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1.
We evaluated two types of wire-mesh minnow traps for sampling mummichogs (Fundulus heteroclitus) from intertidal rivulets on the surface of a salt marsh. In field trials, mean catch (no. of fish trap−1) did not differ significantly between trap types nor across soak times ranging from 30 to 240 min. Catch rate (no. of fish trap−1 min−1) was significantly (K-W ANOVA on ranked data, H4df=24.79; p<0.001) greater at shorter soak times, and larger size classes (>45 mm TL) of fish were relatively more abundant (Kolmogorov-Smirnov test, p<0.0001) in collections from double-funnel cylindrical traps (volume=10,330 cm3) compared to rectangular traps having about twice the volume and a single funnel cylindrical traps (volume=10,330 cm3) compared to rectangular traps having about twice the volume and a single funnel opening. We estimated entry and escape rates by adding marked fish to traps at initial densities of 30, 60, and 120 trap−1 and measuring changes in the numbers of marked and unmarked fish in each trap type at soak times ranging from 15 to 120 min during the flood stage of the tidal cycle. Escape rate was almost, twice as great from the two-funnel cylindrical traps (0.77 fish min−1) than from the single-funnel rectangular type (0.42 fish min−1) but entry rates did not differ significantly (K-W ANOVA, H4df=0.06; p=0.813) between trap types. Escape rate increased and entry rate decreased as fish density within traps was increased. Escape rates were highest immediately following immersion of the traps, but approached a constant value after 30 min. Trap-specific rates of entry and escape can be affected by a variety of factors including physical characteristics of different trap types, method and timing of trap deployment, and fish behavior. Catch data from minnow traps are unlikely to be useful in measuring relative abundance of mummichogs among habitats unless very short soak times (≤60 min) are used and calibration tests are performed. Use of longer soak times virtually ignores the dynamics involved in determining catch, and is unlikely to provide accurate information on either abundance or size distribution of mummichogs from tidal marsh habitats. 相似文献
2.
Alyson E. Santoro 《Hydrogeology Journal》2010,18(1):187-202
Microbial communities inhabiting “subterranean estuaries” along the subsurface freshwater–saltwater continuum determine the fate of nitrogen discharged to coastal waters. Little is known about the microbes that comprise these communities, or what their ecological and biogeochemical responses will be to increased salinity resulting from saltwater intrusion and aquifer salinization. This review covers basic aspects of the nitrogen cycle relevant to the coastal subsurface and provides a framework for predicting the types of microbes and nitrogen transformations that exist in different subterranean estuary systems. Literature concerning the freshwater–saltwater mixing zones of surficial estuaries, where microbial communities are better characterized, is also reviewed to explore what is known about the impact of increasing salinity on both the community composition and biogeochemical function of the microbial assemblage. Collectively, these studies suggest that salinization will alter microbial community composition for all functional groups involved in nitrogen cycling, and may lead to decreases in nitrification and coupled nitrification-denitrification, and increases in dissimilatory nitrate reduction to ammonium (DNRA). Future collaboration between hydrogeologists and microbial ecologists is needed to fully predict the impact of saltwater intrusion on subsurface microbial communities. 相似文献
3.
Raúl Prellezo Paolo AccadiaJesper L. Andersen Bo S. AndersenErik Buisman Alyson LittleJ. Rasmus Nielsen Jan Jaap PoosJeff Powell Christine Röckmann 《Marine Policy》2012,36(2):423-431
The lessons learned from a review of thirteen existing European bio-economic models used in the evaluation of EU policies are presented. How these models compare and differ in terms of their biological and economic components, the integration between the components, which indicators are selected and how they are used, are described and analysed. The article concludes that the multitude of construction differences reflects the necessity of adapting the modelling approach to answer different questions. Since real life questions in fisheries are so diverse, answering them requires a diversity of models. 相似文献
4.
Alyson Cartwright Jay Quade Scott Stine Kenneth D. Adams Wallace Broecker Hai Cheng 《Quaternary Research》2011,76(3):430-440
Evidence from shoreline and deep-lake sediments show Laguna Cari-Laufquén, located at 41°S in central Argentina, rose and fell repeatedly during the late Quaternary. Our results show that a deep (> 38 m above modern lake level) lake persisted from no later than 28 ka to 19 ka, with the deepest lake phase from 27 to 22 ka. No evidence of highstands is found after 19 ka until the lake rose briefly in the last millennia to 12 m above the modern lake, before regressing to present levels. Laguna Cari-Laufquén broadly matches other regional records in showing last glacial maximum (LGM) highstands, but contrasts with sub-tropical lake records in South America where the hydrologic maximum occurred during deglaciation (17–10 ka). Our lake record from Cari-Laufquén mimics that of high-latitude records from the Northern Hemisphere. This points to a common cause for lake expansions, likely involving some combination of temperature depression and intensification of storminess in the westerlies belt of both hemispheres during the LGM. 相似文献
5.
