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Ocean and coastal acidification (OCA) present a unique set of sustainability challenges at the human-ecological interface. Extensive biogeochemical monitoring that can assess local acidification conditions, distinguish multiple drivers of changing carbonate chemistry, and ultimately inform local and regional response strategies is necessary for successful adaptation to OCA. However, the sampling frequency and cost-prohibitive scientific equipment needed to monitor OCA are barriers to implementing the widespread monitoring of dynamic coastal conditions. Here, we demonstrate through a case study that existing community-based water monitoring initiatives can help address these challenges and contribute to OCA science. We document how iterative, sequential outreach, workshop-based training, and coordinated monitoring activities through the Northeast Coastal Acidification Network (a) assessed the capacity of northeastern United States community science programs and (b) engaged community science programs productively with OCA monitoring efforts. Our results (along with the companion manuscript) indicate that community science programs are capable of collecting robust scientific information pertinent to OCA and are positioned to monitor in locations that would critically expand the coverage of current OCA research. Furthermore, engaging community stakeholders in OCA science and outreach enabled a platform for dialogue about OCA among other interrelated environmental concerns and fostered a series of co-benefits relating to public participation in resource and risk management. Activities in support of community science monitoring have an impact not only by increasing local understanding of OCA but also by promoting public education and community participation in potential adaptation measures.

In this study, we examine how women’s representation in National Science Foundation Ocean Sciences (NSF-OCE) awards changed between 1987 and 2019 and how it varied across different programs, research topics, and award types. Women’s participation in NSF-OCE awards increased at a rate of approximately 0.6% per year from about 10% in 1987 to 30% in 2019, and the strong similarity between the temporal trends in the NSF-OCE awards and the academic workforce suggests that there was no gender bias in NSF funding throughout the 33-year study period. The programs, topics, and award types related to education showed the strongest growth, achieving and surpassing parity with men, while those related to the acquisition of shared instrumentation and equipment for research vessels had the lowest women’s representation and showed relatively little change over time. Despite being vastly outnumbered by men, women principal investigators (PIs) tended to do more collaborative work and had a more diversified “portfolio” of research and research-related activities than men. We also found no evidence of gender bias in the amount awarded to men and women PIs during the study period. These results show that, despite significant increases in women’s participation in oceanography over the past three decades, women have still not reached parity with men. Although there appears to be no gender bias in funding decisions or amount awarded, there are significant differences between women’s participation in specific research subject areas that may reflect overall systemic biases in oceanography and academia more broadly. These results highlight areas where further investment is needed to improve women’s representation.

A dynamic energy budget (DEB) model integrating pCO

Increased interest in using bivalve cultivation to mitigate eutrophication requires a comprehensive understanding of the net carbon (C) and nitrogen (N) budgets associated with cultivation on an ecosystem scale. This study quantified C and N processes related to clam (Mercenaria mercenaria) aquaculture in a shallow coastal environment (Cherrystone Inlet, VA) where the industry has rapidly increased. Clam physiological rates were compared with basin-wide ecosystem fluxes including primary production, benthic nutrient regeneration, and respiration. Although clam beds occupy only 3 % of the ecosystem’s surface area, clams filtered 7–44 % of the system’s volume daily, consumed an annual average of 103 % of the phytoplankton production, creating a large flux of particulate C and N to the sediments. Annually, N regenerated and C respired by clam and microbial metabolism in clam beds were ∼3- and ∼1.5-fold higher, respectively, than N and C removed through harvest. Due to the short water residence time, the low watershed load, and the close vicinity of clam beds to the mouth of Cherrystone Inlet, cultivated clams are likely subsidized by phytoplankton from the Chesapeake Bay. Consequently, much of the N released by mineralization associated with clam cultivation is “new” N as it would not be present in the system without bivalve facilitation. Macroalgae that are fueled by the enhanced N regeneration from clams represents a eutrophying process resulting from aquaculture. This synthesis demonstrates the importance of considering impacts of bivalve aquaculture in an ecosystem context especially relative to the potential of bivalves to remove nutrients and enhance C sinks.

