281 research outputs found

    Quantification of Nursery Habitats for Blue Crabs in Chesapeake Bay

    Get PDF
    The blue crab is an iconic species in Chesapeake Bay, supporting important commercial and recreational fisheries and functioning as a critical link in the food web. Structurally complex habitats are often cited as nurseries for the blue crab, and other commercially important fish and crustacean species, by providing enhanced growth and survival for juveniles. I quantified the value of shallow habitats as nurseries for blue crabs through field studies and a demographic model. In Chapter 2, I utilized a two-year juvenile survey in vegetated habitats of the lower Bay to examine the effect of habitat complexity on the density of juvenile blue crabs. The functional relationship between seagrass cover and juvenile density was exponential, such that there were proportionally more crabs per unit increase in cover of vegetated habitat at high percent cover than at low percent cover. The relationship varied spatially, with higher densities on the eastern shore, and between the two years. The high spatial and annual variability led to questions about how habitat utilization varied throughout the recruitment season. I addressed the timing of recruitment and migration between habitats in Chapter 3 through the development of a survey of shallow habitats in the York River with high temporal and spatial resolution. The study provided evidence for a carrying capacity of juvenile blue crabs in vegetated habitats at 10-15 crabs m2. I found substantially higher densities of small juveniles in shallow unvegetated habitats than previously documented, which suggested that the current paradigm for blue crab recruitment requires modification to include the importance of shallow unvegetated habitats for small juveniles. In Chapter 4, I examined the effect of habitat utilization patterns as a function of age or ontogeny on the blue crab stock assessment by comparing juvenile density and abundance estimates from shallow vegetated and unvegetated habitats to estimates from deep habitats sampled by the primary survey for the stock assessment. Juvenile abundance was very high in both shallow habitats despite the relatively smaller area, thus suggesting that the winter dredge survey substantially underestimated the abundance of juvenile crabs. If this bias is inconsistent inter-annually, potentially as a function of temperature, then stock assessments may be producing biased reference points. Finally, I developed an exploratory habitat-specific demographic model to quantify the effects of habitat on population fitness in Chapter 5. Under all fishing mortality rates, including a complete fishing moratorium, the population growth rate was less than 1 when only unvegetated habitat was present; the increased survival of age-0 crabs provided by vegetated habitats led to increases in the population growth rates. The vegetated habitats provided a buffer from fishing mortality; that is, as the survival of juveniles increased in vegetated habitats, the population could sustain higher fishing mortality rates while still remaining stable or even increasing. Shallow vegetated habitats substantially influence juvenile blue crabs and the overall population growth rate. It is essential that these habitats be considered in future explorations of the dynamics of blue crabs, as well as other species that exhibit ontogenetic shifts in habitat utilization

    Global Extinction Risk for Seahorses, Pipefishes and Their Near Relatives (Syngnathiformes)

    Get PDF
    Few marine taxa have been comprehensively assessed for their conservation status, despite heavy pressures from fishing, habitat degradation and climate change. Here we report on the first global assessment of extinction risk for 300 species of syngnathiform fishes known as of 2017, using the IUCN Red List criteria. This order of bony teleosts is dominated by seahorses, pipefishes and seadragons (family Syngnathidae). It also includes trumpetfishes (Aulostomidae), shrimpfishes (Centriscidae), cornetfishes (Fistulariidae) and ghost pipefishes (Solenostomidae). At least 6% are threatened, but data suggest a mid-point estimate of 7.9% and an upper bound of 38%. Most of the threatened species are seahorses (Hippocampus spp.: 14/42 species, with an additional 17 that are Data Deficient) or freshwater pipefishes of the genus Microphis (2/18 species, with seven additional that are Data Deficient). Two species are Near Threatened. Nearly one-third of syngnathiformes (97 species) are Data Deficient and could potentially be threatened, requiring further field research and evaluation. Most species (61%) were, however, evaluated as Least Concern. Primary threats to syngnathids are (1) overexploitation, primarily by non-selective fisheries, for which most assessments were determined by criterion A (Hippocampus) and/or (2) habitat loss and degradation, for which assessments were determined by criterion B (Microphis and some Hippocampus). Threatened species occurred in most regions but more are found in East and South-east Asia and in South African estuaries. Vital conservation action for syngnathids, including constraining fisheries, particularly non-selective extraction, and habitat protection and rehabilitation, will benefit many other aquatic species

