Influences of Habitat Conditions on Submerged Aquatic Vegetation Development in the Chickahominy River and Other Virginia Tributaries of the Chesapeake Bay

Recently, there has been an expansion of submerged aquatic vegetation (SAV) in the tidal fresh and oligohaline portions of lower Chesapeake Bay tributaries. Much like the resurgence seen in the Potomac in the 1980’s, this spread of SAV in Virginia systems such as the Mattaponi, Pamunkey and Chickahominy seems to have been initiated by the introduction and spread of the invasive species Hydrilla verticillata, and appears to have been rapid. However the resurgence in the Piankatank has occurred in the absence of the introduction of this species. The factors that are influencing the growth of SAV in these tributary environments, including water quality and habitat conditions as well as the potential for interspecific competition between H. verticillata and the other SAV species in these regions are not well known. Annual aerial mapping surveys of the Chickahominy River were used alongside historical water quality data to investigate the patterns and rates of SAV bed development, and the relationships between this development and water quality conditions. Field investigations were performed in order to better understand the seasonal community dynamics relative to water quality conditions and interspecific competition. Historical analysis, field monitoring and field experimentation all showed salinity and turbidity to be the main factors controlling SAV abundance and species distribution along the Chickahominy River. Historical analysis of the Chickahominy River revealed a decline in SAV abundance in 2002, which corresponded with seasonal mean salinities of 4.1 psu. SAV abundance from 1998-2007 showed a significant correlation with vegetation emergence period secchi depth, in which secchi depths of 0.3 meters, the lowest of the time period, occurred during the 2002 SAV decline. Field data showed species zonation, in which H. verticillata was the overall dominant species, but was limited to the upper portion of the river where salinity intrusion remained below 2 psu throughout the growing season. Najas minor was dominant in the lower portion of the river where salinities reached over 4 psu in October. Salinity was the best predictor for H. verticillata’s biomass difference between the upper and lower river. SAV in the Chickahominy was able to grow in a wide range of conditions, with total suspended solids and chlorophyll a concentrations at times greater than 20 mg l-1 and 40 μg l-1, respectively, and sediment organic content ranging from less than 1% to greater than 25%. Comparisons with the Mattaponi and Piankatank rivers revealed ideal habitat for H. verticillata growth in the Mattaponi, where salinities along the vegetated reach of the upper river did not extend above 1 psu. On the other hand, this species was not found growing in the Piankatank, where salinities in the very upper portion of the river reached 3.5 psu. Finally, a field species removal experiment demonstrated that environmental conditions rather than interspecific competition were most important in determining plant performance, as both H. verticillata and N. minor exhibited poor growth in the lower river site, which had higher salinity and turbidity levels than the upper river site

Effects of sediment and salinity on the growth and competitive abilities of three submersed macrophytes

Submersed macrophytes are generally found in multispecies beds, with the dominance of individual species varying in both space and time. In estuarine environments, these plants can grow across a range of environmental conditions which may alter species interactions. Three species common to the Chesapeake Bay region, Vallisneria americana (wild celery), Heteranthera dubia (water stargrass), and Stuckenia pectinata (sago pondweed), were planted in a microcosm designed to test their growth and interactions (relative yielding) under a range of conditions of salinity (0, 5, or 10), sediment type (mud or sand), and species combinations. H. dubia was most sensitive to elevated salinity, while sediment type impacted only V. americana, performing better in mud compared with sand. V. americana and H. dubia were strong competitors, overyielding in many treatments when grown in mixture, while S. pectinata never overyielded and frequently underyielded. Interspecific competition was only strong between H. dubia and S. pectinata under 0 salinity, regardless of sediment type. V. americana on the other hand, showed strong interspecific competition with S. pectinata across multiple salinity and sediment types, indicating that this species is able to compete well across a wider range of environmental conditions. Our results suggest that H. dubia and V. americana are strong candidates for multi-species restoration, as positive interactions were observed when grown together. This measure of complementarity provides evidence for increased mixed bed plant performance under environmental conditions that would typically be more stressful to each growing alone. (C) 2016 Elsevier B.V. All rights reserved

Adaptations by Zostera marina Dominated Seagrass Meadows in Response to Water Quality and Climate Forcing

