High fuel costs have encouraged producers of greenhouse tomato (Solanum lycopersicum L.) in the mid-Atlantic region to reduce air temperatures during the day. However, effects on fruit ripening and yield are not known, especially under the low light conditions found in off-season production. This 2-yr study compared fruit ripening and yield of tomato under two temperature regimes during the fall season. Two sets of 18 tomato plants, three rows of six, were grown in soilless culture under either a warm or cool temperature regime. Temperatures were similar during night hours but allowed to rise to at least 2124 oC in the cool greenhouse section and 23-26 oC in the warm section, depending on daily solar heating. Mean 24 hour temperature difference between zones was less than 2 oC. Ripe tomato fruit were harvested and weighed 3 times per week for 8 weeks and the remaining un-ripened green tomatoes were weighed at the termination of the experiment to obtain total fruit biomass. The warm zone produced significantly greater weight of ripe tomatoes (23%) than the cool zone. However, total fruit weight (ripe and green), was not significantly different. Thus, a relatively small increase in temperature (2 oC) during the mid-day was associated with a significant increase in fruit ripening but not in total fruit weight. This study showed that greenhouse temperature could be used to better manage fruit production to match weekly market demand without affecting total fruit weight and that consistently maintaining a cool greenhouse would delay tomato ripening and likely increase the potential for plant stress due to high fruit loads remaining on the vines.
{"title":"Effect of Greenhouse Temperature on Tomato Yield and Ripening","authors":"M. Kraemer, Christopher D. Mullins, C. Niedziela","doi":"10.25778/2CWE-QY41","DOIUrl":"https://doi.org/10.25778/2CWE-QY41","url":null,"abstract":"High fuel costs have encouraged producers of greenhouse tomato (Solanum lycopersicum L.) in the mid-Atlantic region to reduce air temperatures during the day. However, effects on fruit ripening and yield are not known, especially under the low light conditions found in off-season production. This 2-yr study compared fruit ripening and yield of tomato under two temperature regimes during the fall season. Two sets of 18 tomato plants, three rows of six, were grown in soilless culture under either a warm or cool temperature regime. Temperatures were similar during night hours but allowed to rise to at least 2124 oC in the cool greenhouse section and 23-26 oC in the warm section, depending on daily solar heating. Mean 24 hour temperature difference between zones was less than 2 oC. Ripe tomato fruit were harvested and weighed 3 times per week for 8 weeks and the remaining un-ripened green tomatoes were weighed at the termination of the experiment to obtain total fruit biomass. The warm zone produced significantly greater weight of ripe tomatoes (23%) than the cool zone. However, total fruit weight (ripe and green), was not significantly different. Thus, a relatively small increase in temperature (2 oC) during the mid-day was associated with a significant increase in fruit ripening but not in total fruit weight. This study showed that greenhouse temperature could be used to better manage fruit production to match weekly market demand without affecting total fruit weight and that consistently maintaining a cool greenhouse would delay tomato ripening and likely increase the potential for plant stress due to high fruit loads remaining on the vines.","PeriodicalId":23516,"journal":{"name":"Virginia journal of science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2012-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82156378","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
N. Tibert, J. B. Hubeny, M. Abbott, J. M. Kiker, L. Walker, S. McKenzie
Instrumental tide gauge records indicate that the modern rates of sea-level rise in the Chesapeake Bay more than double the global average of 1.2-1.5 mm yr-1. The primary objective for this study is to establish a relative depositional history for the tidal marshes of the Potomac and Rappahannock Rivers that will help us improve our understanding of processes that influence sedimentation in the proximal tributaries of Chesapeake Bay. Marsh cores were collected from Blandfield Point VA, Tappahannock VA, and Potomac Creek VA. The sedimentary facies include: 1) a lower unit of organic-poor, grey clay with fine sand and silt layers and estuarine foraminifera; and 2) an upper unit of organic-rich clay and peat with abundant brackish to freshwater marsh foraminifera and thecamoebians. AMS 14C dating of bulk marsh sediments yield sedimentation rates at Potomac Creek ranging from 3.04-4.20 mm yr-1 for the past 2500 years. Rates of sedimentation calculated for Blandfield Point indicate 1.37-2.19 mm yr-1 in the basal clays and peat for the past ~3000 years. Foraminiferal census counts indicate a freshening upward trend with a transition from an estuarine Ammobaculites crassus assemblage to a marsh Ammoastuta salsa assemblage with abundant freshwater Thecamoebians. The late Holocene history of sedimentation for the marshes indicates that differential compaction, recent land use practices, and climate change have contributed to the resultant freshening-upward environmental trend and variability in sediment accumulation rates between coring sites. Corresponding author: Neil E. Tibert ntibert@umw.edu 92 VIRGINIA JOURNAL OF SCIENCE INTRODUCTION The Chesapeake Bay watershed comprises numerous tributaries draining from the eastern Appalachian Mountains. The central axis to the Chesapeake has been evaluated in the context of decadal, centennial, and millennial climate changes (Cronin and others 2005, 2010). In the historic Northern Neck region of Virginia, the tidal reaches of the Rappahannock and Potomac Rivers (Fig. 1) have received little detailed study with respect to the nature of the sedimentary record spanning the past several thousand years. Recent estimates for eustatic sea level are estimated to be as high as 1.5-1.88 mm yr (Church and White 2006, Nerem and others 2006) whereas the instrumental tidal -1 FIGURE 1. Location map for the tidal reaches of the Potomac and Rappahannock Rivers. Table1 lists the coordinates and detailed coring information for Sites A-C. Table 2 list coordinates and details for the tide gauge stations (Sites 1-4). Inset shows our location along the eastern Atlantic coast of the USA. Late Holocene Sedimentation 93 records from the Chesapeake Bay indicate rates as high as ~3-4 mm yr (Boon 2012). -1 The disparity between global and regional base level change in the Chesapeake Bay is not well understood and likely reflects the combined effects of allogenic, autogenic, and anthropogenic processes in the region (Cronin 2012). The primar
