Using high-resolution measures of aquatic ecosystem metabolism and water quality, we investigated the importance of hydrological
inputs of phosphorus (P) on ecosystem dynamics in the oligotrophic, P-limited coastal Everglades. Due to low nutrient status
and relatively large inputs of terrestrial organic matter, we hypothesized that the ponds in this region would be strongly
net heterotrophic and that pond gross primary production (GPP) and respiration (R) would be the greatest during the “dry,”
euhaline estuarine season that coincides with increased P availability. Results indicated that metabolism rates were consistently
associated with elevated upstream total phosphorus and salinity concentrations. Pulses in aquatic metabolism rates were coupled
to the timing of P supply from groundwater upwelling as well as a potential suite of hydrobiogeochemical interactions. We
provide evidence that freshwater discharge has observable impacts on aquatic ecosystem function in the oligotrophic estuaries
of the Florida Everglades by controlling the availability of P to the ecosystem. Future water management decisions in South
Florida must include the impact of changes in water delivery on downstream estuaries. 相似文献
In this special issue, we report on efforts to reconstruct paleoclimate/paleolimnology of the Florida Everglades, applying a wide range of techniques including sedimentological, micropaleontological and biogeochemical approaches. The papers included here describe results obtained by studies conducted in Everglades National Park and the greater South Florida Everglades by Florida Coastal Everglades Long Term Ecological Research Program (FCE LTER) collaborators. This multi-investigator project contrasts nutrient dynamics in two inland-to-marine transects aligned along separate drainages in southern Florida that differ in their susceptibility to coastal pressures and in volume of freshwater delivery. This effort focuses on the paleoecological aspects of FCE LTER research that address scales of ecosystem transformations driven by climate variability and change and human activities. The central question addressed by this body of work is “How is the shape of the freshwater-to-marine gradient in the Florida coastal Everglades controlled by changes in climate, freshwater inflow (i.e. through human activities), and disturbance (i.e. sea level rise, hurricanes, fire)?” 相似文献
In an increasingly GIS‐literate world, the availability of quality topographic maps and map databases is critical for the numerous users of spatial data. Particularly governmental agencies, first responders, and utility and transportation services, rely on the completeness and classification correctness of these maps. Estonia has systematically updated its topographic Basic Map in digital form over the past 15 years. An analysis of the Estonian production process in the period 2003‐2006 provides a useful case study of both error types and error frequencies encountered in topographic mapping. Errors of completeness and classification correctness of topographic features are analyzed at two levels of specificity: in general, across all map sheets, and in detail according to the field‐workers who performed the mapping. The structure of errors at the two levels was different by geometry and error types; however, both systematic and individual errors were evident. The systematic errors indicated a need for revision and improvement of the data capture specifications, which was accomplished. The individual errors were addressed by additional training for the field‐workers involved. 相似文献
De Beers kimberlite mine operations in South Africa (Venetia and Voorspoed) and Canada (Gahcho Kué, Victor, and Snap Lake) have the potential to sequester carbon dioxide (CO2) through weathering of kimberlite mine tailings, which can store carbon in secondary carbonate minerals (mineral carbonation). Carbonation of ca. 4.7 to 24.0 wt% (average = 13.8 wt%) of annual processed kimberlite production could offset 100% of each mine site’s carbon dioxide equivalent (CO2e) emissions. Minerals of particular interest for reactivity with atmospheric or waste CO2 from energy production include serpentine minerals, olivine (forsterite), brucite, and smectite. The most abundant minerals, such as serpentine polymorphs, provide the bulk of the carbonation potential. However, the detection of minor amounts of highly reactive brucite in tailings from Victor, as well as the likely presence of brucite at Venetia, Gahcho Kué, and Snap Lake, is also important for the mineral carbonation potential of the mine sites.
This paper systematically reviews the glacial geomorphological evidence of the Loch Lomond Stadial (LLS; Younger Dryas) glaciation in Britain (12.9–11.7 ka). The geomorphology of sub‐regions within Scotland, England and Wales is assessed, providing the most comprehensive synthesis of this evidence to date. The contrasting nature of the evidence at the local scale is reviewed and conceptual themes common to multiple sub‐regions are examined. Advancements in glaciological theory, mapping technologies, numerical modelling and dating have been applied unevenly to localities across Britain, inhibiting a holistic understanding of the extent and dynamics of the LLS glaciation at a regional scale. The quantity and quality of evidence is highly uneven, leading to uncertainties regarding the extent of glaciation and inhibiting detailed analysis of ice dynamics and chronology. Robust dates are relatively scarce, making it difficult to confidently identify the limits of LLS glaciers and assess their synchroneity. Numerical models have allowed the glacier–climate relationships of the LLS to be assessed but have, thus far, been unable to incorporate local conditions which influenced glaciation. Recommendations for future research are made that will allow refined reconstructions of the LLS in Britain and contribute to a more comprehensive understanding of glacier–climate interactions during the Younger Dryas. 相似文献
Coastal wetlands, among the most productive ecosystems, are important global reservoirs of carbon (C). Accelerated sea level rise (SLR) and saltwater intrusion in coastal wetlands increase salinity and inundation depth, causing uncertain effects on plant and soil processes that drive C storage. We exposed peat-soil monoliths with sawgrass (Cladium jamaicense) plants from a brackish marsh to continuous treatments of salinity (elevated (~?20 ppt) vs. ambient (~?10 ppt)) and inundation levels (submerged (water above soil surface) vs. exposed (water level 4 cm below soil surface)) for 18 months. We quantified changes in soil biogeochemistry, plant productivity, and whole-ecosystem C flux (gross ecosystem productivity, GEP; ecosystem respiration, ER). Elevated salinity had no effect on soil CO2 and CH4 efflux, but it reduced ER and GEP by 42 and 72%, respectively. Control monoliths exposed to ambient salinity had greater net ecosystem productivity (NEP), storing up to nine times more C than plants and soils exposed to elevated salinity. Submersion suppressed soil CO2 efflux but had no effect on NEP. Decreased plant productivity and soil organic C inputs with saltwater intrusion are likely mechanisms of net declines in soil C storage, which may affect the ability of coastal peat marshes to adapt to rising seas. 相似文献
In this review we evaluate whether universal behavioral and metabolic mechanisms exist, which permit marine proto‐ and metazooplankton to persist in continuously food‐limited environments such as the North Pacific Subtropical Gyre and other oligotrophic ocean systems. We re‐visit the issue of what processes account for low steady‐state abundance of the dominant groups of planktonic grazers: phagotrophic protists and copepods, by examining evidence for the four processes proposed by Strom et al. (2000) : grazing thresholds, behavioral response to prey patchiness, top–down control of grazers, and mixotrophy (combination of photosynthesis and phagotrophy in protists) and/or omnivory (switching between alternate prey types). Published observations reveal that grazing thresholds, below which feeders reduce their feeding efforts and, with that, their metabolic expenditures, do exist. There are also studies suggesting that both protistan and small metazoan plankton feeders may take advantage of patchiness of food particles and are frequently mixotrophic and/or omnivorous. Predator patchiness in response to prey patches may facilitate top–down control of grazers. Finally, we discuss processes, which may lead to low quasi steady‐state abundances of food particles and feeders. 相似文献