Upstream Land Use Research Articles

Modelling payments for ecosystem services for solving future water conflicts at spatial scales: The Okavango River Basin example

This study aims to resolve a potential water conflict between the upper catchment communities of the Okavango River Basin and the downward communities in the Okavango Delta. A model to payment for ecosystem services is developed at the basin level, recognizing spatial diversity and water flows. It addresses four objectives: (1) To assess relationships between water consumption and land use from a spatial perspective. (2) To estimate water availability under current land use as a reference without any water policy intervention. (3) To optimize water flow generation as intended for getting ecosystem services. This is based on the mechanism of payments for ecosystem services, specifically in terms of land use change as stewardship. (4) To compensate farmers for economic losses due to upstream land use changes. Our study suggests that an integrated basin management should consider payments for ecosystem services to incentivize forest conservation. The annual payments of US$28.7 million could encourage farmers upstream to change their land uses from deforestation to forest conservation. With compensation, approximately 8.7 million hectares of Miombo forests would be maintained in the basin, which would secure 3656 million m3 of water during the rainy season and subsequently benefit the Delta in the dry season.

The conservation activities and land use changes in the upstream Bedadung watershed

Bedadung watershed is one of the largest watersheds in Jember Regency. The Bedadung watershed in upstream area is generally hilly with steep slopes, so it is prone to landslides and potential to erosion. The upstream area is a protected forest that functions as a water catchment area, turning into plantation and production forest to become the target of logging and deforestation. Conservation activities in the upstream watershed area is essential in the management of water resources. Natural resource management activities in the upstream area significantly affect the success of efforts to provide water and control water resources downstream damage. This study aimed to identify conservation activities in the upstream Bedadung watershed and the impact of changes in upstream land use on environmental damage. The conservation activities in the Jompo, Antrokan, Rempangan, and Rembangan Sub-watersheds is coffe plantation, cover crop, forestry, terrace, restoration, bush, grassland. The highest increase in land change in the four sub-watersged was irrigated land / field, while the decrease was non-irrigated land. The results of comparisons between the 2001 RBI map with the 2015 Landsat Image show an 8% forest loss and 7% increase in irrigated fields.

Do water quality, land use, or benthic diatoms drive macroinvertebrate functional feeding groups in a subtropical mountain stream?

ABSTRACT Feeding strategies are traits that reflect the adaptation of a species to environmental conditions. Macroinvertebrates are an important primary consumer in stream food webs, but the abiotic and biotic drivers of functional feeding groups (FFGs), which are categorized based on feeding strategies, require additional clarification. The aim of our study was to quantify the contributions of abiotic factors (water quality and land use at different scales) and biotic factors (important primary producers, such as epilithic diatoms) to the variation of FFGs of macroinvertebrates in the Jinshui River, upper Han River Basin, China, a subtropical mountain river. We conducted campaigns in the Jinshui River during high stream flow (August 2009), low flow (November 2009), and normal flow (April 2010). We performed redundancy analysis and multiple factor analysis to evaluate the relationships among riparian land use at different scales, water quality, the benthic diatom community, and FFGs. We found that water quality, especially the fluoride ion (F−), metals (chromium and cadmium), and chemical oxygen demand, significantly correlated with FFGs, and that the benthic diatom community, especially Ceratoneis arcus var. linearis f. recta and Denticula tenuis, explained a high proportion of the variation in FFGs. The benthic diatom community was significantly correlated with water quality, and variations in FFGs were poorly explained by upstream riparian land use at the entire upstream scale and reach scale (2 km upstream). Further, water quality and the benthic diatom community were significantly correlated with riparian land use at the reach scale. Our findings on how the water quality, riparian land use, and diatom community influence FFGs will provide the scientific foundation for biodiversity research of macroinvertebrate FFGs, conservation of the food web, and management of the riparian zone.

