Salinization and eutrophication are nearly ubiquitous in watersheds with human activity. Despite the known impacts of the freshwater salinization syndrome (FSS) to organisms, we demonstrate a pronounced knowledge gap on how FSS alters wetland biogeochemistry. Most experiments assessing FSS and biogeochemistry pertain to coastal saltwater intrusion. The few inland wetland studies mostly add salt as

Net primary production (NPP) measurements in the open-ocean Gulf of Mexico are scarce and mostly limited to satellite-derived surface estimates. Profiling floats can obtain depth-resolved chlorophyll (Chl) and backscattering (bbp) data for NPP estimates, but historical float data in this region lacked field calibrations. We adjusted the float data with satellite Chl, generating a consistent dataset

The abundance and productivity of phytoplankton constrain energy transfer through marine food webs and the export of organic carbon to the deep ocean. Bio-optical measurements correlate well with phytoplankton carbon (Cphyto), but the effect of taxonomic variability on this relationship is still uncertain. Here, we explore how changes in phytoplankton community composition influence the relationship

Many factors influence how environmental DNA (eDNA) abundance varies in natural environments. One of the least studied contributors to eDNA variation is that of reproduction. Marine organisms that broadcast spawn are expected to shed increased quantities of DNA in association with the release of gametes and the elevated levels of activity associated with reproduction. To test this hypothesis at the

The Magdalena River in Colombia is one of the world's largest (discharge = 7100 m3 s−1) tropical rivers, hosting > 170 aquatic vertebrate species. However, concise synthesis of the current ecological and environmental status is lacking. By documenting the anthropogenic stressors impacting the river on time scales ranging from centuries to decades, we found that the river system is subject to the compounding

Maximum depth is crucial for many lake processes and biota, but attempts to explain its variation have achieved little predictive power. In this paper, we describe the probability distribution of maximum depths based on recent developments in the theory of fractal Brownian motions. The theoretical distribution is right-tailed and adequately captures variations in maximum depth in a dataset of 8164

The authors discovered an error in Figure 3. During preparation for publication, an earlier version of the figure was included, where different scales were used for the terrestrial and ocean datasets, which makes the N fixation rates in the ocean appear much higher than on land. The data archived with Figshare are correct (https://doi.org/10.6084/m9.figshare.14916456.v3). The revised figure is published

Recent studies have described active nitrogen fixation in high-latitude waters, but the ecological controls on the occurrence or activity of nitrogen-fixing organisms (diazotrophs) in such systems remain unknown. Turnover rates and top-down controls are also general knowledge gaps for marine diazotrophs. We detected abundant UCYN-A (endosymbiotic nitrogen-fixing cyanobacteria) in the Gulf of Anadyr

Coastal lagoons are biodiversity hotspots that support neighboring ecosystems and various services. They can exhibit distinct biophysical characteristics compared to the adjacent open sea and act paradoxically as autonomous ecosystems. Using remotely sensed observations and state-of-the-art numerical simulations, the role of water column hydrodynamics in shaping the seasonal succession of phytoplankton

Trichodesmium, a major diazotroph in tropical and subtropical oceans, provides a significant amount of bioavailable nitrogen in oligotrophic oceans. Remarkably, the cyanobacteria carry out nitrogen fixation and photosynthesis simultaneously under high light (HL) conditions. Here, we hypothesize that nickel superoxide dismutase (NiSOD) protects the nitrogen fixation process from oxidative stress generated

Sea level rise (SLR) and saltwater intrusion are driving inland shifts in coastal ecosystems. Here, we make high-resolution (1 m) predictions of land conversion under future SLR scenarios in 81 watersheds surrounding Chesapeake Bay, United States, a hotspot for accelerated SLR and saltwater intrusion. We find that 1050–3748 km2 of marsh could be created by 2100, largely at the expense of forested wetlands

Nano- and picophytoplankton are a major component of open-ocean ecosystems and one of the main plankton functional types in biogeochemical models, yet little is known about their trace metal contents. In cultures of the picoeukaryote Ostreococcus lucimarinus, iron limitation reduced iron quotas by 68%, a fraction of the plasticity known in diatoms. In contrast, a commonly co-occurring cyanobacterium

