Climate change is already impacting coastal communities, and ongoing and future shifts in fisheries species productivity from climate change have implications for the livelihoods and cultures of ...coastal communities. Harvested marine species in the California Current Large Marine Ecosystem support U.S. West Coast communities economically, socially, and culturally. Ecological vulnerability assessments exist for individual species in the California Current but ecological and human vulnerability are linked and vulnerability is expected to vary by community. Here, we present automatable, reproducible methods for assessing the vulnerability of U.S. West Coast fishing dependent communities to climate change within a social-ecological vulnerability framework. We first assessed the ecological risk of marine resources, on which fishing communities rely, to 50 years of climate change projections. We then combined this with the adaptive capacity of fishing communities, based on social indicators, to assess the potential ability of communities to cope with future changes. Specific communities (particularly in Washington state) were determined to be at risk to climate change mainly due to economic reliance on at risk marine fisheries species, like salmon, hake, or sea urchins. But, due to higher social adaptive capacity, these communities were often not found to be the most vulnerable overall. Conversely, certain communities that were not the most at risk, ecologically and economically, ranked in the category of highly vulnerable communities due to low adaptive capacity based on social indicators (particularly in Southern California). Certain communities were both ecologically at risk due to catch composition and socially vulnerable (low adaptive capacity) leading to the highest tier of vulnerability. The integration of climatic, ecological, economic, and societal data reveals that factors underlying vulnerability are variable across fishing communities on the U.S West Coast, and suggests the need to develop a variety of well-aligned strategies to adapt to the ecological impacts of climate change.
Spatial management is a valuable strategy to advance regional goals for nature conservation, economic development, and human health. One challenge of spatial management is navigating the ...prioritization of multiple features. This challenge becomes more pronounced in dynamic management scenarios, in which boundaries are flexible in space and time in response to changing biological, environmental, or socioeconomic conditions. To implement dynamic management, decision‐support tools are needed to guide spatial prioritization as feature distributions shift under changing conditions. Marxan is a widely applied decision‐support tool designed for static management scenarios, but its utility in dynamic management has not been evaluated. EcoCast is a new decision‐support tool developed explicitly for the dynamic management of multiple features, but it lacks some of Marxan's functionality. We used a hindcast analysis to compare the capacity of these 2 tools to prioritize 4 marine species in a dynamic management scenario for fisheries sustainability. We successfully configured Marxan to operate dynamically on a daily time scale to resemble EcoCast. The relationship between EcoCast solutions and the underlying species distributions was more linear and less noisy, whereas Marxan solutions had more contrast between waters that were good and poor to fish. Neither decision‐support tool clearly outperformed the other; the appropriateness of each depends on management purpose, resource‐manager preference, and technological capacity of tool developers.
Article impact statement: Marxan can function as a decision‐support tool for dynamic management scenarios in which boundaries are flexible in space and time.
Herramientas de Apoyo para la Toma de Decisiones en el Manejo Dinámico
Resumen
El manejo espacial es una estrategia valiosa para llevar hacia adelante los objetivos regionales para la conservación de la naturaleza, el desarrollo económico y la salud humana. Uno de los retos del manejo espacial es la navegación a través de la priorización de múltiples caracteres. Este reto se vuelve más pronunciado dentro de los escenarios de manejo dinámico, en los cuales los límites son flexibles en el tiempo y en el espacio como respuesta a las cambiantes condiciones biológicas, ambientales o socioeconómicas. Para implementar el manejo dinámico, se necesitan herramientas de apoyo para la toma de decisiones para guiar a la priorización espacial conforme la distribución de los caracteres se modifica bajo condiciones cambiantes. Marxan es una herramienta de apoyo para la toma de decisiones utilizada ampliamente y diseñada para escenarios de manejo estático, pero su utilidad para el manejo dinámico no ha sido evaluada. EcoCast es una nueva herramienta de apoyo para la toma de decisiones desarrollada explícitamente para el manejo dinámico de múltiples caracteres, pero carece de algunas funcionalidades que tiene Marxan. Usamos un análisis de información retrospectiva para comparar la capacidad de estas dos herramientas para priorizar a cuatro especies marinas en un escenario de manejo dinámico con respecto a la sustentabilidad de las pesquerías. Configuramos exitosamente la herramienta Marxan para que operara dinámicamente con respecto a una escala diaria de tiempo y así se asemejara a EcoCast. La relación entre las soluciones de EcoCast y las distribuciones subyacentes de las especies fue más lineal y menos ruidosa, mientras que las soluciones de Marxan tuvieron un mayor contraste entre las aguas que eran buenas y aquellas que eran pobres para los peces. Ninguna de las dos herramientas de apoyo para la toma de decisiones tuvo un mejor desempeño que la otra; la pertinencia de cada una depende del propósito del manejo, la preferencia del administrador de los recursos y la capacidad tecnológica de quienes desarrollan la herramienta.
