Temperature sensitivity of phytoplankton growth rate is crucial for predicting the effect of global warming on oceanic primary productivity and the efficiency of the biological carbon pump. To investigate how nutrient availability affects the temperature sensitivity of phytoplankton growth, we estimated the activation energy (Ea) of two dominant picocyanobacteria (Prochlorococcus and Synechococcus)

Recent molecular surveys revealed an unexpected diversity of mycoplankton in lakes and oceans. The early diverging fungal lineages are known to be prominent parasites of phytoplankton. However, due to missing fungal reference data, their identity and ecology remain mostly unknown. To overcome this problem, we combined single‐spore‐based DNA barcoding during one sampling season of the eutrophic Lake Inba

The effects of bottom water oxygen concentration on sediment oxygen uptake, oxygen penetration depth, nitrate and ammonium fluxes, anammox, denitrification, dissimilatory nitrate reduction to ammonium, nitrification, and mineralization were investigated off the Changjiang estuary and its adjacent East China Sea, by combining a seasonal comparison with three artificially induced bottom water oxygen

River aufeis (ow′ fīse) are widespread features of the arctic cryosphere. They form when river channels become locally restricted by ice, resulting in cycles of water overflow and freezing and the accumulation of ice, with some aufeis attaining areas of ~ 25 + km2 and thicknesses of 6+ m. During winter, unfrozen sediments beneath the insulating ice layer provide perennial groundwater‐habitat that is

Globally expanding hypoxia in estuaries and coastal oceans has largely been attributed to the elevated river nutrient inputs, whereas the role of river‐delivered terrestrial organic matter (OMterr) in hypoxia formation has been less investigated. This study uses a coupled physical‐biogeochemical model and observations to investigate how OMterr directly (via remineralization) and indirectly (via the

Several years of monitoring in the northern Canadian Arctic Archipelago contrast with a lack of repeated measurements in Queen Maud Gulf. As sea ice cover declines and maritime traffic increases along the Northwest Passage, Queen Maud Gulf, including the protected national historic sites of the HMS Erebus and HMS Terror wrecks, may experience drastic environmental changes. As part of the Kitikmeot

We assessed the influence of the intertidal and salinity gradients and mangrove forest structure on C stocks and sequestration rates in mangrove soils of an estuarine system in Todos os Santos Bay, Eastern Brazil. The accumulation rates of organic C (Corg) during the last century varied between and within estuarine zones, ranging from 65 to 1073 g Corg m−2 yr−1. The mean stocks of Corg and N for the

Coral reefs are known to have extremely high rates of primary production. However, common geochemical methods for determining bulk rates of reef metabolism cannot distinguish which organisms are responsible for primary production. Here we used a “bottom‐up” approach to estimate the contribution of diverse primary producers including hard corals, octocorals, and algae to gross primary production on

Large submarine plateaus impede the eastward flow of the deep‐reaching Antarctic Circumpolar Current (ACC), and at the southern Kerguelen Plateau (SKP), the ACC flow is steered north through the Fawn Trough and south through the Princess Elizabeth Trough. During the Kerguelen Axis study, a regional‐scale ecosystem survey, oceanographic sampling showed the ACC water properties west of the SKP to be

Atrazine contamination is ubiquitous in North American surface waters, but the dependency of the herbicide's distribution on landscape and within‐lake processes is currently poorly known. We sought to identify novel predictors of atrazine and to build a coherent framework to model its concentration in waterbodies through the development of binomial‐gamma hurdle models and LASSO regression models. We

Two important competitive traits in protists, particularly in harmful algal bloom forming species, are lytic toxicity and mixotrophy. This study focuses on Alexandrium pseudogonyaulax, a dinoflagellate species that is both toxic and mixotrophic, and in addition uses a mucus trap to immobilize and capture potential prey. A single strain of A. pseudogonyaulax was subcultured and grown under two different

Autotrophic dissolved organic matter (DOM) is central to the carbon biogeochemistry of aquatic systems, and the full complexity of autotrophic DOM has not been extensively studied, particularly by high‐resolution mass spectrometry (HRMS). Terrestrial DOM tends to dominate HRMS studies in freshwaters due to the propensity of such compounds to ionize by negative mode electrospray, and possibly also because