Coastal water clarity varies at high temporal and spatial scales due to weather, climate, and human activity along coastlines. Systematic observations are crucial to assessing the impact of water clarity change on aquatic habitats. In this study, Secchi disk depths (ZSD) from Boston Harbor, Buzzards Bay, Cape Cod Bay, and Narragansett Bay water quality monitoring organizations were compiled to validate ZSD derived from Landsat 8 (L8) imagery, and to generate high spatial resolution ZSD maps. From 58 L8 images, acceptable agreement was found between in situ and L8 ZSD in Buzzards Bay (N = 42, RMSE = 0.96 m, MAPD = 28%), Cape Cod Bay (N = 11, RMSE = 0.62 m, MAPD = 10%), and Narragansett Bay (N = 8, RMSE = 0.59 m, MAPD = 26%). This work demonstrates the value of merging in situ ZSD with high spatial resolution remote sensing estimates for improved coastal water quality monitoring.

Ocean acidification has the potential to significantly impact both aquaculture and wild-caught mollusk fisheries around the world. In this work, we build upon a previously published integrated assessment model of the US Atlantic Sea Scallop (Placopecten magellanicus) fishery to determine the possible future of the fishery under a suite of climate, economic, biological, and management scenarios. We developed a 4x4x4x4 hypercube scenario framework that resulted in 256 possible combinations of future scenarios. The study highlights the potential impacts of ocean acidification and management for a subset of future climate scenarios, with a high CO2 emissions case (RCP8.5) and lower CO2 emissions and climate mitigation case (RCP4.5). Under RCP4.5 and the highest impact and management scenario, ocean acidification has the potential to reduce sea scallop biomass by approximately 13% by the end of century; however, the lesser impact scenarios cause very little change. Under RCP8.5, sea scallop biomass may decline by more than 50% by the end of century, leading to subsequent declines in industry landings and revenue. Management-set catch limits improve the outcomes of the fishery under both climate scenarios, and the addition of a 10% area closure increases future biomass by more than 25% under the highest ocean acidification impacts. However, increased management still does not stop the projected long-term decline of the fishery under ocean acidification scenarios. Given our incomplete understanding of acidification impacts on P. magellanicus, these declines, along with the high value of the industry, suggest population-level effects of acidification should be a clear research priority. Projections described in this manuscript illustrate both the potential impacts of ocean acidification under a business-as-usual and a moderately strong climate-policy scenario. We also illustrate the importance of fisheries management targets in improving the long-term outcome of the P. magellanicus fishery under potential global change.

Estuaries provide significant cultural ecosystem services, including recreation and tourism. Disruptions of estuarine biogeochemical processes resulting from environmental degradation could interrupt the flow of these services, reducing benefits and diminishing the welfare of local communities. This study focused on recreational shellfishing in Buzzards Bay, Massachusetts (41.55°N, 70.80°W). Relationships among measures of recreational shellfishing, estuarine water quality, and local socioeconomic conditions were tested to understand how the benefits of cultural ecosystem services to local communities might be affected by declining water quality. Transferring estimated economic benefits from an analysis of nearby municipalities, the study finds that increases in Chl a during the 24-year period were associated with losses in recreational shellfishing benefits of $0.08-0.67 million per decade. The approach presented here suggests a more broadly applicable framework for assessing the impacts of changes in coastal ecosystem water quality on the welfare of local communities.

The U.S. Northeast Continental Shelf is experiencing rapid warming, with potentially profound consequences to marine ecosystems. While satellites document multiple scales of spatial and temporal variability on the surface, our understanding of the status, trends, and drivers of the benthic environmental change remains limited. We interpolated sparse benthic temperature data along the New England Shelf and upper Slope using a seasonally dynamic, regionally specific multiple linear regression model that merged in situ and remote sensing data. The statistical model predicted nearly 90% of the variability of the data, resulting in a synoptic time series spanning over three decades from 1982 to 2014. Benthic temperatures increased throughout the domain, including in the Gulf of Maine. Rates of benthic warming ranged from 0.1 to 0.4°C per decade, with fastest rates occurring in shallow, nearshore regions and on Georges Bank, the latter exceeding rates observed in the surface. Rates of benthic warming were up to 1.6 times faster in winter than the rest of the year in many regions, with important implications for disease occurrence and energetics of overwintering species. Drivers of warming varied over the domain. In southern New England and the mid‐Atlantic shallow Shelf regions, benthic warming was tightly coupled to changes in SST, whereas both regional and basin‐scale changes in ocean circulation affect temperatures in the Gulf of Maine, the Continental Shelf, and Georges Banks. These results highlight data gaps, the current feasibility of prediction from remotely sensed variables, and the need for improved understanding on how climate may affect seasonally specific ecological processes., Key Points Marine benthic habitats are warming throughout the entire U.S. Northeast Continental ShelfBenthic warming rates approach or exceed surface rates on Georges Banks and southern New England, and particularly fast in winterSatellite‐based, region models are useful to inform managers regarding status, trends, and regional patterns of benthic marine habitats

