990 resultados para Conquest of Mexico
Resumo:
Precipitation and temperature in Florida responds to climate teleconnections from both the Pacific and Atlantic regions. In this region south of Lake Okeechobee, encompassing NWS Climate Divisions 5, 6, and 7, modern movement of surface waters are managed by the South Florida Water Management District and the US Army Corps of Engineers for flood control, water supply, and Everglades restoration within the constraints of the climatic variability of precipitation and evaporation. Despite relatively narrow, low-relief, but multi-purposed land separating the Atlantic Ocean from the Gulf of Mexico, South Florida has patterns of precipitation and temperature that vary substantially on spatial scales of 101–102 km. Here we explore statistically significant linkages to precipitation and temperature that vary seasonally and over small spatial scales with El Niño-Southern Oscillation (ENSO), the Atlantic Multidecadal Oscillation (AMO), and the Pacific Decadal Oscillation (PDO). Over the period from 1952 to 2005, ENSO teleconnections exhibited the strongest influence on seasonal precipitation. The Multivariate ENSO Index was positively correlated with winter (dry season) precipitation and explained up to 34 % of dry season precipitation variability along the southwest Florida coast. The AMO was the most influential of these teleconnections during the summer (wet season), with significant positive correlations to South Florida precipitation. These relationships with modern climate parameters have implications for paleoclimatological and paleoecological reconstructions, and future climate predictions from the Greater Everglades system.
Resumo:
The effects of nutrient availability and litter quality on litter decomposition were measured in two oligotrophic phosphorus (P)-limited Florida Everglades esturies, United States. The two estuaries differ, in that one (Shark River estuary) is directly connected to the Gulf of Mexico and receives marine P, while the other (Taylor Slough estuary) does not receive marine P because Florida Bay separates it from the Gulf of Mexico. Decomposition of three macrophytes.Cladium jamaicense, Eleochaaris spp., andJuncus roemerianus, was studied using a litter bag technique over 18 mo. Litter was exposed to three treatments: soil surface+macroinvertebrates (=macro), soil surface without macroinvertebrates (=wet), and above the soil and water (=aerial). The third treatment replicated the decomposition of standing dead leaves. Decomposition rates showed that litter exposed to the wet and macro treatments decomposed significantly faster than the aerial treatment, where atmospheric deposition was the only source of nutrients. Macroinvertebrates had no influence on litter decompostion rates.C. jamaicense decomposed faster at sites, with higher P, andEleocharis spp. decomposed significantly faster at sites with higher nitrogen (N). Initial tissue C:N and C:P molar ratios revealed that the nutrient quality of litter of bothEleocharis spp. andJ. roemerianus was higher thanC. jamaicense, but onlyEleocharis spp. decomposed faster thanC. jamaicense. C. jamaicense litter tended to immobilize P, whileEleocharis spp. litter showed net remineralization of N and P. A comparison with other estuarine and wetland systems revealed the dependence of litter decomposition on nutrient availability and litter quality. The results from this experiment suggest that Everglades restoration may have an important effect on key ecosystem processes in the estuarine ecotone of this landscape.
Resumo:
Paracalanus quasimodo and Temora turbinata are two calanoid copepods prominent in the planktonic communities of the southeastern United States. Despite their prominence, the species and population level structure of these copepods is yet unexplored. The phylogeographic, temporal and phylogenetic structure of P. quasimodo and T. turbinata are examined in my study. Samples were collected from ten sites along the Gulf of Mexico and Florida peninsular coasts. Three sites were sampled quarterly for two years. Individuals were screened for unique ITS-1 sequences with denaturing gradient gel electrophoresis. Unique variants were sequenced at the nuclear ITS-1 and mitochondrial COI loci. Sampling sites were analyzed for pairwise community differences and for variances between geographic and temporal groupings. Genetic variants were analyzed for phylogenetic and coalescent topology. Paracalanus quasimodo is highly structured geographically with populations divided between the Gulf of Mexico, temperate Atlantic and subtropical Atlantic, in addition to isolation by distance. No significant differences were detected between the T. turbinata samples. Both P. quasimodo and T. turbinata are stable within sites over time and between sites within a sampling period, with two exceptions. The first was a pilot sample from Miami taken two years prior to the general sampling whose community showed significant differences from most of the other Miami samples. Paracalanus quasimodo had a positive correlation of Fst with time. The second was high temporal variability detected in the samples from Fort Pierce. Phylogenetically, both P. quasimodo and T. turbinata were in well supported, congeneric clades. Paracalanus quasimodo was not monophyletic, divided into two well-supported clades. Temora turbinata variants were in one clade with insignificant support for topology within the clade and very little intraspecific variation. Paracalanus quasimodo and T. turbinata populations show opposite trends. Paracalanus quasimodo occurs near shore and shows population structure mediated by hydrological features and distance, both geographic and temporal. The phylogeny shows two deeply divergent clades suggestive of cryptic speciation. In contrast, T. turbinata populations range further offshore and show little geographic or temporal structure. However, the low genetic variation detected in this region suggests a recent bottleneck event.
