Geology topics
Research about Louisiana
Source-linked reports with geographic coverage including Louisiana.
An examination of organic/carbonate-bound metals in bottom sediments of Bayou Trepagnier, Louisiana
To assess potential impact of metals on the biosphere in bottom sediments, forms were determined for selected metals in a southeastern Louisiana bayou, Bayou (B.) Trepagnier, which has been impacted by industrial activity at its head by a manufacturing complex (MC). Ten pairs of cores along the length of the bayou allowed variation with distance to be studied. Sequential extractions provided data on five chemical partitioning phases for subsamples from each of the cores. Results show that, beyond the mineral residue phase (phase 6 of the extractions) the organic/carbonate phase (phase 4 of the extractions) generally contains the highest concentrations of metals. This paper focuses on phase 4. In addition, metals in phase 4 show significant downstream gradients, though concentrations towards the mouth do not generally appear to differ significantly from those at a control site outside of the bayou. Data were also examined for interrelationships, and high correlation coefficients were the impetus for moving to a multivariate statistical method, polytopic vector analysis (PVA). Six end-members (EMs) were produced. EMs 2, 5, and 6 have high relative proportions of anthropogenic metals and are observed in highest proportions upstream, near the MC. These EMs may reflect industrial input from the MC. EM 3 contains significant calcium, magnesium, and manganese, with minor amounts of lead and barium, and is related to input from nearby Lake Ponchartrain since it increases in weight downstream. EMs 1 and 4 are composed of components commonly found in detrital minerals (e.g., iron, aluminum, magnesium, manganese, and silicon) and are probably not the product of anthropogenic influence. For anthropogenically-weighted end-members (EMs 2, 5, and 6) there appears to be little difference between weights at the mouth of the bayou and weights at the control site outside the bayou.
Marsh loss in coastal Louisiana: Implications for management of North American Anatidae
No abstract available.
1995 Scanned aerial photography of the Kisatchie National Forest in Louisiana
No abstract available.
A spatial decision support system for coastal management: A research project at the National Wetlands Research Center of the U.S. Geological Survey
Environmental resource managers and scientists are being challenged in developing strategies to manage complex coastal systems. From an ecological perspective, there are myriad dynamic, interrelated natural and human-induced processes that affect the health and stability of coastal systems. However, the problems associated with managing coastal resources usually transcend purely ecological factors when one considers societal needs and expectations from these resources. For example, at least nine Federal, State, and local government agencies, often with widely varying responsibilities or interests, are charged with managing environmental resources and/or regulating human activities within Louisiana's coastal systems; that number may be higher in other coastal areas of the United States. In many coastal systems, a declining resource base and environmental quality combined with an expanding human population exert increased demands on those systems. This results in a number of conflicting resource management and environmental impact assessment issues. The issues include determining the most cost-effective strategies for restoring degraded natural systems, local and regional planning for future urban and commercial development in or near sensitive coastal habitats, predicting impacts from acute and chronic pollutant discharges (oil spills, fecal coliform contamination) as well as from natural hazard damages to coastal systems, and optimal partitioning of coastal resources among competing user groups (e.g., commercial and recreational fishermen). Solving such complex environmental resource management problems often involves a multidisciplinary approach, requires computerized analytical modeling abilities to manipulate large quantities of spatial-temporal data according to a defined set of objectives or constraints, and needs a mechanism to provide quick responses for dynamic resource and environmental issues. For this, a GIS-based multifunctional Spatial Decision Support System (SDSS) is being developed at the National Wetlands Research Center of the U.S. Geological Survey (formerly the Southern Science Center of the US. Fish and Wildlife Service/National Biological Service).
Effects of municipal wastewater on baldcypress (Taxodium distichum (L.) rich.) productivity in a Louisiana swamp
No abstract available.
