Sabine Pass Research Articles

Assessing the Impact of Hurricanes Katrina and Rita

In the summer of 2005, while the U.S. economy was growing comfortably despite a few longstanding concerns about deficits and outsourcing, storms were brewing off the Gulf Coast. On August 25, 2005, Hurricane Katrina blasted New Orleans, Louisiana, and the surrounding coastal areas on the Gulf of Mexico. Barely a month later, a second storm, Hurricane Rita, swept through the Gulf region, making landfall between Sabine Pass, Texas, and Johnson's Bayou, Louisiana. Speculation about their likely impact on world energy markets and the U.S. economy began as soon as the hurricanes were forecast to strike the oil-rich Gulf region. This case documents the paths of the storms and provides a summary of the Congressional Budget Office's estimates of the storms' impact on the U.S. economy. It is designed for use in teaching the concept of national income accounts. It can also be used to analyze the impact of exogenous shocks.

Characterizing Bull Shark (Carcharhinus leucas) Assemblages Near the Sabine Pass Inlet

The developmental stages of bull shark (Carcharhinus leucas) life history and the impact of selected environmental variables on the utilization of a Gulf of Mexico habitat by this species were characterized during late spring through summer 1992-1999, Entanglement nets 91.4 min length of varying depth (2.40--4.88 m) and mesh sizes (12.7-25.4 em) were deployed adjacent to jetty and beachfront sites near Sabine Pass. Bull sharks (N = 720) were incidentally captured as part of a study to monitor the population of Ridley sea turtles. The bull shark bycatch portion of the parent study data was expanded in 1997-1999 to record sex and in 1999 to include total length (TL) of individual bull sharks. Bull shark life history stages were estimated for the 1999 study from length and sex. Bull shark TL data when evaluated using size ranges of the Final Fisheries Management Plan for Atlantic Tunas, Swordfish, and Sharks indicate that no adult sharks were captured. Total length frequency compared to generally accepted length at age data supports that 94% of the Sabine Pass captures would be at most 6 yr old. A strongly correlated power model (r2 = 0.91) extended the length-weight relationship data for immature life history stages of bull sharks. Bull shark catch (1992-1999) was positively correlated with water temperature (20.0--40.0°C), salinity (12.3-34.8 parts per thousand), and water clarity (0.0-1.6 m) and inversely correlated with dissolved oxygen (4.4-9.1 mg/liter). The findings suggest that the area surrounding Sabine Pass functions as a nursery I development area for early life-history stages of bull sharks during late spring and summer months when specific environmental factors are present.

The Distribution of Purse-Seine Sets and Catches in the Gulf Menhaden Fishery in the Northern Gulf of Mexico, 1994-98

Captains Daily Fishing Reports (CDFRs) are daily logs of fishing activities that are completed by vessel captains in the gulf menhaden purse-seine fishery. CDFRs of menhaden vessels from Mississippi and Louisiana for 1994-98 were computerized and analyzed. Over the 5-yr study period, 33,780 CDFRs were processed, representing 115,104 purse-seine sets. On average, the fleet made 23,021 sets per year. Airplane pilots assisted for 64.0-75.8% of the sets. Modal number of sets per day ranged from 4 to 5, and median catch per set ranged from 17 to 22 metric tons. Vessels made at least one set on 63-76% of the available fishing days. Vessels failed to leave the dock most often because of adverse weather. Between 86 and 92% of the annual catch occurred off the Louisiana coast, with lesser quantities coming from the Texas, Mississippi, and Alabama waters. Cumulatively, 55% of the harvest occurred within three miles of shore, and 93% came from within 10 miles of shore. Two main centers of fishing activity were located off the Louisiana coast: one, within Breton and Chandeleur sounds and the other along the western Louisiana coast from Atchafalaya Bay to Sabine Pass. Annual catch by 10 X 10-min rectangles of latitude and longitude within these centers of fishing activity regularly exceeded 20,000 metric tons. Areas of the greatest catches and effort tended to cluster near extant menhaden factories. Catch per unit effort was generally high across the range of the gulf menhaden fishery, and exceeded 20 metric tons per purse-seine set in a majority of the areas.