    ANNUAL REPORT 2022 - Data collection and analysis in support of single and multispecies stock assessments in Chesapeake Bay: The Chesapeake Bay Multispecies Monitoring and Assessment Program

    Get PDF
    The threats affecting living marine resources are diverse, including overfishing, climate change, and pollution. In response to long-term challenges in fisheries management, a more holistic evaluation of the natural and anthropogenic drivers of populations sizes is needed. Ecosystem management (EM), a suite of strategies that incorporate ecosystem considerations into fisheries and ecosystem management, can be difficult to implement in practice. In the Mid-Atlantic, efforts to implement EM are ongoing; one output has been the annual ‘State of the Ecosystem Report’ for the region, synthesizes available data on a variety of environmental, ecological, and socioeconomic factors. Historically, the data needed for EM in Chesapeake Bay were either incomplete or nonexistent. In 2002, the Chesapeake Bay Multispecies Monitoring and Assessment Program (ChesMMAP) was developed to assist in filling these data gaps, and ultimately to support Bay-specific species and ecosystem assessment modeling. ChesMMAP is a fishery-independent monitoring survey that uses a bottom trawl designed to sample late juvenile-to-adult fishes in the mainstem of Chesapeake Bay. Since 2002, this program has provided data on relative abundance, length, weight, sex ratio, maturity, age, and trophic interactions for several important fish species that inhabit the Bay seasonally. In this annual progress report, we synthesize available biological data on 12 bony fishes that support local recreational fisheries, including abundance (biomass and number), length- and age-structure, sex ratio, maturity stage, and diet composition. However, in 2019, the survey underwent a major redesign: VIMS took possession of a new research vessel, the R/V Virginia, and the survey bottom trawl gear was replaced with a net consistent with the gear used by other regional bottom trawl surveys (i.e., the Northeast Area Monitoring and Assessment Program and Northeast Fisheries Science Center trawl surveys). At this time, the survey stratification was revised and changes were made to the cruise schedule. During 15 calibration cruises (2019-2022), 516 paired-tows were completed, which was deemed sufficient for robust statistical analysis. Species-specific intercalibrations have been conducted by applying log-Gaussian Cox processes to the paired-tow data and modeling the size distribution of the population at each sampling site and the size-structured clustering of fish at small temporal and spatial scales. The manuscript describing the application to the ChesMMAP calibration data is currently in review. The ChesMMAP data inform Bay- and coast-wide fisheries management decisions and the broader use of these data in theses, dissertations, and the peer-reviewed literature contributes to a better understanding of the Bay ecosystem

    Rape Victimization and High Risk Sexual Behaviors: Longitudinal Study of African-American Adolescent Females