摘要
空间管理是推动区域自然保护、经济发展和人类健康目标的重要战略, 它面临着多个特征物种优先保护决策的挑战。在管理的时空边界会随生物、坏境和经济社会条件变化的动态管理情景中, 这样的挑战更加明显。随着特征物种的分布响应环境变化而变化, 为实现动态管理, 需要用决策支持工具来指导空间优先保护。 Marxan 软件是为静态管理情景设计的一个应用广泛的决策支持工具, 但在动态管理中的实用性尚未得到评估。 EcoCast 软件则是为多个特征物种的动态管理开发的新决策支持工具, 但却缺少 Marxan 软件的一些功能。我们用后报分析比较了这两个工具在渔业可持续性动态管理情景中为四种海洋生物设计优先保护方案的成效。我们通过配置 Marxan 软件, 成功使其像 EcoCast 软件一样在每日时间尺度上动态运作。 EcoCast 设计的决策方案和潜在物种分布的关系更符合线性, 模型噪声更小; 而 Marxan 的方案在适宜与不适宜捕鱼的水域之间差异更明显。这两种决策支持工具都没有压倒性优势, 其适用与否取决于管理目的、资源管理者偏好和工具开发者的技术能力。【翻译: 胡怡思; 审校: 聂永刚】
Given the importance of coastal upwelling systems to ocean productivity, fisheries, and biogeochemical cycles, their response to climate change is of great interest. However, there is no consensus on ...future productivity changes in these systems, which may be controlled by multiple drivers including wind‐driven and geostrophic transport, stratification, and source water properties. Here we use an ensemble of regional ocean projections and recently developed upwelling indices for the California Current System to disentangle these sometimes‐competing influences. Some changes are consistent among models (e.g., decreased mixed layer depth), while for others there is a lack of agreement even on the direction of future change (e.g., nitrate concentration in upwelled waters). Despite models' diverging projections of productivity changes, they agree that those changes are predominantly driven by subsurface nitrate concentrations, not by upwelling strength. Our results highlight the need for more attention to processes governing subsurface nutrient changes, not just upwelling strength.
Plain Language Summary
The California Current System is one of the world's eastern boundary upwelling systems—some of the most productive regions in the global ocean. These regions support a wide range of human activities, such as fisheries and tourism, motivating extensive research on how they might evolve under future climate change. A number of hypotheses have been offered to describe future physical and chemical change in these systems, and in terms of their impacts on primary production (which forms the base of the marine food web), these mechanisms may reinforce or oppose each other. Enhanced nutrient concentrations in upwelling source waters would support higher productivity, increased stratification would limit nutrient supply and productivity, and increased upwelling could enhance productivity to a point but limit productivity if it is too strong. There is no consensus on which mechanism(s) will predominantly drive future productivity changes. Here we provide a detailed analysis of projected physical and biogeochemical changes and how they relate to productivity changes. Even though different models project different futures, we find that in all of them the primary control on productivity is the nitrate concentration of subsurface waters, not the strength of upwelling, which has received more attention to date.