Oceanic methane (CH4) budgets lack data from high-latitude fjords that often behave as intermittently anoxic ecosystems with potentially high methane emissions. We conducted 15 expeditions and 49 in situ lander deployments in an anoxic Scandinavian fjord between 2009 and 2021. Benthic fluxes were highest at the deepest anoxic site (average 516 μmol CH4 m−2 d−1), supporting bottom water methane exceeding

Fish larvae are rarely a major driver of fish mortality, but tunas can produce large batches of larvae that rapidly develop the capacity to kill other fish. We combine a model for the killing potential from Atlantic bluefin tuna (BFT) larvae on larval albacore (ALB) with field observations at a major spawning ground. Both species spawn from June to August, but BFT has a narrow spawning peak at the

About 15 Tg of plastic are estimated to enter the ocean yearly, with this figure growing exponentially every year. Assessments of floating marine plastic amount to 0.2% of the expected plastic stock, implying that 99.8% is stored in a sink yet to be identified. Marine sediments are believed to be the ultimate sink for oceanic plastic, however, there is currently no global estimate of the plastic load

One billion tons of carbon are annually transported to the global ocean, and the fate of this carbon hinges not only on marine processing rates, but also on freshwater processing during downstream transport. Using a cotton-strip assay, we assessed the decomposition of organic matter in marine and freshwater sites and simulated its downstream transport from freshwater to the sea by translocating cotton

Inadequate sampling of oceanic motions, which commonly occurs for both oceanic measurements and simulations, can cause peculiar spectral features and potentially leads to misinterpretations. Here, we combine an extremely high-frequency moored velocity record and a high-resolution numerical simulation with the basic signal-processing theory to quantitatively explore how varying sampling rates affect

The North Atlantic phytoplankton bloom depends on a confluence of environmental factors that drive transient periods of exponential phytoplankton growth and interannual variability in bloom magnitude. I analyze interannual bloom variability in the North Atlantic via extreme value theory where the generalized extreme value distribution (GEVD) is fitted spatially to annual maxima of satellite-measured

The response of tidal range in tidal marshes under sea-level rise (SLR) is essential to the marsh resilience, but how tidal ranges respond to different marsh evolutions remains unclear. Here, we show the existence of bifurcate responses of tidal range to SLR using both numerical model and theoretical analyses. The tidal range tends to increase if marsh accretion keeps pace with SLR; otherwise, the

Large episodic pulses of particulate organic carbon (POC) at the deep-sea (~ 4000 m) time-series Sta. M in the Northeast Pacific Ocean have increased in frequency and magnitude over the past 32 years. We inferred the ecological drivers of these events by quantifying the phytoplankton and biomineral composition within particles collected by bottom-moored sediment traps immediately before, during, and

Trophic cascades are important features of aquatic ecosystems, but much variation in their strength remains unexplained. Disturbance could restrict cascade occurrence by limiting predator distribution, and increase cascade strength by lowering defended herbivore abundance. These possibilities were investigated in 20 New Zealand rivers varying both in flooding disturbance (measured by bed movement)

Salinity is a major environmental predictor of phytoplankton species richness and composition. We hypothesize that the variation in phytoplankton richness along coastal salinity gradients is reflected in essential ecosystem functions like resource use efficiency (RUE)—the proportion of limiting resource that is converted into biomass. To test the hypothesis, we analyzed time series of phytoplankton

Peer review is the formal means by which the scientific community assesses the originality, reproducibility, validity, and quality of a research study (Bakker and Traniello 2019). As such, peer review assures nonexperts that they can trust a study's findings (Jamieson et al. 2019). Despite the critical importance of peer review, graduate students, postdocs, and other early career researchers (ECRs)