The impact of river regulation in the Tigris and Euphrates on the Arvandroud Estuary

The Arvandroud river (also known as Shatt-al-Arab) and its estuary have been degraded due to the changing river flow regime in the Tigris and Euphrates. This study assessed changes in flow from the major rivers and the impacts on the estuary. To assess the river flow changes, three major flow regime attributes were computed: timing (TIF), magnitude (MIF), and variability (VIF). By combining these indices, the total flow regime impact factor (IF) was scaled between 0 and 1, and classified into five groups: Low (0.80<IF<1.0), Incipient (0.60<IF<0.80), Moderate (0.40<IF<0.60), Severe (0.2<IF<0.40), and Drastic (0.0<IF<0.20). Flow regime impact maps were then created for 1941–1955, 1960–1970, 1975–1984, and 1990–2000. These revealed that, over time, the impact has extended along the basin from downstream to upstream, with a significant flow regime change from 1941–1955 to 1990–2000 in the Tigris, Euphrates, and Arvandroud. Analysis of remote sensing data revealed that the change in the flow regime has led to land degradation in the Arvandroud estuary during the past 46 years (1972–2018). In addition, the impact of the Iran–Iraq war (based on degradation of vegetation cover between 1985 and 1988) is 5.1 times of mean rate of change during 1972–2018. This study thus contributes new information on estuaries and the impact of upstream land and water use change.

Fragmentation alters ecological gradients and headwater fish assemblage composition relative to land use in a dendritic river system

The spatial and hydrological properties of headwaters allow dendritic systems to contribute to patterns of regional diversity. However, such ecological gradients may be disrupted as a result of habitat fragmentation. We tested the hypothesis that coarse-scale anthropogenic disturbances such as upstream land use and proximity to reservoirs can alter ecological gradients, thus influencing instream habitat, headwater fish assemblage composition, and species turnover in the Little Tallahatchie River system in north-central Mississippi. To test this hypothesis, we calculated species turnover coefficients, ordinated samples, and examined the correlations between assemblage composition and environmental and anthropogenic variables. Assemblage composition was strongly correlated with instream habitat and river system connectivity, and instream habitat was strongly associated with land use. Gradients in assemblage composition associated with ecological factors were altered due to land use. Our research highlights the importance of headwaters as distinctive habitat patches driving species turnover and the influence of land use in disrupting the ecological gradients that allow for the formation of these distinctive habitat types.

Effects of treated wastewater on the ecotoxicity of small streams - Unravelling the contribution of chemicals causing effects.

Wastewater treatment plant effluents are important point sources of micropollutants. To assess how the discharge of treated wastewater affects the ecotoxicity of small to medium-sized streams we collected water samples up- and downstream of 24 wastewater treatment plants across the Swiss Plateau and the Jura regions of Switzerland. We investigated estrogenicity, inhibition of algal photosynthetic activity (photosystem II, PSII) and growth, and acetylcholinesterase (AChE) inhibition. At four sites, we measured feeding activity of amphipods (Gammarus fossarum) in situ as well as water flea (Ceriodaphnia dubia) reproduction in water samples. Ecotoxicological endpoints were compared with results from analyses of general water quality parameters as well as a target screening of a wide range of organic micropollutants with a focus on pesticides and pharmaceuticals using liquid chromatography high-resolution tandem mass spectrometry. Measured ecotoxicological effects in stream water varied substantially among sites: 17β-estradiol equivalent concentrations (EEQbio, indicating the degree of estrogenicity) were relatively low and ranged from 0.04 to 0.85 ng/L, never exceeding a proposed effect-based trigger (EBT) value of 0.88 ng/L. Diuron equivalent (DEQbio) concentrations (indicating the degree of photosystem II inhibition in algae) ranged from 2.4 to 1576 ng/L and exceeded the EBT value (70 ng/L) in one third of the rivers studied, sometimes even upstream of the WWTP. Parathion equivalent (PtEQbio) concentrations (indicating the degree of AChE inhibition) reached relatively high values (37 to 1278 ng/L) mostly exceeding the corresponding EBT (196 ng/L PtEQbio). Decreased feeding activity by amphipods or decreased water flea reproduction downstream compared to the upstream site was observed at one of four investigated sites only. Results of the combined algae assay (PSII inhibition) correlated best with results of chemical analysis for PSII inhibiting herbicides. Estrogenicity was partly and AChE inhibition strongly underestimated based on measured steroidal estrogens respectively organophosphate and carbamate insecticides. An impact of dissolved organic carbon on results of the AChE inhibition assay was obvious. For this assay more work is required to further explore the missing correlation of bioassay data with chemical analytical data. Overall, the discharge of WWTP effluent led to increased estrogenicity, PSII and AChE inhibition downstream, irrespective of upstream land use.

Using co-occurrence network topology in assessing ecological stress in benthic macroinvertebrate communities.