{"title":"Late Holocene Sedimentation and Paleoenvironmental History for the Tidal Marshes of the Potomac and Rappahannock Rivers, Tributaries to Chesapeake Bay","authors":"N. Tibert, J. B. Hubeny, M. Abbott, J. M. Kiker, L. Walker, S. McKenzie","doi":"10.25778/D2GV-6S53","DOIUrl":"https://doi.org/10.25778/D2GV-6S53","url":null,"abstract":"Instrumental tide gauge records indicate that the modern rates of sea-level rise in the Chesapeake Bay more than double the global average of 1.2-1.5 mm yr-1. The primary objective for this study is to establish a relative depositional history for the tidal marshes of the Potomac and Rappahannock Rivers that will help us improve our understanding of processes that influence sedimentation in the proximal tributaries of Chesapeake Bay. Marsh cores were collected from Blandfield Point VA, Tappahannock VA, and Potomac Creek VA. The sedimentary facies include: 1) a lower unit of organic-poor, grey clay with fine sand and silt layers and estuarine foraminifera; and 2) an upper unit of organic-rich clay and peat with abundant brackish to freshwater marsh foraminifera and thecamoebians. AMS 14C dating of bulk marsh sediments yield sedimentation rates at Potomac Creek ranging from 3.04-4.20 mm yr-1 for the past 2500 years. Rates of sedimentation calculated for Blandfield Point indicate 1.37-2.19 mm yr-1 in the basal clays and peat for the past ~3000 years. Foraminiferal census counts indicate a freshening upward trend with a transition from an estuarine Ammobaculites crassus assemblage to a marsh Ammoastuta salsa assemblage with abundant freshwater Thecamoebians. The late Holocene history of sedimentation for the marshes indicates that differential compaction, recent land use practices, and climate change have contributed to the resultant freshening-upward environmental trend and variability in sediment accumulation rates between coring sites. Corresponding author: Neil E. Tibert ntibert@umw.edu 92 VIRGINIA JOURNAL OF SCIENCE INTRODUCTION The Chesapeake Bay watershed comprises numerous tributaries draining from the eastern Appalachian Mountains. The central axis to the Chesapeake has been evaluated in the context of decadal, centennial, and millennial climate changes (Cronin and others 2005, 2010). In the historic Northern Neck region of Virginia, the tidal reaches of the Rappahannock and Potomac Rivers (Fig. 1) have received little detailed study with respect to the nature of the sedimentary record spanning the past several thousand years. Recent estimates for eustatic sea level are estimated to be as high as 1.5-1.88 mm yr (Church and White 2006, Nerem and others 2006) whereas the instrumental tidal -1 FIGURE 1. Location map for the tidal reaches of the Potomac and Rappahannock Rivers. Table1 lists the coordinates and detailed coring information for Sites A-C. Table 2 list coordinates and details for the tide gauge stations (Sites 1-4). Inset shows our location along the eastern Atlantic coast of the USA. Late Holocene Sedimentation 93 records from the Chesapeake Bay indicate rates as high as ~3-4 mm yr (Boon 2012). -1 The disparity between global and regional base level change in the Chesapeake Bay is not well understood and likely reflects the combined effects of allogenic, autogenic, and anthropogenic processes in the region (Cronin 2012). The primar","PeriodicalId":23516,"journal":{"name":"Virginia journal of science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2012-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86964481","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Red-backed salamanders represent an important component of Virginia ecosystems, but there are few habitat models that can reliably predict the presence/absence of this species. We surveyed the habitats of red-backed salamanders at one site in the Piedmont region of Virginia and collected data on an array of habitat variables with which this species is normally associated. We used logistic regression to develop a model predicting the presence or absence of the species at a given 50m-transect. Our final model incorporated soil organic layer pH variability and mineral layer average pH, and accounted for 30% of the variation in our data. We conclude that soil pH is a limiting determinant of habitat use for this study site, and that it may affect adaptive behaviors for highly acidic soils. INTRODUCTION As researchers address the issues of amphibian decline, there is an increasing need to better understand how salamanders in terrestrial ecosystems interact with their habitat. Greater understanding of the habitat ecology of these species would likely improve our ability to manage and conserve amphibian diversity in local watersheds, thereby reducing the ecosystem damage that would result from the loss of these species (Cushman 2005, Wyman 1990). In the Rappahannock River watershed of Northern Virginia, both Mitchell (1998) and McGhee and Killian (2010) have surveyed amphibian, and specifically, salamander diversity, but little has been done to assess the habitat relationships of commonly detected species. To address this need, we conducted a preliminary study of salamander habitat for a single site in the Rappahannock River drainage at the C. F. Phelps Wildlife Management Area (WMA) concurrent with a species diversity survey and developed a simple habitat model for our most commonly detected terrestrial salamander, Plethodon cinereus Green 1818 (red-backed salamander). Corresponding author: Jay D. McGhee jmcghee@nwmissouri.edu Virginia Journal of Science, Vol. 63, No. 3, 2012 http://digitalcommons.odu.edu/vjs/vol63/iss3 138 VIRGINIA JOURNAL OF SCIENCE The red-backed salamander is common to Virginia forests and the Rappahannock River watershed, and is considered an important component of the local ecosystems in which they occur (Burton and Likens 1975, Davic and Welsh 2004). While several studies have noted particular habitat features associated with this species, such that a hypothetical niche-gestalt can be conceptualized (James 1971), only a few studies have actually developed predictive models of habitat use, primarily to compare the effects of silviculture treatments (Demaynadier and Hunter 1998, Morneault et al. 2004, McKenney et al. 2006). The red-backed salamander occurs in the leaf-litter and well-drained soil underlying deciduous, northern conifer, and mixed deciduous-coniferous forests with numerous cover objects (logs and rocks) and little underbrush (Burger 1935, Petranka 1998, Richmond and Trombulak 2009). This lungless salamander is depend
红背蝾螈是弗吉尼亚州生态系统的重要组成部分，但很少有栖息地模型可以可靠地预测该物种的存在/缺失。我们在弗吉尼亚州皮埃蒙特地区的一个地点调查了红背蝾螈的栖息地，并收集了一系列与该物种通常相关的栖息地变量的数据。我们使用逻辑回归建立了一个模型来预测该物种在给定的50米样带上的存在或不存在。我们的最终模型结合了土壤有机层pH变异性和矿物层平均pH变异性，占我们数据变化的30%。我们得出结论，土壤pH值是该研究地点生境利用的限制性决定因素，并且可能影响高酸性土壤的适应行为。随着研究人员解决两栖动物数量下降的问题，人们越来越需要更好地了解陆地生态系统中蝾螈与栖息地的相互作用。更好地了解这些物种的栖息地生态可能会提高我们管理和保护当地流域两栖动物多样性的能力，从而减少因这些物种的消失而造成的生态系统破坏(Cushman 2005, Wyman 1990)。在北弗吉尼亚的Rappahannock河流域，Mitchell(1998)和McGhee and Killian(2010)都对两栖动物，特别是蝾螈的多样性进行了调查，但很少对常见物种的栖息地关系进行评估。为了满足这一需求，我们在c.f. Phelps野生动物管理区(WMA)的Rappahannock河流域的单个地点对蝾螈栖息地进行了初步研究，同时进行了物种多样性调查，并为我们最常见的陆生蝾螈Plethodon cinereus Green 1818(红背蝾螈)建立了一个简单的栖息地模型。通讯作者:Jay D. McGhee jmcghee@nwmissouri.edu弗吉尼亚科学杂志，Vol. 63, No. 3, 2012 http://digitalcommons.odu.edu/vjs/vol63/iss3 138弗吉尼亚科学杂志红背蝾螈在弗吉尼亚森林和Rappahannock河流域很常见，被认为是当地生态系统的重要组成部分(Burton and Likens 1975, Davic and Welsh 2004)。虽然有几项研究指出了与该物种相关的特定栖息地特征，例如可以概念化假设的生态位格式塔(James 1971)，但实际上只有少数研究开发了栖息地利用的预测模型，主要是为了比较造林处理的效果(Demaynadier和Hunter 1998, Morneault等人2004,McKenney等人2006)。红背蝾螈生活在落叶、北方针叶林和落叶针叶林混交林下的落叶层和排水良好的土壤中，有大量的覆盖物(原木和岩石)和很少的灌木丛(Burger 1935, Petranka 1998, Richmond and Trombulak 2009)。这种无肺蝾螈依靠通过皮肤进行气体交换来呼吸，对湿度和温度的变化很敏感，通常通过垂直移动通过土壤柱来适应这些变化(Taub 1961, heathole 1962, Spotila 1972)。它们倾向于中性的土壤pH值，较低的温度和易于进入较低的土层作为捕食避难所(Bogert 1952, heathole 1962, Spotila 1972, Wyman和Hawksley-Lescault 1987)。雌性将卵产在自然裂缝中或埋在岩石或腐烂的原木下(Petranka 1998)。我们希望确定我们是否可以成功地预测红背蝾螈在给定地点的发生，使用与这些已知的栖息地特征相关的变量，这些特征是它们生态学的关键组成部分。我们假设红背蝾螈会在与覆盖物和中性潮湿、凉爽的土壤条件相关的凋落叶中被检测到。我们预测逻辑回归模型将包括测量覆盖物、土壤湿度和土壤ph的覆盖量的变量。方法我们使用样带取样来定位蝾螈(Jaeger 1994, Jaeger and Inger 1994, Mitchell 2000)。我们使用GPS随机选择样条的起始位置。我们通过在2 10m的间隔内随机放置5个1 m的样方进行取样(Jaeger 1994, Jaeger and Inger 1994, Mitchell 2000)。我们通过移除大的覆盖物(岩石和腐烂的木头)和搜索凋落叶来搜索样方(Mitchell 2000)。我们对捕获的蝾螈进行了物种鉴定，并测量了口鼻长度和总长度，以估计和分配年龄类别(Petranka 1998, Moore和Wyman 2010)。我们在样带水平和样方水平采集了生境数据。