High-frequency, paired measurements of the partial pressure of CO2 (pCO2) and dissolved O2 were combined with dissolved organic matter (DOM) characterization to investigate diurnal (7:00–19:00) and seasonal variations in CO2 dynamics in the lower Ganges River. Diurnal variations in pCO2 shifted seasonally, concurring with changes in DOM optical properties, biodegradable DOM, and O2 departures from

Iron flocculants play a major role in the remediation of water bodies, removing particulate pollutants such as microplastics through floc formation. Such flocs are prone to microbial iron reduction while lying on top of anoxic sediments, which possibly leads the release of bound microplastics. In this study, Shewanella oneidensis was employed to simulate the impact of microbial iron reduction on the

Freshwater salinization of rivers is occurring across the globe because of nonpoint source loading of salts from anthropogenic activities such as agriculture, urbanization, and resource extraction that accelerate weathering and release salts. Multidecadal trends in river salinity are well characterized, yet our understanding of annual regimes of salinity in rivers draining diverse central and western

Limnology and Oceanography Letters was conceived as a fully open science journal where all articles and their underlying data are freely available online (Soranno et al. 2021). The data publication requirement, described in the author guidelines (https://aslopubs.onlinelibrary.wiley.com/hub/journal/23782242/about/author-guidelines#data), ensures that the data set(s) analyzed in each study, and the

The dataset described here includes estimates of historical (1980–2020) daily surface water temperature, lake metadata, and daily weather conditions for lakes bigger than 4 ha in the conterminous United States (n = 185,549), and also in situ temperature observations for a subset of lakes (n = 12,227). Estimates were generated using a long short-term memory deep learning model and compared to existing

Factors driving freshwater salinization syndrome (FSS) influence the severity of impacts and chances for recovery. We hypothesize that spread of FSS across ecosystems is a function of interactions among five state factors: human activities, geology, flowpaths, climate, and time. (1) Human activities drive pulsed or chronic inputs of salt ions and mobilization of chemical contaminants. (2) Geology drives

Spring phytoplankton blooms in the Gulf of Maine (GoM) are sensitive to climate-related local and remote forcing. Nutrient supply through the slope water intrusion has been viewed as critical in regulating the GoM spring blooms, with an assumption that nitrogen is the primary limiting nutrient. In recent years, this paradigm has been challenged, with silicate being recognized as another potential limiting

Climate warming and eutrophication are leading drivers of environmental change, and both are likely to alter the role of freshwaters in the global carbon cycle. Recent studies demonstrate that warming of streams can increase freshwater contributions of CO2 to the atmosphere, yet little is known about how such contributions are modulated by the identity or supply of limiting nutrients. We quantified

Riverine algal groups with distinct life histories can generate unique patterns of structural and functional behavior. As such, novel methods to discriminate between these groups can improve the understanding of river ecosystem processes. We examined benthic vs. planktonic contributions to suspended algal biomass by monitoring suspended chlorophyll concentration and turbidity during 48 storm events

The diatom frustule provides partial protection against copepod grazing. Whether the defense is due to the cells being de-selected or handled for so long that the grazers lose time for foraging is unknown. The mechanism has implications for the population dynamics of both defended and co-occurring, undefended nutrient competitors. We use video-observations to demonstrate that thick-shelled diatoms

Siphonophores are a clade of understudied colonial hydrozoans (Cnidaria) that are abundant predators in oceanic ecosystems, with species present across the water column. We (1) synthesize current knowledge about siphonophore trophic ecology and predator–prey interactions, (2) analyze siphonophore-prey networks to compare food-web topology between shallow and deep-pelagic habitats, (3) discuss contemporary

We quantified whether pore-water exchange flushes out saltmarsh sediment carbon, driving carbon outwelling into the ocean and outgassing into the atmosphere. Radon-derived pore-water exchange released 1.8 times more sediment carbon in the wet than in dry season. Both crab burrow flushing and delayed seepage of surface water infiltrating sediments during the spring tide released sediment carbon to surface