Variations in shoreface progradation and ravinement along the Texas coast, Gulf of Mexico

Shoreface architecture, evolution (mid‐Holocene to present) and depths of transgressive ravinement were examined from Sabine Pass, at the Texas–Louisiana border, to South Padre Island, near the Texas–Mexico border, using 30 shoreface transects. Shoreface transects extend out to 16‐m water depth, each created from an echo‐sounding profile and, on average, seven sediment cores. The shoreface is composed of three broad sedimentological facies: the upper shoreface, composed almost entirely of sand; the proximal lower shoreface, composed of sand with thickly to medium‐bedded (50–10 cm) mud; and the distal lower shoreface, composed dominantly of mud with medium‐ to thinly bedded (20–3 cm) sand. Shoreface architecture and evolution is extremely variable along the Texas coast. Shoreface gradients increase from 2·25 m km–1 in east Texas to 3·50 m km–1 in south Texas. Shoreface sands coarsen towards south Texas. East and south Texas shoreface deposits are thin and retrograding whereas central Texas shoreface deposits are thicker and prograding. Central Texas is characterized by stacked shoreface successions, whereas in east Texas, lower shoreface sands are preserved only in offshore banks. Preservation of shoreface deposits is low in south Texas. Although eustatic fluctuations and accommodation space have a strong impact on overall mid‐Holocene to present shoreface evolution and preservation potential, along‐strike variations in sediment supply and wave energy are the main factors controlling shoreface architecture. The transgressive ravinement surface varies from –6 to –15 m along the Texas coast.

Laboratory Tests and Field Implementation of Gas-Drag-Reduction Chemicals

SummaryDrag reduction in gas-transmission lines can be achieved by applying a thin chemical coating on the pipe inner surface to reduce friction between the flowing gas and pipe wall. Newly identified molecules used for gas-drag reduction can strongly bond to metal surfaces and form a smooth film to mitigate gas turbulence at the gas/solid interface. Effective gas-drag reducers have properties similar to corrosion inhibitors and lubricants or a combination of both. Fatty acids, oxylated fatty acid amines, and/or amides with carbon numbers between 18 and 54 can provide this type of behavior.1 The desired scenario is based on positively charged amine and amide functional groups providing strong binding to the metal surface and the long-chain hydrocarbon part serving as a compliant or lubricating surface to mitigate turbulence at the gas-phase boundary.2A field test using Nalco 945 corrosion inhibitor at High Island 24L [a 7.625-in. inside diameter (ID) and 6.25-mile-long gas line from an offshore platform to the inland facilities in Sabine Pass, Texas] demonstrated gas-throughput improvement up to 20% at its peak performance. The improvement can be defined either as a reduction in pressure drop at a constant flow or as a flow-rate increase at a constant pressure drop. In this case, the gas-drag reducer resulted in a decrease in pressure drop from 180 to 150 psi and an increase in flow rate from 50 to 52 MMscf/D, while maintaining discharge pressure at about 840 psi. Its effectiveness peaked at the third week after one injection treatment, and then gradually tapered off. Benefits lasted more than 2 months.

Modeling and Testing of Cohesive Soil Using Disturbed-State Concept

A new constitutive model for predicting the undrained stress-deformation and pore water pressure response of saturated cohesive soils subjected to cyclic loading is developed using the disturbed-state concept (DSC). The model takes into account inelastic response during loading (virgin) and unloading-reloading (nonvirgin) behavior. Comprehensive laboratory tests have been performed on undisturbed soft (marine) clay samples procured from a site at Sabine Pass, near Houston, Tex. The tests include conventional cylindrical triaxial tests and cyclic triaxial tests in the multiaxial device with pore-water-pressure measurements. The model is verified with respect to the observed behavior of undisturbed clay samples. Verification is performed with respect to laboratory tests that were used, and the independent tests that were not used in the calibration of the model. Overall, the proposed model provides highly satisfactory predictions of the observed behavior during virgin and non-virgin loading.