Jack C. Parker Ungtae Kim Alyson Fortune Steffen Griepke James P. Galligan Amber Bonarrigo 《Ground Water Monitoring & Remediation》2017,37(1):51-66
The objective of in situ thermal treatment is typically to reduce the contaminant mass or average soil concentration below a specified value. Evaluation of whether the objective has been met is usually made by averaging soil concentrations from a limited number of soil samples. Results from several field sites indicate large performance uncertainty using this approach, even when the number of samples is large. We propose a method to estimate average soil concentration by fitting a log normal probability model to thermal mass recovery data. A statistical approach is presented for making termination decisions from mass recovery data, soil sample data, or both for an entire treatment volume or for subregions that explicitly considers estimation uncertainty which is coupled to a stochastic optimization algorithm to identify monitoring strategies to meet objectives with minimum expected cost. Early termination of heating in regions that reach cleanup targets sooner enables operating costs to be reduced while ensuring a high likelihood of meeting remediation objectives. Results for an example problem demonstrate that significant performance improvement and cost reductions can be achieved using this approach. 相似文献
6.
Sarah M. Principato Alexis N. Moyer Alyson G. Hampsch Heather A. Ipsen 《Boreas: An International Journal of Quaternary Research》2016,45(3):470-482
The properties of streamlined glacial landforms and palaeo‐flow indicators in the valleys of Viðidalur, Vatnsdalur and Svínadalur in northern Iceland were quantified using spatial analyses. Drumlins and mega‐scale glacial lineations (MSGL) were visually identified using satellite imagery from Google Earth, the National Land Survey of Iceland (NLSI) Map Viewer and Landsat satellites, and using aerial photographs from the NLSI. A semi‐automated technique was developed using ENVI to determine regions in northern Iceland likely to contain streamlined landforms. The outlines of the identified landforms were manually delineated in Google Earth, and all analyses were conducted in ArcGIS using a 20 m digital elevation model (DEM) of Iceland from the NLSI. Smaller features such as flutes, grooves and striations were measured in the field. At least 543 drumlins and 90 MSGL were identified in the three valleys. Average elongation ratios for Viðidalur, Vatnsdalur and Svínadalur are 4.3:1, 5.2:1 and 6.7:1, respectively. The average density of streamlined landforms is 2.34 landforms per 1 km2. Striations and orientation data of the drumlins and MSGL demonstrate ice flow to the northwest into Húnaflói. Parallel conformity is higher in the valley of Svínadalur (9° standard deviation) than in Viðidalur (12°) and Vatnsdalur (16°). Packing values are generally higher in the centre of each valley. The properties of streamlined landforms in the valleys of Viðidalur, Vatnsdalur and Svínadalur support the presence of palaeo‐ice stream activity on northern Iceland. Palaeo‐ice streams flowed from these regions into Húnaflói, supplying ice to the margin of the Iceland Ice Sheet during the Last Glacial Maximum. These palaeo‐ice streams provide a mechanism for ice centres from the mainland of Iceland to reach the shelf‐slope break. 相似文献
7.
Jennifer M. Fitchett Su-Marie Fortune Gijsbert Hoogendoorn 《Singapore journal of tropical geography》2020,41(2):171-189
Favourable climate forms a key resource in attracting tourists to tropical coastal destinations. Warm temperatures and clear skies are ideal conditions for tourists to spend long days on the beach and engage in outdoor activities. By contrast, rain, strong winds, high humidity and cloud cover serve as a deterrent. These factors influence tourists’ choice of destination, timing and duration of stay, and enjoyment of their vacation, and are therefore imperative to the economic sustainability of a destination. This study explores tourists’ self-reported sensitivity to and satisfaction of weather and climatic conditions during visits to five tropical Indian Ocean Islands through the analysis of 13 618 TripAdvisor reviews. An average of 12 per cent of reviews mentioned climatic factors, indicating a relatively high sensitivity to climate, with a highest proportion of 15.7 per cent of reviews for Maldives. Rain was mentioned most frequently (21 per cent of climate mentions), followed by sunshine and hot conditions. The majority of the reviews were authored in August and May, and more than 40 per cent were written in a neutral tone, with similar but lower proportions of overtly negative and positive reviews. Thematic analysis of reviews highlight the importance of preparedness amongst tourists, emphasizing the need for accurate information communicated. 相似文献
8.
