When, where, and how to intervene? Trade-offs between time and costs in coastal nutrient management.

Policies and regulations designed to address nutrient pollution in coastal waters are often complicated by delays in environmental and social systems. Social and political inertia may delay implementation of cleanup projects, and even after the best nutrient pollution management practices are developed and implemented, long groundwater travel times may delay the impact of inland or upstream interventions. These delays and the varying costs of nutrient removal alternatives used to meet water quality goals combine to create a complex dynamic decision problem with trade-offs about when, where, and how to intervene. We use multi-objective optimization to quantify the trade-offs between costs and minimizing the time to meet in-bay nutrient reduction goals represented as a Total Maximum Daily Load (TMDL). We calculate the impact of using in-bay (in-situ) nutrient removal through shellfish aquaculture relative to waiting for traditional source control to be implemented. We apply these methods to the Three Bays Watershed in Cape Cod, Massachusetts. In gross benefit terms, not accounting for any social costs, this equates to an average value of 37¢ (2035 TMDL target date) and 11¢ (2060 TMDL target date) per animal harvested over the plan implementation period. Our results encourage the consideration of alternative and in-situ approaches to tackle coastal pollution while traditional source control is implemented and its effects realized over time.

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). Edaphic (salinity, pH, surface temperature) factors among sites significantly covaried with GHG fluxes. We found that mangrove systems in more highly-urbanized reaches of the estuary were characterized by relatively lower porewater salinities and substantially larger GHG emissions, particularly CH4, which has a high global warming potential. The magnitude of the CO2 emissions was similar in the mangrove soils and adjacent waters, but the CH4 emissions in the adjacent waters were an order of magnitude higher than in the soils and showed a marked response to urbanization. This study underscores the importance of considering GHG emissions of adjacent waters in carbon cycling dynamics in urbanized, tropical mangrove systems.

A resilience framework for chronic exposures: water quality and ecosystem services in coastal social-ecological systems.

Water quality degradation is a chronic problem which influences the resilience of a social-ecological system differently than acute disturbances, such as disease or storms. Recognizing this, we developed a tailored resilience framework that applies ecosystem service concepts to coastal social-ecological systems affected by degraded water quality. We present the framework as a mechanism for coordinating interdisciplinary research to inform long-term community planning decisions pertaining to chronic challenges in coastal systems. The resulting framework connects the ecological system to the social system via ecological production functions and ecosystem services. The social system then feeds back to the ecological system via policies and interventions to address declining water quality. We apply our resilience framework to the coastal waters and communities of Cape Cod (Barnstable County, Massachusetts, USA) which are affected by nitrogen over-enrichment. This approach allowed us to design research to improve the understanding of the effectiveness and acceptance of water quality improvement efforts and their effect on the delivery of ecosystem services. This framework is intended to be transferable to other geographical settings and more generally applied to systems exposed to chronic disturbances in order to coordinate interdisciplinary research planning and inform coastal management.

A Dynamic Modeling Approach to Estimate Nitrogen Loading in Coastal Bays on Cape Cod, Massachusetts, USA.

Solving estuarine water quality problems on Cape Cod, Massachusetts, or elsewhere, is difficult. Nitrogen from septic systems takes years to decades to travel by groundwater to estuaries, depending on local hydrogeology, meaning that nitrogen loading in future years may exceed current conditions. We created a dynamic nitrogen model of Cape Cod's 54 estuaries to better understand 1. how past and present conditions, including legacy nitrogen in groundwater, influence future nitrogen loading, and 2. how different development and nitrogen abatement scenarios could have additional effects. We find that 43 of 54 estuaries are not in equilibrium with current watershed nitrogen loading levels; this increases to 52 of 54 under a buildout scenario. Watersheds contain up to 1000 tons of legacy nitrogen in groundwater; yet, we find that a rapid investment in source control successfully reduces nitrogen loading, revealing a wide range of potential outcomes that depend ultimately on the resources and attention invested in the problem.

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. Radiometrically dated cores were used to determine sediment accretion and soil C storage and burial rates. Measurements of tree dendrometers coupled with allometric equations were used to estimate aboveground biomass. Estuary-wide mangrove forest C storage and accumulation rates were estimated using interpolation methods and coastal vegetation cover data. In recent decades (1970-2016), the highly urbanized Martin Peña East (MPE) site with low flushing had the highest C storage and burial rates among sites. The MPE soil carbon burial rate was over twice as great as global estimates. Mangrove forest C burial rates in recent decades were significantly greater than historic decades (1930-1970) at Cañno Martin Peña and Piñones. Although MPE and Piñones had similarly low flushing, the landscape settings (clogged canal vs forest reserve) and urbanization (high vs low) were different. Apparently, not only urbanization, but site-specific flushing patterns, landscape setting, and soil fertility affected soil C storage and burial rates. There was no difference in C burial rates between historic and recent decades at the San José and La Torrecilla lagoons. Mangrove forests had soil C burial rates ranging from 88 g m-2 y-1 at the San José lagoon to 469 g m-2 y-1 at the MPE in recent decades. Watershed anthropogenic CO2 emissions (1.56 million Mg C y-1) far exceeded the annual mangrove forest C storage rates (aboveground biomass plus soils: 17,713 Mg C y-1). A combination of maintaining healthy mangrove forests and reducing anthropogenic emissions might be necessary to mitigate greenhouse gas emissions in urban, tropical areas.

