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Tidal marshes and mangroves are threatened by relative sea level rise (RSLR) in certain regions on Earth. Elsewhere, these coastal wetlands can adapt through sediment accretion and resulting surface elevation gain. Studies identifying drivers of the global variability in coastal wetland adaptability to RSLR ignored the role of the tidal pattern, varying from semi-diurnal to diurnal globally. Here, we present a meta-analysis, including 394 marsh and mangrove sites worldwide, and demonstrate that the tidal pattern explains similar to 25% of the variability in wetland elevation response to RSLR. Using a numerical model, we illustrate that less frequent, diurnal tides trigger lower sediment accretion rates, hence higher wetland vulnerability to RSLR, for various values of RSLR rates, tidal range and sediment supply. Our findings reveal a previously overlooked but relevant driver of coastal wetland adaptability to RSLR and call for new research as tidal patterns may affect other wetland ecosystem functions and services.

We introduce three new Empirical Seawater Property Estimation Routines (ESPERs) capable of predicting seawater phosphate, nitrate, silicate, oxygen, total titration seawater alkalinity, total hydrogen scale pH (pHT), and total dissolved inorganic carbon (DIC) from up to 16 combinations of seawater property measurements. The routines generate estimates from neural networks (ESPER_NN), locally interpolated regressions (ESPER_LIR), or both (ESPER_Mixed). They require a salinity value and coordinate information, and benefit from additional seawater measurements if available. These routines are intended for seawater property measurement quality control and quality assessment, generating estimates for calculations that require approximate values, original science, and producing biogeochemical property context from a data set. Relative to earlier LIR routines, the updates expand their functionality, including new estimated properties and combinations of predictors, a larger training data product including new cruises from the 2020 Global Data Analysis Project data product release, and the implementation of a first-principles approach for quantifying the impacts of anthropogenic carbon on DIC and pHT. We show that the new routines perform at least as well as existing routines, and, in some cases, outperform existing approaches, even when limited to the same training data. Given that additional training data has been incorporated into these updated routines, these updates should be considered an improvement over earlier versions. The routines are intended for all ocean depths for the interval from 1980 to ~2030 c.e., and we caution against using the routines to directly quantify surface ocean seasonality or make more distant predictions of DIC or pHT., 1,823

The present study aims at investigating the past and current trophic status of Lake Ossa and evaluating its potential impact on African manatee health. Lake Ossa is known as a refuge for the threatened African manatees in Cameroon. Little information exists on the water quality and health of the ecosystem as reflected by its chemical and biological characteristics. Aquatic biotic and abiotic parameters including water clarity, nitrogen, phosphorous, and chlorophyll concentrations were measured monthly during four months at each of 18 water sampling stations evenly distributed across the lake. These parameters were then compared with historical values obtained from the literature to examine the dynamic trophic state of Lake Ossa. Results indicate that Lake Ossa's trophic state parameters doubled in only three decades (from 1985 to 2016), moving from a mesotrophic to a eutrophic state. The decreasing nutrient gradient moving from the mouth of the lake (in the south) to the north indicates that the flow of the adjacent Sanaga River is the primary source of nutrient input. Further analysis suggests that the poor transparency of the lake is not associated with chlorophyll concentrations but rather with the suspended sediments brought‐in by the Sanaga River. Consequently, our model demonstrated that despite nutrient enrichment, less than 5% of the lake bottom surface sustained submerged aquatic vegetation. Thus, shoreline emergent vegetation is the primary food available for the local manatee population. During the dry season, water recedes drastically and disconnects from the dominant shoreline emergent vegetation, decreasing accessibility for manatees. The current study revealed major environmental concerns (eutrophication and sedimentation) that may negatively impact habitat quality for manatees. The information from the results will be key for the development of the management plan of the lake and its manatee population. Efficient land use and water management across the entire watershed may be necessary to mitigate such issues.

