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IntroductionCoastal infrastructure and property, as well as intertidal wetlands, are increasingly being threatened by shoreline erosion; a consequence of human activities and climate change. Nature-based solutions, such as intertidal engineered oyster reefs, can reduce erosion and promote sediment accretion, thereby promoting the restoration and persistence of salt marshes and preventing the loss of coastal lands. Engineered oyster reef substrate and design options have rapidly expanded in the last decade, yet our understanding of how these approaches influence ecosystems and intertidal morphology is limited. Drones (or small uncrewed aerial systems [sUAS]) coupled with structure-from-motion (SfM) photogrammetry have recently been suggested as a low-cost method that offers optimal spatial coverage, fine-scale resolution, and high vertical accuracy for monitoring changes around living shorelines. MethodsWe evaluated how using different vertical and horizontal uncertainty thresholds for detection of drone-based shoreline change can influence interpretation of performance of engineered oyster reefs on coastal morphology and vegetation. We monitored three sites with engineered oyster reefs installed in 2020 and one reference site located on Carrot Island along Taylor Creek in Beaufort, NC, USA. ResultsComparisons of the Digital Elevation Models (DEMs) and orthomosaics derived from the drone imagery revealed all sites saw marsh edge retreat from 2022 to 2023 (2-3 years post-restoration), and all sites except one low-relief oyster reef site saw elevation loss. Elevation loss was highest at the control site, but marsh edge retreat was highest at one of the engineered oyster reefs. DiscussionWhile horizontal thresholds did not yield statistically different results, vertical thresholds did. Our results support using a 95% confidence interval for conservative volumetric estimates and recommend that future studies consider aligning uncertainty thresholds with monitoring goals and timelines. 

A systematic review of 20 years of studies was conducted to understand wave dissipation trends of hybrid and natural (soft) coastal features, collectively referred to as nature-based solutions (NbS). Of 13,451 studies identified and 470 studies reviewed; only 50 studies consistently reported the basic parameters required to compare wave height dissipation. These studies were used to create a basic understanding of wave dissipation across soft and hybrid features along different cross-shore widths. More specific implementation guidance for NbS is limited due to the lack of consistent monitoring practices and protocol within and between soft and hybrid features. This disparity is greatest between soft and hybrid NbS. To fully understand best practices for the wide variety of soft and hybrid NbS, more uniform monitoring data is needed to assess and more fully define wave dissipation performance. Based on the findings of this review, eight parameters to measure the wave dissipation effectiveness of NbS features are proposed. These findings will inform the development and application of evaluation protocols for future NbS projects. 

Marine ecosystems provide essential services to coastal residents, particularly for indigenous fishing communities that have strong ties to the environment and obtain multiple benefits from their use and management of ocean spaces. However, understanding of how these are impacted by fisheries, external pressures, and ocean management, remains limited due to a focus on economic valuation and aggregated metrics. This study explores the importance of select marine ecosystem services to the wellbeing of an indigenous community in West Hawaiˈi and the observed impacts on these ecosystem services by commercial and subsistence fishing. We used a mixed-methods approach that combined a workshop with an online survey of community perceptions regarding community important marine resources and cultural values. We find that both fish and non-fish species are important to all four well-being categories, including food security, culture, mental wellbeing, and income, though the least importance was given to the economic value. This study also found that commercial fishing is perceived to have a higher negative impact on marine resources and cultural values than subsistence fishing, but a generally lower impact on non-fish than fish species. The lack of community input into legislation development and a lack of enforcement capacity were perceived to aggravate these further, whereas the integration of place-based knowledge, values and rules of the environment was seen as beneficial to both marine and cultural ecosystem services. Overall, this study shows that non-economic and disaggregated valuation approaches are critical for revealing the variable ecosystem services that marine environments provide to local communities and the importance of more inclusive resource management approaches to manage impacts on these services. 

Abstract A growing number of global ocean conflict studies over the last decade have set out to advance sustainability in the Anthropocene. Many of these research projects use multiple case studies to extract lessons for wider contexts. The methods used by these studies, and the extent to which their results have validity beyond the individual case study, often remain unclear. This paper explores the challenges in performing cross-case analysis within what we denote as case-based globally focussed sustainability projects (CB-GSPs) and indicates solutions by combining information from semi-structured interviews with leading scientists from eight CB-GSPs. We identify six distinct challenges that are common across these studies with regard to generating actionable knowledge through cross-case analysis. Based on these findings, we propose a set of best practice recommendations for scientists, project partners, and funders to co-produce actionable knowledge for global projects on ocean conflict.