The oxygen flux between benthic eco- systems and the overlying water column is a measure of metabolic status and a commonly used proxy for carbon cycling. In this study, oxygen flux was meas- ured seasonally using the eddy correlation technique in a restored eelgrass (Zostera marina L.) meadow in the Virginia coastal bays (USA). In 5 intensive field campaigns, we covered seasonal variation in oxygen metabolism and biomass with overlap in late summer to observe interannual variability. The high-resolution measurements allowed identification of the drivers of metabolism at multiple timescales: minute to hourly, daily, and monthly to seasonally. There was a strong correlation between nighttime hourly fluxes and current velocity that varied seasonally with seagrass shoot density and temperature. No similar relationship was observed during the day. A hysteresis effect in oxygen flux throughout the day was observed during October and August that was most likely due to in- creased respiration (R) in the afternoon. In October, net community production was 90% lower in the af- ternoon than in the morning at the same irradiance. From this hysteresis, we calculated that daytime R may be up to 2.5-fold larger than nighttime R. The magnitudes of daily gross primary production (GPP) and R were well correlated throughout the year with close to a 1:1 ratio that reflected a tight coupling be- tween GPP and R on daily to seasonal timescales. Our results document the dynamic nature of oxygen fluxes that, when integrated over time, translate into highly variable rates of ecosystem metabolism over daily to seasonal timescales. This variation must be incorpo- rated to accurately determine trophic status.

The Virginia coastal bays experienced local extinction of eelgrass (Zostera marina) during the early 1930s, and restoration beginning in 2001 has generated an ecosystem state change from bare to vegetated sediments. Oxygen fluxes were measured seasonally using the eddy correlation technique at three sites representing different stages of seagrass colonization: unvegetated (bare), 5 yr, and 11 yr since seeding. Derived seasonal ecosystem respiration (R) and gross primary production (GPP) increased up to 10-fold and 25-fold, respectively, with meadow age. Although hourly oxygen (O2) fluxes were highly correlated with light at the vegetated sites, no identifiable trends with light were observed at the bare site. The light compensation point where O2 production and respiration are in balance increased from 46 µmol photons m−2 s−1 to 257 µmol photons m−2 s−1 and 63 µmol photons m−2 s−1 to 472 µmol photons m−2 s−1 at the 5 yr and 11 yr seagrass sites, respectively, with increasing seasonal temperatures from 12.3°C to 27.9°C and 9.3°C to 30.5°C, respectively. This suggests that more light, and thus more O2 production, is required to offset increasing respiration with both temperature and meadow age. Photosynthesis—irradiance curves generated from hourly O2 fluxes throughout the seasons were used to estimate annual net ecosystem metabolism (NEM). Annual NEM rates at the bare, 5 yr, and 11 yr sites were −7.6, 8.6, and −7.0 mol O2 m−2 yr−1, respectively. Although the system went through a period of net autotrophy during early stages of colonization, the ecosystem state change from unvegetated sediments to dense seagrass meadows changed the magnitude of both GPP and R, but not the overall metabolic balance of the system.