Ecological monitoring of streams has often focused on assessing the biotic integrity of individual benthic macroinvertebrate (BMI) communities through local measures of diversity, such as taxonomic or functional richness. However, as individual BMI communities are frequently linked by a variety of ecological processes at a regional scale, there is a need to assess biotic integrity of groups of communities at the scale of watersheds. Using 4,619 sampled communities of streambed BMIs, we investigate this question using co‐occurrence networks generated from groups of communities selected within California watersheds under different levels of stress due to upstream land use. Building on a number of arguments in theoretical ecology and network theory, we propose a framework for the assessment of the biotic integrity of watershed‐scale groupings of BMI communities using measures of their co‐occurrence network topology. We found significant correlations between stress, as described by a mean measure of upstream land use within a watershed, and topological measures of co‐occurrence networks such as network size (r = −.81, p < 10–4), connectance (r = .31, p < 10–4), mean co‐occurrence strength (r = .25, p < 10–4), degree heterogeneity (r = −.10, p < 10–4), and modularity (r = .11, p < 10–4). Using these five topological measures, we constructed a linear model of biotic integrity, here a composite of taxonomic and functional diversity known as the California Stream Condition Index, of groups of BMI communities within a watershed. This model can account for 66% of among‐watershed variation in the mean biotic integrity of communities. These observations imply a role for co‐occurrence networks in assessing the current status of biotic integrity for BMI communities, as well as their potential use in assessing other ecological communities.

Hydro-Morphological Characteristics Using Flow Duration Curve, Historical Data and Remote Sensing: Effects of Land Use and Climate

Ecohydrological changes in large rivers of the world result from a long history of human dimensions and climate. The increasing human population, intensified land use, and climate change have led to a decline in the most critical aspect of achieving sustainable development, namely, that of water resources. This study assessed recent hydromorphological characteristics of the tropical Tana River in Kenya using flow duration curve, and geospatial techniques to gain a better understanding of human impacts over the last two decades and their consequences for new development projects. The results show that all extremal peak, low, and mean discharges exhibited significant increasing trends over a period of 17 years. Dam construction represents a 13% reduction of the maximum discharge and a 30% decrease in low flows, while post-regulation hydrological changes indicated an increase of 56 and 40% of high flows and low flows respectively. Dominant flow was observed to be higher for the current decade than the previous decade, representing a rise of the dominant streamflow by 33%. The assessment of four morphologically active sites at the downstream reach showed channel adjustments which support the changes in the flow regimes observed. The channel width increased by 8.7 and 1.9% at two sites but decreased by 31.5 and 16.2% for the other two sites under study during the time period. The results underscore the contribution of other main human modifications, apart from regulation, such as increased water abstraction and inter basin transfer, up-stream land use and anthropogenic climate change to assess the ecohydrological status in this river basin. Such streamflow regime dynamics may have implications on water resource management, riverine environments, and development of new water projects.

Effects of Forest Roads on Runoff Initiation in Low‐Order Ephemeral Streams

AbstractUnderstanding hydrologic connectivity is essential for managing ephemeral headwater streams where upstream land use influences downstream aquatic habitats. This study relies on a field‐based approach to evaluate how precipitation and roads affect runoff generation in low‐order ephemeral streams of the U.S. Virgin Islands. Logistic regression analyses show that runoff delivery from unroaded catchments agrees with a water storage conceptual model typical for subsurface storm and saturation overland flow‐dominated settings. Without roads, runoff occurs only about 4 times per year in response to 10 and 78 mm of storm rainfall, depending on antecedent precipitation. In contrast, maximum 15‐min rainfall intensities are a better predictor of runoff generation on unpaved roads than are total rainfall and antecedent conditions. Intensities surpassing ~10 mm/hr lead to road runoff, and this occurs about 40 times per year. Road‐influenced streams represent an intermediate setting for which runoff generation depends on storm and antecedent rainfall, as well as the road surface area captured by drains and flow path distance. In our focus area, roads can provoke streams to deliver runoff to coral bearing waters 10 to 13 times every year as a response to 9.3‐ to 50‐mm storms, depending on antecedent rainfall and road drain characteristics. These results highlight the sensitivity of road connectivity to specific road drain characteristics and display the potential for connectivity as a guiding watershed restoration principle.

Aquatic Bacterial Communities Associated With Land Use and Environmental Factors in Agricultural Landscapes Using a Metabarcoding Approach.