Global assessments of seagrass declines have documented accelerating rates of loss due to anthropogenic sediment and nutrient loadings, resulting in poor water quality. More recently, global temperature increases have emerged as additional major stressors. Seagrass changes in the Chesapeake Bay, USA provide important examples of not only the effects of human disturbance and climate forcing on seagrass loss, but also meadow recovery and resiliency. In the York River sub-tributary of the Chesapeake Bay, the meadows have been monitored intensively using annual aerial imagery, monthly transect surveys, and continuous water quality measurements. Here, Zostera marina has been demonstrating a shift in its historical growth patterns, with its biomass peaking earlier in the growing season and summer declines beginning earlier. We found an increasing trend in the length of the most stressful high temperature summer period, increasing by 22 days since 1950. Over the past 20 years, Z. marina’sabundance has exhibited periods of decline followed by recovery, with recovery years associated with greater spring water clarity and less time spent at water temperatures \u3e 28 °C. Although human disturbance and climatic factors have been altering these seagrass meadows, resilience has been evident by an increase in reproductive output and regrowth from Z. marina seedlings following declines, as well as expansions of Ruppia maritima into areas previously dominated by Z. marina

Water Quality Conditions and Restoration of Submerged Aquatic Vegetation (SAV) in the Tidal Freshwater James River 2009

In 2009, wild celery (Vallisneria americana) and water stargrass (Heteranthera dubia) shoots were transplanted into shallow water sites in the Hopewell region of the tidal James River and sampled for survivorship and growth throughout the SAV growing season. Water quality sampling was conducted at bi-weekly to monthly intervals throughout the year for water column nutrients, chlorophyll a, suspended solids, water transparency and other chemical and physical constituents important for SA V growth. Objectives of this restoration and water quality study were to: 1) expand the SA V transplanted plots within the study areas previously transplanted; 2) conduct water quality sampling to determine the state of water quality for 2009 in the tidal freshwater James relative to current water quality standards and SAV habitat requirements; 3) evaluate SA V transplant performance and compare to water quality conditions; 4) monitor SA V re-growth in the upper tidal James River. SA V transplant growth and survival again occurred at all James River field sites at depths of approximately 0.4-0.5 m below low water. Water stargrass and wild celery stocks originally collected from non-tidal areas of the James and planted into grow out nursery ponds at VIMS, were transplanted into the enclosed tidal restoration sites in 2008. SA V growth throughout the tidal freshwater James continued to expand in 2009 reaching over 350 acres. All three species grew to form beds with canopies of60-90 em and maximum bottom covers of60 to 100%. Powell\u27s Creek plantings continued to expand with coon tail ( Ceratophyllum demersum) plantings mixed with recruited hydrilla reaching over 68 acres in 2008. Water quality monitoring in the tidal James River in 2009 indicated that turbidity levels were again suitable for SA V growth to depths of 0.5 m in most areas, but did not meet levels suitable for SA V growth to 1m depths. Seasonal light levels were at or near water clarity criteria for growth to 0.5m depths at most transplant sites. Turbidity levels were lowest in the upper section of the JMSTF2 near Richmond. When integrated along each of the freshwater segments (JMSTFI and JMSTF2) using continuous underway spatial sampling, turbidity levels for growth to 0.5m were met for all eight SAV growing season cruises. Summertime levels of chlorophyll were generally lower than 2007. When integrated across the entire segments, average concentrations were found to be well above spring and summer limits of 15-23 ).lg r 1 and 10-15 ).lg r 1 for JMSTF1 and JMSTF2 respectively. Similarly, average seasonal concentrations at the transplant sites were above SA V growing season goals of 15 ).lg r 1 and ranged from 30 to 72 ).lg r during the spring and 72-82 11g r during the summer. No noxious blooms or other symptoms of excess algae were observed, however. Nutrient levels generally were comparable with earlier years\u27 monitoring results, although increases in analytical detection limits precluded trend analysis. Total kjeldahl nitrogen, dissolved ammonium and dissolved inorganic phosphorus concentrations were at or below detection for most of the year. Dissolved nitrate plus nitrite also were below detection during the summer, while total phosphorus showed higher concentrations than in previous years. Overall, the success of the SAV restoration and growth in the tidal freshwater James River is encouraging Most water quality parameters remain consistent from earlier years, but continued high levels of chlorophyll are still prevalent during the summer