Changes in Shoreline Position Along the Northern Gulf of Mexico Between 1847 and 1994: Sabine Pass, Louisiana to Dauphin Island, Alabama: ABSTRACT

Changes in Shoreline Position Along the Northern Gulf of Mexico Between 1847 and 1994: Sabine Pass, Louisiana to Dauphin Island, Alabama: ABSTRACT

Constitutive Model for Cyclic Behavior of Clays. I: Theory

One of the main objectives of the present paper and its companion, part II, is to develop an integrated approach in which various factors relevant to the cyclic behavior of piles can be simulated in a unified manner. They include fundamental constitutive models for cyclic loading, appropriate laboratory tests, determination of material constants, validation of the model, and field verification. Development and verification of the constitutive model are described in part I. Here the hierarchical single surface (HiSS) plasticity‐based concept is modified to allow for the cyclic response of a clay that occurs at Sabine Pass, Texas, where the field pile load tests were performed. The new series of Δ* models allows for hardening, normal consolidation and overconsolidation, general stress paths, and fluid pressures. Special procedures are developed to identify and to determine parameters for the models. Triaxial tests performed on undisturbed specimens of Sabine clay are used to find the parameters. The model i...

Auditory brainstem response in a neonatal sperm whale, Physeter spp.

A sperm whale neonate, Physeter spp., was stranded near Sabine Pass, Texas in September of 1989. The Marine Mammal Stranding Network of Texas A&M University removed the animal to Sea-Arama Marineworld, Galveston, Texas where it was kept in a large tank for 8 days in an attempt at rehabilitation. During this period, the auditory brainstem response (ABR) was recorded from suction cup sensors on the surface of the head in response to pulses presented (20 and 40 pps) underwater near the right external auditory meatus and lower jaw. These are the first ABR records from a great whale and the first recordings from a neonate of any cetacean species. The ABR waves of this Physeter, in response to pulses ranging in peak frequency from 2.5 to 60 kHz, were similar in appearance to those seen in other mammals, and very similar to those previously observed in other odontocetes [S. H. Ridgway et al., Proc. Natl. Acad. Sci. USA 78, 1943–1947 (1981)]. The ABRs of highest amplitude were those to frequencies of 5, 10, and 20 kHz. Responses to 60 kHz were much weaker but definitely present. Latencies were prolonged compared with ABRs of other juvenile and adult odontocetes.

Sounds made by a neonatal sperm whale, Physeter spp.

A sperm whale neonate, Physeter spp., was stranded near Sabine Pass, Texas in September 1989. The Stranding Network of Texas A&M University removed the animal to a large tank 6×12.2 m in Galveston, where it was nursed for 8 days. During this period, sounds were recorded with a broadband Racal recorder and two matched broadband B&K hydrophones placed 1 m ahead of the blowhole and 1 m lateral to the fight eye. Sounds could be divided into two classes. The click class consisted of clicks of two different types: (a) high-frequency, low-amplitude clicks with peak frequencies of 5 to 12 kHz and 1- to 2-ms duration; (b) low-frequency, high-amplitude clicks with peak frequencies of 400 to 900 Hz and durations of 7 to 20 ms. The second or grunt class consisted of different sounds, mostly below 700 Hz, described by listeners as “croaks,” “growls,” “grunts,” and “‘lion-purr growls.” Palpation of the head during phonation, listening with a stethoscope and in air at mid-head, and arrival times at the two hydrophones, suggested that click-class sounds were produced near the blowhole (distal sac and museau) while the grunt class originated 60 to 70 cm posterior to the blowhole (frontal sac).

