Laying it on thick: Ecosystem effects of sediment placement on a microtidal Rhode Island salt marsh.

Heightened recognition of impacts to coastal salt marshes from sea-level rise has led to expanding interest in using thin-layer sediment placement (TLP) as an adaptation tool to enhance future marsh resilience. Building on successes and lessons learned from the Gulf and southeast U.S. coasts, projects are now underway in other regions, including New England where the effects of TLP on marsh ecosystems and processes are less clear. In this study, we report on early responses of a drowning, microtidal Rhode Island marsh (Ninigret Marsh, Charlestown, RI) to the application of a thick (10-48 cm) application of sandy dredged material and complimentary extensive adaptive management to quickly build elevation capital and enhance declining high marsh plant species. Physical changes occurred quickly. Elevation capital, rates of marsh elevation gain, and soil drainage all increased, while surface inundation, die-off areas, and surface ponding were greatly reduced. Much of the marsh revegetated within a few years, exhibiting aspects of classic successional processes leading to new expansive areas of high marsh species, although low marsh Spartina alterniflora recovered more slowly. Faunal communities, including nekton and birds, were largely unaffected by sediment placement. Overall, sediment placement provided Ninigret Marsh with an estimated 67-320 years of ambient elevation gain, increasing its resilience and likely long-term persistence. Project stakeholders intentionally aimed for the upper end of high marsh plant elevation growth ranges to build elevation capital and minimize maintenance costs, which also resulted in new migration corridors, providing pathways for future marsh expansion.

Evaluation of Plot-Scale Methods for Assessing and Monitoring Salt Marsh Vegetation Composition and Cover.

Vegetation is a key component of salt marsh monitoring programs, but different methods can make comparing datasets difficult. We compared data on vegetation composition and cover collected with 3 methods (point-intercept, Braun-Blanquet visual, and floristic quality assessment [FQA]) in 3 Rhode Island salt marshes. No significant differences in plant community composition were found among the methods, and differences in individual species cover in a marsh never exceeded 6% between methods. All methods were highly repeatable, with no differences in data collected by different people. However, FQA was less effective at identifying temporal changes at the plot scale. If data are collected from many plots in a marsh, any of the methods are appropriate, but if plot-scale patterns are of interest, we recommend point-intercept.

Top-down and bottom-up controls on southern New England salt marsh crab populations.

Southern New England salt marsh vegetation and habitats are changing rapidly in response to sea-level rise. At the same time, fiddler crab (Uca spp.) distributions have expanded and purple marsh crab (Sesarma reticulatum) grazing on creekbank vegetation has increased. Sea-level rise and reduced predation pressure drive these changing crab populations but most studies focus on one species; there is a need for community-level assessments of impacts from multiple crab species. There is also a need to identify additional factors that can affect crab populations. We sampled crabs and environmental parameters in four Rhode Island salt marshes in 2014 and compiled existing data to quantify trends in crab abundance and multiple factors that potentially affect crabs. Crab communities were dominated by fiddler and green crabs (Carcinus maenas); S. reticulatum was much less abundant. Burrow sizes suggest that Uca is responsible for most burrows. On the marsh platform, burrows and Carcinus abundance were negatively correlated with elevation, soil moisture, and soil percent organic matter and positively correlated with soil bulk density. Uca abundance was negatively correlated with Spartina patens cover and height and positively correlated with Spartina alterniflora cover and soil shear strength. Creekbank burrow density increased dramatically between 1998 and 2016. During the same time, fishing effort and the abundance of birds that prey on crabs decreased, and water levels increased. Unlike in other southern New England marshes where recreational overfishing is hypothesized to drive increasing marsh crab abundance, we propose that changes in crab abundance were likely unrelated to recreational finfish over-harvest; instead, they better track sea-level rise and changing abundances of alternate predators, such as birds. We predict that marsh crab abundance will continue to expand with ongoing sea-level rise, at least until inundation thresholds for crab survival are exceeded.

Beaver Ponds: Resurgent Nitrogen Sinks for Rural Watersheds in the Northeastern United States.

