57 research outputs found
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Distribution of Benthic Macroinvertebrates Beaumont Port Arthur Area
On March 1, 1976, the Bureau of Economic Geology initiated an extensive program of benthic sampling in the State submerged lands (McGowen and Morton, 1979). The state-owned submerged lands of Texas cover nearly 6,000 square miles (15,540 km2) and extend from Mexico to Louisiana. This area includes bays, estuaries, lagoons, and the inner continental shelf located 10.3 miles (16.6 km) seaward of the Gulf shoreline (see fig. 1). Benthic samples were collected at 1-mile (1.6-km) intervals. By January 1978, a total of 6,697 samples had been collected. Sample analysis encompassed textural studies (grain size properties), geochemistry (trace elements and total organic carbon), and biological studies.
This report focuses on the biology of the submerged lands in the Beaumont-Port Arthur area and provides preliminary information on benthic macroinvertebrate assemblages and diversity. It serves as a baseline inventory of biological data necessary to predict and assess potential problems and environmental impacts related to energy production, food production, recreation, and transportation.Bureau of Economic Geolog
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Sedimentation in Fluvial Deltaic Wetlands and Estuarine Areas, Texas Gulf Coast -- Literature Synthesis
Deltaic and associated alluvial areas at the mouths of rivers that discharge into the bay-estuary-lagoon system along the Texas coast are the sites of extensive salt-, brackish-, and freshwater marshes that are essential components of these biologically productive estuarine systems. These bayhead depositional systems are constructed primarily by fluvial sediments, sediments transported and deposited by the major rivers that enter estuarine waters. The loss of over 10,000 acres of wetlands in alluvial and deltaic areas of the Neches (White and others, 1987) and San Jacinto Rivers (White and others, 1985) has emphasized the need to examine in more detail the processes that establish and maintain, as well as degrade, these important natural resources along the Texas coast.Bureau of Economic Geolog
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Colorado River Diversion Project Reconnaissance Work to Establish Monitoring Stations in Matagorda Bay Near the Mouth of the Colorado River
Fifteen monitoring stations were established in the eastern arm of Matagorda Bay, west of the Colorado River Delta, in the area where the river is to be diverted by the U.S. Army Corps of Engineers (see fig. 1). All stations shown on figure 1 were located by triangulation, and their positions were recorded with respect to features existing on nautical chart 11319 or with respect to features located and plotted on the chart during the field survey. Twenty-foot sections of 2.5-inch PVC pipe were driven into the sediments at eight stations (see table 1) to mark selected deep-water and bay-center sites. The PVC pipes extend about 3 ft above the water. Six cedar posts, 2 inches in diameter by 6 ft long, were placed on land at strategic locations along the bayward side of Matagorda Peninsula. The locations of the posts were confirmed with reference to aerial photographs and were plotted on the nautical chart. The posts were used as reference markers to locate bay-margin sampling sites. The tops of the PVC pipes and fence posts were painted and flagged with orange fluorescent paint and tape. Because the sampling stations were also located by triangulation using more permanent navigation aids such as water tanks, radio antennas, houses, and bay markers, they can be relocated should the PVC pipes or cedar posts be removed.Bureau of Economic Geolog
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Sedimentation in Fluvial Deltaic Wetlands and Estuarine Areas, Texas Gulf Coast - Summary
Deltaic and associated riverine deposits near the mouths of rivers that discharge into estuaries along the Texas coast are the sites of extensive salt-, brackish-, and freshwater marshes that are essential components of biologically productive estuarine systems. These bay-head depositional features are constructed primarily by fluvial sediments, sediments transported and deposited by the major rivers that enter estuarine waters. The loss of over 10,000 acres of wetlands in alluvial and deltaic areas of the Neches (White and others, 1987) and San Jacinto Rivers (White and others, 1985) emphasized the need to examine in more detail the processes that establish and maintain, as well as degrade, these important natural resources along the Texas coast.Bureau of Economic Geolog
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Sedimentation in Fluvial Deltaic Wetlands and Estuarine Areas, Texas Gulf Coast
Deltaic and associated riverine deposits near the mouths of rivers that discharge into estuaries along the Texas coast are the sites of extensive salt, brackish, and fresh-water marshes that are essential components of biologically productive estuarine systems. These bay-head depositional features are constructed primarily by fluvial sediments, sediments transported and deposited by the major rivers that enter estuarine waters. The loss of over 10,000 acres of wetlands in alluvial and deltaic areas of the Neches (White and others, 1987) and San Jacinto Rivers (White and others, 1985) emphasized the need to examine in more detail the processes that establish and maintain, as well as degrade, these important natural resources along the Texas coast.Bureau of Economic Geolog
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Status and Trends of Inland Wetland and Aquatic Habitats in the Corpus Christi Area
