Ecological processes in salt marshes of the southeastern U.S. have historically been considered to be controlled largely by bottom-up forces (i.e. nutrient cycling, salinity, productivity), however, recent studies have demonstrated that top-down pressures such as herbivory and predation can be just as or more influential in the regulation of these ecological processes. Barrier islands of the southeastern U.S. support dense populations of top order consumers such as the American alligator (Alligator mississippiensis).

 Changes in biodiversity are predicted to have a major impact on ecosystem processes.  A fundamental challenge for ecologists is to determine the influence of species on ecosystem processes prior to declines or losses, and to determine whether there are species that may compensate for the loss of other species.

Urbanization has led to an increase of combustion-derived, organic carbon emissions that can deposit diffusely to soils within and surrounding cities. One of the most common types of urban pollutants, Polycyclic Aromatic Hydrocarbons (PAHs), may be toxic and are detrimental to environmental quality. Despite this concern, there is a considerable gap in our knowledge about the environmental fate of PAHs in highly populated urban areas.

In the McMurdo Dry Valleys of Antarctica, glaciers are hydrologically linked to closed-basin lakes at the valley floor by glacial melt water streams. We propose that the dynamics of meltwater generation and sub-stream thaw depth control the potential for the hyporheic zone and benthic communities to influence transport of nutrients and dissolved ions downstream. Little is known about the temporal variability of nutrient fluxes to the Dry Valley lakes.

This study was conducted in Taylor River in the southern mangrove ecotone region of Taylor Slough in the Florida Everglades between two FCE-LTER water quality observation stations. This system is characterized by a series of interconnected creeks and ponds that make up the larger Taylor River. During wet season months from June to November, there is a distinct freshwater input to the mangrove estuary from the north, which essentially “flushes” most of the river and lowers salinity to less than 1 ppt.

Woody debris is a recalcitrant carbon pool, storing carbon in complex molecules for extended periods of time. It has been shown that temperature and moisture are major drivers in decomposition from this pool. Additionally, under certain circumstances, both species and size can influence decomposition. It is not known, however, how the woody debris carbon pool in the moist, temperate forests of New England will respond to climate change, specifically soil warming.

Black carbon (BC) is produced from the incomplete combustion of fossil fuels and biomass. It has been detected in many important geochemical pools (soils, sediments, aerosols) and has been shown to be a significant portion of soil organic matter in some locations (45% in frequently burned soils). BC is ubiquitous in nature and its presence in long–term carbon reservoirs is well documented. Uncertainties exist in the BC global and regional budgets with respect to sources and sinks. The terrestrial soil sink is poorly constrained due to the lack of data.

Urban lakes provide a range of ecosystem services to their communities but there is little information about the long term biogeochemical behavior of these systems. We have been investigating basic water chemistry and dissolved organic carbon dynamics in Tempe Town Lake, Tempe AZ since Jan 2005. This man-made lake provides both recreational and flood-control services. High-resolution time-series measurements of water chemistry, nutrients, DOC content and DOC composition from Jan.

 Tropical reef ecosystems lie at the interface of productive, populated terrestrial coastlines and unproductive, oligotrophic oceanic waters. Corals and other dominant reef organisms maintain complex symbiotic interactions with both surficial and planktonic aquatic microbial communities, but the processes defining the composition and life history of these communities are poorly understood.

Leaf leaching is a potentially important source of nutrients and carbon in tropical streams. This study examined the leaching rate and variability among species and condition (fresh vs. senesced) of DOC, NH4, NO3, PO4, and other major anions and cations from leaves of common riparian tree species in the Luquillo Experimental Forest in Puerto Rico. Uniform leaf disks were leached in deionized water for one, three, and seven days and the carbon and nutrient content of the resulting leachate was determined.