Key Points
Future changes in the California Current System are evaluated using an ensemble of downscaled ocean projections
We evaluate changes in Ekman and geostrophic transports, water column structure, and subsurface nitrate concentrations
Across models, phytoplankton biomass changes are more closely tied to subsurface nitrate concentration than upwelling strength
Forecasting weather has become commonplace, but as society faces novel and uncertain environmental conditions there is a critical need to forecast ecology. Forewarning of ecosystem conditions during ...climate extremes can support proactive decision-making, yet applications of ecological forecasts are still limited. We showcase the capacity for existing marine management tools to transition to a forecasting configuration and provide skilful ecological forecasts up to 12 months in advance. The management tools use ocean temperature anomalies to help mitigate whale entanglements and sea turtle bycatch, and we show that forecasts can forewarn of human-wildlife interactions caused by unprecedented climate extremes. We further show that regionally downscaled forecasts are not a necessity for ecological forecasting and can be less skilful than global forecasts if they have fewer ensemble members. Our results highlight capacity for ecological forecasts to be explored for regions without the infrastructure or capacity to regionally downscale, ultimately helping to improve marine resource management and climate adaptation globally.
In the California Current System (CCS), changes in the phenology (i.e., seasonal timing) of coastal upwelling alter the functioning of this productive marine ecosystem. Recently developed coastal ...upwelling indices that account for upwelling strength and nutrient flux to the surface provide a more complete understanding of bottom‐up forcing in the region. Using these indices, we describe CCS upwelling phenological variability in vertical transport and nutrient flux. Physical and biogeochemical spring transitions generally co‐occur in winter or spring, followed by increased upwelling and nutrient flux. In the latter half of the year, upwelling continues but nutrient flux wanes as declining source nutrient concentrations limit the biological efficacy of coastal upwelling. Earlier spring transitions and higher season‐integrated upwelling intensity occur during strong La Niña events at all latitudes, driven largely by stronger alongshore wind stress. Understanding phenological changes in coastal upwelling is critical, as they could have significant ecosystem consequences.
Plain Language Summary
In the California Current System (CCS), coastal upwelling carries nutrient‐rich waters to the surface, supporting primary production and driving the coastal ecosystem. This upwelling varies on a seasonal and interannual basis, as reflected in recently developed indices that account for the amount of water upwelled to the surface as well as the amount of nutrients carried in that water. Generally upwelling and nutrient transport are high in the first half of the year. Upwelling persists into the second half of the year, but nutrient transport decreases as the deep‐water sources of these nutrients are depleted. Upwelling in the CCS is also affected by the El Niño Southern Oscillation. During La Niña conditions, strong trade winds enhance upwelling and nutrient transport on the California coast. This paper presents regional, seasonal and interannual patterns of upwelling and nutrient delivery in the CCS, which are important drivers of change to this coastal ecosystem.
Key Points
We define new upwelling phenology indices for the California Current System that include nutrient transport
We identify spatial, seasonal, and interannual patterns of upwelling and nutrient delivery
We relate the physical mechanisms of coastal upwelling with its biological efficacy
A regional ocean model is used to evaluate the roles of wind, surface heat flux, and basin‐scale climate variability in regulating the upwelled nitrate supply in the California Current. A strong ...positive trend in nitrate flux from 1980 to 2010 was driven almost entirely by enhanced equatorward winds, negating a weak negative trend associated with increased surface heat flux. Increased upwelling and nitrate flux are consistent with cooler surface temperatures and higher phytoplankton concentrations observed over the same period. Changes in remote ocean forcing, resulting primarily from basin‐scale climate variability (e.g., El Niño–Southern Oscillation and Pacific Decadal Oscillation), drive considerable interannual fluctuations and may dominate the ecosystem response on interannual to decadal time scales. However, comparison with previously published findings suggests that local wind intensification persists through changing basin‐scale climate regimes. Understanding the different time scales of variability in forcing mechanisms, and their interactions with each other, is necessary to distinguish transient ecosystem impacts from secular trends.