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. We examined N storage and accumulation rates in recent (1970 - 2016) and historic (1930 - 1970) decades in the context of urbanization in the San Juan Bay Estuary (SJBE, Puerto Rico), using mangrove soil cores that were radiometrically dated. Local anthropogenic stressors can alter N storage rates in peri-urban mangrove systems either directly by increasing N soil fertility or indirectly by altering hydrology (e.g., dredging, filling, and canalization). Nitrogen accumulation rates were greater in recent decades than historic decades at Piñones Forest and Martin Peña East. Martin Peña East was characterized by high urbanization, and Piñones, by the least urbanization in the SJBE. The mangrove forest at Martin Peña East fringed a poorly drained canal and often received raw sewage inputs, with N accumulation rates ranging from 17.7 to 37.9 g -2 y-1 in recent decades. The Piñones Forest was isolated and had low flushing, possibly exacerbated by river damming, with N accumulation rates ranging from 18.6 to 24.2 g -2 y-1 in recent decades. Nearly all (96.3%) of the estuary-wide mangrove N (9.4 Mg ha-1) was stored in the soils with 7.1 Mg ha-1 sequestered during 1970-2017 (0-18 cm) and 2.3 Mg ha-1 during 1930-1970 (19-28 cm). Estuary-wide mangrove soil N accumulation rates were over twice as great in recent decades (0.18 ± 0.002 Mg ha-1y-1) than historically (0.08 ± 0.001 Mg ha-1y-1). Nitrogen accumulation rates in SJBE mangrove soils in recent times were twofold larger than the rate of human-consumed food N that is exported as wastewater (0.08 Mg ha-1 y-1), suggesting the potential for mangroves to sequester human-derived N. Conservation and effective management of mangrove forests and their surrounding watersheds in the Anthropocene are important for maintaining water quality in coastal communities throughout tropical regions.

An R Package for Open, Reproducible Analysis of Urban Water Systems, With Application to Chicago.

Urban water systems consist of natural and engineered flows of water interacting in complex ways. System complexity can be understood via mass conservative models that account for the interrelationships among all major flows and storages. We have developed a generic urban water system model in the R package CityWaterBalance. CityWaterBalance provides a reproducible workflow for studying urban water systems by facilitating automated retrievals of open data and post-processing with open source R functions. It allows the user to 1) rapidly assemble a quantitative, comprehensive assessment of flows thorough an urban area, and 2) easily change the spatial and temporal boundaries of analysis. We use CityWaterBalance to evaluate the water system in the Chicago metropolitan area on a monthly basis for water years 2001-2010. Results are used to consider 1) impacts of management decisions aimed at reducing stormwater and combined sewer overflows and 2) the significance of future changes in precipitation.

Loneliness and implicit attention to social threat: A high-performance electrical neuroimaging study.

Prior research has suggested that loneliness is associated with an implicit hypervigilance to social threats-an assumption in line with the evolutionary model of loneliness that indicates feeling socially isolated (or on the social perimeter) leads to increased attention and surveillance of the social world and an unwitting focus on self-preservation. Little is known, however, about the temporal dynamics for social threat (vs. nonsocial threat) in the lonely brains. We used high-density electrical neuroimaging and a behavioral task including social and nonsocial threat (and neutral) pictures to investigate the brain dynamics of implicit processing for social threat vs. nonsocial threat stimuli in lonely participants (N = 10), compared to nonlonely individuals (N = 9). The present study provides evidence that social threat images are differentiated from nonsocial threat stimuli more quickly in the lonely (~116 ms after stimulus onset) than nonlonely (~252 ms after stimulus onset) brains. That speed of threat processing in lonely individuals is in accord with the evolutionary model of loneliness. Brain source estimates expanded these results by suggesting that lonely (but not nonlonely) individuals showed early recruitment of brain areas involved in attention and self-representation.

Implicit attention to negative social, in contrast to nonsocial, words in the Stroop task differs between individuals high and low in loneliness: Evidence from event-related brain microstates.

Being on the social perimeter is not only sad, it is dangerous. Our evolutionary model of the effects of perceived social isolation (loneliness) on the brain as well as a growing body of behavioral research suggests that loneliness promotes short-term self-preservation, including an increased implicit vigilance for social, in contrast to nonsocial, threats. However, this hypothesis has not been tested previously in a neuroimaging study. We therefore used high density EEG and a social Stroop interference task to test the hypothesis that implicit attention to negative social, in contrast to nonsocial, Words in the Stroop task differs between individuals high versus low in loneliness and to investigate the brain dynamics of implicit processing for negative social (vs nonsocial) stimuli in lonely individuals, compared to nonlonely individuals (N = 70). The present study provides the first evidence that negative social stimuli are differentiated from negative nonsocial stimuli more quickly in the lonely than nonlonely brains. Given the timing of this differentiation in the brain and the fact that participants were performing a Stroop task, these results also suggest that these differences reflect implicit rather than explicit attentional differences between lonely and nonlonely individuals. Source estimates were performed for purposes of hypothesis generation regarding underlying neural mechanisms, and the results implicated the neural circuits reminiscent of orienting and executive control aspects of attention as contributing to these differences. Together, the results are in accord with the evolutionary model of loneliness.