Subtropical seagrass meadows play a major role in the coastal carbon cycle, but the nature of air–water CO2 exchanges over these ecosystems is still poorly understood. The complex physical forcing of air–water exchange in coastal waters challenges our ability to quantify bulk exchanges of CO2 and water (evaporation), emphasizing the need for direct measurements. We describe the first direct measurements

Lakes around the world are sensitive to water quality degradation and eutrophication through increases in primary production. Understanding the drivers of primary production has been a fundamental question in limnology since its early days. Here, we conducted a systematic review to develop a dataset of water chemistry and lake morphometry for 3874 lakes distributed across 47 countries around the world

The impact of marine animals on the iron (Fe) cycle has mostly been considered in terms of their role in supplying dissolved Fe to phytoplankton at the ocean surface. However, little attention has been paid to how the transformation of ingested food into fecal matter by animals alters the relative Fe‐richness of particles, which could have consequences for Fe cycling in the water column and for the

Water quality of freshwater lakes within the Laurentian Great Lakes region is vulnerable to degradation owing to multiple environmental stressors including climate change, alterations in land use, and the introduction of invasive species. Our research questions were two‐fold: (1) What are the temporal patterns and trends in water quality? (2) Are climate, invasive species and lake morphology associated

Factors that regulate planktonic communities under lake ice may be vastly different from those during the open‐water season. Expected changes in light availability, ice cover, and snowfall associated with climate change have accelerated the need to understand food web processes under ice. We hypothesized that light limitation (bottom‐up control) outweighs zooplankton grazing (top‐down control) influence

Pelagic primary production is the main input of organic energy for benthic production below the photic zone. In the Baltic Sea, spring phytoplankton blooms are dominated by diatoms that sink out rapidly and export nutritionally favorable matter to benthic secondary production, while the summer blooms have more variable sedimentation rates and nutritional profile. Changes in phytoplankton species composition

The seasonality of gross primary production (GPP) in streams is driven by multiple physical and chemical factors, yet incident light is often thought to be most important. In Arctic tundra streams, however, light is available in saturating amounts throughout the summer, but sharp declines in nutrient supply during the terrestrial growing season may constrain aquatic productivity. Given the opposing

In parts of the Baltic Sea, the phytoplankton spring bloom communities, commonly dominated by diatoms, are shifting toward the co‐occurrence of diatoms and dinoflagellates. Although phytoplankton are known to shape the composition and function of associated bacterioplankton communities, the potential bacterial responses to such a decrease of diatoms are unknown. Here we explored the changes in bacterial

Size‐spectral approaches quantify the efficiency of energy transfer through food webs, but theory and field studies disagree over how changes in temperature, nutrients, and extreme weather impact on this efficiency. We address this at two scales: via 6 years of weekly sampling of the plankton size spectrum at the Plymouth L4 shelf sea site, and via a new, global‐scale, meta‐analysis of aquatic size

Coastal wetlands are significant sources of dissolved organic carbon (DOC) to adjacent waters and, consequently, exert a strong influence on the quantity and quality of DOC exported to the coastal oceans. Our understanding of the factors that control the exchange of DOC at the tidal marsh‐estuarine interface, however, remains limited. We hypothesize that tidal marsh soils act as a regulator and that

Climate change is decreasing watershed glacial coverage throughout Alaska, impacting the biogeochemistry of downstream ecosystems. We collected streamwater fortnightly over the glacial runoff period from three streams of varying watershed glacier coverage (0–49%) and a subglacial outflow to assess how glacier recession impacts the relative contributions of glacier and terrestrial plant derived dissolved

Biogeochemical cycling of silicon (Si), largely affected by biological drivers, is pivotal to the ecological functioning of the ocean. Most knowledge regarding biological utilization of Si derives from research on phototrophic organisms circumscribed to the photic ocean (i.e., diatoms). Utilization of Si in the aphotic ocean, where heterotrophic silicifiers become relevant Si users, remains poorly