Food availability and feeding preferences of breeding fulvous whistling-ducks in Louisiana ricefields
Expansion of the breeding distribution of the Fulvous whistling-duck ( Dendrocygna bicolor ) into the southeastern United States after the mid-1800s coincided with the establishment of rice ( Oryza sativa) cultures in Texas, Louisiana, and Florida. In southern Louisiana, where approximately 80% of rice is aerially seeded in water, Fulvous whistling-ducks are suspected of feeding extensively on planted rice and are considered a nuisance. To determine the extent of rice utilization by ducks nesting in southwestern Louisiana, we estimated food availability in ricefields and assessed feeding preferences. We also examined effects of sex and stage of reproduction on food selection. Feeding sites in Louisiana ricefields that were tilled and flooded in preparation for spring planting, contained abundant foods (mean ± SE = 109.0 ± 18.0 g/m2, especially seeds of moist soil plants such as signalgrass ( Brachiaria extensa ), beakrush ( Rhynchospora sp.), and flatsedge ( Cyperus iria ). Diets of males and females were similar (P = 0.080), but varied through the reproductive cycle (P = 0.008). Consumption of plant material was slightly reduced during the period of rapid ovarian follicle growth in females; however, ingestion of animal foods never exceeded 4%. Fulvous whistling-ducks exhibited feeding preferences (P < 0.001) with aquatic earthworms (Oligochaeta) and wild millet seeds ( Echinochloa sp.) being preferred over other food taxa. Rice made up <4% of the diet and was selected in proportion to its availability before and during period of rapid follicle development. Almost 25% of the diet of incubating females consisted of rice; however, we concluded that crop depredation by Fulvous whistling-ducks (≤0.1%) was of minor importance relative to other potential sources of crop loss. Indeed, use of ricefields by whistling-ducks may actually benefit farmers if ingestion of seeds of undesirable plants reduces the need for costly herbicide treatments.
The effects of vertebrate herbivory on plant community structure in the coastal marshes of the Pearl River, Louisiana, USA
In this study, we investigated the impacts of herbivory by the introduced aquatic herbivore, nutria ( Myocastor coypus ), on three marsh communities of the Pearl River using fenced exclosures and control plots. Although total community above-ground biomass was reduced by 30% in the plots exposed to herbivory as compared to those protected from herbivory, we found species richness to be unaffected. When individual species were examined within each community, Panicum virgatum and Aster subulatus were found to be significantly reduced by herbivory in the freshwater community, Panicum virgatum and Vigna luteola were significantly increased by herbivory in the oligohaline community, and no species were significantly affected in the mesohaline community. We conclude that this herbivory has some specific effects on some plant species as well as having a general community effect.
Effect of increased water depth on growth of a common perennial freshwater-intermediate marsh species in Coastal Louisiana
The response of Sagittaria lancifolia to increased water depths of 7.5 and 15 cm was examined in this field study. Water-depth treatments were achieved by digging sods containing one or two individual plants or ramets of S. lancifolia from the marsh, removing sediment from the resulting hole, and replacing the sods in their original location at the appropriate lower elevation. Plants subjected to increased water depth of 15 cm had higher mean and maximum leaf heights than disturbed control plants. Aboveground biomass was not affected by water-depth treatment; however, 15-cm treatment plants had reduced root biomass and lowered leaf tissue concentrations of Ca, Cu, Fe, Mg, and Zn. Marsh sods at 15 cm below the marsh surface had the lowest redox potential and highest interstitial water sulfide concentration, indicating that this treatment created the most stressful belowground environment. Sagittaria lancifolia plants responded to the level of stress imposed by the experimental conditions with an altered growth form of increased leaf height.
Comparison of condition indices in migratory passerines at a stopover site in coastal Louisiana
We evaluated the utility of four nondestructive condition indices—body mass, body mass scaled by wing chord length, fat scoring, and total body electrical conductivity method (TOBEC)—as predictors of lipid levels in migrating Wood Thrushes ( Hylocichla mustelina ), Swainson's Thrushes ( Catharus ustulatus ), and Summer Tanagers ( Piranga rubra ). The Red-winged Blackbird ( Agelaius phoeniceus ), a winter resident, was examined for comparative purposes. In addition, we examined differences among species in relationships of total body lipids and condition indices. Body mass was the best index of lipid levels, explaining 36%-82% of the variation in total body lipids in all four species. The relative contributions of the other indices to the prediction of lipid mass varied among species although TOBEC was selected for inclusion in each regression equation. For two species, equations including TOBEC measurements had lower errors in lipid prediction than equations only using the other nondestructive indices. Errors in lipid prediction were large for all the regression equations based on condition indices. In many cases it will be necessary to develop species-specific equations to predict lipid levels with condition indices.