Key Points
We quantify wind, heat, and remote ocean forcing impacts on upwelled nitrate
For 1980‐2010, enhanced wind negates surface heating, increasing nitrate flux
Wind and heat flux trends persist through basin‐scale decadal variability
This paper investigates environmental drivers of U.S. West Coast petrale sole (Eopsetta jordani) recruitment as an initial step toward developing an environmental recruitment index that can inform ...the stock assessment in the absence of survey observations of age‐0 and age‐1 fish. First, a conceptual life history approach is used to generate life‐stage‐specific and spatio‐temporally specific mechanistic hypotheses regarding oceanographic variables that likely influence survival at each life stage. Seven life history stages are considered, from female spawner condition through benthic recruitment as observed in the Northwest Fisheries Science Center West Coast Groundfish Bottom Trawl Survey (age‐2 fish). The study area encompasses the region from 40 to 48°N in the California Current Ecosystem. Hypotheses are tested using output from a regional ocean reanalysis model outputs and model selection techniques. Four oceanographic variables explained 73% of the variation in recruitment not accounted for by estimates based exclusively on the spawning stock size. Recruitment deviations were (a) positively correlated with degree days during the female precondition period, (b) positively correlated with mixed‐layer depth during the egg stage, (c) negatively correlated with cross‐shelf transport during the larval stage, and (d) negatively correlated with cross‐shelf transport during the benthic juvenile stage. While multiple mechanisms likely affect petrale sole recruitment at different points during their life history, the strength of the relationship is promising for stock assessment and integrated ecosystem assessment applications.
Aim
Advances in ecological and environmental modelling offer new opportunities for estimating dynamic habitat suitability for highly mobile species and supporting management strategies at relevant ...spatiotemporal scales. We used an ensemble modelling approach to predict daily, year‐round habitat suitability for a migratory species, the blue whale (Balaenoptera musculus), and demonstrate an application for evaluating the spatiotemporal dynamics of their exposure to ship strike risk.
Location
The California Current Ecosystem (CCE) and the Southern California Bight (SCB), USA.
Methods
We integrated a long‐term (1994–2008) satellite tracking dataset on 104 blue whales with data‐assimilative ocean model output to assess year‐round habitat suitability. We evaluated the relative utility of ensembling multiple model types compared to using single models, and selected and validated candidate models using multiple cross‐validation metrics and independent observer data. We quantified the spatial and temporal distribution of exposure to ship strike risk within shipping lanes in the SCB.
Results
Multi‐model ensembles outperformed single‐model approaches. The final ensemble model had high predictive skill (AUC = 0.95), resulting in daily, year‐round predictions of blue whale habitat suitability in the CCE that accurately captured migratory behaviour. Risk exposure in shipping lanes was highly variable within and among years as a function of environmental conditions (e.g., marine heatwave).
Main conclusions
Daily information on three‐dimensional oceanic habitats was used to model the daily distribution of a highly migratory species with high predictive power and indicated that management strategies could benefit by incorporating dynamic environmental information. This approach is readily transferable to other species. Dynamic, high‐resolution species distribution models are valuable tools for assessing risk exposure and targeting management needs.
Time‐area closures are an important tool for reducing fisheries bycatch, but their effectiveness and economic impact can be influenced by the changes in species distributions. For fisheries targeting ...highly mobile species, the economic impact of a closure may by highly dynamic, depending on the current suitability of the closed area for the target species.