Surface water mercury (Hg) and dissolved organic carbon (DOC) concentrations and their ratios, which play a critical role in food chain bioaccumulation of Hg, were examined in lakes from southern boreal, sub‐Arctic taiga, Arctic tundra and polar desert landscapes of eastern and northern Canada. The study sites investigated span a 30° latitudinal gradient representing differences in climate, ecosystem

The solubility of iron (Fe) in seawater is greatly enhanced by complexation with organic ligands, predominantly occurring as humic substances (HS) in coastal areas. Mining exploitation is believed to change the natural biogeochemical cycle of Fe in coastal waters, even though its impacts on the physical and chemical speciation of the Fe fractions are not known. Here we show that dissolved and soluble

Dissolved organic matter (DOM) composition exerts a direct control on its degradation and subsequent persistence in aquatic ecosystems. Yet, under certain conditions, the degradation patterns of DOM cannot be solely explained by its composition, highlighting the relevance of environmental conditions for DOM degradation. Here, we experimentally assessed the relative influence of composition vs. environment

Carbonate budgets are increasingly being used as a key metric to establish reef condition. To better understand spatial variations in framework and sediment net carbonate budgets, we quantified biogenic carbonate production, erosion, and dissolution within and between five distinct geomorphological habitats of Heron Reef on the southern Great Barrier Reef. The protected reef slope had the greatest

The current lack of knowledge on the trophic ecology of scyphozoans, particularly at the benthic stage, prevents a full understanding of the controls on many jellyfish blooms. The blooming scyphozoan (Aurelia coerulea) completes its entire life cycle in the Thau lagoon (southern France), where the annual population dynamics of both its benthic and pelagic stages have been described. This offered an

We measured the concentration and turnover rates of dimethylsulfoxide (DMSO) across the northeast Subarctic Pacific (NESAP) to better understand the role of this compound in regional sulfur cycling and phytoplankton physiological ecology. Using ship‐track observations and Lagrangian drifter surveys, we examined the spatial and temporal components of DMS and DMSO variability, comparing rates of DMSO

Environmental filtering and spatial processes have been associated with variation in ecological communities and biodiversity; however, their relative importance on multiple dimensions of beta diversity has not been fully explored in montane streams. Here, we examined the relative contribution of local, catchment and climate environmental variables and spatial factors to variation in three dimensions

Submarine groundwater discharge (SGD) is an important transporter of solutes and fresh water in coastal systems worldwide. In high island systems with a mixed semidiurnal tidal cycle driving SGD, coastal biogeochemistry is temporally and spatially variable. Past studies have shown that SGD covaries with the local species composition, diversity, and richness of biological communities on a scale of meters

The Barents Sea is considered a warming hotspot in the Arctic; elevated sea surface temperatures have been accompanied with increased inflow of Atlantic water onto the shelf sea. Such hydrodynamic changes and a concomitant reduction of sea ice coverage enables a prolonged phytoplankton growing season, which will inevitably affect nutrient stoichiometry and the controls on primary production. During

Phytoplankton are major contributors of labile dissolved organic matter to marine euphotic zone ecosystems. Viral‐mediated phytoplankton lysis releases a considerable amount of bioavailable cellular contents and facilitates localized heterotrophic bacterial growth. The rapid turnover times of this labile organic matter renders it difficult to trace their transformation within natural environments.

Macroalgae structure coastal ecosystems affecting metabolism, nutrient dynamics, and food webs. Spatially explicit prediction of macroalgal abundance is critical for understanding coastal ecosystems and trajectories. However, models of macroalgal distribution tend to be mechanistic and generalize poorly, or biogeographic and too coarse to use over spatial scales most appropriate to ecosystem research

Gelatinous zooplankton can be present in high biomass and taxonomic diversity in planktonic oceanic food webs, yet the trophic structuring and importance of this “jelly web” remain incompletely understood. To address this knowledge gap, we provide a holistic trophic characterization of a jelly web in the eastern tropical Atlantic, based on δ13C and δ15N stable isotope analysis of a unique gelatinous