© 2020 John Wiley & Sons, Ltd. City managers need to understand how land use and land cover (LULC) change in an urban landscape can affect future land degradation and conditions for ecosystem services (ESs) supply and demand. Optimal land use and land management requires explicit spatial mapping of ESs supply and demand under alternative land use scenarios. In this study, we applied spatially explicit models to predict changes in ESs supply and demand, and their coupling mechanisms, under one baseline scenario and three stakeholder-defined LULC change scenarios (developed, planning, policy) in Shanghai municipality, China. The results suggest that the policy scenario could significantly increase ESs supply and restore degraded urban areas, but would not guarantee that supply meets demand for four key ESs tested: water retention, particulate matter removal, carbon sequestration, and recreation. However, the policy scenario significantly reduced the shortfalls and spatial mismatches in water retention, particulate matter removal and recreation services, and also greatly restored deficit areas for all four ESs. This is valuable scientific evidence that ESs supply and demand information can be incorporated into urban land management planning in a spatially explicit manner, in order to control or prevent future potential land degradation. This study was supported by the National Natural Science Foundation of China (grant nos. 41601616 and 41771571) and the Key Laboratory of Watershed Geographic Sciences, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences (grant no. NIGLAS2016QY02).

The increased input of nutrients into biological systems has been shown to result in altered biotic interactions through changes in food availability. The aim of this study was to test for an association between phytoplankton nutrient content and epibiont variables in natural zooplankton populations. Via a field survey, we studied how a gradient in food quantity and quality impacted host population density and epibiont variables in Daphnia pulex . We found a significant decrease in epibiont prevalence and infracommunity richness, which could mainly be attributed to a changing phytoplankton N : P ratio (caused by P‐limitation). We performed a lab experiment in which we exposed Daphnia magna to different algal nutrient ratios and the epibionts detected in the field study. P‐limitation in the algae affected D. magna performance and resulted in similar trends of food quality effects in the epibiont variables. The experiment, however, also reflected subtle differences between different epibiont species.

Scientists often debate on the evolving state of their fields and future research directions, but empirical studies on research trends are rare and this limits our capacity to disentangle perceptions from facts within the mass of available data. We used ecological and paleolimnological approaches to assess how the “community” of words most commonly used in limnological studies presented at the Association for the Sciences of Limnology and Oceanography (ASLO) meetings and published in Web of Science have evolved over the last decades. We found that the field of limnology has become increasingly focused on global abiotic research themes, especially in rivers, while there was a decrease in the proportion of organismal studies. We hypothesize that this results from both major influential publications highlighting the importance of framing limnology in a global context and the methodological limitations of organismal studies that prevent data from scaling up as quickly as their abiotic counterparts.

Research article, Microbes in the dark ocean are exposed to hydrostatic pressure increasing with depth. Activity rate measurements and biomass production of dark ocean microbes are, however, almost exclusively performed under atmospheric pressure conditions due to technical constraints of sampling equipment maintaining in situ pressure conditions. To evaluate the microbial activity under in situ hydrostatic pressure, we designed and thoroughly tested an in situ microbial incubator (ISMI). The ISMI allows autonomously collecting and incubating seawater at depth, injection of substrate and fixation of the samples after a preprogramed incubation time. The performance of the ISMI was tested in a high-pressure tank and in several field campaigns under ambient hydrostatic pressure by measuring prokaryotic bulk 3H-leucine incorporation rates. Overall, prokaryotic leucine incorporation rates were lower at in situ pressure conditions than under to depressurized conditions reaching only about 50% of the heterotrophic microbial activity measured under depressurized conditions in bathypelagic waters in the North Atlantic Ocean off the northwestern Iberian Peninsula. Our results show that the ISMI is a valuable tool to reliably determine the metabolic activity of deep-sea microbes at in situ hydrostatic pressure conditions. Hence, we advocate that deep-sea biogeochemical and microbial rate measurements should be performed under in situ pressure conditions to obtain a more realistic view on deep-sea biotic processes., IEO-CSIC, FWF, KAKENHI, ERC and GAIN