The geomorphology of the Mississippi River chenier plain

The chenier plain of the Mississippi River is a shore-parallel zone of alternating transgressive clastic ridges separated by progradational mudflats. The term chenier is derived from the cajun term chene for oak, the tree species that colonizes the crests of the higher ridges. The Mississippi River chenier plain stretches 200 km from Sabine Pass, Texas, to Southwest Point, Louisiana and ranges between 20 and 30 km wide, with elevations of 2–6 m. The timing and the process of formation could be re-evaluated in the light of new chronostratigraphic findings in the Mississippi River delta plain. The stratigraphic relationship between the Teche and Lafourche delta complexes and Ship Shoal offshore indicates that these delta complexes belong to different delta plains that developed at different sealevels. It appears that the Teche delta complex is associated with the late Holocene delta plain which developed 7000 to 3000 yrs B.P. when sealevel stood 5–6 m lower than present. A regional transgression occurred between approximately 3000 BP and 2500 yrs B.P., leading to the transgressive submergence of the late Holocene delta plain, producing the regional Teche shoreline. The timing of this transgression conforms to the age of the most landward ridge in the chenier plain, the Little Chenier-Little Pecan Island trend, which dates at about 2500 yrs B.P. This ridge trend was originally interpreted as representing the Teche delta complex switching event with the landward Holocene/Pleistocene contact representing the high stand shoreline. The implication of this new interpretation is that the Little Chenier-Little Pecan Island trend represents the high stand shoreline, a continuation of the Teche shoreline separating the late Holocene and Recent delta plains, and that the Holocene/Pleistocene contact represents the leading edge of the marshes transgressing onto the Prairie Terrace. Significant mudflat progradation seems to require a westerly position of the Mississippi River, but the numerous different forms and ages of cheniers do not correspond well to the timing of major delta complex switching. Progradation of the chenier plain appears to be associated with building of the Recent delta plain and not the Teche complex of the late Holocene delta plain. The occurrence of individual ridges appears to be primarily tied to delta lobe switching within the Lafourche complex and variations in sediment supply from local rivers. The recent development of the Atchafalaya delta complex to the west is the closest position of an active distributary to the chenier plain since sealevel stabilization; a new episode of rapid mudflat progradation is thus taking place.

Miocene Stratigraphy and Structure of Sabine Pass, West Cameron, and East Cameron Outer Continental Shelf Areas, Louisiana: ABSTRACT

Mapping of Miocene stratigraphy and structure of the Sabine Pass, West Cameron, and East Cameron areas of the western Louisiana outer continental shelf - based on over 1300 mi of seismic data on a 4-mi grid, paleotops from 60 wells, and logs from 35 wells - resulted in time-structure and isochron maps at six intervals from the upper Pliocene to lower Miocene. The most pronounced structural features are the fault systems, which trend east-northeast to east along the Miocene stratigraphic trend. Isolated normal faults with small displacements characterize the inner inner shelf, whereas interconnected faults with greater displacements characterize the outer inner shelf. The inner inner shelf faults exhibit little growth, but expansion across the interconnected outer inner shelf fault ranges up to 1 sec two-way traveltime. The interconnected faults belong to two structurally independent fault families. The innermost shelf faults appear to root in the sediment column. A third set of faults located in the Sabine Pass area trends north-south. This fault set is thought to be related to basement movement and/or basement structure. Very little salt is evident in the area. A single diapir is located in West Cameron Block 110 and vicinity. There is little evidence ofmore » deep salt. Overall sediment thickness probably exceeds 20,000 ft, with the middle Miocene accounting for 8000 ft.« less

Sea Level Control on Facies Architecture of Incised Valley-Fill Sequences: Case Study of Sabine and Trinity Valleys, Texas Continental Shelf: ABSTRACT

The rate of sea level rise likely has varied during the late Wisconsinan-Holocene transgression. The authors are investigating the sea level history of the northwest Gulf of Mexico by examining the sequence stratigraphy of incised valleys on the Texas continental shelf. Glaciologists argue that mass wasting of marine ice sheets can cause rapid and episodic relative sea level (RSL) rises on the order of 5 m/100 years. Such an event would produce a large (/approx/25 km) landward translation of the shoreline on low-gradient shelves like that of north Texas. RSL rise events are expected to be manifested as discontinuities in valley-fill sedimentation and as changes in valley shape. Nearly 1000 km of high-resolution seismic profiles collected in an area extending from Sabine Pass to Galveston and to 60 km offshore were integrated with engineering borings, vibracores, and piston cores; these data allow mapping of incised valleys and valley-fill facies associated with the ancestral Sabine and Trinity rivers. An RSL rise event is characterized by a change from slow rate of rise to rapid and back to slow. The period of rapid rise produces a major flooding surface; bayhead delta development is suppressed, and lower estuarine or marine deposits lie directlymore » on fluvial deposits. Because accommodation increases as rapidly as RSL rises, valley-fill deposition is limited to the original, deeply incised valley. In map view, the valley appears relatively straight and narrow. The valley just offshore Galveston Island represents this situation. During a period of slow rise, bayhead deltas prograde and downlap onto estuarine deposits. In this case, sediments may completely fill the original incised valley, and the river supplying this valley may meander beyond previous valley edges. In map view, such a valley will be broad and irregular in shape, much like modern Galveston Bay.« less