    Get PDF
    Objectives: African-American women are affected by disproportionately high rates of violence and sexually transmitted infections (STI)/human immunodeficiency virus (HIV) infection. It is imperative to address the intersection of these two urgent public health issues, particularly as these affect African-American adolescent girls. This study assessed the prevalence of rape victimization (RV) among a sample of African-American adolescent females and examined the extent to which participants with a history of RV engage in STI/HIV associated risk behaviors over a 12-month time period.Methods: Three hundred sixty-seven African-American adolescent females ages 15-21, seeking sexual health services at three local teenager-oriented community health agencies in an urban area of the Southeastern United States, participated in this study. Participants were asked to complete an audio computer-assisted self-interview (ACASI) at baseline, six- and 12-month follow-up. We assessed sociodemographics, history of RV and sexual practices. At baseline, participants indicating they had experienced forced sex were classified as having a history of RV.Results: Twenty-five percent of participants reported a history of RV at baseline. At six- and 12-months, victims of RV had significantly lower proportions of condom-protected sex (p=.008), higher frequency of sex while intoxicated (p=.005), more inconsistent condom use (p=.008), less condom use at last sex (p=.017), and more sex partners (p=.0001) than non-RV victims. Over the 12-month follow-up period, of those who did not report RV at baseline, 9.5% reported that they too had experienced RV at some point during the 12-month time frame.Conclusion: African-American adolescent females who experience RV are engaging in more risky sexual behaviors over time than non-RV girls, thereby placing themselves at higher risk for contracting STIs. In light of the results from this unique longitudinal study, we discuss considerations for policies and guidelines targeting healthcare, law enforcement and educational and community settings. The complexities of RV screening in healthcare settings are examined as is the need for tighter collaboration between healthcare providers and law enforcement. Finally, we consider the role of prevention and intervention programs in increasing awareness about RV as well as serving as an additional safe environment for screening and referral. [West J Emerg Med. 2011;12(3):333-342.

    Troubled Waters: Threats and Extinction Risk of the Sharks, Rays and Chimaeras of the Arabian Sea and Adjacent Waters

    Get PDF
    The extinction risk of sharks, rays and chimaeras is higher than that for most other vertebrates due to low intrinsic population growth rates of many species and the fishing intensity they face. The Arabian Sea and adjacent waters border some of the most important chondrichthyan fishing and trading nations globally, yet there has been no previous attempt to assess the conservation status of species occurring here. Using IUCN Red List of Threatened Species Categories and Criteria and their guidelines for application at the regional level, we present the first assessment of extinction risk for 153 species of sharks, rays and chimaeras. Results indicate that this region, home to 15% of described chondrichthyans including 30 endemic species, has some of the most threatened chondrichthyan populations in the world. Seventy-eight species (50.9%) were assessed as threatened (Critically Endangered, Endangered or Vulnerable), and 27 species (17.6%) as Near Threatened. Twenty-nine species (19%) were Data Deficient with insufficient information to assess their status. Chondrichthyan populations have significantly declined due to largely uncontrolled and unregulated fisheries combined with habitat degradation. Further, there is limited political will and national and regional capacities to assess, manage, conserve or rebuild stocks. Outside the few deepsea locations that are lightly exploited, the prognosis for the recovery of most species is poor in the near-absence of management. Concerted national and regional management measures are urgently needed to ensure extinctions are avoided, the sustainability of more productive species is secured, and to avoid the continued thinning of the regional food security portfolio

    A genome-wide association study for blood lipid phenotypes in the Framingham Heart Study

