GBIC Materials Available at Jack K. Williams Library
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Browsing GBIC Materials Available at Jack K. Williams Library by Subject "abundance"
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Item The abundance and distribution of fishes in the cooling-water canal system of an electric generating station, with emphasis on the effect of cooling towers.(Texas A&M University., 1978) Margraf, F.J.;Trawl collections were taken from June 1974 to September 1975 to determine the abundance and distribution of fishes in the canal system of the Houston Lighting and Power Company's P.H. Robinson Generating Station with emphasis on evaluating the effect of cooling towers. Surface and bottom, day and night collections were taken from two stations in the intake canal, two stations in the discharge canal afferent to the cooling towers and one station in the discharge canal efferent to the cooling towers. A total of 91,770 specimens of 63 taxa were taken in 464 collections. Abundant species included bay anchovy, Anchoa mitchilli; Gulf menhaden, Brevoortis patronus; Atlantic croaker, Micropogon undulatus; striped anchovy, Anchoa hepsetus; spot, Leiostomus xanthurus; sand seatrout, Cynoscion arenarius; and sea catfish, Arius felis. These seven species accounted for 98.5% of the total catch. Striped anchovy, bay anchovy, sea catfish, and sand seatrout had peak abundance in the intake canal during summer, but were generally absent from the discharge canal. Gulf menhaden, spot and Atlantic croaker were most numerous during winter months and were often present in the discharge canal at this time. There was evidence from length frequency data that the spot and Atlantic croaker had established resident populations in the discharge during winter. In general, most fish captured in the discharge canal were recruited from the intake canal via impingement on the plant's revolving intake screens and subsequent sluicing to the discharge. The number of organims captured in the discharge canal was also dependent on their survival and retention time. During the summer, catches from the discharge canal were generally quite small both afferent and efferent to the cooling towers, and differed little from catches made prior to the construction of the cooling towers. Therefore, it appears that the cooling towers have been generally ineffective in promoting the survival of fishes.Item Abundance and distribution of fishes in the Galveston Bay system, 1963-1964(1983) Sheridan, Peter F.; Contributions in Marine ScienceThe fish fauna inhabiting the Galveston Bay estuarine system was studied from January 1963 through December 1964. Ninety-six species and 364,815 individuals were collected by trawl. Dominant in the system was Micropogonias undulatus (51.2% by number, 36.5% by wet weight). Other numerically important fishes were: Anchoa mitchilli , 22.3%; Stellifer lanceolatus , 8.0%; Leiostomus xanthurus , 4.1%; Cynoscion arenarius , 3.3%; and Arius felis , 2.4. In terms of biomass, other important species were: L. xanthurus , 9.1%; Mugil cephalus , 7.6%; S. lanceolatus , 6.5%; A. felis , 5.7%; and C. arenarius , 5.0%. Fishes were most abundant in the upper estuary, while the number of species recorded was highest in the shallow Gulf of Mexico just offshore from the estuaryItem Abundance and distribution of fishes in the Galveston Bay system, 1963-1964(Port Aransas Marine Laboratory, University of Texas Marine Science Institute, 1983) Sheridan, P.F.; Contributions in Marine ScienceThe fish fauna inhabiting the Galveston Bay estuarine system was studied from January 1963 through December 1964. Ninety-six species and 364,815 individuals were collected by trawl. Dominant in the system was Micropogonias undulatus (51.2% by number, 36.5% by wet weight). Other numerically important fishes were: Anchoa mitchilli, 22.3%; Stellifer lanceolatus, 8.0%; Leiostomus xanthurus, 4.1%; Cynoscion arenarius, 3.3%; and Arius felis, 2.4%. In terms of biomass, other important species were: L. xanthurus, 9.1%; Mugil cephalus, 7.6%; S. lanceolatus, 6.5%; A. felis, 5.7%;and C. arenarius, 5.0%. Fishes were most abundant in the upper estuary, while the number of species recorded was highest in the shallow Gulf of Mexico just offshore from the estuary. Stellifer lanceolatus was the most abundant fish in the channel zones of the estuary and co-dominated with C. arenarius in Gulf waters. Anchoa mitchilli was the dominant fish in the waters of the main tidal pass. In all other zones (open, near shore, and peripheral waters) and bay subareas, Micropogonias undulatus was numerically dominant.Mean number of fishes per tow was significantly higher in 1963 than in 1964, attributable mainly to larger catches of A. mitchilli and S. lanceolatus in several months of 1963. However, on an annual basis, mean fish biomass per tow was stable even though monthly differences were noted. No other system-wide studies of the fish fauna of Galveston Bay have been conducted. Results of the few limited investigations conducted before or after 1963-1964 conflict with the results of the latter. Resultant differences might equally be attributed to natural fish population fluctuations, differences in sampling methodology, and rapid human development and use of the estuary and surrounding lands.Item The abundance and distribution of macro-invertebrates in the cooling water canal system of the P.H. Robinson Generating Station located on Galveston Bay, Texas, with emphasis on the effect of supplemental cooling towers.