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  • Trinity - San Jacinto estuary: A study of the influence of freshwater inflows

    Texas Department of Water Resources (Texas Department of Water ResourcesAustin, TX, 1981-04)
    The provision of sufficient freshwater inflow to Texas bays and estuaries is a vital factor in maintaining estuarine productivity, and a factor contributing to the near-shore fisheries productivity of the Gulf of Mexico. This report analyzes the interrelationships between freshwater inflows and estuarine productivity, and established the seasonal and monthly freshwater inflow needs, for a range of alternative management policies, for the Trinity- San Jacinto estuary of Texas. Simplifying assumptions must be made in order to estimate freshwater inflow requirements necessary to maintain Texas estuarine ecosystems. A basic premise developed in this report is that freshwater inflow and estuarine productivity can be examined through analysis of certain key indicators. The key physical and chemical indicators include freshwater inflows, circulation and salinity patterns, and nutrients. Biological indicators of estuarine productivity include selected commercially important species. Useful species are generally chosen on the basis of their wide distribution throughout each estuarine system, a sensitivity to change in the system, and an appropriate life cycle to facilitate association of the organism with estuarine productivity.
  • Shoreline changes on Galveston Island (Bolivar Roads to San Luis Pass): An analysis of historical changes of the Texas Gulf shoreline.

    Morton, R.A. (University of Texas at Austin, Texas Bureau of Economic GeologyAustin, TX, 1974)
    Historical monitoring along Galveston Island records the type and magnitude of changes in position of the shoreline and vegetation line and provides insight into the factors affecting those changes. Documentation of changes is aided by the compilation of shoreline and vegetation line position from topographic maps, aerial photographs, and coastal charts of various vintages. Major and minor factors affecting shoreline changes include: (1) climate, (2) storm frequency, (3) local and eustatic sea-level conditions, (4) sediment budget, and (5) human activities. The major factors affecting shoreline changes along the Texas Coast, including Galveston Island, are a deficit in sediment supply and relative sea-level rise or compactional subsidence. Changes in the vegetation line are primarily related to storms. Studies indicate that shoreline and vegetation line changes on Galveston Island are largely the result of natural processes and their effects is requisite to avoid or minimize physical and economic losses associated with development and use of the beach.
  • Geothermal Resources Frio Formation, Upper Texas Coast

    Bebout, D.G.; Loucks, R.G.; Bosch, S.C.; Dorfman, M.H. (University of Texas Bureau of Economic Geology, 1976)
    The objective of this study is to identify major sand trends, which, along with subsurface temperatures and pressures, aid in evaluating the potential of producing geothermal energy from the Frio Formation, Upper Texas Gulf Coast. During the Tertiary, huge quantities of terrigenous sediments were deposited as gulfward-thickening sedimentary wedges along the Texas Gulf Coast. The sand and shale making up these wedges were transported across a broad fluvial plain and deposited in deltaic complexes or were reworked by marine processes into strandplains and barrier islands. Growth faults developed contemporaneously at the site of maximum deposition as a result of rapid loading of large quantities of deltaic and strandplain sands onto previously deposited prodelta and shelf muds. These growth faults allowed the accumulation of extremely thick sections of sand and also caused the isolation of many of these sand bodies from porous updip sands; pressured reservoirs developed after further loading and copaction (Bruce, 1973; Jones, 1975). This study is investigating geopressured geothermal reservoirs in this setting. Limited data obtained from deep wells drilled for oil and gas indicate that many of these large sand reservoirs are filled with water which has high temperature, is relatively low in total dissolved solids, and is saturated with methane gas. To be suitable for electric power generation, the reservoir shouls have a volume greater than 3 cubic miles (which is equivalent to 300 feet of sand distributed areally over more than 50 square miles), permeability greater than 20 millidarcies, and subsurface temperatures higher than 300 degrees F. This report reviews the results of the Bureau of Economic Geology regional study of the Frio Formation in the Upper Texas Gulf Coast. It is a continuation of two similar studies of the Frio in the Lower and Middle Texas Gulf Coast (Bebout, Dorfman, and Agagu, 1975; Bebout, Agagu, and Dorfman, 1975). The objective of these reports is to outline areas (fairways) which appear the most prospective for producing geothermal energy and which therefore deserve further, more detailed study.
  • Oyster population trends in Galveston Bay, 1973-1978