    Get PDF
    <p>Abstract</p> <p>Background</p> <p>Blood lipid levels including low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), and triglycerides (TG) are highly heritable. Genome-wide association is a promising approach to map genetic loci related to these heritable phenotypes.</p> <p>Methods</p> <p>In 1087 Framingham Heart Study Offspring cohort participants (mean age 47 years, 52% women), we conducted genome-wide analyses (Affymetrix 100K GeneChip) for fasting blood lipid traits. Total cholesterol, HDL-C, and TG were measured by standard enzymatic methods and LDL-C was calculated using the Friedewald formula. The long-term averages of up to seven measurements of LDL-C, HDL-C, and TG over a ~30 year span were the primary phenotypes. We used generalized estimating equations (GEE), family-based association tests (FBAT) and variance components linkage to investigate the relationships between SNPs (on autosomes, with minor allele frequency ≄10%, genotypic call rate ≄80%, and Hardy-Weinberg equilibrium p ≄ 0.001) and multivariable-adjusted residuals. We pursued a three-stage replication strategy of the GEE association results with 287 SNPs (P < 0.001 in Stage I) tested in Stage II (n ~1450 individuals) and 40 SNPs (P < 0.001 in joint analysis of Stages I and II) tested in Stage III (n~6650 individuals).</p> <p>Results</p> <p>Long-term averages of LDL-C, HDL-C, and TG were highly heritable (h<sup>2 </sup>= 0.66, 0.69, 0.58, respectively; each P < 0.0001). Of 70,987 tests for each of the phenotypes, two SNPs had p < 10<sup>-5 </sup>in GEE results for LDL-C, four for HDL-C, and one for TG. For each multivariable-adjusted phenotype, the number of SNPs with association p < 10<sup>-4 </sup>ranged from 13 to 18 and with p < 10<sup>-3</sup>, from 94 to 149. Some results confirmed previously reported associations with candidate genes including variation in the lipoprotein lipase gene (<it>LPL</it>) and HDL-C and TG (rs7007797; P = 0.0005 for HDL-C and 0.002 for TG). The full set of GEE, FBAT and linkage results are posted at the <b>d</b>ata<b>b</b>ase of <b>G</b>enotype <b>a</b>nd <b>P</b>henotype (dbGaP). After three stages of replication, there was no convincing statistical evidence for association (i.e., combined P < 10<sup>-5 </sup>across all three stages) between any of the tested SNPs and lipid phenotypes.</p> <p>Conclusion</p> <p>Using a 100K genome-wide scan, we have generated a set of putative associations for common sequence variants and lipid phenotypes. Validation of selected hypotheses in additional samples did not identify any new loci underlying variability in blood lipids. Lack of replication may be due to inadequate statistical power to detect modest quantitative trait locus effects (i.e., <1% of trait variance explained) or reduced genomic coverage of the 100K array. GWAS in FHS using a denser genome-wide genotyping platform and a better-powered replication strategy may identify novel loci underlying blood lipids.</p

    Images of sexual stereotypes in rap videos and the health of African American female adolescents

    Get PDF
    ABSTRACT Objective: This study sought to determine whether perceiving portrayals of sexual stereotypes in rap music videos was associated with adverse health outcomes among African American adolescent females. Methods: African American female adolescents (n â€«Űâ€Ź 522) were recruited from community venues. Adolescents completed a survey consisting of questions on sociodemographic characteristics, rap music video viewing habits, and a scale that assessed the primary predictor variable, portrayal of sexual stereotypes in rap music videos. Adolescents also completed an interview that assessed the health outcomes and provided urine for a marijuana screen. Results: In logistic regression analyses, adolescents who perceived more portrayals of sexual stereotypes in rap music videos were more likely to engage in binge drinking (OR 3.8, 95% CI 1.32-11.04, p â€«Űâ€Ź 0.01), test positive for marijuana (OR 3.4, 95% CI 1.19-9.85, p â€«Űâ€Ź 0.02), have multiple sexual partners (OR 1.9, 95% CI 1.01-3.71, p â€«Űâ€Ź 0.04), and have a negative body image (OR 1.5, 95% CI 1.02-2.26, p Ï­ 0.04). This is one of the first studies quantitatively examining the relationship between cultural images of sexual stereotypes in rap music videos and a spectrum of adverse health outcomes in African American female adolescents. Conclusions: Greater attention to this social issue may improve the health of all adolescent females. 115

    MESSENGER Observations of a Flux-Transfer-Event Shower at Mercury

    Get PDF
    Analysis of MESSENGER magnetic field observations taken in the southern lobe of Mercury's magnetotail and the adjacent magnetosheath on 11 April 2011 indicates that a total of 163 flux transfer events (FTEs) occurred within a 25 min interval. Each FTE had a duration of ∌2-3 s and was separated in time from the next by ∌8-10 s. A range of values have been reported at Earth, with mean values near ∌1-2 min and ∌8 min, respectively. We term these intervals of quasiperiodic flux transfer events "FTE showers." The northward and sunward orientation of the interplanetary magnetic field during this shower strongly suggests that the FTEs observed during this event formed just tailward of Mercury's southern magnetic cusp. The point of origin for the shower was confirmed with the Cooling model of FTE motion. Modeling of the individual FTE-type flux ropes in the magnetosheath indicates that these flux ropes had elliptical cross sections, a mean semimajor axis of 0.15RM (where RM is Mercury's radius, or 2440 km), and a mean axial magnetic flux of 1.25 MWb. The lobe magnetic field was relatively constant until the onset of the FTE shower, but thereafter the field magnitude decreased steadily until the spacecraft crossed the magnetopause. This decrease in magnetic field intensity is frequently observed during FTE showers. Such a decrease may be due to the diamagnetism of the new magnetosheath plasma being injected into the tail by the FTEs

