among patients and 153 out of 178 (86.0%) in control group (p=0.24). The frequency of CA genotype was 15 (9.3%) and 23 (12.9%) in patients and controls, respectively (p=0.38). No AA genotype was observed among patients but this genotype was observed with the frequency of 2 out of 178 (1.1%) in control subjects. The minor allele frequency (MAF) was 0.07 in the population. Conclusion: No correlation was found between the investigated genotypes and clinicopathological characteristics of the patients. Conclusively, results of this investigation do not support the association of 16C/A SNP (rs4359426; Asp2Ala) in CCL22 gene with susceptibility to, and progression of, breast cancer in Iranian population.     

Genetic diversity and antimicrobial resistance of enterococcal isolates from Southern region of Brazil

In the present study, a total of 455 enterococcal isolates, recovered from patients living in the city of Porto Alegre, State of Rio Grande do Sul, Brazil, during the period from July 1996 to June 1997, were identified to the species level by conventional biochemical and microbiological tests, and assayed for their susceptibilities to antimicrobial agents. The genetic diversity of antimicrobial resistant strains was evaluated by pulsed-field gel electrophoresis (PFGE) analysis of SmaI restricted chromosomal DNA. The most frequent species was Enterococcus faecalis (92.8%). Other species identified were: E. faecium (2.9%), E. gallinarum (1.5%), E. avium (1.1%), E. hirae (0.7%), E. casseliflavus (0.4%), E. durans (0.4%) and E. raffinosus (0.2%). The overall prevalence of isolates with high-level resistance (HLR) to aminoglycosides was 37.8%. HLR to gentamicin was found in 24.8%. No strains with acquired resistance to vancomycin were found. PFGE analysis showed the predominance of clonal group A, comprising strains isolated from different clinical specimens obtained from patients in three hospitals. These results suggest intra and inter-hospital dissemination of one predominant clonal group of E. faecalis isolates with HLR to gentamicin in the hospitals included in this study.     

Genetic characterization of patients with Bernard-Soulier syndrome and their relatives from Southern Iran

Bernard-Soulier syndrome (BSS) is a rare recessively inherited bleeding disorder caused by the deficiency of the platelet glycoprotein (Gp) complex Ib/IX/V that is the von Willebrand factor receptor on platelets. In patients suffering from BSS platelet adhesion is typically impaired, while platelet aggregation is normal; macrothrombocytopenia is a common feature. In this study three different families from Southern Iran were investigated. GpIb/IX/V platelet expression as detected by flow cytometry was less than 2% of normal in six cases and 12% in the remaining one. Platelet count was 35,000 platelets/microliter and iron deficiency anemia was common. All patients suffered from mucocutaneous bleeding at presentation and were born from consanguineous marriages. Genetic analysis demonstrated the presence of the same GpIX Phe55Ser missense mutation in two families and of a single base insertion (GP1BA C3221 ins), a never described mutation causing a frameshift in the GpIbalpha gene, in the third family. Among the family members studied several heterozygotes were identified. None of them, with one exception, had macrothrombocytopenia. In one family a slight reduction of GpIb/IX/V expression was observed.     

Genetic characterization of patients with Bernard-Soulier syndrome and their relatives from Southern Iran

Bernard-Soulier syndrome (BSS) is a rare recessively inherited bleeding disorder caused by the deficiency of the platelet glycoprotein (Gp) complex Ib/IX/V that is the von Willebrand factor receptor on platelets. In patients suffering from BSS platelet adhesion is typically impaired, while platelet aggregation is normal; macrothrombocytopenia is a common feature. In this study three different families from Southern Iran were investigated. GpIb/IX/V platelet expression as detected by flow cytometry was less than 2% of normal in six cases and 12% in the remaining one. Platelet count was 35?000 platelets/microliter and iron deficiency anemia was common. All patients suffered from mucocutaneous bleeding at presentation and were born from consanguineous marriages. Genetic analysis demonstrated the presence of the same GpIX Phe55Ser missense mutation in two families and of a single base insertion (GP1BA C3221 ins), a never described mutation causing a frameshift in the GpIbα gene, in the third family. Among the family members studied several heterozygotes were identified. None of them, with one exception, had macrothrombocytopenia. In one family a slight reduction of GpIb/IX/V expression was observed.     

