ABSTRACT. Small-scale fisheries (SSFs) are social-ecological systems that play a critical role in terms of food security and poverty alleviation in Latin America. These fisheries are increasingly threatened by anthropogenic and climatic drivers acting at multiple scales. We review the effects of climate variability on Latin American SSFs, and discuss the combined effects of two additional human drivers: globalization of markets and governance. We show drastic long-term and large-scale effects of climate variability, e.g., sea surface temperature anomalies, wind intensity, sea level, and climatic indices, on SSFs. These variables, acting in concert with economic drivers, have exacerbated stock depletion rates in Latin American SSFs. The impact of these drivers varied according to the life cycle and latitudinal distribution of the target species, the characteristics of the oceanographic systems, and the inherent features of the social systems. Our review highlights the urgent need to improve management and governance systems to promote resilience as a way to cope with the increasing uncertainty about the impacts of climate and globalization of markets on Latin American SSFs.RESUMEN. Las pesquerías artesanales son sistemas sociales-ecológicos que desempeñan un papel clave en términos de seguridad alimentaria y la mitigación de la pobreza en América Latina. Estas pesquerías se encuentran cada vez más amenazadas por las presiones antropogénicas y climáticas que actúan a múltiples escalas temporales y espaciales. En este trabajo se ha evaluado la relación entre la variabilidad climática y los recursos pesqueros como una aproximación para comprender los posibles efectos a corto y largo plazo del cambio climático sobre las pesquerías artesanales en América Latina, teniendo en cuenta el efecto combinado de dos factores de estrés humanos adicionales: la globalización de los mercados y la gobernanza. En base al análisis cuantitativo de las extensas bases de datos utilizadas y empleando el enfoque de casos de estudio, este trabajo demuestra que se están produciendo efectos dramáticos a largo plazo y a gran escala de la variabilidad climática, que actuando de manera concertada con factores bioeconómicos, han exacerbado las tasas de depleción de los stocks en América Latina. En particular, hemos identificado dos principales factores del cambio global: (1) la variabilidad del clima a través de las anomalías de temperatura superficial del mar, de la intensidad del viento, del incremento del nivel del mar y del uso de índices climáticos, y (2) el aumento en los precios unitarios en las pesquerías artesanales que se encuentran altamente integradas en el mercado mundial de productos de la pesca. Los resultados también indican que el impacto de estos factores varía según el ciclo de vida y la distribución latitudinal de las especies objetivo, las características intrínsecas de los sistemas oceanográficos y las particularidades inherentes de los sistemas sociales. Nuestros resultados ponen de manifiesto la necesidad urgente de desar...
Ocean circulation shapes marine phytoplankton communities by setting environmental conditions and dispersing organisms. In addition, processes acting on the water column (e.g., heat fluxes and mixing) affect the community structure by modulating environmental variables that determine in situ growth and loss rates. Understanding the scales over which phytoplankton communities vary in time and space is key to elucidate the relative contributions of local processes and ocean circulation on phytoplankton distributions. Using a global ocean ecosystem model, we quantify temporal and spatial correlation scales for phytoplankton phenotypes with diverse functional traits and cell sizes. Through this analysis, we address these questions: (1) Over what timescales do perturbations in phytoplankton populations persist? and (2) over what distances are variations in phytoplankton populations synchronous? We find that correlation timescales are short in regions of strong currents, such as the Gulf Stream and Antarctic Circumpolar Current. Conversely, in the subtropical gyres, phytoplankton population anomalies persist for relatively long periods. Spatial correlation length scales are elongated near ocean fronts and narrow boundary currents, reflecting flow paths and frontal patterns. In contrast, we find nearly isotropic spatial correlation fields where current speeds are small, or where mixing acts roughly equally in all directions. Phytoplankton timescales and length scales also vary coherently with phytoplankton body size. In addition to aiding understanding of phytoplankton population dynamics, our results provide global insights to guide the design of biological ocean observing networks and to better interpret data collected at long-term monitoring stations.Plain Language Summary Using a global model of the marine planktonic ecosystem, we quantify the temporal and spatial correlation scales of diverse types of phytoplankton. The timescales reflect the persistence of anomalies in time and the stability of the planktonic system. The spatial scales measure over what distances variations in phytoplankton populations are synchronous. We find that timescales and length scales vary with cell size and that global patterns of correlation are shaped by ocean currents. These results provide valuable insights for the design of ocean observing systems with a unique ecological perspective. We also discuss how regional differences in phytoplankton community correlation scales are relevant for interpreting data collected at long-term monitoring stations.
Abstract. Continental shelf regions in the ocean play an important role in the global cycling of carbon and nutrients, but their responses to global change are understudied. Global Earth system models (ESMs), as essential tools for building understanding of ocean biogeochemistry, are used extensively and routinely for projections of future climate states; however, their relatively coarse spatial resolution is likely not appropriate for accurately representing the complex patterns of circulation and elemental fluxes on the shelves along ocean margins. Here, we compared 29 ESMs used in the Intergovernmental Panel on Climate Change (IPCC)'s Assessment Reports (ARs) 5 and 6 and a regional biogeochemical model for the northwest North Atlantic (NWA) shelf to assess their ability to reproduce surface observations of temperature, salinity, nitrate and chlorophyll. The NWA region is biologically productive, influenced by the large-scale Gulf Stream and Labrador Current systems and particularly sensitive to climatically induced changes in large-scale circulation. Most ESMs compare relatively poorly to observed surface nitrate and chlorophyll and show differences with observed surface temperature and salinity that suggest spatial mismatches in their large-scale current systems. Model-simulated nitrate and chlorophyll compare better with available observations in AR6 than in AR5, but none of the models perform equally well for all four parameters. The ensemble means of all ESMs, and of the five best-performing ESMs, strongly underestimate observed chlorophyll and nitrate. The regional model has a much higher spatial resolution and reproduces the observations significantly better than any of the ESMs. It also simulates reasonably well vertically resolved observations from gliders and bi-monthly ship-based monitoring observations. A ranking of the ESMs indicates that only one ESM has good and consistent performance for all variables. An additional evaluation of the ESMs along the regional model boundaries shows larger variability but is generally consistent with the ranking on the shelf. Overall, 11 ESMs were deemed satisfactory for use in the NWA, either directly or for regional downscaling.
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