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281.
Lindsay A. Glass Jay R. Rooker Richard T. Kraus G. Joan Holt 《Journal of Sea Research》2008,59(4):259-268
Several flatfish species, including southern flounder (Paralichthys lethostigma) recruit to estuaries during early life. Therefore, evaluation of estuarine sites and habitats that serve as nurseries is critical to conservation and management. The present study used density data in conjunction with biochemical condition and growth measurements to evaluate settlement sites used by southern flounder in the Galveston Bay Estuary (GBE). In 2005, beam-trawl collections were made in three major sections of the GBE (East Bay, Galveston Bay, West Bay). Three sites were sampled in each bay. Within each sampling site, replicate collections were taken from three habitats: 1) marsh edge (< 1 m depth), 2) intermediate zone (10–20 m from marsh interface; 1 m depth), and 3) bay zone (typically > 100 m from marsh interface; depth > 1 m). Average size of southern flounder collected was 12–19 mm standard length, and peak densities occurred in January and February. Catch data indicated that densities of southern flounder were significantly greater in East Bay (2.75 per 100 m2) than in Galveston Bay (0.91 per 100 m2) or in West Bay (0.45 per 100 m2). Densities were statistically similar among habitats. Otolith-based estimates of age indicated that the majority of southern flounder collected were 35–45 days old and derived from early December to early January hatch-dates. Growth rates were similar among bays and among habitats, with the average growth rate being 0.40 mm day− 1 (range: 0.21–0.76 mm day− 1). RNA:DNA was above the established baseline value for nutritional stress, indicating that newly settled southern flounder in the GBE were in relatively high condition. Habitat-specific differences in RNA:DNA ratios were not observed; however, ratios were significantly lower in West Bay (average 8.0) than in East Bay (average 9.5) or in Galveston Bay (average 9.8), suggesting the condition of new recruits may vary spatially within the GBE. Findings from the current study suggest density and condition of newly settled southern flounder vary at the bay scale, suggesting that parts of GBE do not function equally as nurseries. 相似文献
282.
J. L. Granja Bruña A. Muñoz-Martín U. S. ten Brink A. Carbó-Gorosabel P. Llanes Estrada J. Martín-Dávila D. Córdoba-Barba M. Catalán Morollón 《Marine Geophysical Researches》2010,31(4):263-283
The Muertos Trough in the northeast Caribbean has been interpreted as a subduction zone from seismicity, leading to infer
a possible reversal subduction polarity. However, the distribution of the seismicity is very diffuse and makes definition
of the plate geometry difficult. In addition, the compressive deformational features observed in the upper crust and sandbox
kinematic modeling do not necessarily suggest a subduction process. We tested the hypothesized subduction of the Caribbean
plate’s interior beneath the eastern Greater Antilles island arc using gravity modeling. Gravity models simulating a subduction
process yield a regional mass deficit beneath the island arc independently of the geometry and depth of the subducted slab
used in the models. This mass deficit results from sinking of the less dense Caribbean slab beneath the lithospheric mantle
replacing denser mantle materials and suggests that there is not a subducted Caribbean plateau beneath the island arc. The
geologically more realistic gravity model which would explain the N–S shortening observed in the upper crust requires an overthrusted
Caribbean slab extending at least 60 km northward from the deformation front, a progressive increase in the thrusting angle
from 8° to 30° reaching a maximum depth of 22 km beneath the insular slope. This new tectonic model for the Muertos Margin,
defined as a retroarc thrusting, will help to assess the seismic and tsunami hazard in the region. The use of gravity modeling
has provided targets for future wide-angle seismic surveys in the Muertos Margin. 相似文献
283.
The seasonal and interannual dynamics of the biomass and spatial distribution of a macrophyte meadow were explored in a Mediterranean coastal lagoon (Albufera des Grau, Balearic Islands) from 2002 to 2007. The dynamics in the main physicochemical variables were also analysed to assess the factors involved in the spatiotemporal variability of the submerged macrophytes. 相似文献
284.
Joan E. Cartes Emanuela Fanelli Vanesa Papiol Francesc Maynou 《Journal of Sea Research》2010,63(3-4):180-190
The spatial and temporal changes of near-bottom macrofauna (suprabenthos and macroplankton) and the trophic relationships of megabenthic decapod crustaceans were analyzed off the Catalonian coasts (western Mediterranean) around Berenguera submarine canyon in four periods (April and December 1991, March and July 1992) and four zones (within Berenguera Canyon at ca. 450 m, and on adjacent slope at ca. 400, 600 m and 1200 m). In March 1992, we found the highest macrofauna abundance and the smallest sizes in the canyon, suggesting a positive effect of river discharges on suprabenthos recruitment. By contrast, macroplankton (decapods, fishes and euphausiids) did not show higher recruitment into canyons. After analyzing the diet of 23 decapod crustaceans, we found a significant segregation between guilds feeding on zooplankton and on benthos. Zooplankton (euphausiids and Pasiphaeidae) and infauna (polychaetes, Calocaris macandreae and ophiuoroids) were consistently the main prey exploited by decapod crustaceans around Berenguera Canyon. We also found some macrophyte (Posidonia oceanica) consumption, which was higher in periods of water column homogeneity (winter–spring and late autumn). Positive correlations between decapods' gut fullness (F) and decapod abundance indicate feeding aggregations, while positive correlations were also found between F and Llobregat River (situated ca. 18 km from Berenguera head) flow 1 to 2 months before sampling. Increases in F were delayed only 1 month when zooplankton feeders were analyzed alone, while benthos feeders did not show significant relationships with any environmental variables. That indicates that the response of megabenthic decapods feeding on benthos to environmental shifts is slower than that of zooplankton feeders. The importance of river flows in enhancing food supply of macro- and megabenthos dwelling close to submarine canyons was apparent, with a delay in the fauna response of 0–2 months after river flow peaks. 相似文献
285.