(Texas A&M University., 1977) Margraf, F.J.;Trawl collections were taken from June 1974 to September 1975 to determine the abundance, distribution and survival rate of macro-invertebrates present in the cooling-water canal system of Houston Lighting and Power Company's P.H. Robinson Generating Station. Surface and bottom, day and night collections were taken from two stations in the intake canal, two stations in the discharge canal afferent to the cooling towers and one station in the discharge canal efferent to the cooling towers. A total of 11,655 specimens of 14 species were taken in 464 collections. Abundant species included white shrimp, Penaeus setiferus; brown shrimp, P. aztecus; blue crabs, Callinectes sapidus; and the grass shrimps, Palaemonetes pugio and P. vulgaris. Catches of macro-invertebrates in the intake canal were strongly influenced by seasonal aspects of the life history and migratory patterns of each species. Most captured in the discharge canal were recruited from the intake canal via impingement on the plant's revolving intake screens and subsequent sluicing to the discharge. The number of organisms captured was dependent on their survival rates and retention times. During the summer, catches were generally quite small afferent to the cooling towers and were generally large efferent to the towers. Prior to construction of the cooling towers, catches from both areas of the canal were small during the summer. The cooling towers increased survival rates of macro-invertebrates efferent to the towers by reducing temperatures during the summer. Based on the presence or absence of live and dead individuals in the trawl collections, the estimated upper lethal temperature was 37 C for brown shrimp, 38 C for white shrimp, and 40 C for blue crab. It appears that the supplemental cooling towers have been generally effective in promoting the survival of macro-invertebrates in the heated discharge efferent to the cooling towers.Item The abundance and distribution of Mysidacea in the shallow waters of Galveston Island, Texas.(Texas A&M University., 1976) Price, W.W.;The distribution, relative and seasonal abundances, and population structures of the species of mysids were sampled for 2 years in the various habitats in the shallow waters of Galveston, Texas. From February, 1971 through January, 1972, monthly collections were made and from February, 1973 through February, 1974 bimonthly collections were made with a beam trawl in the nearshore area. During the second year bimonthly samples were taken with an Ockelmann dredge along transects across Tucker Bayou and West Bay. Mysidopsis almyra was the dominant species in the study, composing 82 percent of the collections. The next 3 most abundant species were Mysidopsis bahia (10 percent), Mysidopsis bigelowi (5 percent), and Metamysidopsis swifti (4 percent). The ecological distributions of the mysids showed a pattern of habitat segregation among the species: Mysidopsis almyra occurred in lower salinity shallow waters of bayous and bays; Mysidopdid bahia in shallow bay waters of higher salinity; Mysidopsis bigelowi in deeper bay waters and offshore; Mysidopsis swifti in seaside surf; and Brasilomysis castori and Promysis atlantica in deeper offshore waters. Microdistribution studies showed that M. almyra inhabits the layer of water just above the bottom during the day and night. As the tide ebbed, its numbers increased and as the tide flooded numbers decreased. All mysid species displayed similar cycles of rapid reproduction and larger numbers during the summer months and slow reproduction and low numbers during the winter months. It was concluded that photoperiodicity and temperature were the major factors involved in these seasonal changes. The largest gravid females of all species were collected in the winter months and were replaced by progressively smaller ones in the spring and summer. The number of eggs and young per brood was calculated to be a linear function of the volume (length cubed) of female M. almyra, M. bahia, and M. swifti.Item Abundance and size distributions of Penaeus spp. shrimps in the Northern and Northwestern Gulf of Mexico during the 1982 closure period.