Using Remote Sensing and Spatial Information Technologies to Detect and Map Two Aquatic Macrophytes

This paper describes the light reflectance characteristics ofwaterhyacinth [Eichhornia crassipes (Mort.) Solms] and hydrilla [Hydrilla verticillata (L.F.) Royle] and the application of airborned videography with global positioning system (GPS) and geographic information system (GIS) technologies for distinguishing and mapping the distribution of these two aquatic weeds in waterways of southern Texas. Field reflectance measurements made at several locations showed that waterhyacinth generally had higher near-infrared (NIR) reflectance than associated plant species and water. Hydrilla had lower NIR reflectance than associated plant species and higher NIR reflectance than water. Reflectance measurements made on hydrilla plants submerged below the water surface had similar spectral characteristics to water. Waterhyacinth and hydrilla could be distinguished in color-infrared (CIR) video imagery where they had bright orange-red and reddish-brown image responses, respectively. Computer analysis of the imagery showed that waterhyacinth and hydrilla infestaions could be quantified. An accuracy assessment performed on the classified image showed an overall accuracy of 87.7%. Integration of the GPS with the video imagery permitted latitude/longitude coordinates of waterhyacinth and hydrilla infestation to be recorded on each image. A portion of the Rio Grande River in extreme southern Texas was flown with the video system to detect waterhyacinth and hydrilla infestaions. The GPS coordinates on the CIR video scenes depicting waterhyacinth and hydrilla infestations were entered into a GIS to map the distribution of these two noxious weeds in the Rio Grande River

Diffusion-based DNA target colocalization by thermodynamic mechanisms

In eukaryotic cell nuclei, a variety of DNA interactions with nuclear elements occur, which, in combination with intra- and inter- chromosomal cross-talks, shape a functional 3D architecture. In some cases they are organized by active, i.e. actin/myosin, motors. More often, however, they have been related to passive diffusion mechanisms. Yet, the crucial questions on how DNA loci recognize their target and are reliably shuttled to their destination by Brownian diffusion are still open. Here, we complement the current experimental scenario by considering a physics model, in which the interaction between distant loci is mediated by diffusing bridging molecules. We show that, in such a system, the mechanism underlying target recognition and colocalization is a thermodynamic switch-like process (a phase transition) that only occurs if the concentration and affinity of binding molecules is above a threshold, or else stable contacts are not possible. We also briefly discuss the kinetics of this "passive-shuttling" process, as produced by random diffusion of DNA loci and their binders, and derive predictions based on the effects of genomic modifications and deletions

The Biology of the Facultative Halophyte Atriplex patula L.

Atriplex patula L. is a facultative halophyte that tolerates low to moderate levels of salinity and occurs on the margins of coastal salt marshes, roadsides, in agricultural fields, and in other areas where disturbance has occurred. The genus Atriplex L. is represented by about 250 species globally and has recently been included in the family Amaranthaceae subfamily Chenopodioidae. Atriplex patula was possibly introduced in North America from Europe, Asia or North Africa in the 18th century. Because the stems and leaves accumulate and store heavy metal pollutants, A. patula has been suggested for use in habitat remediation

Biological Flora of Coastal Freshwater and Brackish Marshes: Cladium jamaicense Crantz

Cladium jamaicense Crantz, also known as sawgrass, has a broad distributional range from the Atlantic coast of Virginia to Florida, to southern Texas, the Caribbean, and along the Atlantic coast of Mexico to Central America, and to Brazil. Cladium jamaicense typically occurs in oligotrophic sloughs and fresh and brackish marshes where optimal salinity values range from 0 to 3.5 ppt. This species is a long-lived perennial with a highly developed rhizome system with rhizomes up to 20 cm long and 2.5 to 10 mm in diameter. Asexual reproduction is common. Its fibrous root system comprises short dauciform roots characterized by a dense number of long root hairs. Culms are 1.0 to 3.0 m tall. Leaf blades are coarse, flat, or broadly involute; leaf margins and the abaxial midvein have sharp, hacksaw-like teeth. Typha domingensis (cattail) is C. jamaicense’s most important competitor, especially in sites that have been enhanced with phosphorus. Restoration of sawgrass marshes requires managing long-term changes in ecosystem functions and hydrological management strategies

Biological Flora of Coastal Wetlands: Sporobolus cynosuroides (L.) P.M. Peterson & Saarela