This study applied a 16S rRNA gene metabarcoding approach to characterize bacterial community compositional and functional attributes for surface water samples collected within, primarily, agriculturally dominated watersheds in Ontario and Québec, Canada. Compositional heterogeneity was best explained by stream order, season, and watercourse discharge. Generally, community diversity was higher at agriculturally dominated lower order streams, compared to larger stream order systems such as small to large rivers. However, during times of lower relative water flow and cumulative 2-day rainfall, modestly higher relative diversity was found in the larger watercourses. Bacterial community assemblages were more sensitive to environmental/land use changes in the smaller watercourses, relative to small-to-large river systems, where the proximity of the sampled water column to bacteria reservoirs in the sediments and adjacent terrestrial environment was greater. Stream discharge was the environmental variable most significantly correlated (all positive) with bacterial functional groups, such as C/N cycling and plant pathogens. Comparison of the community structural similarity via network analyses helped to discriminate sources of bacteria in freshwater derived from, for example, wastewater treatment plant effluent and intensity and type of agricultural land uses (e.g., intensive swine production vs. dairy dominated cash/livestock cropping systems). When using metabarcoding approaches, bacterial community composition and coexisting pattern rather than individual taxonomic lineages, were better indicators of environmental/land use conditions (e.g., upstream land use) and bacterial sources in watershed settings. Overall, monitoring changes and differences in aquatic microbial communities at regional and local watershed scales has promise for enhancing environmental footprinting and for better understanding nutrient cycling and ecological function of aquatic systems impacted by a multitude of stressors and land uses.

Monitoring river channel dynamics using remote sensing and GIS techniques

River channel dynamics are natural autogenic occurrences for fluvial rivers with influences from human modifications and climatic factors. Remote sensing and geographic information system tools and techniques, aerial photographs, and satellite imagery have been used to determine epochal channel erosion, accretion, and unchanged locations along Tana River, Kenya's longest river. Six reaches within a 142-km Saka-Mnazini stretch were studied by comparing sequential changes in the position of the channel in 1975–1986, 1986–2000, 2000–2017, and 1975–2017 epochs. Manual and automatic digital processing procedures and GIS tools were applied to visualize and quantify the reach-wise spatial and temporal morphological changes. The erosion and accretion channel changes over the study period were observed and quantified at all reaches. Meandering and switching off or abandoning the main active channel was also illustrated. The potential driving forces of morphological changes included varying hydrological regime, upstream land use practices, nature of channel gradient, and riparian vegetation occurrence changes. We found no clear evidence to link river regulation with the river channel dynamics. Results deliver the latest evidence on the dynamics of Tana River. This information is crucial for understanding river evolution characteristics and aid in planning and management at the lower reaches which has remained poorly understood. Use of remote sensing data in concert with GIS provides efficient and economical quantitative spatial and temporal analysis of river channel changes.

A probabilistic appraisal of rainfall-runoff modeling approaches within SWAT in mixed land use watersheds

A probabilistic approach is presented to assess the performance validity of the empirical Curve Number (CN) and physically-based Green and Ampt (G&A) rainfall-runoff methods in the SWAT model. Specifically, the effects of modeling uncertainties on characterization of the hydrologic budgets and streamflow regimes at various spatial scales and upstream land use conditions are investigated. A Bayesian total uncertainty assessment framework, which explicitly accounts for uncertainties from model parameters, inputs, structure, and measurement data, was employed to explore uncertainties in streamflow simulation using SWAT with different rainfall-runoff methods in a mixed-land use watershed. While the models were trained for streamflow estimation only at the watershed outlet, the performances of the models were compared at different stream locations within the watershed. At the watershed outlet, the CN method had a slightly better, but not significant, performance in terms of streamflow error statistics. Similar results were obtained for the predominantly forested and agricultural tributaries. However, in tributaries with higher percentage of developed land, G&A outperformed the CN method in simulating streamflow based on various performance metrics. In general, the 95% prediction intervals from the models with G&A method covered a higher percentage of observed streamflow especially during the high flow events. However, they were approximately 20–45% wider than the corresponding 95% prediction intervals from the CN methods. Using 95% prediction interval for estimated flow duration curves, results indicated that the models with CN methods underestimated high flow events especially in tributaries with highly developed land use. However, the CN methods generated higher water yields to streams than the G&A method. The results of this study have important implications for the selection and application of appropriate rainfall-runoff methods within complex distributed hydrologic models particularly when simulating hydrologic responses in mixed-land use watersheds. In the present study, while CN and G&A methods in the SWAT model performed similarly at the outlet of a mixed-land use watershed, G&A captured the internal processes more realistically. The subsequent effects on the representation of internal hydrological processes and budgets are discussed.