Wetland and aquatic habitats are essential components of estuarine systems along the Texas coast. These valuable resources are highly productive biologically and chemically and are part of an ecosystem on which a variety of flora and fauna depend. Scientific investigations of wetland distribution and abundance through time are prerequisites to effective habitat management, thereby ensuring their protection and preservation and directly promoting long-term biological productivity and public use. This report presents results of an investigation to determine the current status and historical trends of wetlands and associated aquatic habitats in the Corpus Christi area from Lamar Peninsula to Encinal Peninsula. The study area encompasses most of the mainland between the Gulf Intracoastal Waterway (GIWW) and the Texas General Land Office Coastal Management Program boundary, an area located within Refugio, Aransas, San Patricio, and Nueces Counties (Fig. 1). Natural environments include wetlands, wind-tidal flats, riparian woodlands, and bay shorelines. The methods and classification system used in this report follow those found in the Texas coastal barrier-island report for the Coastal Bend (White et al., 2002).Bureau of Economic Geolog
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Fluvial-Estuarine Sedimentation Texas Gulf Coast
Deltaic and associated alluvial areas located at the mouths of rivers that flow into the bay-estuary-lagoon system along the Texas coast serve as habitats for extensive salt, brackish, and fresh-water marshes, which are crucial components of biologically productive estuarine ecosystems. These bay-head depositional systems are predominantly formed by fluvial sediments transported and deposited by the major rivers that discharge into the estuarine waters. The loss of over 10,000 acres of wetlands in the alluvial and deltaic areas of the Neches and San Jacinto Rivers underscores the necessity to closely examine the processes that establish, sustain, and degrade these vital natural resources along the Texas coast.Bureau of Economic Geolog
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Sedimentation and Historical Changes in Fluvial Deltaic Wetlands Along the Texas Gulf Coast with Emphasis on the Colorado and Trinity River Deltas
The most extensive losses in coastal wetlands in the United States over the last two decades have occurred along the Gulf Coast. Wetlands are disappearing at an alarming rate on the Mississippi River Deltaic Plain, indicating a reversal in the trend of net progradation of the delta that characterized much of the past 5,000 years (Gagliano and others, 1981). The land-loss rates have accelerated geometrically during the 20th century, apparently as a result of natural and artificial processes, the latter including artificial levees and control structures that have harnessed the Mississippi River and virtually eliminated the deltaic sedimentation processes of overbank flooding, crevassing, and upstream diversion; extensive canalization and accelerated subsidence related to mineral extraction compound the problem (Gagliano and others, 1981). Investigations of marsh losses in Louisiana indicate that marsh aggradation (vertical accretion) rates are not keeping pace with relative (apparent) sea-level rise (Delaune and others, 1983; Hatton and others, 1983; Baumann and others, 1984; Boesch and others, 1984).
Although less extensive than in Louisiana, losses in wetlands along the Texas coast have also been documented (McGowen and Brewton, 1975; Gosselink and others, 1979; Johnston and Ader, 1983; White and others, 1984; 1985; 1987). Some of the most dramatic changes have occurred in fluvial-deltaic areas such as near the mouths of the San Jacinto and Neches Rivers where wetland losses totaled more than 4,000 hectares (10,000 acres) between the mid-1950s and the late 1970s (White and others, 1985; 1987). The losses are characterized by submergence and displacement of marshes, swamps, and fluvial woodlands by shallow subaqueous flats and open water, indicating, as in Louisiana, that marsh aggradation rates are not keeping pace with relative sea-level rise.Bureau of Economic Geolog
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Submerged Lands of Texas, Brownsville-Harlingen Area: Sediments, Geochemistry, Benthic Macroinvertebrates..
Surface sediment textures, sediment geochemistry, and benthic fauna of the State-owned submerged lands were mapped and described using bottom samples collected at 1-mi (1.6-km) intervals from bays, estuaries, and lagoons, and the inner continental shelf. In one area of Laguna Madre samples were collected at 0.5-mi (0.8-km) intervals. In addition, the distribution of wetlands in adjacent areas was mapped using color infrared photographs taken primarily in 1979.
Textural maps of the Brownsville-Harlingen area show that sand and muddy sand, having a mean grain size of between 2.5 and 5, are the dominant sediment types in bay-estuary-lagoon and inner-shelf areas. Generally, in Laguna Madre sands occur on the barrier island side of the lagoon, whereas muddier sediments are more abundant along the mainland side and in deeper areas. Muddy sand is dominant in the relatively wide southern end of Laguna Madre, and sand is dominant along the narrower, northern two-thirds of the lagoon where broad sandy wind-tidal flats on Padre Island grade into shallow subaqueous lagoon sands. Dominantly sand-sized sediments blanket most of the inner shelf and extend about 10 mi (16 km) offshore from Padre Island. The greatest extent of sand is associated with marine reworked late Pleistocene fluvial-deltaic deposits that underlie much of the inner shelf. Water depths average about 90 ft (30 m) at the outer limits of this sand-rich area. A nearshore patch of mud occurs near the mouth of the Rio Grande and represents the most recent deposition of the river. To the east and north the mud grades into muddy sand that represents a mixture of relict shelf sands and more modern fluvial muds.Bureau of Economic Geolog
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