Beaver-created ponds and dams, on the rise in the northeastern United States, reshape headwater stream networks from extensive, free-flowing reaches to complexes of ponds, wetlands, and connecting streams. We examined seasonal and annual rates of nitrate transformations in three beaver ponds in Rhode Island under enriched nitrate-nitrogen (N) conditions through the use of N mass balance techniques on soil core mesocosm incubations. We recovered approximately 93% of the nitrate N from our mesocosm incubations. Of the added nitrate N, 22 to 39% was transformed during the course of the incubation. Denitrification had the highest rates of transformation (97-236 mg N m d), followed by assimilation into the organic soil N pool (41-93 mg N m d) and ammonium generation (11-14 mg N m d). Our denitrification rates exceeded those in several studies of freshwater ponds and wetlands; however, rates in those ecosystems may have been limited by low concentrations of nitrate. Assuming a density of 0.7 beaver ponds km of catchment area, we estimated that in nitrate-enriched watersheds, beaver pond denitrification can remove approximately 50 to 450 kg nitrate N km catchment area. In rural watersheds of southern New England with high N loading (i.e., 1000 kg km), denitrification from beaver ponds may remove 5 to 45% of watershed nitrate N loading. Beaver ponds represent a relatively new and substantial sink for watershed N if current beaver populations persist.

Utilizing self-assessment software to evaluate student wax-ups in dental morphology.

Traditionally, evaluating student work in preclinical courses has relied on the judgment of experienced clinicians utilizing visual inspection. However, research has shown significant disagreement between different evaluators (interrater reliability) and between results from the same evaluator at different times (intrarater reliability). This study evaluated a new experimental software (E4D Compare) to compare 66 student-produced tooth wax-ups at one U.S. dental school to an ideal standard after both had been digitally scanned. Using 3D surface-mapping technology, a numerical evaluation was generated by calculating the surface area of the student's work that was within a set range of the ideal. The aims of the study were to compare the reliability of faculty and software grades and to determine the ideal tolerance value for the software. The investigators hypothesized that the software would provide more consistent feedback than visual grading and that a tolerance value could be determined that closely correlated with the faculty grade. The results showed that a tolerance level of 450 µm provided 96% agreement of grades compared with only 53% agreement for faculty. The results suggest that this software could be used by faculty members as a mechanism to evaluate student work and for students to use as a self-assessment tool.

Cardiac-restricted overexpression or deletion of tissue inhibitor of matrix metalloproteinase-4: differential effects on left ventricular structure and function following pressure overload-induced hypertrophy.

Historically, the tissue inhibitors of matrix metalloproteinases (TIMPs) were considered monochromatic in function. However, differential TIMP profiles more recently observed with left ventricular (LV) dysfunction and matrix remodeling suggest more diverse biological roles for individual TIMPs. This study tested the hypothesis that cardiac-specific overexpression (TIMP-4OE) or deletion (knockout; TIMP-4KO) would differentially affect LV function and structure following pressure overload (LVPO). LVPO (transverse aortic constriction) was induced in mice (3.5 ± 0.1 mo of age, equal sex distribution) with TIMP-4OE (n = 38), TIMP-4KO (n = 24), as well as age/strain-matched wild type (WT, n = 25), whereby indexes of LV remodeling and function such as LV mass and ejection fraction (LVEF) were determined at 28 days following LVPO. Following LVPO, both early (7 days) and late (28 days) survival was ~25% lower in the TIMP-4KO group (P < 0.05). While LVPO increased LV mass in all groups, the relative hypertrophic response was attenuated with TIMP-4OE. With LVPO, LVEF was similar between WT and TIMP-4KO (48 ± 2% and 45 ± 3%, respectively) but was higher with TIMP-4OE (57 ± 2%, P < 0.05). With LVPO, LV myocardial collagen expression (type I, III) increased by threefold in all groups (P < 0.05), but surprisingly this response was most robust in the TIMP-4KO group. These unique findings suggest that increased myocardial TIMP-4 in the context of a LVPO stimulus may actually provide protective effects with respect to survival, LV function, and extracellular matrix (ECM) remodeling. These findings challenge the canonical belief that increased levels of specific myocardial TIMPs, such as TIMP-4 in and of themselves, contribute to adverse ECM accumulation following a pathological stimulus, such as LVPO.

Cyclosporin A in left ventricular remodeling after myocardial infarction.