{"title":"Exploratory Modeling Indicates Red-Backed Salamander Detections are Sensitive to Soil pH at C. F. Phelps Wildlife Management Area, Virginia","authors":"J. D. McGhee, Michael D. Killian","doi":"10.25778/X2ZQ-FF94","DOIUrl":"https://doi.org/10.25778/X2ZQ-FF94","url":null,"abstract":"Red-backed salamanders represent an important component of Virginia ecosystems, but there are few habitat models that can reliably predict the presence/absence of this species. We surveyed the habitats of red-backed salamanders at one site in the Piedmont region of Virginia and collected data on an array of habitat variables with which this species is normally associated. We used logistic regression to develop a model predicting the presence or absence of the species at a given 50m-transect. Our final model incorporated soil organic layer pH variability and mineral layer average pH, and accounted for 30% of the variation in our data. We conclude that soil pH is a limiting determinant of habitat use for this study site, and that it may affect adaptive behaviors for highly acidic soils. INTRODUCTION As researchers address the issues of amphibian decline, there is an increasing need to better understand how salamanders in terrestrial ecosystems interact with their habitat. Greater understanding of the habitat ecology of these species would likely improve our ability to manage and conserve amphibian diversity in local watersheds, thereby reducing the ecosystem damage that would result from the loss of these species (Cushman 2005, Wyman 1990). In the Rappahannock River watershed of Northern Virginia, both Mitchell (1998) and McGhee and Killian (2010) have surveyed amphibian, and specifically, salamander diversity, but little has been done to assess the habitat relationships of commonly detected species. To address this need, we conducted a preliminary study of salamander habitat for a single site in the Rappahannock River drainage at the C. F. Phelps Wildlife Management Area (WMA) concurrent with a species diversity survey and developed a simple habitat model for our most commonly detected terrestrial salamander, Plethodon cinereus Green 1818 (red-backed salamander). Corresponding author: Jay D. McGhee jmcghee@nwmissouri.edu Virginia Journal of Science, Vol. 63, No. 3, 2012 http://digitalcommons.odu.edu/vjs/vol63/iss3 138 VIRGINIA JOURNAL OF SCIENCE The red-backed salamander is common to Virginia forests and the Rappahannock River watershed, and is considered an important component of the local ecosystems in which they occur (Burton and Likens 1975, Davic and Welsh 2004). While several studies have noted particular habitat features associated with this species, such that a hypothetical niche-gestalt can be conceptualized (James 1971), only a few studies have actually developed predictive models of habitat use, primarily to compare the effects of silviculture treatments (Demaynadier and Hunter 1998, Morneault et al. 2004, McKenney et al. 2006). The red-backed salamander occurs in the leaf-litter and well-drained soil underlying deciduous, northern conifer, and mixed deciduous-coniferous forests with numerous cover objects (logs and rocks) and little underbrush (Burger 1935, Petranka 1998, Richmond and Trombulak 2009). This lungless salamander is depend","PeriodicalId":23516,"journal":{"name":"Virginia journal of science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2012-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79806757","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In summer 2005, plots were surveyed along roads passing through forest habitats at the Grassy Hill Natural Area Preserve in Franklin County, Virginia to assess the distributions and abundances of Microstegium vimineum in transects located at increasing distances away from roadsides into forest interiors. Across plots, Microstegium was encountered almost exclusively in roadside transects, where abundances were relatively high. While forest composition and topographic features were similar across plots, percent canopy cover and leaf litter depth were greater in interior compared to roadside transects due to undisturbed tree canopies and ground cover located in interior plot areas. Results imply that Microstegium was restricted to forest roadsides at Grassy Hill at the time of the study, likely due to factors that differ between forest edges and interiors.
{"title":"Distributions and Abundances of Microstegium vimineum along Forest Roadsides at the Grassy Hill Natural Area, Franklin County, Virginia","authors":"Gregory D. Turner","doi":"10.25778/HSXX-MK73","DOIUrl":"https://doi.org/10.25778/HSXX-MK73","url":null,"abstract":"In summer 2005, plots were surveyed along roads passing through forest habitats at the Grassy Hill Natural Area Preserve in Franklin County, Virginia to assess the distributions and abundances of Microstegium vimineum in transects located at increasing distances away from roadsides into forest interiors. Across plots, Microstegium was encountered almost exclusively in roadside transects, where abundances were relatively high. While forest composition and topographic features were similar across plots, percent canopy cover and leaf litter depth were greater in interior compared to roadside transects due to undisturbed tree canopies and ground cover located in interior plot areas. Results imply that Microstegium was restricted to forest roadsides at Grassy Hill at the time of the study, likely due to factors that differ between forest edges and interiors.","PeriodicalId":23516,"journal":{"name":"Virginia journal of science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2011-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74749226","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The gray treefrog complex consists of two sibling species that are indistinguishable morphologically, the diploid Hyla chrysoscelis and the tetraploid Hyla versicolor. Identification is possible in the field only by audio recognition of male advertisement call trill rates (pulses/second). During 1979-1983 we evaluated taped calls of these two species taken from 89 populations from throughout Virginia to map their respective ranges and to evaluate differences in call parameters. Hyla chrysoscelis occurs in the Coastal Plain, eastern and southern Piedmont, and in southwestern Virginia. Hyla versicolor occurs in the Piedmont, Blue Ridge, and Ridge and Valley regions south to Wythe and Tazewell counties. Sympatric sites occur in several locations in the Piedmont and both species are syntopic in several of them. Male trill rates are significantly related to ambient and body temperatures. Rates produced by male H. chrysoscelis (>31/s) are twice as fast as that for H. versicolor (<30/s); they did not overlap in our samples at any temperature. Trill rates and call duration in southwestern Virginia populations of H. chrysoscelis differed significantly from those in eastern populations when adjusted for ambient temperature. Adjusted trill rate and duration in H. chrysoscelis populations in sympatry with H. versicolor were not significantly different from allopatric populations but were for H. versicolor.