Age-class separation of blue-winged ducks
Accurate determination of age is of fundamental importance to population and life history studies of waterfowl and their management. Therefore, we developed quantitative methods that separate adult and immature blue-winged teal ( Anas discors ), cinnamon teal ( A. cyanoptera ), and northern shovelers ( A. clypeata ) during spring and summer. To assess suitability of discriminant models using 9 remigial measurements, we compared model performance (% agreement between predicted age and age assigned to birds on the basis of definitive cloacal or rectral feather characteristics) in different flyways (Mississippi and Pacific) and between years (1990-91 and 1991-92). We also applied age-classification models to wings obtained from U.S. Fish and Wildlife Service harvest surveys in the Mississippi and Central-Pacific flyways (wing-bees) for which age had been determined using qualitative characteristics (i.e., remigial markings, shape, or wear). Except for male northern shovelers, models correctly aged lt 90% (range 70-86%) of blue-winged ducks. Model performance varied among species and differed between sexes and years. Proportions of individuals that were correctly aged were greater for males (range 63-86%) than females (range 39-69%). Models for northern shovelers performed better in flyway comparisons within year (1991-92, La. model applied to Calif. birds, and Calif. model applied to La. birds: 90 and 94% for M, and 89 and 76% for F, respectively) than in annual comparisons within the Mississippi Flyway (1991-92 model applied to 1990-91 data: 79% for M, 50% for F). Exclusion of measurements that varied by flyway or year did not improve model performance. Quantitative methods appear to be of limited value for age separation of female blue-winged ducks. Close agreement between predicted age and age assigned to wings from the wing-bees suggests that qualitative and quantitative methods may be equally accurate for age separation of male blue-winged ducks. We interpret annual and flyway differences in remigial measurements and reduced performance of age classification models as evidence of high variability in size of blue-winged ducks' remiges. Variability in remigial size of these and other small-bodied waterfowl may be related to nutrition during molt.
The Lake Pontchartrain Basin: Louisiana's troubled urban estuary
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Geochemistry of sediments from coastal marshes of Louisiana
As a part of the U.S. Geological Survey Global Change and Climate History Program we have been studying the biogeochemistry of coastal marshes in Terrebonne Basin, Louisiana. Louisiana has about 40 percent of the coastal wetlands in the conterminous U.S. and it is losing wetlands at one of the highest rates in the U.S. with the conversion of about 65 km2/yr of marsh to open water (Britsch and Dunbar, 1993). The losses have been attributed to human and natural causes including saltwater intrusion through man-made canals, reduced sediment input, and regional subsidence. The net effect of these influences is to change the salinity of interior marshes in a fashion similar to a eustatic sea level rise. We are studying the cycling of carbon, sulfur, and other elements in sediments, waters, and marsh macrophytes in fresh, intermediate/brackish, and saltwater marshes in order to better understand how sea level rise, one aspect of global change, will influence and in turn be influenced by cycling of these elements. By characterizing the critical biogeochemical processes and the recent past environments in these rapidly changing marshes, we can improve predictions of future changes and interpretations of the historic geologic record in similar environments. In this report we describe our coastal marsh study sites in Louisiana, the types of samples collected, the collection methods, the chemical analysis methods, and selected chemical analysis results. Also included are summaries of the project quality control results. The raw chemical analysis results are provided in this report without interpretation. Interpretations will be provided in subsequent reports.
Water resources data, Louisiana, water year 1994
Water resources data for the 1994 water year for Louisiana consists of records of stage, discharge, and water quality of streams; stage, contents, and water quality of lakes and reservoirs; and water levels and water quality of ground water. This report contains records for water discharge at 64 gaging stations; stage only for 45 gaging stations and 6 lakes; water quality for 51 surface-water stations (including 24 gage stations) and 84 wells; and water levels for 209 observation wells. Also included are data for 115 crest-stage and flood-profile partial-record stations. Additional water data were collected at various sites not involved in the systematic data-collection program, and are published as miscellaneous measurements. These data represent that part of the National Water Data System operated by the U.S. Geological Survey and cooperating State and Federal agencies in Louisiana.
Quality of water in the Red River alluvial aquifer, Pool 2, Red River waterway area, Ruby, Louisiana
No abstract available.
Louisiana ground-water map no. 6: Potentiometric surface, 1990, and water-level changes, 1974-90, of the Mississippi River alluvial aquifer in northeastern Louisiana
The Mississippi River alluvial aquifer is the largest source of fresh ground water in northeastern Louisiana. In 1990, an average of 170 million gallons per day was withdrawn from the aquifer in 12 northeast Louisiana parishes. Additional knowledge about ground-water flow and the effects of withdrawals on the Mississippi River alluvial aquifer is needed for future ground-water development and protection of the resource. Generalized contours of the altitude of water levels in September 1990 and changes of water levels from 1974 to 1990 in the Mississippi River alluvial aquifer in northeastern Louisiana are shown on maps. Water-level trands in the aquifer are shown in hydrographs of selected wells.
Survey for blood parasites in redheads (Aythya americana) wintering at the Chandeleur Islands, Louisiana
We detected no infections with species of Plasmodium , Haemoproteus , Leucocytozoon , Sarcocystis or Trypanosoma in blood smears, liver and spleen impressions, and muscle tissue from 136 redheads ( Aythya americana ) collected or captured at the Chandeleur Islands, Louisiana (USA), during three winters (1987 to 1990). One bird, a juvenile male, was infected with an unidentified species of microfilaria. Thus, we found no evidence that hematozoa had an effect on redheads during the course of the study.