Recent studies suggest that an increase in apoptosis within the myocardium may be a contributing factor for the progression of late adverse left ventricular (LV) remodeling following myocardial infarction (MI). Given that apoptosis is often triggered by induction of the mitochondrial permeability transition (MPT) pore, the goal of this study was to evaluate the therapeutic efficacy of cyclosporin A (CsA), an MPT blocker, to prevent cells from undergoing apoptosis and consequently attenuate late LV remodeling post-MI. MI was induced in C57BL/6 mice and then randomized to either vehicle or CsA groups. Beginning 48 h after surgery after infarction had already occurred, mice were gavaged with CsA (2 mg/kg) or vehicle once daily. LV end-diastolic volume and LV ejection fraction were assessed by echocardiography before MI induction and terminally at either 7 days (n = 7) or 28 days (n = 8) post-MI. LV end-diastolic volume increased and LV ejection fraction decreased in all MI groups with no difference between the CsA-treated and untreated groups. After vehicle and CsA, areas of necrosis were present at 7 and 28 days post-MI with no difference between treatment groups. Caspase-3 activity and terminal deoxynucleotidyl transferase dUTP-mediated nick-end labeling in distal nonnecrotic LV both increased after MI but were lower in CsA-treated mice compared with vehicle (P < 0.05). In conclusion, CsA decreased apoptosis occurring late after MI, confirming involvement of a CsA-sensitive MPT in the cell death. However, CsA-mediated reduction in apoptosis in non-MI myocardium was not beneficial against late pump dysfunction occurring during post-MI remodeling.

Direct regulation of membrane type 1 matrix metalloproteinase following myocardial infarction causes changes in survival, cardiac function, and remodeling.

The membrane type 1 matrix metalloproteinase (MT1-MMP) is increased in left ventricular (LV) failure. However, the direct effects of altered MT1-MMP levels on survival, LV function, and geometry following myocardial infarction (MI) and the proteolytic substrates involved in this process remain unclear. MI was induced in mice with cardiac-restricted overexpression of MT1-MMP (MT1-MMPexp; full length human), reduced MT1-MMP expression (heterozygous; MT1-MMP(+/-)), and wild type. Post-MI survival was reduced with MT1-MMPexp and increased with MT1-MMP(+/-) compared with WT. LV ejection fraction was lower in the post-MI MT1-MMPexp mice compared with WT post-MI and was higher in the MT1-MMP(+/-) mice. In vivo localization of MT1-MMP using antibody-conjugated microbubbles revealed higher MT1-MMP levels post-MI, which were the highest in the MT1-MMPexp group and the lowest in the MT1-MMP(+/-) group. LV collagen content within the MI region was higher in the MT1-MMPexp vs. WT post-MI and reduced in the MT1-MMP(+/-) group. Furthermore, it was demonstrated that MT1-MMP proteolytically processed the profibrotic molecule, latency-associated transforming growth factor-1-binding protein (LTBP-1), and MT1-MMP-specific LTBP-1 proteolytic activity was increased by over fourfold in the post-MI MT1-MMPexp group and reduced in the MT1-MMP(+/-) group, which was directionally paralleled by phospho-Smad-3 levels, a critical signaling component of the profibrotic transforming growth factor pathway. We conclude that modulating myocardial MT1-MMP levels affected LV function and matrix structure, and a contributory mechanism for these effects is through processing of profibrotic signaling molecules. These findings underscore the diversity of biological effects of certain MMP types on the LV remodeling process.

Continuous localized monitoring of plasmin activity identifies differential and regional effects of the serine protease inhibitor aprotinin: relevance to antifibrinolytic therapy.

BACKGROUND: Antifibrinolytic therapy, such as the use of the serine protease inhibitor aprotinin, was a mainstay for hemostasis after cardiac surgery. However, aprotinin was empirically dosed, and although the pharmacological target was the inhibition of plasmin activity (PLact), this was never monitored, off-target effects occurred, and led to withdrawn from clinical use. The present study developed a validated fluorogenic microdialysis method to continuously measure PLact and tested the hypothesis that standardized clinical empirical aprotinin dosing would impart differential and regional effects on PLact. METHODS/RESULTS: Pigs (30 kg) were instrumented with microdialysis probes to continuously measure PLact in myocardial, kidney, and skeletal muscle compartments (deltoid) and then randomized to high-dose aprotinin administration (2 mKIU load/0.5 mKIU/hr infusion; n = 7), low-dose aprotinin administration (1 mKIU load/0.250 mKIU/hr infusion; n = 6). PLact was compared with time-matched vehicle (n = 4), and PLact was also measured in plasma by an in vitro fluorogenic method. Aprotinin suppressed PLact in the myocardium and kidney at both high and low doses, indicative that both doses exceeded a minimal concentration necessary for PLact inhibition. However, differential effects of aprotinin on PLact were observed in the skeletal muscle, indicative of different compartmentalization of aprotinin. CONCLUSIONS: Using a large animal model and a continuous method to monitor regional PLact, these unique results demonstrated that an empirical aprotinin dosing protocol causes maximal and rapid suppression in the myocardium and kidney and in turn would likely increase the probability of off-target effects and adverse events. Furthermore, this proof of principle study demonstrated that continuous monitoring of determinants of fibrinolysis might provide a novel approach for managing fibrinolytic therapy.