(1982) Matthews, G.A.;Analyses of shrimp populations in shallow coastal waters of the Gulf of Mexico from Alabama to Texas during Texas Closure (May 26-July 14, 1982) were made based on a collection of 299 trawl samples. Shrimp were more abundant off Texas than in the other areas, and were more abundant between 10 and 20 fathoms than at other depths. Catch per unit effort data from our samples indicated shrimp were 25% more abundant during the 1981 Texas Closure than during the 1982 closure. However, the substantial variability among catches caused this difference to not be statistically significant. Populations of brown shrimp were examined through length-frequency analyses. Mean lengths in each 5-fm depth zone showed the typical increases with increasing water depths. Previous-year-class shrimp composed the vast majority of the shallow water (to 30 fm) populations, and new-year-class shrimp accounted for a relatively small portion of these populations. New- year-class shrimp were not as abundant off Texas in 1982 as in 1981. A suggested revisions of sampling strategy is included to aid in completing management goals in the future.Item Abundance of benthic macroinvertebrates in natural and altered estuarine areas.(U.S. National Marine Fisheries Service, 1974) Gilmore, G.; Trent, L.;The abundance of benthic macroinvertebrates during March-October 1969 in West Bay, Texas, was compared between a natural marsh area, an adjacent marsh area altered by channelization, bulkheading, and filling, and an open bay area. Animals representing four phyla were caught. Abundance indices (areas combined) of the four groups in terms of numbers were 66.4% polychaetes, 29.6% crustaceans, 2.5% pelecypods, and 1.5% nemerteans; volumes were 44.0% polychaetes, 40.8% pelecypods, 10.7% nemerteans, and 4.4% crustaceans. When all organisms were combined, they were slightly more abundant numerically and over twice as abundant volumetrically in the marsh than in the canals and were least abundant in the bay. In general, the seasonal abundance of polychaetes and nemerteans varied little during the study, whereas crustaceans and pelecypods were abundant only during the spring and early summer.Item Abundance of bottlenose dolphins, Tursiops truncatus, in the coastal Gulf of Mexico.(1990) Mullin, K.D.; Lohoefener, R.R.; Hoggard, W.; Roden, C.L.; Rogers, C.M.; Northeast Gulf Science.The abundance of bottlenose dolphins (Tursiops truncatus) for many coastal areas of the United States Gulf of Mexico is poorly known. During the spring and fall 1987, we used aircraft and strip transects to estimate bottlenose dolphin abundance within 37 km of the U.S. Gulf shore. Greatest estimated dolphin densities were in the north-central Gulf (spring), northern Florida (fall) and Louisiana study areas (fall) (about 0.30 dolphins/squared km). We estimated the coastal U.S. Gulf population of bottlenose dolphins to be 16,892 +/- 3,628 (95% Cl) and 16,089 +/- 3,338 in spring and fall, respectively. Bottlenose dolphins were found throughout the U.S. Gulf waters searched, but herds offshore of Texas were concentrated near passes and Louisiana herds were more common in and near eastern bays. Our estimates are one of the first assessments of the abundance and density of bottlenose dolphins throughout the coastal U.S. Gulf and may provide useful baseline estimates.Item Abundance of brown shrimp (Penaeus aztecus) as related to the 1982 closure of the Texas territorial sea to shrimping(Texas Parks and Wildlife Department, Coastal Fisheries Branch, 1983) Bryan, C.E. III;NOT AVAILABLE IN HOUSE easItem Abundance of juvenile shrimp.(1962) Baxter, K.N.; U.S. Fish and Wildlife Service CircularTo obtain a possible index of later abundance of adult shrimp, the monitoring of the passage of postlarval shrimp into Galveston Bay was begun November 1959. A station was established inside the entrance to Bolivar Roads near the south jetty on the sand flats. Results indicated a catch per effort for brown bait shrimp was 29.8, 18.3 and 30.4 for 1960, 1961 and 1962 respectively.Item Abundance of macrocrustaceans in a natural marsh and a marsh altered by dredging, bulkheading, and filling.(1976) Trent, L.E.; Pullen, E.J.; Proctor, R.; Fishery BulletinIndices of abundance of macrocrustaceans during March-October 1969 in West Bay, Tex., were determined for day and night and statistically compared between 1) a natural marsh area, 2) upland and bayward canal areas of a housing development, and 3) an open bay area. Significance levels of 5% or 1% were used in the statistical comparisons. Catches of brown shrimp, Penaeus aztecus; white shrimp, Penaeus setiferus; blue crab, Callinectes sapidus; and pink shrimp, P. duorarum, were significantly greater at night than during the day at one or more stations in the marsh. More grass shrimp, Palaemonetes sp., were caught at night than during the day, but the differences were not statistically significant. Individuals of each species appeared to