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Coastal marine ecosystems face a host of pressures from both offshore and land-based human activity. Research on terrestrial threats to coastal ecosystems has primarily focused on agricultural runoff, specifically showcasing how fertilizers and livestock waste create coastal eutrophication, harmful algae blooms, or hypoxic or anoxic zones. These impacts not only harm coastal species and ecosystems but also impact human health and economic activities. Few studies have assessed impacts of human wastewater on coastal ecosystems and community health. As such, we lack a comprehensive, fine-resolution, global assessment of human sewage inputs that captures both pathogens and nutrient flows to coastal waters and the potential impacts on coastal ecosystems. To address this gap, we use a new high-resolution geospatial model to measure and map nitrogen (N) and pathogen—fecal indicator organisms (FIO)—inputs from human sewage for ~135,000 watersheds globally. Because solutions depend on the source, we separate nitrogen and pathogen inputs from sewer, septic, and direct inputs. Our model indicates that wastewater adds 6.2Tg nitrogen into coastal waters, which is approximately 40% of total nitrogen from agriculture. Of total wastewater N, 63% (3.9Tg N) comes from sewered systems, 5% (0.3Tg N) from septic, and 32% (2.0Tg N) from direct input. We find that just 25 watersheds contribute nearly half of all wastewater N, but wastewater impacts most coastlines globally, with sewered, septic, and untreated wastewater inputs varying greatly across watersheds and by country. Importantly, model results find that 58% of coral and 88% of seagrass beds are exposed to wastewater N input. Across watersheds, N and FIO inputs are generally correlated. However, our model identifies important fine-grained spatial heterogeneity that highlight potential tradeoffs and synergies essential for management actions. Reducing impacts of nitrogen and pathogens on coastal ecosystems requires a greater focus on where wastewater inputs vary across the planet. Researchers and practitioners can also overlay these global, high resolution, wastewater input maps with maps describing the distribution of habitats and species, including humans, to determine the where the impacts of wastewater pressures are highest. This will help prioritize conservation efforts.Without such information, coastal ecosystems and the human communities that depend on them will remain imperiled.

Most small-scale fisheries (SSFs) in the developing world are exploited by rural communities, but global trends in coastal urbanization and development are rapidly transforming many SSF landscapes. The implications for livelihood resilience, or the capacity of a livelihood to overcome shocks and stresses, remain unknown. The environmental and economic shocks and stresses experienced by SSF communities are becoming more frequent and severe, highlighting the urgent need to understand how urban and rural SSF contexts influence how fishers build livelihood resilience. To shed light on this issue, we performed a systematic review of the Mexican SSF literature to compare constructions of livelihood resilience across urban and rural communities. Our findings suggest that attributes innate to urbanness and ruralness may influence how these communities and individuals build livelihood resilience. Specifically, our results suggest that population density, isolation, and the diversity of jobs available are associated with several indicator variables for livelihood resilience. Moreover, we find that the greatest threats to livelihood resilience in urban communities are weak incentives to cooperate and threats to ecosystems, while the greatest opportunities to achieve livelihood resilience are easier access to education and ample prospects for additional employment outside the fishing sector. In contrast, livelihood resilience in rural communities is most threatened by the relatively fewer opportunities for education and additional employment, but benefits from strong incentives to cooperate. Efforts to bolster livelihood resilience within SSF communities would benefit from considering these different opportunities and challenges presented by urban and rural contexts.

Kelp forests are one of the earth’s most productive ecosystems and are at great risk from climate change, yet little is known regarding their current conservation status and global future threats. Here, by combining a global remote sensing dataset of floating kelp forests with climate data and projections, we find that exposure to projected marine heatwaves will increase ~6 to ~16 times in the long term (2081–2100) compared to contemporary (2001–2020) exposure. While exposure will intensify across all regions, some southern hemisphere areas which have lower exposure to contemporary and projected marine heatwaves may provide climate refugia for floating kelp forests. Under these escalating threats, less than 3% of global floating kelp forests are currently within highly restrictive marine protected areas (MPAs), the most effective MPAs for protecting biodiversity. Our findings emphasize the urgent need to increase the global protection of floating kelp forests and set bolder climate adaptation goals. Kelp forests could face up to 16 times more marine heatwave exposure by 2100. With less than 3% of kelp forests in highly restrictive marine protected areas, urgent conservation and climate adaptation actions are needed

Marine heatwaves are globally occurring events that can negatively impact fisheries, but their impacts on small-scale operations remain understudied. We investigate the historical and future impacts of marine heatwaves on small-scale fisheries operating along a biogeographic transition zone in the Baja California Peninsula, Mexico. We estimate the impacts of the most intense marine heatwave regime on record on fisheries production of 43 economic units operating in a system of 55 Territorial Use-Rights for Fisheries. During this regime, aggregate landings in the lobster, sea urchin, and sea cucumber fisheries decreased between 15 and 58%. Most operations (56%) presented large reductions in landings, whose losses more than outweigh the small increase detected for the other 44%. Notably, impacts were larger for fisheries operating near an equatorward biogeographic break, and for operations in areas of high historical environmental variation and low historical variation in fisheries production. Climate models predict an increase in the frequency and intensity of exposure to marine heatwaves for all fisheries, but the change in frequency and intensity will be greater for those in the north. In the face of extreme environmental shocks such as marine heatwaves, small-scale fisheries operating near biogeographic transition zones are among the most vulnerable. Intense marine heatwaves led to a reduction in aggregate small-scale fisheries landings of lobsters, sea urchins and sea cucumbers of up to 58% during the last two decades in the Baja California Peninsula, according to an analysis of fisheries data and sea surface temperatures.