Resumo:
Routine monitoring of environmental pollution demands simplicity and speed without sacrificing sensitivity or accuracy. The development and application of sensitive, fast and easy to implement analytical methodologies for detecting emerging and traditional water and airborne contaminants in South Florida is presented. A novel method was developed for quantification of the herbicide glyphosate based on lyophilization followed by derivatization and simultaneous detection by fluorescence and mass spectrometry. Samples were analyzed from water canals that will hydrate estuarine wetlands of Biscayne National Park, detecting inputs of glyphosate from both aquatic usage and agricultural runoff from farms. A second study describes a set of fast, automated LC-MS/MS protocols for the analysis of dioctyl sulfosuccinate (DOSS) and 2-butoxyethanol, two components of Corexit®. Around 1.8 million gallons of those dispersant formulations were used in the response efforts for the Gulf of Mexico oil spill in 2010. The methods presented here allow the trace-level detection of these compounds in seawater, crude oil and commercial dispersants formulations. In addition, two methodologies were developed for the analysis of well-known pollutants, namely Polycyclic Aromatic Hydrocarbons (PAHs) and airborne particulate matter (APM). PAHs are ubiquitous environmental contaminants and some are potent carcinogens. Traditional GC-MS analysis is labor-intensive and consumes large amounts of toxic solvents. My study provides an alternative automated SPE-LC-APPI-MS/MS analysis with minimal sample preparation and a lower solvent consumption. The system can inject, extract, clean, separate and detect 28 PAHs and 15 families of alkylated PAHs in 28 minutes. The methodology was tested with environmental samples from Miami. Airborne Particulate Matter is a mixture of particles of chemical and biological origin. Assessment of its elemental composition is critical for the protection of sensitive ecosystems and public health. The APM collected from Port Everglades between 2005 and 2010 was analyzed by ICP-MS after acid digestion of filters. The most abundant elements were Fe and Al, followed by Cu, V and Zn. Enrichment factors show that hazardous elements (Cd, Pb, As, Co, Ni and Cr) are introduced by anthropogenic activities. Data suggest that the major sources of APM were an electricity plant, road dust, industrial emissions and marine vessels.
Resumo:
The first essay developed a respondent model of Bayesian updating for a double-bound dichotomous choice (DB-DC) contingent valuation methodology. I demonstrated by way of data simulations that current DB-DC identifications of true willingness-to-pay (WTP) may often fail given this respondent Bayesian updating context. Further simulations demonstrated that a simple extension of current DB-DC identifications derived explicitly from the Bayesian updating behavioral model can correct for much of the WTP bias. Additional results provided caution to viewing respondents as acting strategically toward the second bid. Finally, an empirical application confirmed the simulation outcomes. The second essay applied a hedonic property value model to a unique water quality (WQ) dataset for a year-round, urban, and coastal housing market in South Florida, and found evidence that various WQ measures affect waterfront housing prices in this setting. However, the results indicated that this relationship is not consistent across any of the six particular WQ variables used, and is furthermore dependent upon the specific descriptive statistic employed to represent the WQ measure in the empirical analysis. These results continue to underscore the need to better understand both the WQ measure and its statistical form homebuyers use in making their purchase decision. The third essay addressed a limitation to existing hurricane evacuation modeling aspects by developing a dynamic model of hurricane evacuation behavior. A household’s evacuation decision was framed as an optimal stopping problem where every potential evacuation time period prior to the actual hurricane landfall, the household’s optimal choice is to either evacuate, or to wait one more time period for a revised hurricane forecast. A hypothetical two-period model of evacuation and a realistic multi-period model of evacuation that incorporates actual forecast and evacuation cost data for my designated Gulf of Mexico region were developed for the dynamic analysis. Results from the multi-period model were calibrated with existing evacuation timing data from a number of hurricanes. Given the calibrated dynamic framework, a number of policy questions that plausibly affect the timing of household evacuations were analyzed, and a deeper understanding of existing empirical outcomes in regard to the timing of the evacuation decision was achieved.