{"title":"Advertisement Call and Distribution of the Treefrogs Hyla chrysoscelis and Hyla versicolor in Virginia","authors":"J. Mitchell, Chris A. Pague","doi":"10.25778/1DR5-5Z74","DOIUrl":"https://doi.org/10.25778/1DR5-5Z74","url":null,"abstract":"The gray treefrog complex consists of two sibling species that are indistinguishable morphologically, the diploid Hyla chrysoscelis and the tetraploid Hyla versicolor. Identification is possible in the field only by audio recognition of male advertisement call trill rates (pulses/second). During 1979-1983 we evaluated taped calls of these two species taken from 89 populations from throughout Virginia to map their respective ranges and to evaluate differences in call parameters. Hyla chrysoscelis occurs in the Coastal Plain, eastern and southern Piedmont, and in southwestern Virginia. Hyla versicolor occurs in the Piedmont, Blue Ridge, and Ridge and Valley regions south to Wythe and Tazewell counties. Sympatric sites occur in several locations in the Piedmont and both species are syntopic in several of them. Male trill rates are significantly related to ambient and body temperatures. Rates produced by male H. chrysoscelis (>31/s) are twice as fast as that for H. versicolor (<30/s); they did not overlap in our samples at any temperature. Trill rates and call duration in southwestern Virginia populations of H. chrysoscelis differed significantly from those in eastern populations when adjusted for ambient temperature. Adjusted trill rate and duration in H. chrysoscelis populations in sympatry with H. versicolor were not significantly different from allopatric populations but were for H. versicolor.","PeriodicalId":23516,"journal":{"name":"Virginia journal of science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2011-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91102583","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
J. R. Palmieri, Geneva Gehring, Catherine Minichino, S. F. Elswaifi
Currently, nanoparticles are synthesized and used at an unprecedented rate for industrial, medical, and research applications. The use of cerium oxide nanoparticles (CeONP) and yttrium oxide nanoparticles (YtONP) results in their spread as contaminants into the environment. Once in the environment, CeONP and YtONP can be taken up by organisms in the food chain where they may pose a public health risk. In this study we determine whether Acanthamoeba castellanii and Daphnia magna uptake CeONP or YtONP from their environment and thereby play a role in the transmission of the nanoparticles. Using electron microscopy, organisms exposed to the nanoparticles were examined. Our results indicate that the nanoparticles are associated with cell and organelle membranes. These findings have implications for the health risks associated with environmental contamination by CeONP and YtONP. INTRODUCTION In this study we determine whether protists and crustaceans play a role in the transfer of cerium oxide nanoparticles (CeONP) and yttrium oxide nanoparticles (YtONP) from the environment to other organisms within the aquatic food chain. Acanthamoeba castellanii, a common protist, and Daphnia magna, a planktonic crustacean, are important components in many aquatic ecosystems. Because acanthamoebae, such as A. castellanni, are aggressive feeders they consume inorganic and organic compounds from their environment, thereby serving as a link by transferring normally unavailable inorganic components to the food chain (Weekers et al. 1993). D. magna feeds on acanthamoebae and other protists found in lower trophic levels. Because of the high reproductive potential of D. magna, these planktonic crustaceans can substantially alter the structure and functioning of microbial food webs in freshwater ecosystems , such as acidic swamps, freshwater lakes, ponds, rivers and streams (Guisande 1993). D. magna and other aquatic crustaceans have the ability to filter particles of a variety of sizes including nanoparticles (Rosenkranz et al. 2009, Kim et al. 2010, Zhu et al. 2010). The authors hypothesized that CeONP or YtONP in 1 Corresponding author: jpalmieri@vcom.vt.edu Virginia Journal of Science, Vol. 62, No. 1, 2011 https://digitalcommons.odu.edu/vjs/vol62/iss1 4 VIRGINIA JOURNAL OF SCIENCE the natural environment could be taken up by these organisms. Particles engineered at dimensions between 1-100 nm, are referred to as nanoparticles. Currently, nanoparticles are synthesized and used for industrial, medical, and research applications. CeONP are used as diesel fuel additives, in automotive catalytic converters, and are a by-product of many industrial processes, including the polishing of glass and semi-precious stones. CeONP also have potential uses for medical applications acting as an antioxidant (Elswaifi et al. 2009). Yttrium oxide and cerium oxide belong to the rare earth elements. Yttrium oxide nanoparticles (YtONP) are used in the manufacturing of cathode ray tubes for c
{"title":"Uptake of Nanoparticles of Cerium Oxide and Yttrium Oxide by Acanthamoeba castellanii (Protozoa) and Daphnia magna (Crustacea)","authors":"J. R. Palmieri, Geneva Gehring, Catherine Minichino, S. F. Elswaifi","doi":"10.25778/J125-7N12","DOIUrl":"https://doi.org/10.25778/J125-7N12","url":null,"abstract":"Currently, nanoparticles are synthesized and used at an unprecedented rate for industrial, medical, and research applications. The use of cerium oxide nanoparticles (CeONP) and yttrium oxide nanoparticles (YtONP) results in their spread as contaminants into the environment. Once in the environment, CeONP and YtONP can be taken up by organisms in the food chain where they may pose a public health risk. In this study we determine whether Acanthamoeba castellanii and Daphnia magna uptake CeONP or YtONP from their environment and thereby play a role in the transmission of the nanoparticles. Using electron microscopy, organisms exposed to the nanoparticles were examined. Our results indicate that the nanoparticles are associated with cell and organelle membranes. These findings have implications for the health