Holocene Cementation Along the Central Texas Coast

ABSTRACT Sandy biosparite and shelly biomicrite gravel thinly covers a significant portion of the inner shelf from the Rio Grande to Sabine Pass, covering an area of at least 3,000 km2, and similar gravel is also a conspicuous component of beach sediment along rapidly eroding Holocene deltaic headlands of the central Texas coast. Although gravel clasts occur in a normal marine setting, most include shells of brackish to freshwater fluvial-deltaic and estuarine molluscs. Contained cements record lithification in two distinctly different diagenetic settings. Biosparites contain intergranular and intragranular cement that precipitated from meteoric fluids during subaerial exposure, whereas biomicrite cements precipitated in the presence of marine and marine-derived fluids, possibly mix d with connate fluids from depth. Most meteoric cement consists of equant crystals of low-Mg calcite spar precipitated during the partial dissolution and calcitization of molluscan aragonite. Marine cements are predominantly equant to elongate crystals of highMg calcite, but they also include acicular aragonite and radial barite. Unlike most normal marine calcite cements, Texas shelf highMg calcite is enriched in iron and manganese, is luminescent, and is isotopically depleted in carbon. Marine cementation, including baffle precipitation, took place at shallow depths below the sediment/water interface. The presence of brackish to freshwater molluscs in sediment lithified by both meteoric and marine fluids records a complex sequence of Quaternary cementational and erosional events. Meteoric lithification of Pleistocene shelly, deltaic, and estuarine coquinas took place during the Wisconsinan lowstand, whereas marine cementation of other, as yet unlithified, shelly layers began with the subsequent Holocene transgression of the Gulf shoreline to its present position.

An Archaeological Survey of a Pipeline Route Near Sabine Pass, Jefferson County, Texas

In May 1980, the Center for Archaeological Research, The University of Texas at San Antonio, carried out an archaeological survey of the proposed route of an eight-inch pipeline to be installed by the Tennessee Gas Pipeline Company. The pipeline will extend from the Scurlock Oil Company tank farm about one kilometer southwest of Sabine Pass to a landfall on the Gulf Coast at a point about six kilometers west of Texas Point (Fig. 1). The survey was done under contract between the Center for Archaeological Research and the Tennessee Gas Pipeline Company (Independent Contractor-Letter Agreement of May 1980). The fieldwork was carried out by Kenneth M. Brown, Research Associate, under the supervision of Dr. Thomas R. Hester, Center Director, and Jack D. Eaton, Associate Director. The pipeline route is about 4.6 km long; crossing the chenier plain with a north-south orientation. The chenier plain consists of long, low sand and shell ridges, or cheniers, subparallel to the present coast, alternating with saline or brackish marsh and mudflats (Fisher et ale 1973; Kane 1959; Byrne, LeRoy, and Riley 1959). The area is also dotted with many elongate to irregular ponds. Ground visibility during the survey was fair to good on the cheniers, especially on the seaward side where the coarsest sediments were exposed; sandy deflated surfaces are common there. Washovers where the cheniers have been breached during high water also offered good visibility. The marsh between the cheniers, although dry enough during the survey to walk on in most places, is heavily vegetated, with a substrate of wet silt, clay, and organic muck. Ground visibility here was very unfavorable.