    Assessing the cost of global biodiversity and conservation knowledge

    Get PDF
    Knowledge products comprise assessments of authoritative information supported by stan-dards, governance, quality control, data, tools, and capacity building mechanisms. Considerable resources are dedicated to developing and maintaining knowledge productsfor biodiversity conservation, and they are widely used to inform policy and advise decisionmakers and practitioners. However, the financial cost of delivering this information is largelyundocumented. We evaluated the costs and funding sources for developing and maintain-ing four global biodiversity and conservation knowledge products: The IUCN Red List ofThreatened Species, the IUCN Red List of Ecosystems, Protected Planet, and the WorldDatabase of Key Biodiversity Areas. These are secondary data sets, built on primary datacollected by extensive networks of expert contributors worldwide. We estimate that US160million(range:US160million (range: US116–204 million), plus 293 person-years of volunteer time (range: 278–308 person-years) valued at US14million(rangeUS 14 million (range US12–16 million), were invested inthese four knowledge products between 1979 and 2013. More than half of this financingwas provided through philanthropy, and nearly three-quarters was spent on personnelcosts. The estimated annual cost of maintaining data and platforms for three of these knowl-edge products (excluding the IUCN Red List of Ecosystems for which annual costs were notpossible to estimate for 2013) is US6.5millionintotal(range:US6.5 million in total (range: US6.2–6.7 million). We esti-mated that an additional US114millionwillbeneededtoreachpre−definedbaselinesofdatacoverageforallthefourknowledgeproducts,andthatonceachieved,annualmainte−nancecostswillbeapproximatelyUS114 million will be needed to reach pre-defined baselines ofdata coverage for all the four knowledge products, and that once achieved, annual mainte-nance costs will be approximately US12 million. These costs are much lower than those tomaintain many other, similarly important, global knowledge products. Ensuring that biodi-versity and conservation knowledge products are sufficiently up to date, comprehensiveand accurate is fundamental to inform decision-making for biodiversity conservation andsustainable development. Thus, the development and implementation of plans for sustain-able long-term financing for them is critical

    the world wide randomized antibiotic envelope infection prevention wrap it trial long term follow up

    Get PDF
    Abstract Background The WRAP-IT trial reported a 40% reduction in major CIED infection within 12 months of the procedure with the antibacterial-eluting envelope (TYRX). Objective This report describes the longer-term (>12 months) envelope effects on infection reduction and complications. Methods All trial patients that underwent CIED replacement, upgrade, revision, or initial CRT-D implant received standard-of-care infection prophylaxis and were randomized 1:1 to receive the envelope or not. CIED infection incidence, and procedure and system-related complications were characterized through all follow-up (36 months) using Cox proportional hazard regression modeling. Results In total, 6800 patients received their intended randomized treatment (3371 envelope; 3429 control; mean follow-up 21.0±8.3 months). Major CIED-related infection occurred in 32 envelope patients and 51 control patients (KM estimate, 1.3% vs. 1.9%; HR: 0.64, 95% CI: 0.41-0.99; P=0.046). Any CIED-related infection occurred in 57 envelope patients and 84 control patients (KM estimate, 2.1% vs. 2.8%; HR: 0.69, 95% CI: 0.49-0.97; P=0.030). System- or procedure-related complications occurred in 235 envelope patients and 252 control patients (KM estimate, 8.0% vs. 8.2%; HR, 0.95, 95% CI: 0.79-1.13; P Conclusions The effects of the TYRX envelope in reducing the risk of CIED infection are sustained beyond the first year post-procedure, without increased risk of complication
    • 

    corecore