risks associated with environmental contamination by CeONP and YtONP. INTRODUCTION In this study we determine whether protists and crustaceans play a role in the transfer of cerium oxide nanoparticles (CeONP) and yttrium oxide nanoparticles (YtONP) from the environment to other organisms within the aquatic food chain. Acanthamoeba castellanii, a common protist, and Daphnia magna, a planktonic crustacean, are important components in many aquatic ecosystems. Because acanthamoebae, such as A. castellanni, are aggressive feeders they consume inorganic and organic compounds from their environment, thereby serving as a link by transferring normally unavailable inorganic components to the food chain (Weekers et al. 1993). D. magna feeds on acanthamoebae and other protists found in lower trophic levels. Because of the high reproductive potential of D. magna, these planktonic crustaceans can substantially alter the structure and functioning of microbial food webs in freshwater ecosystems , such as acidic swamps, freshwater lakes, ponds, rivers and streams (Guisande 1993). D. magna and other aquatic crustaceans have the ability to filter particles of a variety of sizes including nanoparticles (Rosenkranz et al. 2009, Kim et al. 2010, Zhu et al. 2010). The authors hypothesized that CeONP or YtONP in 1 Corresponding author: jpalmieri@vcom.vt.edu Virginia Journal of Science, Vol. 62, No. 1, 2011 https://digitalcommons.odu.edu/vjs/vol62/iss1 4 VIRGINIA JOURNAL OF SCIENCE the natural environment could be taken up by these organisms. Particles engineered at dimensions between 1-100 nm, are referred to as nanoparticles. Currently, nanoparticles are synthesized and used for industrial, medical, and research applications. CeONP are used as diesel fuel additives, in automotive catalytic converters, and are a by-product of many industrial processes, including the polishing of glass and semi-precious stones. CeONP also have potential uses for medical applications acting as an antioxidant (Elswaifi et al. 2009). Yttrium oxide and cerium oxide belong to the rare earth elements. Yttrium oxide nanoparticles (YtONP) are used in the manufacturing of cathode ray tubes for c","PeriodicalId":23516,"journal":{"name":"Virginia journal of science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2011-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74632082","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Breeding Biology of Oryzomys Palustris, the Marsh Rice Rat, in Eastern Virginia","authors":"R. K. Rose, Erin A. Dreelin","doi":"10.25778/WXHV-ED46","DOIUrl":"https://doi.org/10.25778/WXHV-ED46","url":null,"abstract":"s missing from Volume 62 Number 1 & 2","PeriodicalId":23516,"journal":{"name":"Virginia journal of science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2011-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81683430","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
E. Maurakis, George E. Maurakis, Demetrios E. Maurakis
Objectives were to identify and compare fish species richness, functional feeding group richness and diversity, and delineate distributions of fishes at rocky and sandy beach habitats at St. John, U.S. Virgin Islands. Visual observations using snorkel and mask were made at 3-m intervals seaward from shore during daylight hours. A total of 69 taxa (67 species) representing 33 families of fishes were observed. Total (53) and average fish species richness (32.7) at rocky beach habitats were greater than those (total=43; average=24.3) at sandy beach habitats. Twelve functional feeding groups were identified (diurnal planktivores, excavators/eroders, macroalgae browsers, macrocarnivores, mobile benthic invertivores, general omnivores, strict piscivores, sand invertivores, scrapers, coral/colonial sessile insectivores, territorial algae/detritus, and turf grazers). Total numbers of functional feeding groups (range=10-12) and species (range=29-46) per functional feeding groups at distances greater than 1 m from shore at rocky beach habitats were consistently higher than those (functional feeding group range=8-10; species per functional feeding group=19-30) at sandy beach habitats. Information on the number and composition of functional feeding groups in rocky and sandy beach habitats from this study can serve as a baseline for future investigations as changes in Caribbean habitats continue to occur.
{"title":"Functional Feeding Groups, Species Richness, and Spatial Distributions of Fishes in Rocky and Sandy Beach Habitats of St. John, U.S. Virgin Islands","authors":"E. Maurakis, George E. Maurakis, Demetrios E. Maurakis","doi":"10.25778/PM9F-6V82","DOIUrl":"https://doi.org/10.25778/PM9F-6V82","url":null,"abstract":"Objectives were to identify and compare fish species richness, functional feeding group richness and diversity, and delineate distributions of fishes at rocky and sandy beach habitats at St. John, U.S. Virgin Islands. Visual observations using snorkel and mask were made at 3-m intervals seaward from shore during daylight hours. A total of 69 taxa (67 species) representing 33 families of fishes were observed. Total (53) and average fish species richness (32.7) at rocky beach habitats were greater than those (total=43; average=24.3) at sandy beach habitats. Twelve functional feeding groups were identified (diurnal planktivores, excavators/eroders, macroalgae browsers, macrocarnivores, mobile benthic invertivores, general omnivores, strict piscivores, sand invertivores, scrapers, coral/colonial sessile insectivores, territorial algae/detritus, and turf grazers). Total numbers of functional feeding groups (range=10-12) and species (range=29-46) per functional feeding groups at distances greater than 1 m from shore at rocky beach habitats were consistently higher than those (functional feeding group range=8-10; species per functional feeding group=19-30) at sandy beach habitats. Information on the number and composition of functional feeding groups in rocky and sandy beach habitats from this study can serve as a baseline for future investigations as changes in Caribbean habitats continue to occur.","PeriodicalId":23516,"journal":{"name":"Virginia journal of science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2010-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82394936","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