Towed Horizontal Resistance and Spontaneous Potential Survey off Sabine Pass, Texas: ABSTRACT

A program of electrical measurements on unconsolidated marine sediments was started by the geologic oceanographers at Texas A&M University in 1968. It consisted of measuring resistance and spontaneous potential on extruded cores and in situ in the field, and correlating the electrical values with various sediment and geotechnical properties. The present phase of research concentrates on delimiting and defining sediment lithologies using a towed horizontal array. Several combinations and electrode spacings were tried across Heald Bank, off Sabine Pass, Texas. Bottom-water and sediment samples were collected from well-defined submarine lithologies. Preliminary results indicate that the spontaneous potential is uniformly highest in mud and clay areas. Large variations occur over shelly sands and shell debris. Resistance is largely uniform across Heald Bank, with relative values depending on electrode End_Page 2208------------------------------ separation. Towed electrical measurements are complementary to high-resolution subbottom profiling. Sediment samples collected from Heald Bank were placed in a small wooden trough to appraise some of the properties that control the sediments' resistance and spontaneous potential as well as to obtain insight into the relation between depth of measurement with various electrode spacings. The experimental electrical studies show the same spontaneous potential variations as were found over Heald Bank. End_of_Article - Last_Page 2209------------

Moreau-Caminada Chenier Complex, Southeastern Louisiana: ABSTRACT

The Moreau-Caminada chenier complex south of New Orleans is the only sub-Holocene chenier system on the surface in Louisiana east of the classic western Louisiana cheniers. It occupies an area 16 km long and up to 5 km wide east of the mouth of Bayou Lafourche. About 60 ridges, 50-120 m wide and up to 7.5 km long, form the complex; the highest ridge elevation is only 1.2 m. Large new exposures along Louisiana Highway 1 revealed that the sand, which at places is at least 30 ft thick, is very fine grained and very well sorted. Detrital lignite grains make up as much as 7.6% of this chenier sand. Shell fragments, abundant in the western Louisiana cheniers, are absent. Autochthonous and detrital peat layers and laminae 1 mm or more thick are interlayered with the sand. Dating of three autochthonous peat samples from the Louisiana Construction Company and Plaisance Dragline and Dredging Company sand borrow pits revealed 2,940±120 to 2,340±120 years B.P. ages. Thus the cheniers are much older than the surrounding Lafourche- and Lafourche-Terrebonne subdelta sediments. After the last Lafourche distributary stream lost its water supply, substantial erosion started the destruction of the chenier complex. A coastal strip up to 2 km wide was eroded between 1890 and 1934, due to the closing off of the Bayou Lafourche discharge. New information about the Mississippi deltaic plain stratigraphy refutes suggestions that the southwest Louisiana chenier ridges formed during periods when the active delta lobes were on the other end of the deltaic plain. Seven sets of chenier ridges formed in the southwest Louisiana chenier plain between 2,800±600 B.P., while not only the distant St. Bernard distributaries were active but also the much closer Lafourche distributaries. The Moreau-Caminada cheniers were forming also in the proximity of one of the active Lafourche subdeltas. Cyclicity in chenier progradation should be attributed to fluctuations in local sediment supply and hydraulic conditions. Enough sediment must have been present in the littoral drift to prevent the wholesale erosion of the shore and to allow t e construction of ridges. Low ridge elevations in the Moreau-Caminada area are attributed to the great thickness of underlying post-Pleistocene sediments in contrast to the shallow Pleistocene surface in southwestern Louisiana. Shore recession in the chenier plain was accompanied by the reversal of littoral drift directions. The Moreau-Caminada cheniers indicate westward drift whereas the presently prevailing drift direction in the area is eastward. The present drift direction may date back to the construction of the Plaquemines subdelta End_Page 2041------------------------------ which since about 800 B.P. reduced the strength of the currents and waves from the east. Chenier ridge configurations depend primarily on the original outline of the shoreline and upon the conditions of sediment supply from the sea, from deltas, or from the estuaries. Different ridge patterns develop if the dominant littoral drift approach direction is similar or identical with that of the main sediment source area. In the present case a substantial part of the ridge sands came by the drift from the east, and most of the sediment probably came from the west, the area of an active Mississippi subdelta. A similar situation exists on the western bank of the Sabine Pass, eastern Texas, where the ridges developed from the southwest and most of the sediment supply came from the east with the prevailing drift and from the direction of Sabine Lake on the north. End_of_Article - Last_Page 2042------------

A quantitative study of selected nearshore infauna between Sabine Pass and Bolivar Point, Texas : Keith Don C. and Neil C. Hulings, 1965. Publ. Inst. Mar. Sci., Port Aransas, 10: 33–40.