Water quality conditions and restoration of submerged aquatic vegetation (SAV) in the tidal freshwater James River, 2008

In 2008, wild celery (Vallisneria americana), water stargrass (Heteranthera dubia) and hydrilla (Hydrilla verticilata) shoots were transplanted into shallow water sites in the Hopewell region of the tidal James River and sampled for survivorship and growth throughout the SA V growing season. Water quality sampling was conducted at bi-weekly intervals throughout the year for water column nutrients, chlorophyll a, suspended solids, water transparency and other chemical and physical constituents important for SA V growth. Continuous water quality sampling was also conducted along the James River from the mouth of the Chickahominy River to the upstream limits of tidal water at Richmond as part of the Chesapeake Bay Monitoring Program. Objectives of this restoration and water quality study were to: 1) expand the SA V transplanted plots within the study areas previously transplanted; 2) conduct water quality sampling to determine the state of water quality for 2008 in the tidal freshwater James relative to current water quality standards and SA V habitat requirements; 3) evaluate SA V transplant performance and compare to water quality conditions; 4) monitor SA V re-growth in the upper tidal James River. more ...

Water Quality Conditions and Restoration of Submerged Aquatic Vegetation (SAV) in the Tidal Freshwater James River 2007

In 2007, wild celery (Vallisneria americana) and water stargrass (Heteranthera dubia) were planted at sites in the Hopewell region of the tidal James River. The SA V transplants from 2007 and previous years were monitoried by the Virginia Institute of Marine Science (VIMS) for survivorship and growth throughout the growing season. Nursery ponds were constructed at the VIMS campus for development of SA V transplant propagules. Water quality sampling was conducted at bi-weekly intervals throughout the year for water column nutrients, chlorophyll a, suspended solids, water transparency and other chemical and physical constituents important for SAV growth. Continuous water quality sampling was also conducted along the James River from the mouth of the Chickahominy River to the upstream limits of tidal water at Richmond. Objectives ofthis restoration and water quality study were to: 1) expand the SAV transplanted plots within the study sites previously transplanted; 2) conduct water quality sampling to determine the state of water quality in the tidal freshwater James relative to current water quality standards and SAV habitat requirements; 3) evaluate SAV transplant performance and compare to water quality conditions; 4) monitor SA V re-growth in the upper tidal James River. SA V transplant growth and survival occurred at all James River field sites at depths of approximately 0.4 m below low water. Seeds obtained from wild stock and planted within the exclosures germinated and produced adult plants in 2006 and these demonstrated re-growth in 2007. Water stargrass stocks originally collected from non-tidal areas of the James and planted into grow out nursery ponds at VIMS in 2006, along with nursery grown wild celery were replanted into tidal sites in 2007. Both species transplanted in 2007 also were successful and grew throughout 2007. SAV growth throughout the tidal freshwater James continued to expand in 2007 reaching over 300 acres. Powell\u27s Creek plantings continued to expand with coontail (Ceratophyllum demersum) plantings mixed with recruited Hydrilla (Hydrilla verticilata) reaching over 60 acres. Water quality monitoring in the tidal James River in 2007 indicated that turbidity levels were again suitable for SA V growth to depths of 0.5 m in most areas. Seasonal light levels were at or near water clarity criteria for most transplant sites. Turbidity levels were highest in the upper section of the JMSTF1 segment and lower section of the JMSTF2 segment. When integrated along each of the freshwater segments (JMSTF1 and JMSTF2) using continuous underway spatial sampling, turbidity goals were met for all eight SA V growing season cruises. Summertime levels of chlorophyll were the highest recorded over the past five years. When integrated across the entire segments, average concentrations were found to be well above spring and summer limits of 15-23 Jlg r 1 and 10-15 Jlg r 1 for JMSTF1 and JMSTF2 respectively. Similarly, average seasonal concentrations at the transplant sites were above SA V growing season goals of 15 Jlg r1 • Nutrient levels generally were comparable with earlier years\u27 monitoring results, although dissolved ammonium concentrations were at or below detection for most of the year and a decreasing trend has been evident since 2002. Similarly dissolved inorganic phosphate (DIP) levels were very low throughout much of the year and all transplant sites met SAV growing season habitat requirements for DIP. Overall, the success of the SA V restoration in the tidal freshwater James River is encouraging, but the high levels of chlorophyll are of concern and warrant continued monitoring