Interactions between riverine inputs, internal cycling, and oceanic exchange result in dynamic variations in the partial pressure of carbon dioxide (pCO2) in large estuaries. Here, we report the first bay‐wide, annual‐scale observations of surface pCO2 and air–water CO2 flux along the main stem of the Chesapeake Bay, revealing large annual variations in pCO2 (43–3408 μatm) and a spatial‐dependence

Many boreal lakes are experiencing an increase in concentrations of terrestrially derived dissolved organic matter (DOM)—a process commonly labeled “browning.” Browning affects microbial and photochemical mineralization of DOM, and causes increased light attenuation and hence reduced photosynthesis. Consequently, browning regulates lake heterotrophy and net CO2‐efflux to the atmosphere. Climate and

The Southern Ocean provides strong contrasts in rates and directions of change in temperature and sea ice between its sectors, but it is unknown how these affect plankton species that are distributed right around Antarctica. Here, we quantify the changing circumpolar distributions of Antarctic krill, based on the CHINARE 2013/14 circum‐Antarctic expedition, plus independent analyses of compiled abundance

There was an error published in Limnology and Oceanography, 2017, 62 (5), pages: 1963–1983. The equation of the regression line reported in the caption of Fig. 5 was carried over from an earlier version of the manuscript and presents a unit discrepancy in the coefficient and intercept, and an error in the decimal of the intercept. The unit discrepancy was due to different unit used in the earlier version

Spatial and seasonal dynamics of microbial loop fluxes were investigated in contrasting productivity regimes in the Indian sector of the Southern Ocean. Observations carried out in late summer (February–March 2018; project MOBYDICK) revealed higher microbial biomasses and fluxes in the naturally iron‐fertilized surface waters of Kerguelen island in comparison to surrounding off‐plateau waters. Differences

Microorganisms in the seabed of most of the global oceans live at temperatures close to zero degrees, and in the polar regions even below. Respiration rates of endogenous sulfate‐reducing microorganisms in the polar seabed, however, are highest in the range of 18–30°C and much reduced at colder temperature. In the past, this was seen as indicative of poor adaptation to their cold habitat. We challenge

Microzooplankton are the primary herbivores and nutrient regenerators in the marine food web, but their importance is often underestimated, and the quantitative relationships between environmental factors and the biomass and herbivory rate of microzooplankton remain obscure. To fill this gap, we conducted 224 dilution experiments to measure microzooplankton biomass and herbivory rate across a vast

There is increasing interest in the genetic diversity and phylogeography of aquatic invertebrate zooplankton in the Eastern Palearctic, yet these topics remain largely unexplored in China. Here, we investigated the lineage diversity and phylogeography of an important cladoceran taxon, the Chydorus sphaericus (Crustacea: Cladocera) species complex, which is common in various aquatic habitats. We found

Although climate change has shifted the phenological timing of plankton in lakes, few studies have explicitly addressed the relative contributions of climate change and other factors, including planktivory and nutrient availability. The spring clear‐water phase is a period of marked reduction in algal biomass and increased water transparency observed in many lakes. Here, we quantified the phenological

Abundant crab burrows in carbon‐rich, muddy salt marsh soils act as preferential water flow conduits, potentially enhancing carbon transport across the soil–water interface. With increasing recognition of blue carbon systems (salt marshes, mangroves, and seagrass) as hotspots of soil carbon sequestration, it is important to understand drivers of soil carbon cycling and fluxes. We conducted field observations

Over the seasons, Arctic diatom species occupy shifting habitats defined by contrasting light climates, constrained by snow and ice cover dynamics interacting with extreme photoperiod and solar angle variations. How Arctic diatom photoadaptation strategies differ across their heterogeneous light niches remains a poorly documented but crucial missing link to anticipate Arctic Ocean responses to shrinking

This study investigated the consumption of oxygen (O2) in 11 European lakes ranging from 48 m to 372 m deep. In lakes less than ~ 100 m deep, the main pathways for O2 consumption were organic matter (OM) mineralization at the sediment surface and oxidation of reduced compounds diffusing up from the sediment. In deeper lakes, mineralization of OM transported through the water column to the sediment