Freshwater salinization is a widespread issue, but evidence of ecological effects on aquatic communities remains scarce. We experimentally exposed salt-naive plankton communities of a north-temperate, freshwater lake to a gradient of chloride (Cl−) concentration (0.27–1400 mg Cl L−1) with in situ mesocosms. Following 6 weeks, we measured changes in the diversity, composition, and abundance of eukaryotic

Human-induced salinization increasingly threatens inland waters; yet we know little about the multifaceted response of lake communities to salt contamination. By conducting a coordinated mesocosm experiment of lake salinization across 16 sites in North America and Europe, we quantified the response of zooplankton abundance and (taxonomic and functional) community structure to a broad gradient of environmentally

Freshwater ecosystems are experiencing increased salinization. Adaptive management of harmful algal blooms (HABs) contributes to eutrophication/salinization interactions through the hydrologic transport of blooms to coastal environments. We examined how nutrients and salinity interact to affect growth, elemental composition, and cyanotoxin production/release in two common HAB genera. Microcystis aeruginosa

Coastal groundwater-dependent ecosystems benefit from lowered salinity, nutrient-rich submarine groundwater discharge (SGD). Across Pacific islands marine macroalgae appear to have been challenged by and adapted to the stress of lowered salinity with a trade-off of nutrient subsidies delivered by SGD. Human alterations of groundwater resources and climate change-driven shifts brought modifications

Anthropogenic salt sources have contributed to rising salinities in the Laurentian Great Lakes. In Lake Michigan, chloride concentrations have risen from ~ 1–2 mg L−1 in the 1800s to > 15 mg L−1 in 2020. The watersheds of the approximately 300 tributaries of Lake Michigan vary in size and represent a wide range of land use, from undeveloped forested watersheds to urbanized and agricultural areas. The

Water movement in ice-covered lakes is known to be driven by wind, sediment heat flux, solar radiation, saline density flows, and advective stream discharge. In large ice-covered lakes, wind-induced oscillations have been found to play a major role in horizontal flows. Here, we report recurrent, wind-driven, barotropic seiches in a small lake with a thick (~4 m) permanent ice-cover. Between 2010 and

Diverse phytoplankton exude polysaccharides that can form a viscous mucus layer surrounding their cells, facilitating complex chemical exchanges with bacteria. An unexplored ramification of mucus production is the influence of its viscosity on the diffusion of nutrients such as vitamins to the cell. Here, I use simulations to demonstrate that mucus viscosity increases the nutrient concentration gradient

Increasing marine microplastic pollution has detrimentally impacted organismal physiology and ecosystem functioning. While previous studies document negative effects of microplastics on coral reef animals, the potential responses of organisms such as large benthic foraminifera (LBF) are largely unknown. Here, we document the impact of microplastics on heterotrophic feeding behavior of LBF. Specimens

Tidal marsh survival in the face of sea level rise (SLR) and declining sediment supply often depends on the ability of marshes to build soil vertically. However, numerical models typically predict survival under rates of SLR that far exceed field-based measurements of vertical accretion. Here, we combine novel measurements from seven U.S. Atlantic Coast marshes and data from 70 additional marshes from

Oxidative stress plays a role in many aspects of cellular metabolism, and as a result, antioxidants have the potential to impact cellular stoichiometry and biogeochemical cycles. We reviewed how antioxidant systems influence macronutrient and micronutrient stoichiometry in marine phytoplankton and identified that antioxidant systems have important implications for micronutrient stoichiometry. By leveraging

Millions of lakes inversely stratify during winter. Seemingly subtle variations in the duration of winter stratification can have major ecological effects by, for example, altering the vertical distribution of oxygen and nutrients in lakes. Yet, the influence of climate change on winter stratification has been largely unexplored. To fill this knowledge gap, here we used a lake-climate model ensemble

Whether phytoplankton growth is solely constrained by temperature (hotter is better) or compensated by thermal adaptation is still under debate. We measured the temperature sensitivity of natural phytoplankton communities at both short-term and seasonal timescales using temperature manipulation experiments. The activation energy across communities (mean ± SE: Ei = 0.51 ± 0.12 eV, Q10 = 1.98) is significantly