migrate into the more shallow areas of the marsh at night. At night, brown shrimp and blue crabs were significantly more abundant in the marsh and bayward canal areas than in the upland canal and bay areas, white shrimp were significantly more abundant in the marsh area than in the other three areas, and pink shrimp were significantly more abundant in the marsh than in the upland and bayward canal areas. During the day, brown shrimp were significantly more abundant in the bayward canal area than in the upland canal and bay areas, while pink shrimp were significantly more abundant in the marsh area than in the upland canal area. The generally lower catches of each species in the open bay and upland canal areas when compared with the marsh and bayward canal areas were attributed to: 1) permanent loss of intertidal vegetation in the housing development; 2) low abundance of detrital material and benthic macroinvertebrates in the open bay and upland canal areas; and 3) eutrophic conditions in the upland canal area.Item Abundance of postlarval and juvenile shrimp.(1965) Baxter, K.N.; U.S. Fish and Wildlife Service CircularPostlarval shrimp were collected from Aransas Pass, Galveston, Gilchrist, and Sabine Pass, Texas to predict abundance of adult brown shrimp. An additional study was initiated to determine how year to year differences in shrimp growth may be associated with changes in abundance.Item Abundance of postlarval and juvenile shrimp.(1963) Baxter, K.N.; Furr, C.H.; U.S. Fish and Wildlife Service CircularSampling was conducted in Galveston Bay, Matagorda Bay and Sabine Lake, Texas to determine abundance of postlarval and juvenile shrimp.Item Abundance of postlarval shrimp-one index of future shrimping success.(1962) Baxter, K.N.; Proceedings of the Gulf and Caribbean Fisheries Institute.The feasibility of forecasting offshore abundance of commercial-size shrimp from preseason counts of postlarvae as they enter passes to inshore nursery grounds is discussed. Indices derived from the results of 3 year's postlarvae sampling inside Galveston Entrance are correlated with corresponding measures of juvenile abundance on the nursery grounds and, in turn, with appropriate measure of adult abundance are provided by commercial fishery statistics. The method employed to sample postlarvae is described.Item Abundance patterns of juvenile blue crabs (Callinectes sapidus) in nursery habitats of two Texas bays(Rosenstiel School of Marine and Atmospheric Science, 1990) Thomas, J.L.; Zimmerman, R.J.; Minello, T.J.; Bulletin of Marine ScienceIn Christmas Bay, Texas, monthly densities of juvenile blue crabs, smaller than 40 mm carapace width, were highest is seagrass (2.8 to 50.6 m exp -2), intermediate in salt marsh (1.3 to 22.1 m exp -2) and lowest on bare sand (0.6 to 5.6 m exp -2). In West Bay, Texas, where seagrasses were absent, crab densities were intermediate in salt marsh (2.2 to 13.0 m exp -2) to low on bare mud (0.1 to 1.7 m exp -2). The lowest seasonal abundances occurred in the early spring after mean sizes occurred in the late summer and fall corresponding to seasonal recruitment. Crabs were larger in mean size in salt marsh than in seagrass or nonvegetated habitats. Although seagrasses are often the preferred nursery of Callinectes sapidus, seagrasses occur infrequently in NW Gulf and salt marshes are used as an additional nursery. Features that increase utilization of salt marshes in the NW Gulf compared to other regions are reticulated marsh geomorphology, low tidal amplitude and long periods of tidal inundation.Item Abundance, age distributions, and growth of the Texas hard clam, Mercenaria mercenaria texana in Texas bays.(1986) Craig, M.A.; Bright, T.J.; Contributions in Marine ScienceThe hard clam Mercenaria mercenaria (Linne) has been well studied; however, little information is available on Mercenaria mercenaria texana, the subspecies found in Texas bays. Age and growth of Mercenaria mercenaria texana in Christmas Bay, Texas were determined by sectioning the shell and examining annual growth bands. Christmas Bay harbors a sparse population of older clams with few under five years old. Substrate type plays an important role in distribution and growth of the bivalve. Christmas Bay clams exhibited poorer recruitment and slower first year growth than did clams from Texas bays further south. Mercenaria mercenaria texana shows a pattern of growth similar to that reported in the literature for hybrids of Mercenaria mercenaria (Linne) and Mercenaria campechiensis (Gmelin).Item Abundance, distribution, and injury of four decapod crustaceans collected from the Dickinson Bayou and Bay and the revolving screens, intake and discharge canals of the P.H. Robinson Generating Station.