An increase in the anthelmintic resistance of parasites in small ruminants and a push towards non-chemical farming has lead researchers to search for alternative forms of anthelmintics. The efficacy of treating sheep by using natural garlic extract with respect to changes in weight, fecal egg counts (FEC), and packed cell volume (PCV) was investigated. Sheep were treated every 4 weeks for 8 weeks with saline (control), Ivermectin, or natural garlic extract and samples were collected weekly to determine FEC and PCV. Sheep were weighed at the time of sample collection to determine weight change. There were no significant differences between the Ivermectin and natural garlic extract treated sheep with respect to weight changes, FEC or PCV. The Ivermectin and natural garlic extract treated sheep had significantly greater (P < 0.05) weight changes and PCV compared to the control. The control sheep had a significantly higher (P < 0.05) FEC compared to the Ivermectin and natural garlic extract treated sheep. Administering natural garlic extract as anthelmintic is a variable alternative to Ivermectin. INTRODUCTION Small ruminant gastrointestinal nematodes potentially reduce production and cause profit loss throughout the sheep industry (Perry and Randolph, 1999). Traditionally, producers have used commercially available anthelmintics (benzimidazoles, imidazothiazoles-tetrahydropyrimidines, and avermectins-milbemycins) to control parasites. However, an increase in the anthelmintic resistance of parasites is currently a serious threat and research is being done to find alternative forms of anthelmintics (Larson, 2006). The societal push towards non-chemical (eco-friendly, green, organic) farming has also hastened the search for viable alternatives to chemical anthelmintics (Waller and Thamsborg, 2004). Haemonchus Contortus, often referred to as the "barber pole" worm, punctures the lining of the abomasum, causing blood plasma and protein loss in sheep. Since it is usually the most prevalent nematode parasite in sheep and causes the most destruction, a majority of the research in alternative forms of anthelmintics has been targeting H. Contortus. Copper oxide wire particles administered to sheep have been shown to reduce the number of H. Contortus strongyle eggs shed in lambs (Burke et al., 2004) as well as pregnant ewes (Burke et al., 2005). Developing vaccinations against parasites is becoming a reality with the use of recombinant protein-based vaccines (Knox, 2000), however the economical availability of such vaccines to producers is Corresponding Author: B. D. Whitaker, University of Findlay, 1000 1 North Main Street, Findlay OH, 45840, USA. E-mail: whitaker@findlay.edu Virginia Journal of Science, Vol. 61, No. 1, 2010 http://digitalcommons.odu.edu/vjs/vol61/iss1 4 VIRGINIA JOURNAL OF SCIENCE currently not a possibility. Additional research has shown that feeding forages high in tannin content reduces the fecal egg counts (FEC) and number of worms in go
小型反刍动物体内寄生虫对驱虫药耐药性的增强，以及对非化学农业的推动，促使研究人员寻找替代形式的驱虫药。研究了天然大蒜提取物对绵羊体重、粪蛋数(FEC)和堆积细胞体积(PCV)的影响。每4周给羊进行生理盐水(对照)、伊维菌素或天然大蒜提取物治疗，连续8周，每周采集样品测定FEC和PCV。在采集样品时称量绵羊体重，以确定体重变化。伊维菌素和天然大蒜提取物处理的绵羊在体重变化、FEC和PCV方面没有显著差异。伊维菌素和天然大蒜提取物处理绵羊的体重变化和PCV显著高于对照组(P < 0.05)。对照绵羊的FEC显著高于伊维菌素和天然大蒜提取物处理的绵羊(P < 0.05)。施用天然大蒜提取物作为驱虫药是伊维菌素的可变替代品。小型反刍胃肠道线虫可能会降低整个绵羊产业的产量并造成利润损失(Perry和Randolph, 1999)。传统上，生产者使用市售的驱虫药(苯并咪唑、咪唑噻唑-四氢嘧啶和阿维菌素-米贝霉素)来控制寄生虫。然而，寄生虫对驱虫药耐药性的增加目前是一个严重威胁，正在进行研究以寻找替代形式的驱虫药(Larson, 2006)。社会对非化学(生态友好、绿色、有机)农业的推动也加速了寻找化学驱虫药的可行替代品(Waller和Thamsborg, 2004)。弯曲血蜱，通常被称为“理发杆”蠕虫，会刺穿皱胃的内壁，导致绵羊的血浆和蛋白质流失。由于它通常是绵羊中最普遍的线虫寄生虫，并且造成最大的破坏，因此大多数替代形式的驱虫剂的研究一直针对H. Contortus。给羊注射氧化铜丝颗粒已被证明可以减少小羊羔(Burke et al.， 2004)和怀孕母羊(Burke et al.， 2005)的圆形圆孔圆孔卵的数量。利用重组蛋白为基础的疫苗开发针对寄生虫的疫苗正在成为现实(Knox, 2000)，然而这种疫苗对生产者的经济可用性是。通讯作者:B. D. Whitaker, University of Findlay, 1000 1 North Main Street, Findlay OH, 45840, USA。E-mail: whitaker@findlay.edu Virginia Journal of Science, Vol. 61, No. 1, 2010 http://digitalcommons.odu.edu/vjs/vol61/iss1 4 Virginia Journal of Science目前不可能。进一步的研究表明，饲喂高单宁含量的饲料可减少山羊的粪蛋数(FEC)和蠕虫数量(Shaik et al.， 2006)。强有力的证据表明，在绵羊中使用衣孢子(线虫摄取真菌)作为驱虫剂是非常成功的(Fontenot et al.， 2004)，但尚未显示其针对H. Contortus。虽然不是一种替代治疗方法，但研究表明，培育和选择具有较高遗传优势的母羊作为羔羊生长，以及具有较高体重遗传优势的羔羊，成年后对感染的抵抗力都更强(Vanimisetti et al.， 2004)。任何新的处理方法都需要容易地纳入生产者群体管理，并在经济上可行(van Wyk et al.， 2006)。目前可用于测试任何治疗效果的技术是血清学测试、基于眼膜粘膜颜色的FAMACHA图表(测量贫血的相对水平)(van Wyk和Bath, 2002)和FEC (Cringoli等人，2004)。新的治疗和管理系统应该能够使用上述技术进行评估。因此，本研究的目的是通过血清学分析，比较天然大蒜提取物与伊维菌素作为绵羊驱虫剂在以下方面的差异:1)体重(BW)变化;2)FEC变化;3)细胞体积(PCV)。材料与方法实验地点和实验组本研究于2009年5月至9月在弗吉尼亚州Ferrum的Ferrum学院农业中心(36o92n)进行。试验场地海拔430 m，由0.5 ha的地块组成，地块中含有干净的羊茅和果园草混合。在整个研究过程中，可以免费获得无限量的水。共有14只90天的羊(美国黑脸羊)，体重从18到32公斤(平均= 26公斤)，随机分配口服生理盐水(对照组)、天然大蒜提取物(大蒜屏障，格兰代尔CA, 1茶匙/头)或伊维菌素(梅里亚伊芙米克，亚特兰大，42毫克/公斤体重)。在为期9周的研究中，所有羊在第0周和第4周接受治疗。 每周采集样本进行分析。每周使用电子称(A and A Scales LLC, Prospect Park, NJ, USA)称羊体重以监测体重变化。用手戴手套法从直肠取下粪便，保存在摄氏4度以下，待分析。所有FEC均采用McMaster方法进行(Cringoli et al.， 2004)。简单地说，将大约4.0 g粪便放入50 mL刻度圆筒中，加入硝酸钠(1.2 - 1.25比重)使最终体积达到26 mL。将溶液均质，通过2层粗棉布过滤，并立即将1.0 mL所得溶液置于麦克马斯特载玻片上。在室温下孵育5分钟，使卵浮到溶液顶部，使用复合光学显微镜以100倍计数圆形卵。全血通过颈静脉穿刺获得(BD Vacutainer, 12 mg EDTA, Franklin Lakes, NJ)，保存在4<C保存直到分析。PCV的测定采用造血比容管。实验采用完全随机设计，数据采用SAS (SAS Institute, Cary, NC, USA)的一般线性模型(GLM)程序进行分析。模型的影响包括治疗和时间。对时间没有显著影响，从最终模型中删除。采用最小二乘均值(LSMEANS)语句和可能概率值(PDIFF)选项分析处理间的显著性。在所有分析中，P < 0.05被认为是显著的。结果用最小二乘平均值±s.e.m表示。体重测量天然大蒜提取物处理的绵羊体重变化(0.23±0.17 kg)与伊维菌素处理的绵羊体重变化(0.36±0.15 kg)无显著差异。天然大蒜提取物和伊维菌素处理的绵羊明显比对照组重(-0.26±0.17 kg) (P < 0.05)(图1)。在给药前第一周，各处理组之间的粪蛋数量无显著差异。在研究的其余时间里，天然大蒜提取物处理的绵羊FEC(1805.0±613.0个鸡蛋/g粪便)与伊维菌素处理的绵羊FEC(863.0±548.0个鸡蛋/g粪便)无显著差异。对照绵羊的FEC(4993.0±613.0个蛋/g粪便)显著高于天然大蒜提取物和伊维菌素处理的绵羊(P < 0.05)(图2)。免疫反应在研究的第一周和第二周，任何处理组之间的PCV均无显著差异。在接下来的研究中，天然大蒜提取物处理的绵羊的PCV(25.5±1.1%)与伊维菌素处理的绵羊的PCV(27.5±1.0%)没有显著差异。天然大蒜提取物和伊维菌素处理绵羊的PCV显著高于对照绵羊(18.9±1.1%)(P < 0.05)(图3)。本文的结果比较了在绵羊寄生虫管理中使用市售的驱虫剂(伊维菌素)和使用非化学替代品(天然大蒜提取物)的情况。随着绵羊生产者继续看到其羊群中抗驱虫寄生虫的增加，越来越需要找到替代目前做法的方法(Larson, 2006年)。我们的研究结果表明，在与商业驱虫药相同的时间指导下口服天然大蒜提取物(大蒜屏障)，与商业处理的绵羊相比，体重、FEC和PCV没有显著差异。弗吉尼亚