We present an analysis to quantify the fine‐scale economic impact of time‐area closures: the ‘lost economic opportunity’, which is the percentage of total potential profit for an entire fishing season that occurs within and during a time‐area closure. Our analysis integrates a spatially explicit and environment‐informed catch model with a utility model that quantifies fishing revenues and costs, and thus incorporates a dynamic target species distribution in the estimated economic impact of a closure. We demonstrate this approach by evaluating the economic impact of the Loggerhead Conservation Area (LCA) on California's drift gillnet swordfish Xiphias gladius fishery.
The lost economic opportunity due to the LCA time‐area closure ranged from 0% to 6% per season, with variation due to port location and trip duration, as well as inter‐annual changes in swordfish distribution. This increased by 40%–90% when a seasonally varying swordfish price was considered.
There was a clear signal in economic impact associated with a shift from warm to cool conditions in the California Current following the 1998 El Niño, with increased lost economic opportunity from 1999. This signal was due to higher swordfish catch inside the LCA during the cool phase, associated with increased water column mixing, and due to higher catches outside the LCA in the warmer phase, associated with increased sea‐surface temperature.
Synthesis and applications. We found small economic impact from a fishery closure, but with meaningful inter‐annual variation due to environmental change and the dynamic distribution of a target species. Our approach could be used to help determine the timing of closures, simulate impacts of proposed closures and, more generally, assess some economic consequences of climate‐induced shifts in species’ ranges.
We found small economic impact from a fishery closure, but with meaningful inter‐annual variation due to environmental change and the dynamic distribution of a target species. Our approach could be used to help determine the timing of closures, simulate impacts of proposed closures and, more generally, assess some economic consequences of climate‐induced shifts in species’ ranges.
A confluence of subarctic, tropical, and subtropical water masses feed the California Current System (CCS), supporting a highly productive ecosystem and wide array of marine ecosystem services. ...Long‐term declines in oxygen have been observed in this region, causing habitat compression and other ecosystem consequences. Here we quantify the water masses and processes causing deoxygenation in the subsurface CCS from 1993–2018, and we find that deoxygenation was caused both by changes in the advection of source waters and increased remineralization in the source waters. The historical deoxygenation trend can be attributed primarily (81%) to the Northern Equatorial Pacific Intermediate Water, the deep Pacific Equatorial Water mass transported in the California Undercurrent. We also find that advection and remineralization share nearly equal contributions to deoxygenation. This improved understanding of the mechanisms affecting the aerobic habitat of the CCS will inform projections of ecological impacts and mitigation of future deoxygenation.
Plain Language Summary
The California Current System (CCS) supports rich populations of finfish and marine invertebrates, rendering it ecologically and economically important. Climate change threatens these populations with increased temperatures, more acidic waters, and lower oxygen concentrations. From 1993 to 2018, we found the mean oxygen concentration in the southern, subsurface CCS decreased by 25%. This decrease can be attributed to the contributions of six water masses that feed the CCS, though they originate far afield in the Pacific Ocean. We discovered that from 1993–2018, 24 μM of deoxygenation occurred, and 81% of the observed deoxygenation was caused by a single water mass, the Northern Equatorial Pacific Intermediate Water. This water mass is transported into the CCS from the Eastern Tropical North Pacific via the California Undercurrent. Within the 81% of observed deoxygenation, 24% was caused by internal changes within the core of this water mass before it reached the CCS, likely in the Eastern Tropical North Pacific off Mexico. Understanding the drivers that influence oxygen availability in the CCS will assist with efforts to simulate biogeochemical changes. It will also improve projections about the ways that deoxygenation will impact this ecosystem and inform possibilities to mitigate future deoxygenation caused by climate change.
Key Points
Source water masses are responsible for −0.92 ± 0.04 μM year−1 of deoxygenation in the subsurface, southern CCS
Northern Equatorial Pacific Intermediate Water drove 81% (−0.78 ± 0.05 μM year−1) of deoxygenation in the southern CCS from 1993 to 2018
Outside of the CCS, remineralization within source water masses caused 32% (−0.31 ± 0.04 μM year−1) of deoxygenation
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