Shobha Sriharan

The effects of nutrients and temperature on biomass, growth, lipid production, and fatty acid composition ofCyclotella cryptica Reimann, Lewin, and Guillard

Batch cultures ofCyclotella cryptica Reimann, Lewin, and Guillard were grown at two different nutrient (nitrogen/silica) levels and at two different temperatures (20 and 30°C). Biomass and cell yields decreased with decreased levels of both the nutrients (nitrogen and silica) at 20 and 30°C; whereas lipids (total, neutral, and polar) increased with decreased levels of nutrients at these two temperatures. Changes in fatty acid composition were also noted; the diatoms produced increased amounts of fatty acids C14:0 and C16:0 when grown in nutrient-deficient medium. The influence of nutrient stress and temperature is discussed.

Effect of root extracts of Mexican marigold, Tagetes minuta (Asterales: Asteraceae), on six nontarget aquatic macroinvertebrates

Abstract Water-soluble root extracts of the Mexican marigold, Tagetes minuta L., composed mainly of the compounds alpha-gurjunene, 5-(But-3-ene-1-inyl)-2,2′-bithiophene, palmitic acid, alpha-terthienyl, and 5-(4-Acetoxy-1-butenyl)-2,2′-bithiophene, were assessed to determine their impact on six species of nontarget aquatic invertebrates. Test organisms were collected from a polluted stream—Gammarus lacustris Sars (Amphipoda)—as well as from a local nearly pristine stream—Lepidostoma pluviale (Milne) (Trichoptera), Drunella grandis (McDunnough) (Ephemeroptera), Baetis tricaudatis (Dodds) (Ephemeroptera), Rhithrogena morrisoni (Banks) (Ephemeroptera) and Hydropsyche cockerelli (Banks) (Trichoptera). Root extract of T. minuta, formulated with a commercial combination of petroleum solvents and surfactants, caused mortality to some of the organisms tested. Some mortality was attributable to presence of the inert, surfactant/petroleum-based solvent. For example, with L. pluviale, the LT50 for 4 ppm marigold root extract formulated with 0.01 ppm inert materials was 54.7 h (CI 48.1, 64.2), and for 0.01 ppm inert materials alone was 69.8 h (CI 55.8, 101.2). Of the macroinvertebrates tested, R. morrisoni was the most sensitive to inert materials (LT50 0.01 ppm inert = 4.5 h) and G. lacustris was the least sensitive (LT50 0.01 ppm inert = 400 h; LC50 96 h = 1.2 ppm). Marigold root extracts did have a toxic effect at the highest concentration (4 ppm) used on all macroinvertebrates tested. Although previous studies reported the effects of one compound in the root extract, alpha-terthienyl, our research is the first published report evaluating effects of full-formulation marigold root extract on immature aquatic nontarget insect species and a crustacean. If root extracts of T. minuta are to be used as a pesticide, further research should focus on effects of inert surfactants used in marigold extract formulation on nontarget macroinvertebrates.

Influence of insecticidal plant materials used during storage on sensory attributes and instrumental hardness of dry edible beans (Phaseolus vulgaris L.).

Three plant products with known insecticidal properties, a dry extract of flowers ofChrysanthemum cinerariaefolium (Trevir.) Vis. produced in Rwanda, an ethanol extract of seeds of neem,Azadirachta indica A. Juss., and crushed leaves ofTetradenia riparia Hochst Codd., a traditional Rwandan medicine, were mixed with beans,Phaseolus vulgaris L., for storage protection. These plant-protected beans were compared with ‘off the shelf’ beans that were being sold to consumers by the Rwandan National Agricultural Products Marketing Organization (OPROVIA). A trained sensory panel determined that beans treated with neem andC. cinerariaefolium were as acceptable after 8 months storage as those being sold throughout Rwanda by the marketing organization. Beans marketed by this organization were all treated with the standard insecticide application in Rwanda, 0.01% weight/weight pirimiphos methyl in a powder formulation. Instrumental hardness (% hard-to-cook/mean gram force) after 20 months of storage was acceptable for beans stored with neem or withC. cinerariaefolium or with the conventional government application of pirimiphos methyl. Use of either neem orC. cinerariaefolium for storage protection should not affect consumer acceptance of dry beans.

Using hyperspectral remote sensing for land cover classification

This project used hyperspectral data set to classify land cover using remote sensing techniques. Many different earth-sensing satellites, with diverse sensors mounted on sophisticated platforms, are currently in earth orbit. These sensors are designed to cover a wide range of the electromagnetic spectrum and are generating enormous amounts of data that must be processed, stored, and made available to the user community. The Airborne Visible-Infrared Imaging Spectrometer (AVIRIS) collects data in 224 bands that are approximately 9.6 nm wide in contiguous bands between 0.40 and 2.45 mm. Hyperspectral sensors acquire images in many, very narrow, contiguous spectral bands throughout the visible, near-IR, and thermal IR portions of the spectrum. The unsupervised image classification procedure automatically categorizes the pixels in an image into land cover classes or themes. Experiments on using hyperspectral remote sensing for land cover classification were conducted during the 2003 and 2004 NASA Summer Faculty Fellowship Program at Stennis Space Center. Research Systems Inc.s (RSI) ENVI software package was used in this application framework. In this application, emphasis was placed on: (1) Spectrally oriented classification procedures for land cover mapping, particularly, the supervised surface classification using AVIRIS data; and (2) Identifying data endmembers.