{"title":"Garlic as an Alternative Anthelmintic in Sheep","authors":"A. Curry, B. Whitaker","doi":"10.25778/5SFW-ZE15","DOIUrl":"https://doi.org/10.25778/5SFW-ZE15","url":null,"abstract":"An increase in the anthelmintic resistance of parasites in small ruminants and a push towards non-chemical farming has lead researchers to search for alternative forms of anthelmintics. The efficacy of treating sheep by using natural garlic extract with respect to changes in weight, fecal egg counts (FEC), and packed cell volume (PCV) was investigated. Sheep were treated every 4 weeks for 8 weeks with saline (control), Ivermectin, or natural garlic extract and samples were collected weekly to determine FEC and PCV. Sheep were weighed at the time of sample collection to determine weight change. There were no significant differences between the Ivermectin and natural garlic extract treated sheep with respect to weight changes, FEC or PCV. The Ivermectin and natural garlic extract treated sheep had significantly greater (P < 0.05) weight changes and PCV compared to the control. The control sheep had a significantly higher (P < 0.05) FEC compared to the Ivermectin and natural garlic extract treated sheep. Administering natural garlic extract as anthelmintic is a variable alternative to Ivermectin. INTRODUCTION Small ruminant gastrointestinal nematodes potentially reduce production and cause profit loss throughout the sheep industry (Perry and Randolph, 1999). Traditionally, producers have used commercially available anthelmintics (benzimidazoles, imidazothiazoles-tetrahydropyrimidines, and avermectins-milbemycins) to control parasites. However, an increase in the anthelmintic resistance of parasites is currently a serious threat and research is being done to find alternative forms of anthelmintics (Larson, 2006). The societal push towards non-chemical (eco-friendly, green, organic) farming has also hastened the search for viable alternatives to chemical anthelmintics (Waller and Thamsborg, 2004). Haemonchus Contortus, often referred to as the \"barber pole\" worm, punctures the lining of the abomasum, causing blood plasma and protein loss in sheep. Since it is usually the most prevalent nematode parasite in sheep and causes the most destruction, a majority of the research in alternative forms of anthelmintics has been targeting H. Contortus. Copper oxide wire particles administered to sheep have been shown to reduce the number of H. Contortus strongyle eggs shed in lambs (Burke et al., 2004) as well as pregnant ewes (Burke et al., 2005). Developing vaccinations against parasites is becoming a reality with the use of recombinant protein-based vaccines (Knox, 2000), however the economical availability of such vaccines to producers is Corresponding Author: B. D. Whitaker, University of Findlay, 1000 1 North Main Street, Findlay OH, 45840, USA. E-mail: whitaker@findlay.edu Virginia Journal of Science, Vol. 61, No. 1, 2010 http://digitalcommons.odu.edu/vjs/vol61/iss1 4 VIRGINIA JOURNAL OF SCIENCE currently not a possibility. Additional research has shown that feeding forages high in tannin content reduces the fecal egg counts (FEC) and number of worms in go","PeriodicalId":23516,"journal":{"name":"Virginia journal of science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2010-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81107462","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Aquatic salamanders represent an important component of Virginia river watersheds, but despite potential declines, few specifics are known about their habitat preferences. We surveyed the habitats of the northern two-lined salamander and collected data on an array of habitat variables associated with the species. We used a logistic regression analysis to develop a model predicting its presence or absence for a given 50m-transect. Our final model incorporated the variation in stream depth and direction of stream flow and accounted for 25% of the variation in our data. We conclude that stream depth variation is an important feature of salamander habitat ecology, and surmise that direction of flow is of site-specific importance possibly related to stream order. Both features may be behavioral adaptations to avoid fish predation. INTRODUCTION Stream-dwelling salamanders are an important component of aquatic ecosystems. They account for a significant proportion of the biomass of a stream ecosystem, and act as a key trophic link, important as both predators and prey (Spight 1967, Burton and Likens 1975, Rocco and Brooks 2000). Consequently, these salamanders have potential to act as an indicator of stream health (Rocco and Brooks 2000, Barr and Babbitt 2002). This is particularly true for headwater streams were salamanders may act as the dominant vertebrate predator (Davic and Welsh 2004). Accordingly, it would be beneficial to better understand how these species make use of their available habitat. This is especially important in the face of on-going amphibian declines (Alford and Richards 1999). Knowledge of this type may provide better insights into the conservation of these species and their associated ecosystems (Cushman 2005). Previous surveys of stream and terrestrial amphibian diversity have been carried out in the Rappahannock River watershed of northern Virginia; however, more needs to be done to quantify the habitat preferences of important stream species (Mitchell 1998, McGhee and Killian 2010). To begin addressing this need, we conducted a preliminary study of salamander habitat at C.F. Phelps Wildlife Management Area (WMA) located in the Rappahannock River watershed and developed a simple habitat model for the Virginia Journal of Science Volume 61 Number 4 Winter 2010 1 Corresponding author. E-mail: jaymcghee@rmc.edu Virginia Journal of Science, Vol. 61, No. 4, 2010 http://digitalcommons.odu.edu/vjs/vol61/iss4 152 VIRGINIA JOURNAL OF SCIENCE northern two-lined salamander (Eurycea bislineata), a common stream species for the area (McGhee and Killian 2010). Northern two-lined salamanders are common to northern Virginia forest streams within the Rappahannock River watershed (Mitchell and Reay 1999). While they are considered potentially important components of the local ecosystems in which they occur, few studies have developed predictive models of habitat use (Davic and Welsh 2004). They occupy stream margins and seeps, using submerged rock