Influence of Rising Water Temperature on the Temperate Seagrass Species Eelgrass (Zostera marina L.) in the Northeast USA

Sea surface temperature (SST) has increased worldwide since the beginning of the 20th century, a trend which is expected to continue. Changes in SST can have significant impacts on marine biota, including population-level shifts and alterations in community structure and diversity, and changes in the timing of ecosystem events. Seagrasses are a group of foundation species that grow in shallow coastal and estuarine systems, where they provide many ecosystem services. Eelgrass, Zostera marina L., is the dominant seagrass species in the Northeast United States of America (USA). Multiple factors have been cited for losses in this region, including light reduction, eutrophication, and physical disturbance. Warming has the potential to exacerbate seagrass loss. Here, we investigate regional changes in eelgrass presence and abundance in relation to local water temperature using monitoring data from eight sites in the Northeastern USA (New Hampshire to Maryland) where a consistent monitoring protocol, SeagrassNet, has been applied. We use a hurdle model consisting of a generalized additive mixed model (GAMM) with binomial and beta response distributions for modeling eelgrass presence and abundance, respectively, in relation to the local summer average water temperature. We show that summer water temperature one year prior to monitoring is a significant predictor of eelgrass presence, but not abundance, on a regional scale. Above average summer temperatures correspond to a decrease in probability of eelgrass presence (and increased probability of eelgrass absence) the following year. Cooler than average temperatures in the preceding year, down to approximately 0.5°C below the site average, are associated with the highest predicted probability of eelgrass presence. Our findings suggest vulnerability in eelgrass meadows of the Northeast USA and emphasize the value of unified approaches to seagrass monitoring, conservation and management at the seascape scale

Large-Scale Gene-Centric Meta-Analysis across 39 Studies Identifies Type 2 Diabetes Loci

To identify genetic factors contributing to type 2 diabetes (T2D), we performed large-scale meta-analyses by using a custom similar to 50,000 SNP genotyping array (the ITMAT-Broad-CARe array) with similar to 2000 candidate genes in 39 multiethnic population-based studies, case-control studies, and clinical trials totaling 17,418 cases and 70,298 controls. First, meta-analysis of 25 studies comprising 14,073 cases and 57,489 controls of European descent confirmed eight established T2D loci at genome-wide significance. In silico follow-up analysis of putative association signals found in independent genome-wide association studies (including 8,130 cases and 38,987 controls) performed by the DIAGRAM consortium identified a T2D locus at genome-wide significance (GATAD2A/CILP2/PBX4; p = 5.7 x 10(-9)) and two loci exceeding study-wide significance (SREBF1, and TH/INS; p <2.4 x 10(-6)). Second, meta-analyses of 1,986 cases and 7,695 controls from eight African-American studies identified study-wide-significant (p = 2.4 x 10(-7)) variants in HMGA2 and replicated variants in TCF7L2 (p = 5.1 x 10(-15)). Third, conditional analysis revealed multiple known and novel independent signals within five T2D-associated genes in samples of European ancestry and within HMGA2 in African-American samples. Fourth, a multiethnic meta-analysis of all 39 studies identified T2D-associated variants in BCL2 (p = 2.1 x 10(-8)). Finally, a composite genetic score of SNPs from new and established T2D signals was significantly associated with increased risk of diabetes in African-American, Hispanic, and Asian populations. In summary, large-scale meta-analysis involving a dense gene-centric approach has uncovered additional loci and variants that contribute to T2D risk and suggests substantial overlap of T2D association signals across multiple ethnic groups

Формирование эмоциональной культуры как компонента инновационной культуры студентов