As a member of the “High Level Panel for a Sustainable Ocean Economy”, Mexico has committed to expand community-based marine conservation. We draw from more than two decades of experience to outline how existing resources may be leveraged to help inform the country’s ambitious conservation plans. A total of 514.12 km 2 have already been protected under community-based marine reserves. 14 years of ecological survey data, more than 130 community surveyors, more than one hundred publications, and an entire digital infrastructure provide a solid platform on which to continue building the community-based marine conservation movement. Parallel and complimentary efforts have advanced regulation, action, data access and transparency, and coordination. Future interventions should innovate, but leverage existing resources and continue to involve communities.

Marine reserves are implemented to achieve a variety of objectives, but are seldom rigorously evaluated to determine whether those objectives are met. In the rare cases when evaluations do take place, they typically focus on ecological indicators and ignore other relevant objectives such as socioeconomics and governance. And regardless of the objectives, the diversity of locations, monitoring protocols, and analysis approaches hinder the ability to compare results across case studies. Moreover, analysis and evaluation of reserves is generally conducted by outside researchers, not the reserve managers or users, plausibly thereby hindering effective local management and rapid response to change. We present a framework and tool, called \"MAREA\", to overcome these challenges. Its purpose is to evaluate the extent to which any given reserve has achieved its stated objectives. MAREA provides specific guidance on data collection and formatting, and then conducts rigorous causal inference analysis based on data input by the user, providing real-time outputs about the effectiveness of the reserve. MAREA's ease of use, standardization of state-of-the-art inference methods, and ability to analyze marine reserve effectiveness across ecological, socioeconomic, and governance objectives could dramatically further our understanding and support of effective marine reserve management.

The costs and benefits of customary top-down Marine Protected Areas (MPAs) have been studied at length. But the costs and benefits of community-based MPAs –an increasingly common tool in conservation and fisheries management– remain understudied. Here, we quantify the operational costs of maintaining community-based MPA monitoring programs in nine small-scale fishing communities in Mexico. We then compare these costs to the potential extractive use value of invertebrate and fish biomass contained in the reserves. We find that the annual monitoring costs (median: 1,130 MXN/ha; range: 23-3,561 MXN/ha) represent between 0.3% and 55% of the extractive use value of the biomass contained in the reserves (median: 21.31 thousand MXN/ha; 5.22 - 49/12 thousand MXN/ha). These results suggest that the direct monetary benefits of community-based marine conservation can outweigh the costs of monitoring programs, providing further support for these types of management schemes. While further research should explore other mechanisms that would allow fishers to leverage the non-extractive use value of reserves ( e.g. , tourism) or the non-use value ( i.e. existence value of biodiversity) to sustainably finance their conservation efforts, a stop-gap measure to ensuring long-term monitoring costs are covered might include limited extractive use of resources contained in the reserves.

Are climate-resilient small-scale fisheries more resilient in general? Small-scale fisheries are increasingly exposed to a multitude of shocks that threaten their productivity and existence. Understanding whether resilience is specific to, or generalizable across, “domains” (e.g. environmental, market, social) can help design policy interventions to support small-scale fisheries. Here, we test whether fishing economic units that exhibit higher resistance to climate shocks are also more resistant to shocks from other domains. We analyzed long-term fisheries production data from 237 economic units that were subject to two recent major shocks: a period of frequent and intense marine heatwaves (2015-2016) and market disruptions caused by the COVID-19 pandemic (2020–2022). In 86.1% of the cases ( N  = 204), economic units exhibited similar resistance for both shocks, and concordance was higher for fishing units with low catch diversity and a balanced market portfolio. Our work suggests that resilience may be generalizable across domains.

Moored fish aggregating devices (MFADs) are promoted in small-scale fisheries around the world as tools to increase fisher incomes, enhance food security, and ease pressure on degraded inshore fisheries. Despite their growing popularity, the biophysical and socioeconomic contexts in which MFAD fisheries are implemented - and the implications of these contexts for MFAD fishery success - remain poorly understood. Here we develop a framework identifying and evaluating factors likely to influence MFAD fishery outcomes and apply it across states in the insular Caribbean region. We highlight the heterogeneity in MFAD regulatory strength, catch marketability, social need, and costs among states and discuss best approaches for optimizing MFAD benefits across different socioeconomic scenarios.

Two of the largest protected areas on earth are U.S. National Monuments in the Pacific Ocean. Numerous claims have been made about the impacts of these protected areas on the fishing industry, but there has been no ex post empirical evaluation of their effects. We use administrative data documenting individual fishing events to evaluate the economic impact of the expansion of these two monuments on the Hawaii longline fishing fleet. Surprisingly, catch and catch-per-unit-effort are higher since the expansions began. To disentangle the causal effect of the expansions from confounding factors, we use unaffected control fisheries to perform a difference-in-differences analysis. We find that the monument expansions had little, if any, negative impacts on the fishing industry, corroborating ecological models that have predicted minimal impacts from closing large parts of the Pacific Ocean to fishing. There are concerns that expansion of marine protected areas could have negative effects on the fishing industry. Here Lynham et al. demonstrate that the expansion of two of the world’s largest protected areas did not have a negative impact on catch rates in the Hawaii longline fishery.