A 42-d flow-through experiment was conducted to evaluate the effects of the organo-phosphate pesticide, chlorpyrifos, and microcosm size (small: 144 cm2; large: 400 cm2) on benthic estuarine macroinvertebrate colonization. Nested central and perimeter (outside margin) cores were used to assess animal distribution within microcosms. Fine-grained, organically-rich (approximately 4.0% organic carbon and 20% dry wt) sediments were nominally fortified with chlorpyrifos controls, low (1.0) and high treatments (10.0 μg−1 wet sediment). Large microcosms contained a significantly (p < 0.05) higher average taxa richness (10.9) than small microcosms (8.6) but small microcosms contained a significantly greater average animal density (295.8; numerical abundance adjusted to unit area) than large microcosms (120.5). Density of the polychaete, Neanthes succinea, the amphipod, Corophium acherusicum, and the barnacle, Balanus sp., was significantly greater in small microcosms but density of Ensis minor was significantly greater in large microcosms. In small and large microcosms, respectively, densities averaged significantly greater numbers in perimeter cores (e.g. 203.1 and 75.1) vs central cores (71.9 and 45.4). Average density decreased significantly with increasing chlorpyrifos concentration from controls (326.8), to low (123.8) and high (78.8) treatments. The density decrease was significantly related only to C. acherusicum whose densities decreased from controls (285.8) to low (88.5) and high (43.9) dosed microcosms. Application of an equilibrium partitioning model indicated that density of C. acherusicum was sensitive to an estimated interstitial water concentration of approximately 0.48 μg liter−1. Non-metric multidimensional scaling ordination analyses provided important insights into response patterns not available through ANOVA procedures. A permutation procedure (ANOSIM) detected a significant size effect (p < 0.0001) and a significant effect between controls and low (p < 0.042) and high doses (p < 0.013) but not between low and high chlorpyrifos treatments (p < 0.465). A single species, C. ascherusicum, as in the ANOVA analyses, dominated contributions to community average percent dissimilarity in most combinations of microcosm size and chlorpyrifos treatment effects (range: 8.4–21.9%). Community structure differed significantly in several combinations of microcosm size, core position and chlorpyrifos treatment. Results confirm earlier work that intrinsic design factors influence benthic macroinvertebrate community structure and determine taxa available to pesticide exposure in microcosms.

Late Quaternary Geology of Sabine Lake and Vicinity, Texas and Louisiana: ABSTRACT

The late Pleistocene and Recent sediments, faunas, and geomorphology were mapped in the vicinity of Sabine Lake, in an area that straddles the Texas-Louisiana state line and extends into the Gulf of Mexico. The former valley of the Neches and Sabine rivers is entrenched into oxidized Pleistocene deposits to a minimum depth of 120 feet at the Gulf of Mexico shoreline. This valley has been filled in by the streams and closed off at its southern end, except for Sabine Pass, by prograding of the Gulf shoreline to form the present lake estuary, Sabine Lake. The erosion and subsequent alluviation were caused by a fall and rise in sea-level due to waxing and waning of continental glaciers late in Quaternary time. Lithology and fauna, especially the Foraminifera, were determined from cores and clam-shell samples taken in the Sabine Lake estuary and Gulf of Mexico nearshore neritic environments. No End_Page 2519------------------------------ lithologic criteria for distinguishing these two environments were evident in the surface sediments or in core samples taken 3 feet and 6 feet below the surface. Foraminiferal biofacies, however, do differentiate clearly the estuarine and the nearshore neritic environments. The species and their percentages in the bottom sediments of Sabine Lake differ from those of the Gulf of Mexico, and from those in the core samples from 3 and 6 feet. The biofacies of the core samples from under the lake are similar to those of the present Gulf, indicating greater circulation of saline waters from the Gulf of Mexico before the south end of Sabine Lake was restricted. End_of_Article - Last_Page 2520------------

Dick Dowling and The Battle of Sabine Pass

Dick Dowling and The Battle of Sabine Pass