    Hofstetter, R.P. (Texas Parks and Wildlife Department, Coastal Fisheries BranchAustin, TX, 1983)
    Severe flooding on the Trinity River in 1973 destroyed oyster (Crassostrea virginica) populations in Trinity Bay and damaged those in the major harvest area in central Galveston Bay. Recovery was slow. Poor reproduction during 1975, 1976 and 1977 caused near depletion of oyster populations by spring 1978. However, abundant spat setting during 1978 resulted in an increase in small (seed) oysters in fall. Because market size oysters were scarce and seed oysters vulnerable to damage from oyster dredging, oystering in Galveston Bay was prohibited by proclamation of the Texas Parks and Wildlife Department (TPWD) effect 15 December 1978. Seasonal oyster harvests from public reefs in Galveston Bay ranged from 1.1 million kg (2.4 million lb) during 1976-77 to 8.7 thousand kg (19.2 thousand lb) during the abbreviated (45 day) 1978-79 seasons. As market oysters became scarce in Galveston Bay, oystering increased in mid-central bays. During the 1978-79 season, San Antonio Bay became the leading oyster producing area. The harvest of 359.5 thousand kg (792.7 thousand lb) established a record for that bay system. Private oyster lease production (confined to Galveston Bay) set a new record of 5861 meters cubed (7666.2 yards cubed). During 1976 only to be broken in 1977 when 7261 meters cubed (9497.4 yards cubed) were reported. Over a 23-year period, a decline in sample abundance of spat and small oysters has been observed although market oyster stocks remained relatively constant. A relationship between spring salinity values and spat setting was noted. Best spat sets usually occurred when salinity ranged 17-24 parts per thousand during spring. When salinity fell below 8 parts per thousand substantial spat sets did not occur.
  • Geothermal resources of the Texas Gulf Coast- Environmental concerns arising from the production and disposal of geothermal waters.

    Gustavson, T. C.; Kreitler, C. W.; Bureau of Economic Geology (University of Texas at Austin, Bureau of Economic Geology.Austin, TX, 1976)
    Disposal and temporary storage of spent geothermal fluids and surface subsidence and faulting are the major environmental problems that could arise from geopressured geothermal water production. Geopressured geothermal fluids are moderately to highly saline (8,000 to 72,000 parts per million total dissolved solids) and may contain significant amounts of boron (19 to 42 parts per million). Disposal of hot saline geothermal water in the subsurface saline aquifers will present the least hazard to the environment. It is not known, however, whether the disposal of as much as 54,000 m3 (310,000 barrels) of spent fluids per day into saline aquifers at the production site is technically or economically feasible. If saline aquifers adequate for fluid disposal cannot be found, geothermal fluids may have to be disposed of by open watercourses, canals and pipelines to coastal bays on the Gulf of Mexico. Overland flow or temporary storage of geothermal fluids may cause negative environmental impacts. As the result of production of large volumes of geothermal fluid, reservoir pressure declines may cause compaction of sediments within and adjacent to the reservoir. The amount of compaction depends on pressure decline, reservoir thickness, and reservoir compressibility. At present, these parameters can only be estimated. Reservoir compaction may be translated in part to surface subsidence. When differential compaction occurs across a subsurface fault, fault activation may occur and be manifested as differential subsidence across the surface trace of the fault or as an actual rupture of the land surface. The magnitude of environmental impact of subsidence and fault activation varies with current land use; the greatest impact would occur in urban areas, whereas relatively minor impacts would occur in rural, undeveloped agricultural areas. Geothermal resource production facilities on the Gulf Coast of Texas could be subject to a series of natural hazards: (1) hurricane- or storm-induced flooding, (2) winds from tropical storms, (3) coastal erosion, or (4) expansive soils. None of these hazards is generated by geothermal resource production, but each has potential for damaging geothermal production and disposal facilities that could, in turn, result in leakage of hot saline geothermal fluids.
  • Population Studies of the Blue Crabs of the Galveston Bay System - Studies of the Blue Crab Populations of the Texas Coast