Homozygosity has long been associated with rare, often devastating, Mendelian disorders1 and Darwin was one of the first to recognise that inbreeding reduces evolutionary fitness2. However, the effect of the more distant parental relatedness common in modern human populations is less well understood. Genomic data now allow us to investigate the effects of homozygosity on traits of public health importance by observing contiguous homozygous segments (runs of homozygosity, ROH), which are inferred to be homozygous along their complete length. Given the low levels of genome-wide homozygosity prevalent in most human populations, information is required on very large numbers of people to provide sufficient power3,4. Here we use ROH to study 16 health-related quantitative traits in 354,224 individuals from 102 cohorts and find statistically significant associations between summed runs of homozygosity (SROH) and four complex traits: height, forced expiratory lung volume in 1 second (FEV1), general cognitive ability (g) and educational attainment (nominal p<1 × 10−300, 2.1 × 10−6, 2.5 × 10−10, 1.8 × 10−10). In each case increased homozygosity was associated with decreased trait value, equivalent to the offspring of first cousins being 1.2 cm shorter and having 10 months less education. Similar effect sizes were found across four continental groups and populations with different degrees of genome-wide homozygosity, providing convincing evidence for the first time that homozygosity, rather than confounding, directly contributes to phenotypic variance. Contrary to earlier reports in substantially smaller samples5,6, no evidence was seen of an influence of genome-wide homozygosity on blood pressure and low density lipoprotein (LDL) cholesterol, or ten other cardio-metabolic traits. Since directional dominance is predicted for traits under directional evolutionary selection7, this study provides evidence that increased stature and cognitive function have been positively selected in human evolution, whereas many important risk factors for late-onset complex diseases may not have been

Global Retinoblastoma Presentation and Analysis by National Income Level.

Importance: Early diagnosis of retinoblastoma, the most common intraocular cancer, can save both a child's life and vision. However, anecdotal evidence suggests that many children across the world are diagnosed late. To our knowledge, the clinical presentation of retinoblastoma has never been assessed on a global scale. Objectives: To report the retinoblastoma stage at diagnosis in patients across the world during a single year, to investigate associations between clinical variables and national income level, and to investigate risk factors for advanced disease at diagnosis. Design, Setting, and Participants: A total of 278 retinoblastoma treatment centers were recruited from June 2017 through December 2018 to participate in a cross-sectional analysis of treatment-naive patients with retinoblastoma who were diagnosed in 2017. Main Outcomes and Measures: Age at presentation, proportion of familial history of retinoblastoma, and tumor stage and metastasis. Results: The cohort included 4351 new patients from 153 countries; the median age at diagnosis was 30.5 (interquartile range, 18.3-45.9) months, and 1976 patients (45.4%) were female. Most patients (n = 3685 [84.7%]) were from low- and middle-income countries (LMICs). Globally, the most common indication for referral was leukocoria (n = 2638 [62.8%]), followed by strabismus (n = 429 [10.2%]) and proptosis (n = 309 [7.4%]). Patients from high-income countries (HICs) were diagnosed at a median age of 14.1 months, with 656 of 666 (98.5%) patients having intraocular retinoblastoma and 2 (0.3%) having metastasis. Patients from low-income countries were diagnosed at a median age of 30.5 months, with 256 of 521 (49.1%) having extraocular retinoblastoma and 94 of 498 (18.9%) having metastasis. Lower national income level was associated with older presentation age, higher proportion of locally advanced disease and distant metastasis, and smaller proportion of familial history of retinoblastoma. Advanced disease at diagnosis was more common in LMICs even after adjusting for age (odds ratio for low-income countries vs upper-middle-income countries and HICs, 17.92 [95% CI, 12.94-24.80], and for lower-middle-income countries vs upper-middle-income countries and HICs, 5.74 [95% CI, 4.30-7.68]). Conclusions and Relevance: This study is estimated to have included more than half of all new retinoblastoma cases worldwide in 2017. Children from LMICs, where the main global retinoblastoma burden lies, presented at an older age with more advanced disease and demonstrated a smaller proportion of familial history of retinoblastoma, likely because many do not reach a childbearing age. Given that retinoblastoma is curable, these data are concerning and mandate intervention at national and international levels. Further studies are needed to investigate factors, other than age at presentation, that may be associated with advanced disease in LMICs