Understanding the life-stage specific vulnerability of ectotherms to temperature increases is crucial to accurately predicting the consequences of current and future global climate change. Here, we examined ontogeny-specific thermal vulnerability of three intertidal, bimodal (i.e., air and water) breathing crabs from tropical and warm temperate latitudes to address this issue. Spawning females and

We investigated temperature sensitivities of picophytoplankton growth along a natural 10°C (18–28°C) temperature gradient in the eastern Indian Ocean characterized by deep mixing and consistently low dissolved nitrogen. Population biomass (B), cell carbon, and chlorophyll were measured by flow cytometry. Instantaneous growth (μ) and production (P) were calculated from dilution incubations at four light

The end of the polar night with the concurrent onset of photosynthetic biomass production ultimately leads to the spring bloom, which represents the most important event of primary production for the Arctic marine ecosystem. This dataset shows, for the first time, significant in situ biomass accumulation during the dark–light transition in the high Arctic, as well as the earliest recorded positive

It has recently been shown that Southern Ocean phytoplankton species have evolved to optimize their light-harvesting potential without increasing the high iron-requiring proteins used for photosynthesis. We measured molecular and physiological responses of phytoplankton cultures under a combination of iron and light conditions. While iron-replete cultures mostly increased biovolume, photochemical efficiency

We searched the literature for experimental and observational studies assessing the effects of seagrass overgrazing on erosion of sediment and sedimentary organic carbon (SOC) and found that most studies reported a significant impact, likely caused by a cascading effect (i.e., seagrass shoot loss → belowground biomass degradation → sediment destabilization or SOC erosion). However, there appears to

Establishing the foundations for a sustainable use of deep-sea resources relies on increasing knowledge on this inaccessible ecosystem, which is challenging with traditional methods. The analysis of environmental DNA (eDNA) emerges as an alternative, but it has been scarcely applied to deep-sea fish. Here, we have analyzed the fish eDNA contained in oceanic vertical profile samples (up to 2000 m depth)

Host-associated microbial communities are fundamental to host physiology, yet it is unclear how these communities will respond to environmental disturbances. Here, we disentangle the environment-linked and host-linked effects of ocean acidification on oyster-associated microbial communities. We exposed adult oysters (Crassostrea virginica) to CO2-induced ocean acidification (400 vs. 2800 ppm) for 80 d

Body size is considered an important structuring mechanism of food webs because consumers are usually larger and more mobile than their prey and may couple energy among habitats. We explored the links among trophic position (TP), body size, and the coupling of different energy channels (phytoplankton and C4-marsh plants) in a saltmarsh landscape in the northern Gulf of Mexico—a dynamic system considered

Lateral fluxes (i.e., outwelling) of dissolved organic (DOC) and inorganic (DIC) carbon and total alkalinity were estimated using radium isotopes at the groundwater, mangrove creek, and continental shelf scales in the Amazon region. Observations of salinity and radium isotopes in the creek indicated tidally driven groundwater exchange as the main source of carbon. Radium-derived transport rates indicate

Novel analysis of in situ acoustic and optical data collected in a shallow, wave- and current-driven environment enabled determination of (1) particle characteristics that were most affected by near-bed physical forcing over seasonal scales and (2) characteristic shear stress, τchar, at which the rate of change to particle characteristics was most pronounced. Near-bed forcing and particle responses

Sewage released from lakeside development can introduce nutrients and micropollutants that can restructure aquatic ecosystems. Lake Baikal, the world's most ancient, biodiverse, and voluminous freshwater lake, has been experiencing localized sewage pollution from lakeside settlements. Nearby increasing filamentous algal abundance suggests benthic communities are responding to localized pollution. We

N2 fixation is a major component of the global N cycle and has been extensively studied in open-ocean and terrestrial ecosystems. Yet rates and ecological dynamics remain virtually unknown for the inland and coastal aquatic ecosystems (lakes, wetlands, rivers, streams, and estuaries) that connect terrestrial and marine biomes. This is due to the diversity of these habitats as well as the traditional