The El Niño-Southern Oscillation (ENSO) drives large changes in global climate patterns from year to year, yet its sensitivity to continued anthropogenic greenhouse forcing is uncertain. We analyzed fossil coral reconstructions of ENSO spanning the past 7000 years from the Northern Line Islands, located in the center of action for ENSO. The corals document highly variable ENSO activity, with no evidence for a systematic trend in ENSO variance, which is contrary to some models that exhibit a response to insolation forcing over this same period. Twentieth-century ENSO variance is significantly higher than average fossil coral ENSO variance but is not unprecedented. Our results suggest that forced changes in ENSO, whether natural or anthropogenic, may be difficult to detect against a background of large internal variability.

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Several lines of evidence indicate that microorganisms in the mesoand bathypelagic ocean are metabolically active and respiring carbon. In addition, growing evidence suggests that archaea are fixing inorganic carbon in this environment. However, direct quantification of the contribution from deep ocean carbon sources to community production in the dark ocean remains a challenge. In this study, carbon flow through the microbial community at 2 depths in the mesopelagic zone of the North Pacific Subtropical Gyre was examined by exploiting the unique radiocarbon signatures (⌬ 14 C) of the 3 major carbon sources in this environment. The radiocarbon content of nucleic acids, a biomarker for viable cells, isolated from size-fractionated particles (0.2-0.5 m and >0.5 m) showed the direct incorporation of carbon delivered by rapidly sinking particles. Most significantly, at the 2 mesopelagic depths examined (670 m and 915 m), carbon derived from in situ autotrophic fixation supported a significant fraction of the free-living microbial community (0.2-0.5 m size fraction), but the contribution of chemoautotrophy varied markedly between the 2 depths. Results further showed that utilization of the ocean's largest reduced carbon reservoir, 14 C-depleted, dissolved organic carbon, was negligible in this environment. This isotopic portrait of carbon assimilation by the in situ, free-living microbial community, integrated over >50,000 L of seawater, implies that recent, photosynthetic carbon is not always the major carbon source supporting microbial community production in the mesopelagic realm.microbial metabolism ͉ particle flux ͉ particulate organic carbon (POC) ͉ chemoautotrophy

Individuals relying on natural resource extraction for their livelihood face high income variability driven by a mix of environmental, biological, management, and economic factors. Key to managing these industries is identifying how regulatory actions and individual behavior affect income variability, financial risk, and, by extension, the economic stability and the sustainable use of natural resources. In commercial fisheries, communities and vessels fishing a greater diversity of species have less revenue variability than those fishing fewer species. However, it is unclear whether these benefits extend to the actions of individual fishers and how year-to-year changes in diversification affect revenue and revenue variability. Here, we evaluate two axes by which fishers in Alaska can diversify fishing activities. We show that, despite increasing specialization over the last 30 years, fishing a set of permits with higher species diversity reduces individual revenue variability, and fishing an additional permit is associated with higher revenue and lower variability. However, increasing species diversity within the constraints of existing permits has a fishery-dependent effect on revenue and is usually (87% probability) associated with increased revenue uncertainty the following year. Our results demonstrate that the most effective option for individuals to decrease revenue variability is to participate in additional or more diverse fisheries. However, this option is expensive, often limited by regulations such as catch share programs, and consequently unavailable to many individuals. With increasing climatic variability, it will be particularly important that individuals relying on natural resources for their livelihood have effective strategies to reduce financial risk. diversity-stability relationship | Bayesian variance function regression | income variability | natural resource management | ecological portfolio effects I t can be difficult for individuals to sustain a livelihood from natural resource extraction. These livelihoods tend to have high annual variability in income relative to other professions (1, 2). In addition to income variability from economic sources, such as changes in demand or prices, individuals dependent on natural resources are also subject to biological and environmental variability (3). For example, drought and flooding are a major source of risk for agricultural food security and farmers' incomes (4), and catastrophic disease outbreaks and wildfires increase risk for the logging industry (5).Individuals who rely on natural resources for income develop strategies to reduce income variability. For example, farmers may diversify their crops or include off-farm income sources to buffer against environmental and market shocks, as well as longterm climatic trends and seasonality (6-8). However, otherwise well-intentioned regulations may limit how individuals diversify, or may incentivize against diversification. For instance, crop subsidies in the United States may incentivize some farms ...