Resumo:
From the multitudinous streets of Mexico City through the lonely highways of the United States, this collection of poetry charts strategies of representation across complex territories of culture and gender. These poems represent dialogues and negotiations with popular and poetic narratives of the Americas, as well as individual quests for identification against a backdrop of postmodern and postcolonial concerns. The effect is like that of a collage that elicits the reader's participation in order to produce individual signification. The figures alluded to in these pieces enact the struggle to situate the self within multiple registers of discourse and identity, as well as to establish a site from which to speak.
Resumo:
The cores and dredges described in this report were taken during the Vema 17 Expedition from December 1960 until October 1961 by the Lamont Geological Observatory, Columbia University from the R/V Vema. An approximate total of 210 cores, dredges and camera stations were recovered and are available at Lamont-Doherty Earth Observatory for sampling and study.
Resumo:
The present data compilation includes dinoflagellates growth rate, grazing rate and gross growth efficiency determined either in the field or in laboratory experiments. From the existing literature, we synthesized all data that we could find on dinoflagellates. Some sources might be missing but none were purposefully ignored. We did not include autotrophic dinoflagellates in the database, but mixotrophic organisms may have been included. This is due to the large uncertainty about which taxa are mixotrophic, heterotrophic or symbiont bearing. Field data on microzooplankton grazing are mostly comprised of grazing rate using the dilution technique with a 24h incubation period. Laboratory grazing and growth data are focused on pelagic ciliates and heterotrophic dinoflagellates. The experiment measured grazing or growth as a function of prey concentration or at saturating prey concentration (maximal grazing rate). When considering every single data point available (each measured rate for a defined predator-prey pair and a certain prey concentration) there is a total of 801 data points for the dinoflagellates, counting experiments that measured growth and grazing simultaneously as 1 data point.
Resumo:
The metabolic rate of organisms may either be viewed as a basic property from which other vital rates and many ecological patterns emerge and that follows a universal allometric mass scaling law; or it may be considered a property of the organism that emerges as a result of the organism's adaptation to the environment, with consequently less universal mass scaling properties. Data on body mass, maximum ingestion and clearance rates, respiration rates and maximum growth rates of animals living in the ocean epipelagic were compiled from the literature, mainly from original papers but also from previous compilations by other authors. Data were read from tables or digitized from graphs. Only measurements made on individuals of know size, or groups of individuals of similar and known size were included. We show that clearance and respiration rates have life-form-dependent allometries that have similar scaling but different elevations, such that the mass-specific rates converge on a rather narrow size-independent range. In contrast, ingestion and growth rates follow a near-universal taxa-independent ~3/4 mass scaling power law. We argue that the declining mass-specific clearance rates with size within taxa is related to the inherent decrease in feeding efficiency of any particular feeding mode. The transitions between feeding mode and simultaneous transitions in clearance and respiration rates may then represent adaptations to the food environment and be the result of the optimization of tradeoffs that allow sufficient feeding and growth rates to balance mortality.
Resumo:
Site 619, located in the Pigmy Basin off the coast of Louisiana, penetrated the late Quaternary Ericson Zones X, Y, and Z. The penetrated section can be divided into four intervals. The lower interval (below 157 m sub-bottom) comprises 51 m of displaced sediments which probably originated from the Louisiana continental shelf. The upper three intervals (above 157 m) are dominated by pelagic/hemipelagic sedimentation associated with a closed basin. These are divided on the basis of planktonic foraminifers into Zones X, Y, and Z. These warm-cool water intervals are identified mainly by using the Globorotalia menardii complex (warm) and G. inflata (cool). The intervals correlate with published curves taken from piston core samples in the western Gulf of Mexico.