Some challenges of an "upside down" nitrogen budget--science and management in Greenwich Bay, RI (USA).

When nutrients impact estuarine water quality, scientists and managers instinctively focus on quantifying and controlling land-based sources. However, in Greenwich Bay, RI, the estuary opens onto a larger and more intensively fertilized coastal water body (Narragansett Bay). Previous inventories of nitrogen (N) inputs to Greenwich Bay found that N inputs from Narragansett Bay exceeded those from the local watershed, suggesting that recent efforts to reduce local watershed N loads may have little effect on estuarine water quality. We used stable isotopes of N to characterize watershed and Narragansett Bay N sources as well as the composition of primary producers and consumers throughout Greenwich Bay. Results were consistent with previous assessments of the importance of N inputs to Greenwich Bay from Narragansett Bay. As multiple N sources contribute to estuarine water quality, effective management requires attention to individual sources commensurate with overall magnitude, regardless of the political complications that may entail.

Hemodynamics and myocardial blood flow patterns after placement of a cardiac passive restraint device in a model of dilated cardiomyopathy.

BACKGROUND: The present study examined a cardiac passive restraint device which applies epicardial pressure (HeartNet Implant; Paracor Medical, Inc, Sunnyvale, Calif) in a clinically relevant model of dilated cardiomyopathy to determine effects on hemodynamic and myocardial blood flow patterns. METHODS: Dilated cardiomyopatht was established in 10 pigs (3 weeks of atrial pacing, 240 beats/min). Hemodynamic parameters and regional left ventricular blood flow were measured under baseline conditions and after acute placement of the HeartNet Implant. Measurements were repeated after adenosine infusion, allowing maximal coronary vasodilation and coronary flow reserve to be determined. RESULTS: Left ventricular dilation and systolic dysfunction occurred relative to baseline as measured by echocardiography. Left ventricular end-diastolic dimension increased and left ventricular fractional shortening decreased (3.8 ± 0.1 vs 6.1 ± 0.2 cm and 31.6% ± 0.5% vs 16.2% ± 2.1%, both P < .05, respectively), consistent with the dilated cardiomyopathy phenotype. The HeartNet Implant was successfully deployed without arrhythmias and a computed median mid-left ventricular epicardial pressure of 1.4 mm Hg was applied by the HeartNet Implant throughout the cardiac cycle. Acute HeartNet placement did not adversely affect steady state hemodynamics. With the HeartNet Implant in place, coronary reserve was significantly blunted. CONCLUSIONS: In a large animal model of dilated cardiomyopathy, the cardiac passive restraint device did not appear to adversely affect basal resting myocardial blood flow. However, after acute HeartNet Implant placement, left ventricular maximal coronary reserve was blunted. These unique results suggest that cardiac passive restraint devices that apply epicardial transmural pressure can alter myocardial blood flow patterns in a model of dilated cardiomyopathy. Whether this blunting of coronary reserve holds clinical relevance with chronic passive restraint device placement remains unestablished.

Anthropogenic enhancement of Egypt's Mediterranean fishery.

The highly productive coastal Mediterranean fishery off the Nile River delta collapsed after the completion of the Aswan High Dam in 1965. But the fishery has been recovering dramatically since the mid-1980s, coincident with large increases in fertilizer application and sewage discharge in Egypt. We use stable isotopes of nitrogen (delta(15)N) to demonstrate that 60%-100% of the current fishery production may be from primary production stimulated by nutrients from fertilizer and sewage runoff. Although the establishment of the dam put Egypt in an ideal position to observe the impact of rapid increases in nutrient loading on coastal productivity in an extremely oligotrophic sea, the Egyptian situation is not unique. Such anthropogenically enhanced fisheries also may occur along the northern rim of the Mediterranean and offshore of some rapidly developing tropical countries, where nutrient concentrations in the coastal waters were previously very low.