Reservoir Sedimentation Rates in the Little Washita River Experimental Watershed, Oklahoma: Measurement and Controlling Factors

AbstractForty‐five flood control reservoirs, authorized in the Watershed Protection and Flood Prevention Act 1954, were installed by United States Department of Agriculture (USDA) between 1969 and 1982 in the Little Washita River Experimental Watershed (LWREW), located in central Oklahoma. Over time, these reservoirs have lost sediment and flood storage capacity due to sedimentation, with rates dependent on upstream land use and climate variability. In this study, sedimentation rates for 12 reservoirs representing three major land use categories within LWREW were measured based on bathymetric surveys that used acoustic profiling system. Physiographic and climate attributes of drainage area of surveyed reservoirs were extracted from publicly available data sources including topographic maps, digital elevation models, USDA Natural Resource Conservation Service soils, and weather station databases. Correlation, principal component analysis, and stepwise regression were utilized to analyze the relationship between normalized reservoir sedimentation rates (ReSRa) and the drainage area characteristics to determine the major variables controlling sedimentation within the LWREW. Percent of drainage area with extreme slopes, saturated hydraulic conductivity, and maximum daily rainfall event recorded in spring explained most of the variability in ReSRa. It was also found that percent reduction in reservoir surface area can be used as a surrogate for estimating ReSRa. The implications of the results are discussed.

Agricultural Land Carrying Capacity and Shift of Land Use in Upstream of Grompol Watershed, Central Java Province

This research was conducted in the upstream of Grompol watershed. This study aims to identify: 1) the changes of agricultural land carrying capacity, and 2) the shift of agricultural land use. Primary data of the research were obtained from field observation to know land use in Grompol watershed, while the secondary data were obtained from various stakeholders that were in accordance with the required data. The result of data analysis and data interpretation, it can be known that: 1) the agricultural land carrying capacity in Grompol watershed is in deficit state. In 2003, Karang is the only village that is surplus, while in 2007 and 2014 both Karang and Tohkuning experienced a deficit; 2) the shift of agricultural land use in the upstream of Grompol watershed sampled by Karang and Tohkuning village in 2000, 2007, and 2015 shows that the paddy fields and unirrigated field turned into settlements. During the last sixteen years, the agricultural land in the upstream of Grompol watershed has decreased about 15.68 ha.

Predictive mapping of the biotic condition of conterminous U.S. rivers and streams.

Understanding and mapping the spatial variation in stream biological condition could provide an important tool for conservation, assessment, and restoration of stream ecosystems. The USEPA's 2008-2009 National Rivers and Streams Assessment (NRSA) summarizes the percentage of stream lengths within the conterminous United States that are in good, fair, or poor biological condition based on a multimetric index of benthic invertebrate assemblages. However, condition is usually summarized at regional or national scales, and these assessments do not provide substantial insight into the spatial distribution of conditions at unsampled locations. We used random forests to model and predict the probable condition of several million kilometers of streams across the conterminous United States based on nearby and upstream landscape features, including human-related alterations to watersheds. To do so, we linked NRSA sample sites to the USEPA's StreamCat Dataset; a database of several hundred landscape metrics for all 1:100,000-scale streams and their associated watersheds within the conterminous United States. The StreamCat data provided geospatial indicators of nearby and upstream land use, land cover, climate, and other landscape features for modeling. Nationally, the model correctly predicted the biological condition class of 75% of NRSA sites. Although model evaluations suggested good discrimination among condition classes, we present maps as predicted probabilities of good condition, given upstream and nearby landscape settings. Inversely, the maps can be interpreted as the probability of a stream being in poor condition, given human-related watershed alterations. These predictions are available for download from the USEPA's StreamCat website. Finally, we illustrate how these predictions could be used to prioritize streams for conservation or restoration.

The Relationship between Land Use and Vulnerability to Nitrogen and Phosphorus Pollution in an Urban Watershed.

