Recent Carbon Storage and Burial Exceed Historic Rates in the San Juan Bay Estuary Peri-Urban Mangrove Forests (Puerto Rico, United States).

Mangroves sequester significant quantities of organic carbon (C) because of high rates of burial in the soil and storage in biomass. We estimated mangrove forest C storage and accumulation rates in aboveground and belowground components among five sites along an urbanization gradient in the San Juan Bay Estuary, Puerto Rico. Sites included the highly urbanized and clogged Caño Martin Peña in the western half of the estuary, a series of lagoons in the center of the estuary, and a tropical forest reserve (Piñones) in the easternmost part.

Recent Nitrogen Storage and Accumulation Rates in Mangrove Soils Exceed Historic Rates in the Urbanized San Juan Bay Estuary (Puerto Rico, United States).

Tropical mangrove forests have been described as "coastal kidneys," promoting sediment deposition and filtering contaminants, including excess nutrients. Coastal areas throughout the world are experiencing increased human activities, resulting in altered geomorphology, hydrology, and nutrient inputs. To effectively manage and sustain coastal mangroves, it is important to understand nitrogen (N) storage and accumulation in systems where human activities are causing rapid changes in N inputs and cycling.

Greenhouse Gas Fluxes of Mangrove Soils and Adjacent Coastal Waters in an Urban, Subtropical Estuary.

Mangroves are known to sequester carbon at rates exceeding even those of other tropical forests; however, to understand carbon cycling in these systems, soil-atmosphere fluxes and gas exchanges in mangrove-adjacent shallow waters need to be quantified. Further, despite the ever-increasing impact of development on mangrove systems, there is even less data on how subtropical, greenhouse gas (GHG) fluxes are affected by urbanization. We quantified carbon dioxide (CO2) and methane (CH4) fluxes from mangrove soils and adjacent, coastal waters along a gradient of urbanization in the densely-populated, subtropical San Juan Bay Estuary (PR).

Unexpected nitrogen sources in a tropical urban estuary.

Tropical urban estuaries are severely understudied. Little is known about the basic biogeochemical cycles and dominant ecosystem processes in these waterbodies, which are often low-lying and heavily modified. The San Juan Bay Estuary (SJBE) in San Juan, Puerto Rico is an example of such a system.

Seasonal variation in apparent conductivity and soil salinity at two Narragansett Bay, RI salt marshes.

Measurement of the apparent conductivity of salt marsh sediments using electromagnetic induction (EMI) is a rapid alternative to traditional methods of salinity determination that can be used to map soil salinity across a marsh surface. Soil salinity measures can provide information about marsh processes, since salinity is important in determining the structure and function of tidally influenced marsh communities. While EMI has been shown to accurately reflect salinity to a specified depth, more information is needed on the potential for spatial and temporal variability in apparent conductivity measures that may impact the interpretation of salinity data.

Nitrogen isotope fractionation in a continuous culture system containing phytoplankton and blue mussels.

An experiment was conducted to examine the fractionation of nitrogen stable isotopes in a continuous culture system containing field collected estuarine phytoplankton and blue mussels, Mytilus edulis. Nitrate and phosphate were added to culture vessels at concentrations above ambient levels and nitrogen isotope ratios (δN) were measured in particulate matter (PM) and blue mussels over the course of the 15-day experiment. The added nutrients resulted in large productivity and chlorophyll increases in the system.

Discontinuities in soil strength contribute to destabilization of nutrient-enriched creeks.

In a whole-ecosystem, nutrient addition experiment in the Plum Island Sound Estuary (Massachusetts), we tested the effects of nitrogen enrichment on the carbon and nitrogen contents, respiration, and strength of marsh soils. We measured soil shear strength within and across vegetation zones. We found significantly higher soil percent organic matter, carbon, and nitrogen in the long-term enriched marshes and higher soil respiration rates with longer duration of enrichment.

How the distribution of anthropogenic nitrogen has changed in Narragansett Bay (RI, USA) following major reductions in nutrient loads.

Over the past decade, nitrogen (N) loads to Narragansett Bay have decreased by more than 50%. These reductions were, in large part, the direct result of multiple wastewater treatment facility upgrades to tertiary treatment, a process which employs N removal. Here we document ecosystem response to the N reductions and assess how the distribution of sewage N in Narragansett Bay has changed from before, during, and shortly after the upgrades.

Burrowing and foraging activity of marsh crabs under different inundation regimes.

New England salt marshes are susceptible to degradation and habitat loss as a result of increased periods of inundation as sea levels rise. Increased inundation may exacerbate marsh degradation that can result from crab burrowing and foraging. Most studies to date have focused on how crab burrowing and foraging can impact the dominant low marsh plant species, .

Preliminary Evidence for the Amplification of Global Warming in Shallow, Intertidal Estuarine Waters.

Over the past 50 years, mean annual water temperature in northeastern U.S. estuaries has increased by approximately 1.

Below the disappearing marshes of an urban estuary: historic nitrogen trends and soil structure.

Marshes in the urban Jamaica Bay Estuary, New York, USA are disappearing at an average rate of 13 ha/yr, and multiple stressors (e.g., wastewater inputs, dredging activities, groundwater removal, and global warming) may be contributing to marsh losses.

Carbon stable isotopes as indicators of coastal eutrophication.

Coastal ecologists and managers have frequently used nitrogen stable isotopes (delta15N) to trace and monitor sources of anthropogenic nitrogen (N) in coastal ecosystems. However, the interpretation of delta15N data can often be challenging, as the isotope values fractionate substantially due to preferential retention and uptake by biota. There is a growing body of evidence that carbon isotopes may be a useful alternative indicator for eutrophication, as they may be sensitive to changes in primary production that result from anthropogenic nutrient inputs.