Xing Zhao Ya Zhiyu Wang Zhaowei Sun Bing Fu Hongrui Bénédicte Massamba-Courtois Joanès 《Water Resources》2020,47(1):95-102
Water Resources - The baffled flasks were used to simulate regular wave and breaking wave at different oscillation intensities to study the effects of wave strength, reaction time, and dispersant... 相似文献
286.
Sunil Varma Jim Underschultz Tess Dance Robert Langford Joan Esterle Kevin Dodds Dominique van Gent 《Marine and Petroleum Geology》2009
Coal-fired power stations in Collie, Western Australia emit 10 million tonnes of CO2 per year. This study assesses the potential opportunities of geological storage of CO2 both within the Collie Basin and the onshore part of the adjacent Southern Perth Basin of Western Australia within 50 km of Collie town site through a desktop evaluation of existing data. The aquifers and coal formations within both basins have been evaluated for their suitability for storage based on geological, geographical and environmental criteria related to storage capacity, injectivity, proximity to sources of CO2, location of other natural resources and containment security. The study has concluded that there is limited scope for large-scale storage of CO2 within the Collie Basin. In addition the potential for storage within coals of either basin is not a viable solution. This assessment is based on published criteria for CO2 storage in sedimentary basins and coal-bearing formations. 相似文献
287.
E. Ortega-Retuerta I. Reche E. Pulido-Villena S. Agustí C.M. Duarte 《Marine Chemistry》2009,115(1-2):59-65
Transparent exopolymer particles (TEP) are formed by the assembly of dissolved precursors, mainly mono and polysaccharides (DMCHO and DPCHO) that are released by microorganisms. Although TEP formation plays a significant role in carbon export to deep waters and can affect gas exchange at the sea surface, simultaneous measurements of TEP and their precursors in natural waters have been scantly reported. In this study, we described the spatial (vertical and regional) distribution of TEP, DMCHO and DPCHO in a region located around the Antarctic Peninsula, assessed their contribution to the total organic carbon pool, and explored their relationships with phytoplankton (with chlorophyll a (chl a) as a proxy) and bacteria. TEP concentration ranged from undetectable values to 48.9 µg XG eq L− 1 with a mean value of 15.4 µg XG eq L− 1 (11.6 µg TEP-C L− 1). DMCHO and DPCHO showed average values of 4.3 µmol C L− 1 and 8.6 µmol C L− 1, respectively. We did not find simple relationships between the concentrations of TEP and dissolved carbohydrates, but a negative correlation between DMCHO and DPCHO was observed. Chl a was the best regressor of TEP concentration in waters within the upper mixed layer, while bacterial production was the best regressor of TEP concentration below the mixed layer, underlining the direct link between these particles and bacterial activity in deep waters. 相似文献
288.
Joan E. Cartes Francesc Maynou Emanuela Fanelli Chiara Romano Valeria Mamouridis Vanesa Papiol 《Journal of Sea Research》2009,61(4):244-257
The distribution of megabenthic epifauna (invertebrates) in the Balearic Basin (western Mediterranean) has been analyzed at depths between 427 and 2265 m after compiling samplings performed in 1985–1992 and 2007–2008 with an OTSB-14 bottom trawl. 84 epibenthic taxa of invertebrates (excluded decapod crustaceans) were collected. Epibenthic assemblages were organized in five groups (n-MDS analyses) as a function of increasing depth: upper slope assemblage, U, hauls between 427 and 660 m; middle slope assemblages M1 and M2, hauls between 663–876 m and 864–1412 m, respectively; lower slope assemblages L1 and L2, hauls between 1488–1789 m and 1798–2265 m, respectively). We found significant differences in assemblage composition between all depth-adjacent pairs of groups. Trends in the distribution of biomass vs. depth and within assemblages varied when hauls taken over insular were compared to those over mainland slopes. Over insular slopes we found (n-MDS) only four distinct depth assemblages, with significant differences between all depth-adjacent group pairs, except between L1 and L2. Over the mainland slope, two peaks of biomass situated at U (427–660 m) and at L1 (1488–1789 m) were clearly identified, attributable to the echinoid Brissopsis lyrifera and holothurian Molpadia musculus at U and to the synallactid holothurian Mesothuria intestinalis at L1. The distribution of biomass vs. depth on insular slopes did not follow this pattern, showing no significant biomass peak below 1000 m and a total biomass an order of magnitude lower than adjacent to the mainland. After compiling available environmental data over the mainland slope off Barcelona, we found coincidence between the peak biomass of Mesothuria intestinalis and: i) a significant increase of labile OM (%OrgC, C/N, hydrolizable aminoacids–EHAA, and the EHAA/THAA-total hydrolizable aminoacids-ratio) over 1600 m; and ii) an increase of turbidity and T at 1500–1600 m in February 2008. We suggest that such OM inputs must likely be associated to the formation of nepheloid layers close to submarine canyons, probably associated with oceanographic processes in deep water masses in the area. This would explain why aggregations of M. intestinalis were linked to the mainland part of the Balearic basin, with highest densities located south of canyons. If hotspots of biomass as cited here for M. intestinalis are regulated by factors such as river inputs, both natural climatic changes (e.g. changes in rainfall regimes) and human impact (e.g. river damming) may affect deep-Mediterranean communities below 1000 m. 相似文献
289.
290.