    More, William R.; Moffett, Alan W. (Texas Parks and Wildlife DepartmentAustin, TX, 1965)
    Abundance peaks of small blue crabs, Callinectes sapidus, were found in the samples in February, July, and December. Rough estimates of crab growth were made by tracing modal size progressions based on 60-foot seine data. Crab landings during 1964 were 91 per cent higher than those reported in 1963. Tagging studies are discussed and recommendations for improving the sampling program are offered.
  • Check list of the flora of area M-2

    Renfro, W. C. (Texas Game and Fish CommissionAustin, TX, 1959-05-21)
    Samples of vegetation were obtained by hand, plankton net, trawl, and other means. Collections were made in conjunction with other jobs in the project. The several species were identified, and their distribution and seasonal abundance plotted.
  • Coordination of the Blue Crab Studies of the Texas Coast - Studies of the Blue Crab Populations of the Texas Coast

    Childress, U.R. (Texas Parks and Wildlife DepartmentAustin, TX, 1965)
    Blue crab (Callinectes sapidus) landings in the Galveston area increased from 1,062,091 pounds (live weight) in 1963 to 1,506,300 pounds in 1964. Peak production occurred in May and June. In the Matagorda area 671,000 pounds were reported as compared to 864,451 pounds in 1963. Peak months of production occurred in May and June. The Aransas-Corpus Christi area produced 307,100 pounds. This was about two-thirds less than in 1963 when 1,019,289 pounds were produced.
  • Study of the Hydrography and Meteorology of the Texas coast - Analysis of Populations of Sports and Commercial Fin-Fish and of Factors Which Affect These Populations in the Coastal Bays of Texas

    Schultz, Ronnee L. (Texas Parks and Wildlife DepartmentAustin, TX, 1965)
    Each bay area along the Texas Coast is an entity with its own particular hydrographic problems. The Galveston, Matagorda and San Antonio Bay Systems have an average annual rainfall in excess of 25 inches, plus large river drainage systems which tend to maintain relatively low salinities. From Aransas Bay to the Laguna Madre, rainfall decreases to less than 20 inches and hypersalinity becomes a problem. Fisheries landings indicate that hydrographic conditions affect the productivity and abundance of shrimp, crab and some species of fish. During drought periods salinities become high and catches decline, while during periods of normal rainfall salinities become comparable to those of true estuarine systems and catches increase.
  • Hydrographic and Meteorological Study of the Galveston Bay System - Analysis of Populations of Sports and Commercial Fin-Fish and of Factors Which Affect These Populations in the Coastal Bays of Texas

    More, William R. (Texas Parks and Wildlife DepartmentAustin, TX, 1965)
    Hydrographic data obtained in the field and climatological data taken from publications are presented in this report. Salinities varied little from 1963 readings, but were higher than 1962 figures. Trinity River discharge was 56 per cent less than that recorded in 1963. Above average water and air temperatures occurred during November and December.
  • Populations Studies of the Sports and Commercial Fin-Fish of the Galveston Bay System - Analysis of Populations of Sports and Commercial Fin-Fish and of Factors Which Affect These Populations in the Coastal Bays of Texas

    More, William R. (Texas Parks and Wildlife DepartmentAustin, TX, 1965)
    Survival of Year-Class O redfish (Sciaenops ocellata) and southern flounder (Paralichthys lethostigma) was high and good standing crops of both species were present during late fall. Trends in the relative availability of adult game fish were not clear as drag seine data were weak and incomparable. Commercial landings decreased slightly from 1963 figures, due mainly to a reduction in the speckled trout (Cynoscion nebulosus) catch.
  • Study of the Oyster Population in the Galveston Bay Area - Survey of Oyster Populations and Associated Organisms

    Hofstetter, R. P. (Texas Parks and Wildlife DepartmentAustin, TX, 1965-10-18)
    The sample abundance of oyster (Crassostrea virginica) spat decreased in 1963 as compared to 1962, and a further decline occurred in 1964. Seed oysters also declined in sample abundance during 1963 as a result of poor survival among the 1963 (and possibly 1962) oyster spat sets. The seed stock increased slightly during the fall 1964, indicating better survival of the 1964 oyster spat set. Market oysters were abundant in the samples during 1963 but decreased considerably in 1964.
  • Survey of Oyster Diseases in the Galveston Bay Area - Survey of Oyster Populations and Associated Organisms