水生蝾螈是弗吉尼亚河流域的重要组成部分，尽管它们的数量可能会下降，但人们对它们的栖息地偏好知之甚少。我们调查了北双线蝾螈的栖息地，并收集了与该物种相关的一系列栖息地变量的数据。我们使用逻辑回归分析来开发一个模型，预测给定的50米样带的存在或不存在。我们的最终模型包含了河流深度和水流方向的变化，占我们数据变化的25%。我们认为河流深度变化是蝾螈栖息地生态的一个重要特征，并推测水流方向可能与河流顺序有关。这两种特征都可能是为了躲避鱼类捕食而做出的行为适应。水栖蝾螈是水生生态系统的重要组成部分。它们占溪流生态系统生物量的很大比例，是一个关键的营养环节，既是捕食者也是猎物(Spight 1967, Burton and Likens 1975, Rocco and Brooks 2000)。因此，这些蝾螈有可能作为河流健康状况的指标(Rocco and Brooks 2000, Barr and Babbitt 2002)。对于源头溪流来说尤其如此，因为蝾螈可能是主要的脊椎动物捕食者(Davic and Welsh 2004)。因此，更好地了解这些物种如何利用它们现有的栖息地将是有益的。在两栖动物数量持续减少的情况下，这一点尤为重要(Alford and Richards 1999)。这种类型的知识可以更好地了解这些物种及其相关生态系统的保护(Cushman 2005)。以前对河流和陆地两栖动物多样性的调查已经在弗吉尼亚州北部的拉帕汉诺克河流域进行了;然而，需要做更多的工作来量化重要河流物种的栖息地偏好(Mitchell 1998, McGhee和Killian 2010)。为了开始解决这一需求，我们对位于Rappahannock河流域的C.F. Phelps野生动物管理区(WMA)的蝾螈栖息地进行了初步研究，并开发了一个简单的栖息地模型，发表在《弗吉尼亚科学杂志》2010年冬季第61卷第4期。E-mail: jaymcghee@rmc.edu Virginia Journal of Science, Vol. 61, No. 4, 2010 http://digitalcommons.odu.edu/vjs/vol61/iss4 152 Virginia Journal of Science北双线蝾螈(Eurycea bislineata)，该地区常见的溪流物种(McGhee and Killian 2010)。北双线蝾螈在拉帕汉诺克河流域的北弗吉尼亚森林溪流中很常见(Mitchell和Reay 1999)。虽然它们被认为是当地生态系统的潜在重要组成部分，但很少有研究开发了栖息地利用的预测模型(Davic和Welsh, 2004年)。它们占据溪流边缘和渗漏处，利用水下岩石和木质碎屑作为掩护;但可能周期性地在陆地高地发现(Petranka 1998)。雌性在源头溪流中不同表面积的水下岩石下产卵(Jakubanis et al. 2008)。该物种的幼虫是底栖捕食者，与低淤泥的溪流池有关(Smith and Grossman 2003, Petranka 1998)。双线蝾螈能够进入通常食肉鱼类无法进入的低阶溪流，并且已经适应了这些上游溪流环境(Vannote et al. 1980, Davic and Welsh 2004)。我们假设，在凉爽、狭窄、浅的溪流中或附近会发现双线蝾螈。根据这一假设，我们预测在logistic回归模型中重要的生境变量是河流温度、河流深度和河流宽度。我们通过随机选择一个GPS起始位置来选择采样点，该位置限制在c.f. Phelps WMA范围内，并从该点移动到最近的溪流。然后我们在上游或下游随机选择50米的距离，并在下游铺设50米的样条。我们通过搜索放置在2个样带的5个10米剖面内的5个1米样方来采样溪流样带。在这些10米区间内随机选择样方的特定位置(Jaeger 1994, Jaeger and Inger 1994)。我们通过寻找较大的覆盖物(如岩石或腐烂的原木，叶包，凋落叶)来搜索样方，并使用标准网目水族馆浸水网(1/16英寸网目大小)来取样溪流底部(Mitchell 2000)。我们将捕获的蝾螈分为两种(Petranka 1998)。在样带和样方水平上收集数据(表1)。我们使用逻辑回归选择与样带水平上捕获的蝾螈最相关的预测变量的模型。在样方水平上测量的变量取平均值，并用平均值和标准差作为单独的预测变量。 由于我们测量的变量之间可能发生协同效应，我们也创建了一个先验的乘法变量来进行测试(表1)。我们在SPSS (SPSS Inc.， Chicago IL)中使用前向逐步选择(P = 0.05进入，0.10删除)。我们使用-2对数似然的变化来评估变量系数，并使用Nagelkerke的r来评估模型的解释价值(Ryan 1997, Hosmer and Lemeshow 1989, Nagelkerke 1991)。对于所有统计数据
{"title":"A Habitat Model for the Detection of Two-lined Salamanders at C. F. Phelps Wildlife Management Area, Fauquier and Culpeper Counties, Virginia","authors":"J. D. McGhee, Michael D. Killian","doi":"10.25778/9s42-h193","DOIUrl":"https://doi.org/10.25778/9s42-h193","url":null,"abstract":"Aquatic salamanders represent an important component of Virginia river watersheds, but despite potential declines, few specifics are known about their habitat preferences. We surveyed the habitats of the northern two-lined salamander and collected data on an array of habitat variables associated with the species. We used a logistic regression analysis to develop a model predicting its presence or absence for a given 50m-transect. Our final model incorporated the variation in stream depth and direction of stream flow and accounted for 25% of the variation in our data. We conclude that stream depth variation is an important feature of salamander habitat ecology, and surmise that direction of flow is of site-specific importance possibly related to stream order. Both features may be behavioral adaptations to avoid fish predation. INTRODUCTION Stream-dwelling salamanders are an important component of aquatic ecosystems. They account for a significant proportion of the biomass of a stream ecosystem, and act as a key trophic link, important as both predators and prey (Spight 1967, Burton and Likens 1975, Rocco and Brooks 2000). Consequently, these salamanders have potential to act as an indicator of stream health (Rocco and Brooks 2000, Barr and Babbitt 2002). This is particularly true for headwater streams were salamanders may act as the dominant vertebrate predator (Davic and Welsh 2004). Accordingly, it would be beneficial to better understand how these species make use of their available habitat. This is especially important in the face of on-going amphibian declines (Alford and Richards 1999). Knowledge of this type may provide better insights into the conservation of these species and their associated ecosystems (Cushman 2005). Previous surveys of stream and terrestrial amphibian diversity have been carried out in the Rappahannock River watershed of northern Virginia; however, more needs to be done to quantify the habitat preferences of important stream species (Mitchell 1998, McGhee and Killian 2010). To begin addressing this need, we conducted a preliminary study of salamander habitat at C.F. Phelps Wildlife Management Area (WMA) located in the Rappahannock River watershed and developed a simple habitat model for the Virginia Journal of Science Volume 61 Number 4 Winter 2010 1 Corresponding author. E-mail: jaymcghee@rmc.edu Virginia Journal of Science, Vol. 61, No. 4, 2010 http://digitalcommons.odu.edu/vjs/vol61/iss4 152 VIRGINIA JOURNAL OF SCIENCE northern two-lined salamander (Eurycea bislineata), a common stream species for the area (McGhee and Killian 2010). Northern two-lined salamanders are common to northern Virginia forest streams within the Rappahannock River watershed (Mitchell and Reay 1999). While they are considered potentially important components of the local ecosystems in which they occur, few studies have developed predictive models of habitat use (Davic and Welsh 2004). They occupy stream margins and seeps, using submerged rock","PeriodicalId":23516,"journal":{"name":"Virginia journal of science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2010-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86657475","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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