The eddy correlation technique has become a widely used approach to measure ecosystem scale fluxes in aquatic benthic environments; however, there are few theoretical studies designed to guide deployment planning, the characterization of flux variability, or how to correctly interpret measured fluxes. Here, a three-dimensional numerical model for the turbulent transport and mixing in the near-bottom water was used to examine how well variations in vertical flux due to heterogeneities in the benthic community are integrated in eddy correlation measurements. The results showed that an appropriate choice of measuring height above the sediment surface is crucial to obtain an accurate average of the vertical flux from heterogeneous benthic communities. Through regression analysis of modeling results, a set of simple analytical expressions were derived for this threshold measuring height as a function of two parameters: heterogeneity patch size and sediment surface roughness. The same model was also used to examine the time lag between when a change in vertical flux occurs at the sediment surface and when it reaches the measuring point. The results showed that this response time varies by several orders of magnitude depending on flow velocity, sediment surface roughness, and measuring height. Simple analytical expressions were also derived for the response time. Overall, the findings indicate that both the spatial variability in benthic communities and the response to temporal changes are important factors that should be considered in planning eddy correlation measurements and interpreting eddy correlation fluxes.

Based on noninvasive eddy correlation measurements at a marine and a freshwater site, this study documents the control that current flow and light have on sediment–water oxygen fluxes in permeable sediments. The marine sediment was exposed to tidal-driven current and light, and the oxygen flux varied from night to day between 229 and 78 mmol m22 d21. A fitting model, assuming a linear increase in oxygen respiration with current flow, and a photosynthesis–irradiance curve for light-controlled production reproduced measured fluxes well (R2 5 0.992) and revealed a 4-fold increase in oxygen uptake when current velocity increased from , 0t o 20 cm s 21. Application of the model to a week-long measured record of current velocity and light showed that net ecosystem metabolism varied substantially among days, between 227 and 31 mmol m22 d21, due to variations in light and current flow. This variation is likely typical of many shallow-water systems and highlights the need for long-term flux integrations to determine system metabolism accurately. At the freshwater river site, the sediment–water oxygen flux ranged from 2360 to 137 mmol m22 d21. A direct comparison during nighttime with concurrent benthic chamber incubations revealed a 4.1 times larger eddy flux than that obtained with chambers. The current velocity during this comparison was 31 cm s 21 , and the large discrepancy was likely caused by poor imitation by the chambers of the natural pore-water flushing at this high current velocity. These results emphasize the need for more noninvasive oxygen flux measurements in permeable sediments to accurately assess their role in local and global carbon budgets.

The Antarctic coast and seas are considered some of the most pristine marine systems on Earth. Their comprehensive assessment is critical because meeting ambitious conservation objectives while maintaining sustainable human uses will be increasingly challenging with growing climate change impacts, recovery from past overharvesting, and potential revision of activities permitted with future revisions of the existing governance structure. We used the Ocean Health Index (OHI) to deliver an integrated assessment of the Antarctic marine ecosystems’ evolving ecological and social dimensions. The OHI provides a framework to evaluate sustainable delivery of benefits people want from healthy oceans by measuring progress towards 10 widely-held societal goals. These goals include, conservation objectives, as well as other objectives, so as to identify tradeoffs across multiple priorities. We adapted the Index to the unique aspects and data availability of Antarctica. OHI scores were calculated for each sub-region defined by the Convention for the Conservation of Antarctic Marine Living Resources (CCAMLR) as well as the region overall. OHI scores for conservation-related goals (biodiversity, clean water) were generally high, though with some stressor impacts (i.e., climate-driven decline of sea-ice, and pathogen pollution). However, a sensitivity test on the sea-ice habitat indicator showed biodiversity scores might be much lower in the vicinity of the Antarctic Peninsula. Preservation of lasting special places, captured in the sense of place sub-goal, scored relatively low due to limited extent of Marine Protected Areas in the Southern Ocean. In several cases, scores are low due to under-utilization of resources, rather than environmentally unsustainable practices (e.g., food provision, natural products, tourism and recreation). However, increased human activities would intensify the risk of pollution, pathogen contamination, and disturbance to wildlife, particularly if compounded with future climate change impacts. Therefore, scores may reflect the need to select more conservative targets for human use, articulated in international treaties, taking future risks into account. Our results highlight the need for more research on both natural and social science aspects of the Antarctic system, as well as the need to evaluate targets under different scenarios, so as to provide robust science-based advice for future decision-making in the region.