Existing, high-fidelity models for sewer network modelling are accurate but too slow and inflexible for modern applications such as optimisation or scenario analysis. Reduced complexity surrogate modelling has been applied in response to this, however, current approaches are expensive to set up and still require high-fidelity simulations to derive parameters. In this study, we compare and develop graph partitioning algorithms to automatically group sections of sewer networks into semi-distributed compartments. These compartments can then be simulated using sewer network information only in the integrated modelling framework, CityWat-SemiDistributed (CWSD), which has been developed for application to sewer network modelling in this study. We find that combining graph partitioning with CWSD can produce accurate simulations 100-1,000x faster than existing high-fidelity modelling. Because we anticipate that many CWSD users will not have high-fidelity models available, we demonstrate that the approach provides reasonable simulations even under significant parametric uncertainty through a sensitivity analysis. We compare multiple graph partitioning techniques enabling users to specify the spatial aggregation of the partitioned network, also enabling them to preserve key locations for simulation. We test the impact of temporal resolution, finding that accurate simulations can be produced with timesteps up to one hour. Our experiments show a log-log relationship between temporal/spatial resolution and simulation time, enabling users to pre-specify the efficiency and accuracy needed for their applications. We expect that the efficiency and flexibility of our approach may facilitate novel applications of sewer network models ranging from continuous simulations for long-term planning to spatially optimising the placement of network sensors.

Mono Lake is a closed‐basin, hypersaline, alkaline lake located in Eastern Sierra Nevada, California, that is dominated by microbial life. This unique ecosystem offers a natural laboratory for probing microbial community responses to environmental change. In 2017, a heavy snowpack and subsequent runoff led Mono Lake to transition from annually mixed (monomictic) to indefinitely stratified (meromictic). We followed microbial succession during this limnological shift, establishing a two‐year (2017–2018) water‐column time series of geochemical and microbiological data. Following meromictic conditions, anoxia persisted below the chemocline and reduced compounds such as sulfide and ammonium increased in concentration from near 0 to ~400 and ~150 µM, respectively, throughout 2018. We observed significant microbial succession, with trends varying by water depth. In the epilimnion (above the chemocline), aerobic heterotrophs were displaced by phototrophic genera when a large bloom of cyanobacteria appeared in fall 2018. Bacteria in the hypolimnion (below the chemocline) had a delayed, but systematic, response reflecting colonization by sediment “seed bank” communities. Phototrophic sulfide‐oxidizing bacteria appeared first in summer 2017, followed by microbes associated with anaerobic fermentation in spring 2018, and eventually sulfate‐reducing taxa by fall 2018. This slow shift indicated that multi‐year meromixis was required to establish a sulfate‐reducing community in Mono Lake, although sulfide oxidizers thrive throughout mixing regimes. The abundant green alga Picocystis remained the dominant primary producer during the meromixis event, abundant throughout the water column including in the hypolimnion despite the absence of light and prevalence of sulfide. Our study adds to the growing literature describing microbial resistance and resilience during lake mixing events related to climatic events and environmental change.

Ultraviolet (UV) disinfection is a critical and growing application for the disinfection of water. Current UV systems for disinfection applications are designed around the use of Low Pressure (LP) and High Pressure (HP) mercury based lamps. Increasing demand to reduce and ideally remove the use of mercury requires innovative adaptations and novel approaches to current technology. A potential alternative technology could be Light Emitting Diodes (LEDs) however with current low efficiencies, high costs and low operating powers a development gap for a high power mercury source has been identified. A mercury free tellurium based high pressure plasma was developed and assessed. Although relatively low efficiencies were measured compared to current mercury based technology rapid improvements are likely obtainable. Such an approach enables a novel adaptation to current technology utilising established; manufacturing facilities, approaches of UV system design and validation protocols. As a consequence it offers the potential for a rapid low cost transition to mercury free UV disinfection where no alternative is currently available.

High‐resolution data are improving our ability to resolve temporal patterns and controls on river productivity, but we still know little about the emergent patterns of primary production at river‐network scales. Here, we estimate daily and annual river‐network gross primary production (GPP) by applying characteristic temporal patterns of GPP (i.e., regimes) representing distinct river functional types to simulated river networks. A defined envelope of possible productivity regimes emerges at the network‐scale, but the amount and timing of network GPP can vary widely within this range depending on watershed size, productivity in larger rivers, and reach‐scale variation in light within headwater streams. Larger rivers become more influential on network‐scale GPP as watershed size increases, but small streams with relatively low productivity disproportionately influence network GPP due to their large collective surface area. Our initial predictions of network‐scale productivity provide mechanistic understanding of the factors that shape aquatic ecosystem function at broad scales.

