Engaging the next generation of editorial talent through a hands-on fellowship model.

Peer-review and subject-matter editing is the backbone of scientific publishing. However, early-career researchers (ECRs) are given few opportunities to participate in the editorial process beyond reviewing articles. Thus, a disconnect exists: science needs high-quality editorial talent to conduct, oversee and improve the publishing process, yet we dedicate few resources to building editorial talent nor giving ECRs formal opportunities to influence publishing from within. ECRs can contribute to the publishing landscape in unique ways given their insight into new and rapidly developing publishing trends (e.g. open science). Here, we describe a two-way fellowship model that gives ECRs a "seat" at the editorial table of a field-leading journal. We describe both the necessary framework and benefits that can stem from editorial fellowships for ECRs, editors, journals, societies, and the ​broader scientific community.

Greenhouse gas emissions from an arid-zone reservoir and their environmental policy significance: Results from existing global models and an exploratory dataset.

Reservoirs in arid regions often provide critical water storage but little is known about their greenhouse gas (GHG) footprint. While there is growing appreciation of the role reservoirs play as GHG sources, there is a lack of understanding of GHG emission dynamics from reservoirs in arid regions and implications for environmental policy. Here we present initial GHG emission measurements from Lake Powell, a large water storage reservoir in the desert southwest United States. We report CO2-eq emissions from the shallow (< 15 m) littoral regions of the reservoir that are higher than the global average areal emissions from reservoirs (9.4 vs. 5.8 g CO2-eq m-2 d-1) whereas fluxes from the main reservoir were two orders of magnitude lower (0.09 g CO2-eq m-2 d-1). We then compared our measurements to modeled CO2 + CH4 emissions from the reservoir using four global scale models. Factoring these emissions into hydropower production at Lake Powell yielded low GHG emissions per MWh-1 as compared to fossil-fuel based energy sources. With the exception of one model, the estimated hydropower emissions for Lake Powell ranged from 10-32 kg CO2-eq MWh-1, compared to ∼400-1000 kg CO2-eq MWh-1 for natural gas, oil, and coal. We also estimate that reduced littoral habitat under low water levels leads to ∼50% reduction in the CO2 equivalent emissions per MWh. The sensitivity of GHG emissions to reservoir water levels suggests that the interaction will be an important policy consideration in the design and operation of arid region systems.

Methane Emissions from Artificial Waterbodies Dominate the Carbon Footprint of Irrigation: A Study of Transitions in the Food-Energy-Water-Climate Nexus (Spain, 1900-2014).

Irrigation in the Mediterranean region has been used for millennia and has greatly expanded with industrialization. Irrigation is critical for climate change adaptation, but it is also an important source of greenhouse gas emissions. This study analyzes the carbon (C) footprint of irrigation in Spain, covering the complete historical process of mechanization. A 21-fold total, 6-fold area-based, and 4-fold product-based increase in the carbon footprint was observed during the 20th century, despite an increase in water use efficiency. CH4 emissions from waterbodies, which had not previously been considered in the C footprint of irrigation systems, dominated the emission budget during most of the analyzed period. Technologies to save water and tap new water resources greatly increased energy and infrastructure demand, while improvements in power generation efficiency had a limited influence on irrigation emissions. Electricity production from irrigation dams may contribute to climate change mitigation, but the amount produced in relation to that consumed in irrigation has greatly declined. High uncertainty in CH4 emission estimates from waterbodies stresses a need for more spatially resolved data and an improved empirical knowledge of the links between water quality, water level fluctuations, and emissions at the regional scale.

Reservoir Water-Level Drawdowns Accelerate and Amplify Methane Emission.

Water-level fluctuations due to reservoir management could substantially affect the timing and magnitude of reservoir methane (CH4) fluxes to the atmosphere. However, effects of such fluctuations on CH4 emissions have received limited attention. Here we examine CH4 emission dynamics in six Pacific Northwest U.S. reservoirs of varying trophic status, morphometry, and management regimes. In these systems, we show that water-level drawdowns can, at least temporarily, greatly increase per-area reservoir CH4 fluxes to the atmosphere, and can account for more than 90% of annual reservoir CH4 flux in a period of just a few weeks. Reservoirs with higher epilimnetic [chlorophyll a] experienced larger increases in CH4 emission in response to drawdown (R2 = 0.84, p < 0.01), suggesting that eutrophication magnifies the effect of drawdown on CH4 emission. We show that drawdowns as small as 0.5 m can stimulate ebullition events. Given that drawdown events of this magnitude are quite common in reservoirs, our results suggest that this process must be considered in sampling strategies designed to characterize total CH4 fluxes from reservoirs. The extent to which (and the mechanisms by which) drawdowns short-circuit connections between methanogenesis and methanotrophy, thereby increasing net CH4 fluxes to the atmosphere, should be a focus of future work.

Greenhouse Gas Emissions from Reservoir Water Surfaces: A New Global Synthesis.

Collectively, reservoirs created by dams are thought to be an important source of greenhouse gases (GHGs) to the atmosphere. So far, efforts to quantify, model, and manage these emissions have been limited by data availability and inconsistencies in methodological approach. Here, we synthesize reservoir CH4, CO2, and N2O emission data with three main objectives: (1) to generate a global estimate of GHG emissions from reservoirs, (2) to identify the best predictors of these emissions, and (3) to consider the effect of methodology on emission estimates. We estimate that GHG emissions from reservoir water surfaces account for 0.8 (0.5-1.2) Pg CO2 equivalents per year, with the majority of this forcing due to CH4. We then discuss the potential for several alternative pathways such as dam degassing and downstream emissions to contribute significantly to overall emissions. Although prior studies have linked reservoir GHG emissions to reservoir age and latitude, we find that factors related to reservoir productivity are better predictors of emission.

Experimental reductions in subdaily flow fluctuations increased gross primary productivity for 425 river kilometers downstream.

Aquatic primary production is the foundation of many river food webs. Dams change the physical template of rivers, often driving food webs toward greater reliance on aquatic primary production. Nonetheless, the effects of regulated flow regimes on primary production are poorly understood. Load following is a common dam flow management strategy that involves subdaily changes in water releases proportional to fluctuations in electrical power demand. This flow regime causes an artificial tide, wetting and drying channel margins and altering river depth and water clarity, all processes that are likely to affect primary production. In collaboration with dam operators, we designed an experimental flow regime whose goal was to mitigate negative effects of load following on ecosystem processes. The experimental flow contrasted steady-low flows on weekends with load following flows on weekdays. Here, we quantify the effect of this experimental flow on springtime gross primary production (GPP) 90-to-425 km downstream of Glen Canyon Dam on the Colorado River, AZ, USA. GPP during steady-low flows was 41% higher than during load following flows, mostly owing to nonlinear reductions in sediment-driven turbidity. The experimental flow increased weekly GPP even after controlling for variation in weekly mean discharge, demonstrating a negative effect of load following on GPP. We estimate that this environmental flow increased springtime carbon fixation by 0.27 g C m-2 d-1, which is ecologically meaningful considering median C fixation in 356 US rivers of 0.44 g C m-2 d-1 and the fact that native fish populations in this river are food-limited.