Nitrogen and chlorophyll-a concentrations in estuarine systems often correlate positively with increased nitrogen input. To determine the interactions between nitrogen load, physical drivers, and water quality indicators, we estimated nitrogen inputs to 28 estuaries within the Buzzards Bay, Massachusetts (USA) watershed from 1985 to 2013. Estimates were derived by combining parcel specific wastewater disposal, point source wastewater discharge, land use, and atmospheric nitrogen deposition data with a previously verified nitrogen loading model. Linear regression analysis was used to quantify temporal trends in individual data sets and characterize relationships between variables. The land-use data indicated that fractional coverage of impervious surfaces increased with time for all sub-watersheds at the expense of vegetation and agriculture land use classes, reflecting a growth in residential unit density. Nitrogen loads decreased with time for most watersheds on the western side of Buzzards Bay, reflecting decreased atmospheric nitrogen deposition combined with management efforts to mitigate wastewater pollution. For most of Buzzards Bay's eastern watersheds, increases in nitrogen sourced from wastewater, driven primarily by the development of homes with on-site wastewater disposal, resulted in stable or overall nitrogen load increases. The relationship between nitrogen load and mean summer in situ chlorophyll a underwent a shift to more chlorophyll a per unit nitrogen input over time that was partially correlated to climatic variables such as increased precipitation and warming water column temperatures.

Accurate light measurements are important in the analysis of photosynthetic systems. Many commercial instruments are available to determine light; however, the comparison of light estimates between studies is difficult due to the differences in sensor types and their calibrations. The measurement of underwater irradiance is also complicated by the scattering and attenuation of light due to interactions with particulates, molecules, and the bottom. Here, three sensor types are compared to evaluate the calibration of light intensity loggers to estimate photosynthetically active radiation (PAR). We present a simple calibration of light intensity loggers that agree within 3.8% to factory-calibrated scalar PAR sensors under a wide range of environmental conditions. Under the same range of conditions, two identical factory-calibrated PAR sensors showed a similar difference of 3.7%. The light intensity loggers were calibrated to a high-quality PAR sensor using an exponential fit (r2 = 0.983) that accounts for differences in sensor types with respect to the angle of incoming light, scattering, and attenuation. The light loggers are small, robust, and simple to operate and install, and thus well-suited for typical subsurface research. They are also useful for small-scale measurements, when broad spatial coverage is needed, or in research requiring multiple sensors. Many studies have used these simple light intensity sensors to estimate PAR, yet their limitations and advantages in mimicking PAR have not been well defined previously. We present these small and user-friendly loggers as an excellent alternative to more sophisticated scalar PAR sensors.

Degradation of coastal ecosystems by eutrophication is largely defined by nitrogen loading from land via surface water and groundwater flows. However, indicators of water quality are highly variable due to a myriad of other drivers, including temperature and precipitation. To evaluate these drivers, we examined spatial and temporal trends in a 22-year record of summer water quality data from 122 stations in 17 embayments within Buzzards Bay, MA (USA), collected through a citizen science monitoring program managed by Buzzards Bay Coalition. To identify spatial patterns across Buzzards Bay's embayments, we used a principle component and factor analysis and found that rotated factor loadings indicated little correlation between inorganic nutrients and organic matter or chlorophyll a (Chl a) concentration. Factor scores showed that embayment geomorphology in addition to nutrient loading was a strong driver of water quality, where embayments with surface water inputs showed larger biological impacts than embayments dominated by groundwater influx. A linear regression analysis of annual summertime water quality indicators over time revealed that from 1992 to 2013, most embayments (15 of 17) exhibited an increase in temperature (mean rate of 0.082 ± 0.025 (SD) °C yr−1) and Chl a (mean rate of 0.0171 ± 0.0088 log10 (Chl a; mg m−3) yr−1, equivalent to a 4.0 % increase per year). However, only seven embayments exhibited an increase in total nitrogen (TN) concentration (mean rate 0.32 ± 0.47 (SD) µM yr−1). Average summertime log10(TN) and log10(Chl a) were correlated with an indication that the yield of Chl a per unit total nitrogen increased with time suggesting the estuarine response to TN may have changed because of other stressors such as warming, altered precipitation patterns, or changing light levels. These findings affirm that nitrogen loading and physical aspects of embayments are essential in explaining the observed ecosystem response. However, climate-related stressors may also need to be considered by managers because increased temperature and precipitation may worsen water quality and partially offset benefits achieved by reducing nitrogen loading.