© 2019 The Authors. Limnology and Oceanography published by Wiley Periodicals, Inc. on behalf of Association for the Sciences of Limnology and Oceanography. Connectivity and dispersal are important factors for ecosystem dynamics, conservation, and resource management. Dispersal and recruitment success are determined in early life for many marine species. For those larvae that are pelagic, transport from spawning to nursery grounds is driven by hydrodynamic processes. Other environmental factors such as temperature and biological factors such as ecophysiology, behavior, and reproductive strategy (spawning period and spawning grounds) influence the final dispersal pattern and larval survival. We utilized a Lagrangian particle tracking model coupled with a three-dimensional hydrodynamic model (Larvae&Co) to assess the connectivity patterns between spawning and nursery grounds of six commercially exploited flatfish species in the North Sea over a 10-yr period (1997–2006). Standardized analyses have highlighted how spawning and nursery grounds are connected under the combined pressure of environment and life-history traits. Results showed that the six flatfishes can be divided in two groups, each with their specific connectivity patterns. Turbot, common sole, and brill live in two subpopulations in the North Sea; common dab, European flounder, and European plaice represent a single mixed population. In general, the modeled and genetic patterns match, hence showing the strong impact of larval connectivity. The large overlap in connectivity for species that spawn during the same period and the seasonal change in hydrodynamics highlight the strong impact of a summer front in larval dispersal. Our results prove that individual-based modeling is a powerful tool to guide resource management, even in cases of limited biological information. ispartof: LIMNOLOGY AND OCEANOGRAPHY vol:64 issue:3 pages:1150-1171 status: published

Bluefin tunas across the world migrate long distances to spawn in particularly warm and oligotrophic areas constrained by oceanographic fronts. The low abundance of predators in these areas increases survival chances of their early life stages, but its importance for choice of spawning habitat is unknown. Here, we use estimated clearance rates and data on spatial distributions of Atlantic bluefin tuna larvae Thunnus thynnus and metaephyrae of the jellyfish Pelagia noctiluca to quantify predation at a major spawning ground in the Mediterranean Sea. We found that high densities of P. noctiluca can rapidly deplete tuna eggs and preflexion larvae, but their patchy distribution and low spatial and temporal overlap results in overall low predation. The specific distribution of the spawning sites suggests that bluefin tunas may use local oceanography as cues to spawn outside areas with high predator densities., SI

Sewage sludge is the essential by‐product of wastewater treatment and approaching 100% of the sludge generated in the United Kingdom is recycled to agricultural land. In collaboration with three major Water Utility companies in the United Kingdom, a critical statistical analysis of historical and contemporary sludge quality data was completed to demonstrate the long‐term patterns and improvements in the trace element (TE) content of sludge recycled to agriculture since 1989, and to indicate the current status of sludge quality in the United Kingdom. Comparisons with pollutant emission inventory data showed most of the TE concentrations in sludge were strongly linked to declining environmental emissions. A soil accumulation model showed that zinc and copper would be the first to approach their statutory soil limits in the long term and that nickel, cadmium, lead and mercury are no longer significant and, from a practical perspective, could be removed from the regulatory controls on agricultural use.

Based on three rainfall run-off-induced sediment transport data for bare surface experimental plots, the generalized regression neural network (GRNN) and empirical models were developed to predict sediment load. Rainfall intensity, slope, rainfall duration, soil particle median diameter, clay content of the soil, rill density and soil particle mass density constituted the input variables of the models while sediment load was the target output. The GRNN model was trained and tested. The GRNN model was found successful in predicting sediment load. Sensitivity analysis by the GRNN model revealed that slope and rainfall duration were the most sensitive parameters. In addition to the GRNN model, two empirical models were proposed: (1) in the first empirical model, all the input variables were related to the sediment load, and (2) in the second empirical model, only rainfall intensity, slope and rainfall duration were related to the sediment load. The empirical models were calibrated and validated. At the calibration stage, the coefficients and the exponents of the empirical models were obtained using the genetic algorithm optimization method. The validated empirical models were also applied to two more experimental data sets: (1) one data set was from a field experiment, and (2) one set was from a laboratory experiment. The results indicated the success of the empirical models in predicting sediment load from bare land surfaces. © 2018 CIWEM