    Hofstetter, Robert P. (Texas Parks and Wildlife DepartmentAustin, TX, 1965)
    Moralities among tray-held oysters (Crassostrea virginica) were studied during a two year period at stations located on Switchover Reef and Hannah Reef. In 1963 moralities at both stations showed similar patterns, increasing during the summer months (with peaks in August-September) and declining during the fall and winter. The summer moralities were associated with high infections of Dermocystidium marinum. From March through December 1963 oysters at the Switch over station suffered a mortality of 52.6%. From April through December, 1963 a mortality of 42.2% occurred among the Hanna oysters.
  • Summary of Oyster Studies Along the Texas Coast - Survey of Oyster Populations and Associated Organisms

    Hofstetter, R. P. (Texas Parks and Wildlife DepartmentAustin, TX, 1965-10-13)
    Both seed oyster Crassostrea virginica stock and market oyster stock continued to decline in Aransas, San Antonio, Matagorda, and Galveston Bays. Losses appeared to be most severe in the Aransas Bay area, diminishing up the coast to Galveston Bay. Much of the loss in the middle coast was attributed to Aransas Bay disease which affected young seed oysters as well as the older market oysters. The disease was found in 1963 in Aransas Bay and was apparently associated with the moralities in San Antonio and Lavaca Bays. During 1964 the disease spread into Copano Bay, most of San Antonio Bay, Lavaca Bay, and Matagorda Bay. The organism responsible for Aransas Bay disease was identified by Dr. J.G. Mackin as an intre-cell organism similar to that associated with Malpeque Bay disease in Canadian waters. Sever moralities in Tres Palacios Bay appeared to be caused by Dermocystidium marinum judging by the high infection incidence found in samples during the late summer. However, the catastrophic losses among seed oysters was more characteristic of Aransas Bay disease. In Galveston Bay Dermocstidium spread further up the bay than in 1963 and was assumed to be the primary cause of oyster moralities. Tray studies at two stations showed an annual mortality rate of approximately 50 percent, both in 1963 and 1964. Most of the mortality at each station was due to Dermocystidium. Oyster production, in spite of high moralities, set a new record during the 1964-65 season. Most of the harvest came from Galveston Bay where heavy fishing pressure compensated for the relatively low abundance of market oysters.
  • Biological Survey of the Commercial Shrimp and Associated Organisms in the Inshore Gulf of Mexico - Study of the Texas Shrimp Populations

    Compton, Jr., H. (Texas Parks and Wildlife DepartmentAustin, TX, 1964)
    Regular stations were set up for weekly samples in the inshore Gulf off Port Aransas, Texas, in depths of 2 to 15 fathoms, in the inshore Gulf off of Port Mansfield, and Port Isabel, Texas for monthly samples in 2 to 20 fathoms, and in the inshore Gulf off Galveston samples under 10 fathoms annually. Brown shrimp, Penaeus aztecus, were very abundant in the southern Gulf off Port Isabel in May and were predominantly undersize; this same situation existed in June in the Gulf off Port Aransas. Significant numbers of white shrimp, P. setiferus, were found off Port Aransas in January when most were undersize. Pink shrimp, P. duorarum, were most abundant in May off Port Isabel. Seabobs, Xiphopeneus kroyeri, were abundant in January off Port Aransas and were not taken in the southern zone. Abundance of the various species was not noticeably different from that of 1963. Salinity and temperature were similar to those of 1963. Undersized brown shrimp could profitably be protected in the southern waters beginning in May and beginning in June off Port Aransas. Protection of small white shrimp in the southern waters at any time is probably unnecessary, although protection is indicated for the inshore gulf off Port Aransas in January.
  • Study of the Texas Bay Populations of Juvenile Shrimp, Penaeus aztecus, Penaeus setiferus, and Penaeus duorarum - Study of the Texas Shrimp Population