Mapping Riparian and Wetland Weeds with High Resolution Satellite Imagery

QuickBird multi-spectral satellite imagery was evaluated for detecting weeds in waterways and wetlands in Texas. Plant species studied included giant reed (Arundo donax L.), waterhyacinth [Eichhornia crassipes (Mart.) Solms], and giant salvinia (Salvinia molesta Mitchell). Accuracy assessment results performed on the unsupervised classified maps for each species were: giant reed, 94.4% producers accuracy and 100% users accuracy; waterhyacinth, 100% producers accuracy and 80% users accuracy; and giant salvinia, 93.9% producers accuracy and 92% users accuracy. These results indicate that QuickBird imagery can be used successfully to map infestations of these three weeds.

Geospatial analysis of soil information for Flat Creek Watershed resource assessment

Performing a geospatial analysis of soil information for a watershed resource assessment requires an integration of various software and geospatial data elements from numerous sources. ESRIs ArcView 3.x GIS software and specialized extensions were used to delineate the watershed boundary of the selected project for Flat Creek Watershed in Amelia County, Virginia. Since this study was performed with availing assistance from the USDA-NRCS Water Quality office on the campus of Virginia State University, the geospatial data watershed delineation was calculated using the CE465 Hydrol ArcView Extension with the USGS DEM (digital elevation model) data. Another specialized ArcView Extension called CRWR-raster was used to make a seamless join of multiple raster elevation files needed to cover the entire watershed area. For verification of work the watershed boundary was also calculated by hand using contour lines on the USGS topoquads, overlaid with US EPA RF3 stream segments, and USDA NRCS hydrologic unit boundaries. The information on complex soil spatial and attribute data are from the USDA NRCS SSURGO (National Soil Survey Geospatial Database) and NASIS (National Soil Information System) data sets. These data were converted to the appropriate map projection, imported into the ArcView project, and integrated with the soil Data Viewer extension developed by the USDA NRCS. The poster describes various soil interpretations and soil property reports to demonstrate useful watershed resource assessment for area management, including agriculture use, building site development, recreation and water management

Delaware Inland Bays and Market Oyster (Crassostrea virginica) Quality for Consumption

Consumption of raw oysters is known to cause serious health conditions due to bioaccumulation of contaminants. As filter feeders, oysters ingest bacteria along with phytoplankton from their surrounding habitats. Ensuring seafood safety for human consumption is always a concern. Since oysters are consumed raw, disease causing organisms, environmental contaminants, toxins, chemicals, and even physical hazards such as soils and metals retained in the oysters can enter through feeding. The objective of this study was to determine the quality of oysters collected from Delaware Inland Bays (DIB) and compare them with market oysters. Environmental parameters were monitored from local waters of DIB classified as closed versus open for shellfish harvesting. Total aerobic bacteria and vibrio were higher in market oysters during the warmer months, with open water having the least microbial loads. There were no significant differences in total vibrio counts between the study sites ( ), but significant differences were recorded over time ( ). Water temperature and turbidity were directly proportional to total vibrio in oysters, and salinity was inversely related. Research findings in this study may help bring awareness of changes in bacterial loads due to seasonal changes and additional handling and storage.

Geographic Information System (GIS) and Remote Sensing (RS): Undergraduate Academic Curriculum and Precollege Training Program

Geographic information system (GIS), Global Positioning System (GPS) and remote sensing (RS) are important tools in the emerging agricultural revolution called precision agricultural or site-specific management. GIS and GPS are inherently linked technologies. Together, they form a powerful tool to measure, map, monitor, and model resources and environmental data for both scientific and commercial applications. Many students and faculty of agricultural colleges from minority institutions have little experience with these new technologies. This paper summarizes how GIS, GPS, and Remote Sensing instruction was incorporated into the existing agriculture/natural science curriculums at the Land-Grant Institutions, Virginia State University (VSU), Delaware State University (DSU), Southern University (SU), and Historically Black Colleges and Universities (HBCUs) such as Elizabeth City State University (ECSU) and Bethune-Cookman University (BCU). The curricular materials were developed through a series of faculty development workshops at VSU, ECSU, and DSU. These workshops were coordinated by the Principal Investigator (Shobha Sriharan, senior author of this presentation) of the USDA Capacity Building Teaching Grant. The USDA collaborators, James Everitt and Reginald Fletcher provided training in the use of ArcGIS, GPS and remote sensing techniques. In addition, a summer faculty workshop was hosted at the Remote Sensing Laboratory of the Integrated Farming and Natural Resources Research, Weslaco, Texas, for exposing the faculty members to the applications of GIS and RS in agricultural fields.

Using Airborne and Satellite Imagery to Distinguish and Map Black Mangrove Along the South Texas Gulf Coast

Color-infrared (CIR) aerial photography, CIR aerial digital imagery, and high resolution QuickBird multispectral satellite imagery were evaluated for distinguishing and mapping black mangrove mangrove [Avicennia germinans (L.) L.] populations along the lower Texas gulf coast. Accuracy assessments performed on classified maps of photographic and digital images of the same study site had both producers and users accuracies of 100% for black mangrove. In an accuracy assessment performed on a classified map of a digital image only of a second study site, black mangrove had a producers accuracy of 78.6% and a users accuracy of 100%. In a classification of the satellite image, black mangrove had a producers accuracy of 100% and a users accuracy of 85.7%.