Assessing the wildlife habitat value of New England salt marshes: I. Model and application.

We developed an assessment model to quantify the wildlife habitat value of New England salt marshes based on marsh characteristics and the presence of habitat types that influence habitat use by terrestrial wildlife. Applying the model to 12 salt marshes located in Narragansett Bay, RI resulted in assessment scores that ranged over a factor of 1.5 from lowest to highest. Pre-classifying the results based on marsh size and morphology helped to compare assessment scores between marshes, and demonstrated that even the lower ranking marshes had substantial habitat value. Stepwise multiple regression analysis of assessment scores and model components demonstrated that salt marsh morphology, the degree of anthropogenic modification, and salt marsh vegetative heterogeneity were significant variables and accounted for 91.3% of the variability in component scores. Our results suggest that targeting these components for restoration may lead to improved assessment scores for our study marshes. We also examined the use of lower resolution remote sensing data in the assessment in order to minimize the time and effort required to complete the model. Scores obtained using smaller-scale, lower resolution data were significantly lower than those obtained using larger-scale, higher resolution data (df = 11; t = 2.2; p < 0.001). The difference was significantly positively correlated with the portion of the assessment score that could be attributed to trees, pools, and pannes and marsh size (r (2) =0.50, F = 4.6, p = 0.04), and could indicate a bias against smaller, more heterogeneous marshes. We conclude that potential differences need to be weighed against the time benefit of using this type of data, bearing in mind the marsh size and the goals of the assessment. Overall, our assessment can provide information to aid in prioritizing marshes for protection and restoration, identify marshes that may harbor significant biodiversity, or help monitor changes in habitat value over time.

Assessing the wildlife habitat value of New England salt marshes: II. Model testing and validation.

We tested a previously described model to assess the wildlife habitat value of New England salt marshes by comparing modeled habitat values and scores with bird abundance and species richness at sixteen salt marshes in Narragansett Bay, Rhode Island USA. As a group, wildlife habitat value assessment scores for the marshes ranged from 307-509, or 31-67% of the maximum attainable score. We recorded 6 species of wading birds (Ardeidae; herons, egrets, and bitterns) at the sites during biweekly survey. Species richness (r (2)=0.24, F=4.53, p=0.05) and abundance (r (2)=0.26, F=5.00, p=0.04) of wading birds significantly increased with increasing assessment score. We optimized our assessment model for wading birds by using Akaike information criteria (AIC) to compare a series of models comprised of specific components and categories of our model that best reflect their habitat use. The model incorporating pre-classification, wading bird habitat categories, and natural land surrounding the sites was substantially supported by AIC analysis as the best model. The abundance of wading birds significantly increased with increasing assessment scores generated with the optimized model (r (2)=0.48, F=12.5, p=0.003), demonstrating that optimizing models can be helpful in improving the accuracy of the assessment for a given species or species assemblage. In addition to validating the assessment model, our results show that in spite of their urban setting our study marshes provide substantial wildlife habitat value. This suggests that even small wetlands in highly urbanized coastal settings can provide important wildlife habitat value if key habitat attributes (e.g., natural buffers, habitat heterogeneity) are present.

Natural and anthropogenic nitrogen uptake by bloom-forming macroalgae.

The frequency and duration of macroalgal blooms have increased in many coastal waters over the past several decades. We used field surveys and laboratory culturing experiments to examine the nitrogen content and delta(15)N values of Ulva and Gracilaria, two bloom-forming algal genera in Narragansett Bay, RI (USA). The northern end of this bay is densely populated with large sewage treatment plant nitrogen inputs; the southern end is more lightly populated and opens to the Atlantic Ocean. Field-collected Ulva varied in delta(15)N among sites, but with two exceptions had delta(15)N above 10 per thousand, reflecting a significant component of heavy anthropogenic N. This variation was not correlated with a north-south gradient. Both Ulva and Gracilaria cultured in water from across Narragansett Bay also had high signals (delta(15)N= approximately 14-17 per thousand and 8-12 per thousand, respectively). These results indicate that inputs of anthropogenic N can have far-reaching impacts throughout estuaries.

