Land uses and management practices in residential parcels (e.g., aesthetic/recreational/economic uses, land-cover choices, irrigation and chemical applications) impact and are impacted by social (e.g., stratification and status, environmental perceptions, zoning) and ecological (e.g., carbon sequestration, nutrient cycling, water demand and quality) processes.

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.

 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.

Aquatic ecosystems regulate material transfer between terrestrial and coastal systems, and play a significant role in regional to global carbon (C) and nutrient cycles. The functioning of inland waters is being altered by human activities such as land use change, climate change, and hydraulic engineering.

The aim of this working group will be to discuss the upcoming Antarctic Field Season. By holding this meeting at the ASM we will take advantage of the fact that a large group of PAL and MCM investigators, staff, and students will be present and available to attend, although the meeting will be open to all.

Reservoirs are common on medium-sized rivers, and understanding their role in algal production is important. Suspended algal growth typically is limited in rivers because of hydrology and turbidity. Dams are particularly interesting because they increase water residence time and allow algae to be produced. The lower Kalamazoo River has two relatively large impoundments at Morrow Lake and Lake Allegan, which increase the production of algae.

The role abiotic factors play in structuring communities is one of the fundamental questions in ecology. At small spatial and temporal scales, abiotic conditions influence patterns of species movement and habitat use. At larger scales, abiotic factors affect patterns of species abundance and distribution. The structuring effect of abiotic conditions may be particularly important along ecotonal habitats. In the southwestern Everglades, mangrove-lined creeks link freshwater marshes to estuarine habitats.

Phosphorus (P) is often limiting in aquatic ecosystems. The quantity of available P is often determined by sediment binding and release processes. We obtained 32 sediment samples from shallow freshwater ecosystems in Southwest Michigan. Sediment cores were separated into consolidated and flocculent strata for analysis of percent organic matter, total sediment phosphorus (TP), and HCl-extractable iron (HCl~Fe). Sediment TP ranged from 110-3348 ugP/gdw, with an average of 1052 ugP/gdw.

Permafrost plays an important role in shaping the chemistry of streams by restricting subsurface flows through catchments to soils. During the summer thaw of soil, subsurface flows migrate through deeper soil horizons presumably resulting in seasonal shifts in the inputs of carbon and nitrogen to the streams. Within streams, the extent of the hyporheic zone may also shift with seasonal thaw. Hyporheic zones have high mineralization and nitrification rates; thus expansion of the hyporheic zone throughout the season has important implications for stream chemistry.