A distinctive Shell and Sand Sheet found beneath the marine ponds of Anegada, British Virgin Islands, was formed by a post-1650 AD overwash event, but its origin (tsunami or hurricane) was unclear. This study assesses the taphonomic characters of the shell and large clast material (>2?mm) to determine its provenance and origin. Pond-wide stratigraphic units (Shelly Mud, Shell and Sand Sheet, Mud Cap) were analyzed (12 samples) at four sites in Bumber Well and Red Pond along with eight samples from the Shell and Sand Sheet in a 2-km transect of Bumber Well. Mollusks in the pond muds include Anomalocardia spp. and cerithids with no allochthonous shells from the offshore reef-flat. Results show that the shells and clasts (>2?mm) are derived from the erosion and winnowing of the underlying Shelly Mud of the former marine pond, forming a distinctive sheet-like deposit with Homotrema sand. The Shell and Sand Sheet contains articulated Anomalocardia bivalves and moderate numbers of angular fragments (approximately 35%) that are likely from crab predation. Radiocarbon dates of articulated Anomalocardia specimens from the Shell and Sand Sheet range widely (approximately 4000?years), with shell condition (pristine to variably preserved) showing no correlation with age. The articulated condition of the bivalves with the wide-ranging dates suggests erosion and winnowing of the underlying Shelly Mud but minimal transport of the bivalves. The Shell and Sand Sheet has taphonomic characteristics indicative of a widespread tsunami overwash (sheet-like extent and articulated specimens) but lacks allochthonous reef-flat shells. Reef-flat shell material may not have penetrated the pond, as a tsunami would have to cross the reef-flat and overtop high dunes (2.2?m) hindering transport of larger shell material but allowing the Homotrema sand to penetrate. Processes including hurricane overwash, pond wave action, or tidal channel opening and closure are not favoured interpretations as they would not produce extensive sheet-like deposits. Taphonomic analysis is hampered by the limited (400?C500?years BP) depositional history from Anegada??s ponds and the lack of comparative data from other Caribbean locations. 相似文献
9.
New‐build development has become associated with the phase of gentrification that has taken shape since the mid‐1990s. This article examines the gentrification of Deep Deuce, a historically black neighborhood in Oklahoma City. An analysis of property sales identifies the major external agents involved and leads to a discussion of the area's racial turnover. Considering the relational aspects of place, specifically how the identity of Deep Deuce has been constructed in relation to the nearby area of Bricktown, provides new insights on the nature of changes affecting this neighborhood. Supplementing this with an examination of resistance to the gentrification of Deep Deuce shows how city neighborhoods can come to be defined by limited understandings of place, and how historic preservation efforts can generate symbolic capital and facilitate cultural appropriation. This article also contributes to the study of gentrification in smaller metropolitan areas. 相似文献
10.
Nicholas P. Ettinger Toti E. Larson Charles Kerans Alyson M. Thibodeau Kelly E. Hattori Sean M. Kacur Rowan C. Martindale 《Sedimentology》2021,68(1):63-107
Severe global climate change led to the deterioration of environmental conditions in the oceans during the Toarcian Stage of the Jurassic. Carbonate platforms of the Western Tethys Ocean exposed in Alpine Tethyan mountain ranges today offer insight into this period of environmental upheaval. In addition to informing understanding of climate change in deep time, the effect of ancient carbon cycle perturbations on carbonate platforms has important implications for anthropogenic climate change; the patterns of early Toarcian environmental deterioration are similar to those occurring in modern oceans. This study focuses on the record of the early Toarcian Oceanic Anoxic Event (ca 183.1 Ma) in outcrops of the north‐west Adriatic Carbonate Platform in Slovenia. Amidst environmental deterioration, the north‐west Adriatic Platform abruptly transitioned from a healthy, shallow‐water environment with diverse metazoan ecosystems to a partially drowned setting with low diversity biota and diminished sedimentation. An organic carbon‐isotope excursion of ?2.2‰ reflects the massive injection of CO2 into the ocean‐atmosphere system and marks the stratigraphic position of the Toarcian Oceanic Anoxic Event. A prominent dissolution horizon and suppressed carbonate deposition on the platform are interpreted to reflect transient shoaling of the carbonate compensation depth to unprecedentedly shallow levels as the dramatic influx of CO2 overwhelmed the ocean’s buffering capacity, causing ocean acidification. Trace metal geochemistry and palaeoecology highlight water column deoxygenation, including the development of photic‐zone anoxia, preceding and during the Toarcian Oceanic Anoxic Event. Ocean acidification and reduced oxygen levels likely had a profoundly negative effect on carbonate‐producing biota and growth of the Adriatic Platform. These effects are consistent with the approximate doubling of the concentration of CO2 in the ocean‐atmosphere system from pre‐event levels, which has previously been linked to a volcanic triggering mechanism. Mercury enrichments discovered in this study support a temporal and genetic link between volcanism, the Toarcian Oceanic Anoxic Event and the carbonate crisis. 相似文献