Characterization of the vulnerability of water bodies to pollution from natural and anthropogenic sources requires understanding the relationship between land use and water quality. This study aims (i) to explore the influence of upstream land use on annual stream water concentrations and loads of total nitrogen (TN) and phosphorus (TP) and (ii) to characterize the vulnerability of water bodies to TN and TP pollution as a function of land use under varying climatic conditions. Multiple linear regression models were used across 23 stream locations within the Jordan Lake watershed in North Carolina between 1992 and 2012 to explore land use-water quality relationships. The percentage of urban land use and wastewater treatment plant capacity were the most important factors with strong ( 0.7) and significant ( < 0.01) positive correlations with annual TN and TP concentrations and loads. Percent agricultural land was negatively correlated with TN in 18 out of 21 yr of the study period. Using analysis of covariance, significant ( 0.01) differences were determined between models developed for urban land use with TN and TP loads based on annual precipitation. Using concentrations instead of loads resulted in a nonsignificant difference between models for average and wet years. Finally, a procedure was developed to characterize the vulnerability to TN and TP pollution, computed as the probability of exceeding the nutrient standard limits. Results indicated that the vulnerability to TN and TP was controlled primarily by urban land use, with higher values in dry years than normal and wet years.

Effectiveness of Infrastructure Flood Control Due to Development Upstream Land Use: Case Study of Ciliwung Watershed

Effectiveness of Infrastructure Flood Control Due to Development Upstream Land Use: Case Study of Ciliwung Watershed

Global transcriptomic profiling in barramundi (Lates calcarifer) from rivers impacted by differing agricultural land uses.

Most catchments discharging into the Great Barrier Reef lagoon have elevated loads of suspended sediment, nutrients, and pesticides, including photosystem II inhibiting herbicides, associated with upstream agricultural land use. To investigate potential impacts of declining water quality on fish physiology, RNA sequencing (RNASeq) was used to characterize and compare the hepatic transcriptomes of barramundi (Lates calcarifer) captured from 2 of these tropical river catchments in Queensland, Australia. The Daintree and Tully Rivers differ in upstream land uses, as well as sediment, nutrient, and pesticide loads, with the area of agricultural land use and contaminant loads lower in the Daintree. In fish collected from the Tully River, transcripts involved in fatty acid metabolism, amino acid metabolism, and citrate cycling were also more abundant, suggesting elevated circulating cortisol concentrations, whereas transcripts involved in immune responses were less abundant. Fish from the Tully also had an increased abundance of transcripts associated with xenobiotic metabolism. Previous laboratory-based studies observed similar patterns in fish and amphibians exposed to the agricultural herbicide atrazine. If these transcriptomic patterns are manifested at the whole organism level, the differences in water quality between the 2 rivers may alter fish growth and fitness. Environ Toxicol Chem 2017;36:103-112. © 2016 SETAC.

Phosphorus in the Minnesota River Basin: The debate over its source and ways to mitigate impacts

Phosphorus in the Minnesota River Basin: The debate over its source and ways to mitigate impacts

Carbon Sequestration and Sedimentation in Mangrove Swamps Influenced by Hydrogeomorphic Conditions and Urbanization in Southwest Florida

This study compares carbon sequestration rates along two independent tidal mangrove creeks near Naples Bay in Southwest Florida, USA. One tidal creek is hydrologically disturbed due to upstream land use changes; the other is an undisturbed reference creek. Soil cores were collected in basin, fringe, and riverine hydrogeomorphic settings along each of the two tidal creeks and analyzed for bulk density, total organic carbon profiles, and sediment accretion. Radionuclides 137Cs and 210Pb were used to estimate recent sediment accretion and carbon sequestration rates. Carbon sequestration rates (mean ± standard error) for seven sites in the two tidal creeks on the Naples Bay (98 ± 12 g-C m−2·year−1 (n = 18)) are lower than published global means for mangrove wetlands, but consistent with other estimates from the same region. Mean carbon sequestration rates in the reference riverine setting were highest (162 ± 5 g-C m−2·year−1), followed by rates in the reference fringe and disturbed riverine settings (127 ± 6 and 125 ± 5 g-C m−2·year−1, respectively). The disturbed fringe sequestered 73 ± 10 g-C m−2·year−1, while rates within the basin settings were 50 ± 4 g-C m−2·year−1 and 47 ± 4 g-C m−2·year−1 for the reference and disturbed creeks, respectively. These data support our hypothesis that mangroves along a hydrologically disturbed tidal creek sequestered less carbon than did mangroves along an adjacent undisturbed reference creek.