    Moffett, A.W. (Texas Parks and Wildlife DepartmentAustin, TX, 1965)
    Plankton samples from the Aransas Bay area indicated that the post larvae brown shrimp (Penaeus aztecus) immigration peak was reached in March. Sampling in the bays revealed the presence of a large wave of brown shrimp in the spring. In the shallow tertiary bays and along the shore of large bays brown shrimp grew slowly in April and movement to the open water of larger bays was delayed. As the waters warmed growth was rapid and the shrimp began their gulf ward movement on schedule. Samples taken in the inshore Gulf off the Lower Laguna Madre contained large numbers of brown shrimp in May. The samples from the Gulf off Port Aransas indicated that the majority of this species left the Aransas Bay area in June. Shrimp samples from the bays indicated the presence of a large 1964 white shrimp year class. This was confirmed by large commercial catches in the late summer and early fall. Small white shrimp were found in the Gulf in September off the lower coast. In January this species was found in abundance off Port Aransas, but not off Galveston. Brown shrimp commercial landings were somewhat disappointing, however, white shrimp landings were greater than landings reported in 1963.
  • Study of the Juvenile Shrimp Populations of the Galveston Bay System - Study of the Texas Shrimp Populations

    Moffett, A. W. (Texas Parks and Wildlife DepartmentAustin, TX, 1965)
    Penaeus aztecus, brown shrimp, arrived at the tertiary bays in early April, but grew slowly. In May growth accelerated and emigration from the bay began in June when the shrimp were less than 90 mm long. A second wave of brown shrimp arrived in August. White shrimp, P. setiferus, arrived at the tertiary bays in June. This group of shrimp was followed by two smaller groups in August and October. Brown shrimp were found in Sabine Lake in May. The 1964 white shrimp were found in mid-June. In the fall a second wave of white shrimp was observed. Commercial brown shrimp landings reached a peak in July and August, but fell sharply after September. White shrimp production was high.
  • Coastal Hydrographic and Meteorological Study, 1969-1970

    Martinez, A. Rudy (Texas Parks and Wildlife DepartmentAustin, TX, 1969)
    Hydrographic and meteorlogical data collected in the field and taken from publications are presented in the report. River flow measurements were available for six major rivers entering coastal bay areas in 1969 and three in 1970. Measurements were available from January through September. Commercial landings indicate shrimp and crabs were taken in larger numbers in areas of higher rainfall and lower salinities. Finfish were taken in larger numbers in the Laguna Madre where rainfall was lower and salinities were relatively higher. Habitat modifications included routine maintenance dredging of the Intracoastal Waterway and existing channels, dredging of new channels, drilling oil wells, placement of pipelines, bulkheading and filling, mud shell dredging.
  • Study of Sand Seatrout of the Galveston Bay Area

    Benefield, R.L. (Texas Parks and Wildlife DepartmentAustin, TX, 1969)
    Sand seatrout (Cynoscion arenarius Ginsberg) were studied in the Galveston Bay area to provide information on seasonality, population composition, food items, growth, and spawning. Tagging efforts resulted in 518 tagged fish and a return of 16 tags during the 1968-70 period. Tag recovery data suggest a migration from the upper bay to the lower bay and Gulf waters in December and return in March. Electrophoretic analysis of multiple hemoglobin protein types were studied from 96 sand seatrout blood samples. Five protein types were observed without discernible differences that could be attributed to population heterogeneity. Analysis of stomach content revealed crustacea and fish as primary food items. Gonad development stages indicate a spawning period from March through August.
  • Study of Texas Shrimp Populations, 1970

    Moffett, Alan W. (Texas Parks and Wildlife DepartmentAustin, TX, 1969)
    In spring, samples were taken with bar-seines and trawls from Sabine Lake, Galveston Bay, Matagorda Bay, Aransas Bay, and the Lower Laguna Madre to study brown shrimp (Penaeus aztecus) growth, movements, seasonal abundance trends, and environmental needs. The shrimp was abundant in samples from Galveston Bay, Aransas Bay, and the Lower Laguna Madre. Slow growth of juveniles during April in upper coastal bays was attributed to low temperature. Many, however, were 70 to 80 mm long by late May, because growth accelerated as bays warmed.

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