Phylogenetic Networks and Parameters Inferred from HIV Nucleotide Sequences of High-Risk and General Population Groups in Uganda: Implications for Epidemic Control

Phylogenetic inference is useful in characterising HIV transmission networks and assessing where prevention is likely to have the greatest impact. However, estimating parameters that influence the network structure is still scarce, but important in evaluating determinants of HIV spread. We analyzed 2017 HIV pol sequences (728 Lake Victoria fisherfolk communities (FFCs), 592 female sex workers (FSWs) and 697 general population (GP)) to identify transmission networks on Maximum Likelihood (ML) phylogenetic trees and refined them using time-resolved phylogenies. Network generative models were fitted to the observed degree distributions and network parameters, and corrected Akaike Information Criteria and Bayesian Information Criteria values were estimated. 347 (17.2%) HIV sequences were linked on ML trees (maximum genetic distance ≤4.5%, ≥95% bootstrap support) and, of these, 303 (86.7%) that consisted of pure A1 (n = 168) and D (n = 135) subtypes were analyzed in BEAST v1.8.4. The majority of networks (at least 40%) were found at a time depth of ≤5 years. The waring and yule models fitted best networks of FFCs and FSWs respectively while the negative binomial model fitted best networks in the GP. The network structure in the HIV-hyperendemic FFCs is likely to be scale-free and shaped by preferential attachment, in contrast to the GP. The findings support the targeting of interventions for FFCs in a timely manner for effective epidemic control. Interventions ought to be tailored according to the dynamics of the HIV epidemic in the target population and understanding the network structure is critical in ensuring the success of HIV prevention programs.     

Population Ecology of Hantavirus Rodent Hosts in Southern Brazil

In this study we analyze population dynamics of hantavirus rodent hosts and prevalence of infection over a 2-year period in Southern Brazil, a region with a high incidence of hantavirus pulmonary syndrome. The 14 small mammal species captured were composed of 10 rodents and four marsupials, the six most abundant species being Akodon serrensis, Oxymycterus judex, Akodon montensis, Akodon paranaensis, Oligoryzomys nigripes, and Thaptomys nigrita. These species displayed a similar pattern with increasing population sizes in fall/winter caused by recruitment and both, increase in reproductive activity and higher hantavirus prevalence in spring/summer. Specific associations between A. montensis/Jaborá Virus (JABV) and O. nigripes/Juquitiba-like Virus (JUQV-like) and spillover infections between A. paranaensis/JABV, A. serrensis/JABV, and A. paranaensis/JUQV-like were observed. Spillover infection in secondary hosts seems to play an important role in maintaining JABV and JUQV-like in the hantavirus sylvatic cycle mainly during periods of low prevalence in primary hosts.     

Growth and Mortality in Coastal Populations of Winter Flounder: Implications for Recovery of a Depleted Population

We studied growth, mortality, and settlement distributions of juvenile Winter Flounder Pseudopleuronectes americanus in two bays of Long Island, New York, to better understand localized population dynamics of a species experiencing a protracted population decline. Juvenile mortality in Long Island bays ranged between 0.02 and 0.04 per day and was as high as or higher than values reported for other systems. Settlement distributions had multiple peaks (cohorts) occurring between March and late July in 2007 and between February and May in 2008. The presence of multiple cohorts limited the usefulness of field-derived, length-based estimates of growth, resulting in unrealistic values compared with otolith-based measures (field based: ?0.05 to 0.25 cm/d; otolith based: 0.05–0.06 cm/d). Thus, we recommend the use of otolith methods or the repeated measurement of individuals to estimate growth of juvenile Winter Flounder. Otolith-based growth rate was significantly higher for Port Jefferson Harbor during 2007 than for all other year × location combinations. Together with previous research showing genetic differentiation and migratory diversity, our finding of multiple spawning cohorts in Long Island Winter Flounder suggests a degree of isolation, and local management will be needed to support healthy populations. Future research to determine adult spawning, migratory behavior, stock structure, duration of the larval period, and settlement timing is required to unravel the complex behavior of Winter Flounder.

Received July 10, 2014; accepted April 10, 2015