(Texas A&M University Research Foundation, 1973) Strawn, K.; Reimer, R.Four species of commercially important decapod crustaceans collected in the intake area and discharge canal of the P.H. Robinson Generating Station were studied for 13 months. Salinity did not seem to have a great deal to do with abundance of the shrimps Penaeus aztecus and P. setiferus, or the blue crab, Callinectes sapidus. C. similis, on the other hand, although taken at fairly low salinities, seemed to prefer salinities near 15 ppt and higher and their presence in the collecting area was related to changes in salinity. Temperature had a definite affect on abundance in the discharge and intake canals. Maximum summer temperatures in the discharge canal appeared to be lethal. As temperatures approached 40 C, fewer animals were collected from the discharge canal than in the intake canal. The reverse occurred during the winter when temperatures dropped to below 18 C. When temperatures were low in the intake canal, numbers of crustaceans in the discharge canal were usually higher than in the intake canal. Although individuals of P. aztecus, P. setiferus, and C. sapidus were present during the entire study, there were definite annual cycles in abundance. P. aztecus increased in the collections in April and left in September. P. setiferus moved in during late July and left during November. C. sapidus were present throughout the year in larger numbers than the shrimp but the majority were taken from April through October. C. similis probably has a similar cyclic nature but because of the low salinities in the collecting area during the first part of the study, they did not move up into the bay. When salinities increased in July and August, they moved into the area. They began moving out in late October. Injury to crustaceans resulted from both plant operations and techniques used in conducting the research. This prevented a true assessment of plant related damage. Plant related injury was much lower than total injury recorded.Item American alligator study.(Texas Game and Fish Commission, Marine Laboratory., 1975) Smith, J.C.;Three research approaches were made during 1974 and 1975 to gain information about Texas alligator population dynamics: estimates from field researchers, night count surveys, and alligator nest counts. Analysis of 402 field personnel responses to questions about alligator numbers, population trend, and habitat showed total estimates in 1974 of 36,558 alligators in 97 counties with 7,678 square miles of alligator habitat. Twenty alligator night-count survey lines were run in 1974 and 31 in 1975. Analysis of night count survey results show and increase of 11.5% in alligator numbers for comparable lines in 1975. Accordingly, the statewide estimate of alligator numbers is adjusted for 40,672 alligators for 1975, Alligator nests at the J.D. Murphee Wildlife Management Area in Jefferson County were counted in 1974 and 1975 with totals of 61 and 65 nests being recorded. When coupled with 1973 data, results indicate a stable breeding population at high population density levels in the county showing greatest estimated numbers of alligators, Jefferson County.Item Analysis of populations of sport and commercial fin-fish in the coastal bays of Texas.(Texas Parks and Wildlife Department, 1967) Breuer, Joseph P.; Coastal Fisheries project reportsJuvenile game fish were sampled during 1967 in all Texas bay areas, including Galveston, with 60-foot bag seines; adult fish were sampled with trammel nets and drag seines. Coastwide, a general and healthy increase was noted in the production of juvenile redfish, Sciaenops ocellata, trout, Cynoscion nebulosus, and flounder, Paralichthys lethostigma compared to 1966. Juvenile sheepshead, Archosargus probatocephelus, and black drum, Pogonias cromis, declined in abundance in all areas. Adult fish samples indicated that no species increased in abundance in 1967.Item Analysis of Populations of Sports and Commercial Fin-fish in the Coastal Bays of Texas(Texas Parks and Wildlife Department, 1968) Breuer, Joseph P.; Coastal Fisheries Project Reports 1968Juvenile game fish were sampled in 1968 in all Texas bay areas with 60 ft. bag seines; adult fish were sampled in Galveston Bay by drag seine and in Aransas Bay and the Upper and Lower Laguna Madre with trammel nets. A general and significant increase in the relative abundance of juvenile redfish, Sciaenops ocellata, was noted. In the case of trout, Cynoscion nebulosus, flounder, Paralichthys lethostigma, black drum, Pogonias cromis, and sheepshead, Archosargus probatocephalus, there was either a decline in general abundance or no significant change from the previous year. While variations in abundance of adult fish occurred within bays, no coastwide patterns could be discerned. These samples were obtained in order to determine relative abundance, seasonal fluctuations in abundance and success of spawning. Captured fish of sufficient size and in good condition were tagged and released to study movements, migrations and rate of fishing harvest.