Nutrient breakpoints are the concentration at which there is a fundamental change in phytoplankton responses to further increases in nutrient loading. The ecological implication is that nutrient breakpoints signal a community transition from a relatively stable state to an alternate or transition state with marked changes in structure and, by extension, function. Nutrient breakpoints for the total

Chesapeake Bay is a large, dynamic, and productive temperate estuary, which plays an important role in transporting terrestrial materials into the Atlantic Ocean. The bacterioplankton communities experience strong environmental changes both seasonally and along the central axis of the Bay. The goal of this study was to explore the spatiotemporal and interannual patterns of the bacterioplankton communities

The spatial and seasonal variations of methane‐derived carbon contributions to Chironomus plumosus larvae and oligochaetes biomass at four stations in a polymictic, eutrophic lake were examined to determine which factors (CH4 and/or dissolved oxygen) affect the methane‐derived carbon contributions, and quantify impacts of benthic methane‐derived carbon on the lake food web. Methane‐derived carbon contributions

Estimation of marine macrophyte contribution to coastal sediments is key to understand carbon sequestration dynamics. Nevertheless, identification of macrophyte carbon is challenging. We propose environmental DNA (eDNA) metabarcoding as a new approach for identification of sediment contributors, and compared this approach against stable isotopes—the traditional approach. eDNA metabarcoding allowed

Mixotrophic nanoflagellates can account for more than half of the bacterivory in the sunlit ocean, yet very little is known about their ecophysiology. Here, we characterize the grazing ecology of an open‐ocean mixotroph in the genus Florenciella (class Dictyochophyceae). Members of this class were indirectly implicated as major consumers of Prochlorococcus and Synechococcus in the oligotrophic North

Variable fluorescence techniques are increasingly used to assess phytoplankton photosynthesis. All fluorescence techniques and models for photosynthetic electron transport rates (ETRs) are amplitude‐based and are subject to errors, especially when phytoplankton growth is nutrient‐limited. Here we develop a new, kinetic‐based approach to measure, directly and in absolute units, ETRs and to estimate

The role of permeable sediments and subterranean estuaries as coastal nutrient filters is a question of key interest, particularly in areas with high nitrogen loadings. Here, we evaluated the effectiveness of a sandy subterranean estuary in cycling and removing nitrate using stable isotopes of N and O at natural (δ15N‐NO3− and δ18O‐NO3−) and enriched levels (15N). Isotopes were used in conjunction

We investigated the impact of kelp deposition on the geochemistry and microbial community composition of beach sands on the island of Helgoland (North Sea). The composition of the microbial community at a beach with regular kelp deposition appeared shaped by this regular input of organic material, as indicated by significantly higher proportions of aerobic degraders, fermenters, and sulfur cycling

Climate change is expected to alter precipitation patterns worldwide, which can have direct effects on streamflow dynamics. In many tropical regions, climate‐driven changes in rainfall are predicted to decrease streamflow and increase flash flooding, but the implications of these changes for stream ecosystem function are poorly understood. We used a rainfall gradient on Hawaii Island that mimics projected

Enhanced nutrient input and warming have led to the development of low oxygen (hypoxia) in coastal waters globally. For many coastal areas, insight into redox conditions prior to human impact is lacking. Here, we reconstructed bottom water redox conditions and sea surface temperatures (SSTs) for the coastal Stockholm Archipelago over the past 3000 yr. Elevated sedimentary concentrations of molybdenum

Differential responses of diatoms, an important group of marine primary producers to ocean acidification, have been well documented. However, studies so far are based on limited representative strains from key species. Investigation of strain level responses will help us better understand the contrasting discrepancy in diatom responses to ocean acidification. Here, we selected four strains of the model

In the North Atlantic and the Arctic Ocean, four species of the copepod genus Calanus dominate the zooplankton biomass. Because of their morphological resemblance, knowledge of their respective distribution range has long been biased by misidentification, until the recent use of molecular tools uncovered numerous areas of sympatry. As hybridization between Calanus finmarchicus and Calanus glacialis