Large-scale drifting Sargassum biomass, known as golden tides, has caused considerable damage to the local environment and economy associated with the Yellow Sea of China. To understand the reoccurrence of Sargassum horneri golden tides in the Yellow Sea, large-scale spatio-temporal sampling was performed across nine cruises and five coastal surveys. Morphological data indicated that the floating S. horneri thalli with differing reproductive timing coexisted in the Yellow Sea. A total of 196 S. horned samples had identical sequences of partial cox3 and rbcL-S spacer region, revealing very low genetic diversity in the floating biomass. A total of 19 haplotypes for partial cox3 previously found in the Yellow Sea were not detected in our large-scale sampling. Based on four novel mtDNA markers, the 196 samples could be further distinguished into two forms, which varied in proportions at various locations, but coexisted in each of the spatio-temporal sampling. These results indicated that the floating Sargassum biomass in the Yellow Sea came from only two dominating haplotypes. The novel findings uncovered by this work will provide further insight into the underlying mechanisms of reoccurring golden tides in the Yellow Sea, and lead to the improved management of the Sargassum biomass.

Globally, there is little information on freshwater (non-tidal) wetland below ground soil organic carbon (SOC) stocks, sequestration rates and, in particular, their within-wetland variation. This basic information is critical for designing programs to sample SOC stocks and identifying areas that sequester large amounts of carbon so that they can be managed to prevent degradation and carbon loss. Here, focusing on temperate seasonally inundated freshwater wetlands in south-eastern Australia, we compared SOC stocks and sequestration rates (via radiometric dating) among wetlands, within wetland locations (High water mark, Edge and Middle), and with adjacent terrestrial locations. SOC stocks varied most among wetlands but also varied inconsistently within wetlands. Wetland SOC stocks (20.4 ± 0.1 kg C m−2) were significantly greater than adjacent terrestrial locations (13.3 ± 0.1 kg C m−2). Wetland SOC sequestration rates were similar among all locations (i.e., within a wetland, ranging from 70 g C m−2 yr−1 to 87 g C m−2 yr−1). The relative lack of difference in SOC stocks among wetland locations allows for reduced within-wetland sampling and subsequently greater replication at the wetland level, at least for temperate ephemeral freshwater wetlands, although these findings need to be confirmed over a range of wetland types. This study also produced the first estimates of temperate freshwater wetland SOC stocks and sequestration rates in Australia, and is among the first studies globally to demonstrate that seasonally inundated wetlands can sequester carbon at significant rates. It therefore provides important justification to support the protection and rehabilitation of temperate freshwater wetlands worldwide.

While the disciplines of oceanography and limnology often operate in isolate, freshwater, estuarine, and marine ecosystems are intricately linked. The emphasis of this special issue for Limnology and Oceanography is on the aquatic continuum and the connectivity between aquatic ecosystems from headwater streams and inland waters, to coastal and marine systems. Changes in the transport and transformation of elements as well as ecological functions occur along this aquatic continuum. Assemblages of organisms change in a way that reflects the ecological and biogeochemical conditions of the aquatic gradient. Here, we highlight research progress in limnology and oceanography across the aquatic continuum and at the interfaces of headwaters to oceans. Contributions explored nutrient and carbon dynamics which included release, transportation, transformation, and stoichiometry from freshwaters to marine. The special issue also explored food web continua, including functional changes, biodiversity gradients, and photosynthesis and respiration comparisons among ecosystems at different points in the continuum. Rapid improvements in biomolecular techniques, use of long-term datasets, applications of novel statistical methods, and improved upscaling methods can transform the way aquatic scientists are describing biological organisms and communities from freshwaters to oceans. One important conclusion is the recognition that anthropogenic activities such as invasive species and nutrient pollution trigger challenge the current concepts of aquatic continua including the river continuum concept, the land to ocean continuum, river to estuary systems, and the submarine groundwater discharge. Both limnologists and oceanographers have much to gain from exchanging information with one another, especially in light of global change.