Sporobolus cynosuroides (L.) P.M. Peterson & Saarela¼Spartina cynosuroides (L.) Roth is a temperate zone rhizomatous grass that often is a dominant species in coastal brackish marshes on the Gulf coast and Atlantic coasts of the United States where salinity ranges from 0 to 10 psu. Sporobolus cynosuroides (L.) P.M. Peterson & Saarela ¼ Spartina cynosuroides (L.) Roth is usually absent where salinity values are .12 psu. Sporobolus cynosuroides occurs in coastal habitats characterized by infrequent tidal flooding and moderate nutrient levels. Also known as big cordgrass, it may account for net productivity in high marshes that rivals productivity of Sporobolus alterniflorus ¼ Spartina alterniflora the dominant species in saline low marsh environments. Sporobolus cynosuroides and a limited number of cohorts are threatened by climate change and rising sea levels. This species provides important ecological services. In addition, S. cynosurodes provides cover and nutrition for wildlife, and has fair forage potential for livestock

The terrestrial flora of South Padre Island, Texas

The primary aim of this work is to enable the user to identify the flowering plants of South Padre Island; however, it should be useful for identification of plants on other Texas barrier islands and on the Mexican barrier islands. We hope that the keys will aid teachers, students, coastal zone managers, and individuals conducting environmental impact assessments

Perry Center Supplemental Heating

Students will design a supplemental heat system to help increase the temperature of the fluid in the Geothermal heat system.  Currently the Geothermal system does not provide adequate heating for Perry Center during the winter.  A heat exchanger has been proposed by the Physical Plant to remedy the problem

The Biological Flora of Coastal Dunes and Wetlands. Ipomoea imperati (Vahl) Griseb.

Beach morning glory, Ipomoea imperati (Vahl) Griseb. = I. stolonifera (Cirillo) Gmelin is a pantropical, prostrate vine that is an important pioneer species in the backshore of coastal beaches of six continents and many islands. The landward distribution of beach morning glory is influenced by dispersal and competition, and its seaward distribution is determined by the physical environment acting through movement of seeds away from the water and high seedling mortality in the backshore. It is occasionally found in disturbed sites on barrier islands well inland from the shore. Beach morning glory tolerates low levels of soil nutrients, sand scouring, moderate burial by accreting sand, and high substrate temperatures. It flowers from April to December on South Padre Island, Texas, and fruits ripen from March to September on the Veracruz, Mexico, coast. Populations on South Padre Island, Texas, are occasionally damaged by frost, but hurricanes are the cause of major reductions in the species\u27 abundance. Beach morning glory is self-incompatible. Usually, four seeds per capsule are produced. Apparently, seedlings do not survive near adults

Riparian Vegetation of the Lower Rio Grande

The riparian vegetation of the lower reach of the Rio Grande was studied at 7 locations using 3 line intercepts at each location. There were no trees at the mouth of the river and the vegetation was similar to that found along the Laguna Madre shore of barrier islands. Mesquite (Prosopis glandulosa) was the dominant tree near the coast and in the western section of the river near Falcon Dam. Sugar hackberry (Celtis laevigata) was the dominant tree species at all other sites except at Santa Ana National Wildlife Refuge, where cedar elm (Ulmus crassifolia) and anacua (Ehretia anacua) were the dominant trees. Granjeno (Celtis pallida) was a dominant shrub throughout the riparian corridor. The dominant trees and shrubs appeared to be replacing themselves. Species similarity in the tree, shrub, and ground layers was greater among transects at a given site than between sites. The introduced Guinea grass (Panicum maximum) and buffel grass (Pennisetum ciliare) were the dominant species in the ground cover, displacing native species. - La vegetación riparia de la sección baja del Río Bravo fue estudiada en siete localidades utilizando tres líneas de intercepción en cada localidad. No hay árboles en la desembocadura del río y la vegetación es semejante a la de la orilla de las islas barrera de la Laguna Madre. Mesquite (Prosopis glandulosa) es el árbol dominante cerca de la costa y en la sección occidental del río cerca de la Presa Falcón. El palo blanco (Celtis laevigata) es la especie de árbol dominante en todos los demás sitios excepto en el Refugio Silvestre Nacional de Santa Ana donde el olmo (Ulmus crassifolia) y la anacua (Ehretia anacua) son los árboles dominantes. Granjeno (Celtis pallida) es el arbusto dominante en todo el corredor ripario. Parece que los árboles y arbustos dominantes se están reemplazando. La semejanza de especies entre árboles, arbustos y cobertura de tierra es más alta entre transectos en un sitio que entre sitios. Las hierbas exóticas, Panicum maximum y Pennisetum ciliare, son las especies dominantes de la superficie terrestre, desplazando a las especies nativas

Phytogeography of South Padre Island, Texas

The phytogeographic affinities of the native flora of South Padre Island, Texas, are analyzed and the probable dispersal agent(s) for each species identified. The native flora consists of 99 species and 44% of the species also occur on the adjacent Texas mainland; 28% of the native species have tropical affinities. Only three species have probably dispersed from the island to the mainland. Two species may be endemic to Padre Island and the Tamaulipan barrier islands. Most of the tropical species have reached the island by oceanic drift, but birds are the most important dispersal agent for the native species. Man is responsible for the introduction of 117 species