Varying stable nitrogen isotope ratios of different coastal marsh plants and their relationships with wastewater nitrogen and land use in New England, USA.

The stable nitrogen isotope ratios of some biota have been used as indicators of sources of anthropogenic nitrogen. In this study the relationships of the stable nitrogen isotope ratios of marsh plants, Iva frutescens (L.), Phragmites australis (Cav.) Trin ex Steud, Spartina patens (Ait.) Muhl, Spartina alterniflora Loisel, Ulva lactuca (L.), and Enteromorpha intestinalis (L.) with wastewater nitrogen and land development in New England are described. Five of the six plant species (all but U. lactuca) showed significant relationships of increasing delta (15)N values with increasing wastewater nitrogen. There was a significant (P < 0.0001) downward shift in the delta (15)N of S. patens (6.0 +/- 0.48 per thousand) which is mycorrhizal compared with S. alterniflora (8.5 +/- 0.41 per thousand). The downward shift in delta (15)N may be caused by the assimilation of fixed nitrogen in the roots of S. patens. P. australis within sites had wide ranges of delta (15)N values, evidently influenced by the type of shoreline development or buffer at the upland border. In residential areas, the presence of a vegetated buffer (n = 24 locations) significantly (P < 0.001) reduced the delta (15)N (mean = 7.4 +/- 0.43 per thousand) of the P. australis compared to stands where there was no buffer (mean = 10.9 +/- 1.0 per thousand; n = 15). Among the plant species, I. frutescens located near the upland border showed the most significant (R (2) = 0.64; P = 0.006) inverse relationship with the percent agricultural land in the watershed. The delta (15)N of P. australis and I. frustescens is apparently an indicator of local inputs near the upland border, while the delta (15)N of Spartina relates with the integrated, watershed-sea nitrogen inputs.

Denitrification enzyme activity of fringe salt marshes in New England (USA).

Coastal salt marshes are a buffer between the uplands and adjacent coastal waters in New England (USA). With increasing N loads from developed watersheds, salt marshes could play an important role in the water quality maintenance of coastal waters. In this study we examined seasonal relationships between denitrification enzyme activity (DEA) in salt marshes of Narragansett Bay, Rhode Island, and watershed N loadings, land use, and terrestrial hydric soils. In a manipulative experiment, the effect of nutrient enrichment on DEA was examined in a saltmeadow cordgrass [Spartina patens (Aiton) Muhl.] marsh. In the high marsh, DEA significantly (p < 0.05) increased with watershed N loadings and decreased with the percent of hydric soils in a 200-m terrestrial buffer. In the low marsh, we found no significant relationships between DEA and watershed N loadings, residential land development, or terrestrial hydric soils. In the manipulation experiment, we measured increased DEA in N-amended treatments, but no effect in the P-amended treatments. The positive relationships between N loading and high marsh DEA support the hypothesis that salt marshes may be important buffers between the terrestrial landscape and estuaries, preventing the movement of land-derived N into coastal waters. The negative relationships between marsh DEA and the percent of hydric soils in the adjacent watershed illustrate the importance of natural buffers within the terrestrial landscape. Denitrification enzyme activity appears to be a useful index for comparing relative N exposure and the potential denitrification activity of coastal salt marshes.

Assessment of a delta15N isotopic method to indicate anthropogenic eutrophication in aquatic ecosystems.

Increased anthropogenic delivery of nutrients to water bodies, both freshwater and estuarine, has caused detrimental changes in habitat, food web structure, and nutrient cycling. Nitrogen-stable isotopes may be suitable indicators of such increased nutrient delivery. In this study, we looked at the differences in response of macrophyte delta15N values to anthropogenic N across different taxonomic groups and geographic regions to test a stable isotopic method for detecting anthropogenic impacts. Macrophyte delta15N values increased with wastewater input and water-column dissolved inorganic nitrogen (DIN) concentration. When macrophytes were divided into macroalgae and plants, they responded similarly to increases in wastewater N, although macroalgae was a more reliable indicator of both wastewater inputs and water-column DIN concentrations. Smooth cordgrass (Spartina alterniflora Loisel.) Delta15N increased uniformly with wastewater inputs across a geographic range. We used the relationship derived between S. alterniflora and relative wastewater load to predict wastewater loads in locations lacking quantitative land use data. The predictions matched well with known qualitative information, proving the use of a stable isotopic method for predicting wastewater input.