We measured rates of sediment, C, N, and P accumulation at four floodplain sites spanning the nontidal through oligohaline Choptank and Pocomoke Rivers, Maryland, USA. Ceramic tiles were used to ...collect sediment for a year and sediment cores were collected to derive decadal sedimentation rates using 137Cs. The results showed highest rates of short‐ and long‐term sediment, C, N, and P accumulation occurred in tidal freshwater forests at the head of tide on the Choptank and the oligohaline marsh of the Pocomoke River, and lowest rates occurred in the downstream tidal freshwater forests in both rivers. Presumably, watershed material was mostly trapped at the head of tide, and estuarine material was trapped in oligohaline marshes. This hydrologic transport bottleneck at the head of tide stores most available watershed sediment, C, N, and P creating a sediment shadow in lower tidal freshwater forests potentially limiting their resilience to sea level rise.
Key Points
High sediment and elemental deposition occurred in floodplains at head‐of‐tide
Low deposition occurred in riverine tidal freshwater forests downstream
Tidal flow blocks watershed sediment from reaching tidal wetlands impacted by rising sea level
•Freshwater provisioning index maps upstream water sources supporting humans downstream.•82% of global population is served by freshwater provisions exposed to high threat.•Industrialized nations ...abate more threat to freshwater provisions than poorer nations.•Sound upstream management may reduce the need for costly engineering in poorer nations.
A new global scale water indicator, the freshwater provisioning index for humans (FPIh), maps the capacity of upstream source areas to provide water for human populations downstream. The freshwater provisioning index for humans combined with estimates of threats to water source areas assesses the compounded impacts on freshwater provisions at their point-of-service and the humans they support downstream. Nearly the entire world is serviced by freshwater sources compromised to a moderate extent through human activities, with 82% of the world’s population served by upstream areas exposed to high levels of threat. Globally, 75% of the world’s population benefits from engineered remediation of highly impaired source areas. Despite these gains, more than 80% of the global population still experiences moderate levels of threat impacting their freshwater provisions. Industrialized nations greatly limit their exposure to threats via infrastructure investments whereas regions in the developing world with moderate threat and little means of mitigation are viewed as the most vulnerable. Populations served by water source areas in industrialized countries receive highest threat reductions overall (50–70%) while those served by provision areas in the least developed countries receive <20% threat decrease. Better management of upstream source areas in poorer countries represents an opportunity to reduce threat lessening reliance on costly engineering solutions. Viewing the world in terms of the threats imposed on freshwater provisions combined with regional capacity to abate these impairments through infrastructure investments yields a spatial typology of freshwater resource development states reflecting region-specific challenges with unique management implications. Global mapping of threat development states provides a synoptic-scale diagnosis of key water resource challenges we link with state-specific water service management strategies including service area conservation, threat reduction, and green and gray infrastructure investments to more sustainably manage upstream freshwater provisions. This study provides a functional architecture to assess potential investment strategies to sustainably protect and manage critical upstream freshwater provisions addressing unique challenges faced by different regions of the world.
•eDNA and fishing tools were used to monitor the weather loach in Denmark.•Two localities were positive for loach eDNA, and eight were negative.•Results of eDNA were supported by fishing ...surveys.•Monitoring effort and costs were lower with the eDNA method.•eDNA provides a reliable, cost-efficient method for monitoring rare fishes.
The European weather loach (Misgurnus fossilis) represents one of many European freshwater fishes in decline. Efficient monitoring is essential if conservation efforts are to be successful, but due to the species’ cryptic biology, traditional monitoring methods currently in use are inefficient, time consuming and likely prone to non-detection error. Here, we investigate the usefulness of environmental DNA (eDNA) monitoring as an alternative or supplementary method for surveying the Danish weather loach population, which is presumed to consist primarily of a single group of no more than 50 individuals. In 2008, the majority of historical Danish localities were surveyed, using traditional fishing techniques. We then applied eDNA methods to a number of these, as well as other potential localities. We successfully detected the weather loach at multiple sites in the single known remaining locality; a result that was later confirmed when local managers caught eight live specimens. Furthermore, the eDNA method indicated presence of the weather loach in another historical locality, where the species has not been observed since 1995. At the remaining localities, weather loach eDNA was not detected, providing further evidence for its absence. Importantly, the eDNA survey required less effort in person-hours and lower costs than the traditional fishing survey. This study confirms that eDNA monitoring is a valid supplement to traditional monitoring methods currently applied to monitor rare freshwater fishes. We propose that by providing reliable distribution data at lower cost and limited effort, the eDNA method can allow for increased management efficiency of endangered freshwater species such as the European weather loach.
•Freshwater U37K temperature calibration from northern Alaska.•Environmental controls on freshwater alkenones.•Tri-unsaturated alkenone isomers as chemotaxonomic biomarkers for Group I ...haptophytes.•RIK37 – a new index to assess species effects on alkenone temperature reconstructions.
Alkenones are a class of unsaturated long-chain ketone biomarkers that have been used to reconstruct sea surface temperature and, more recently, continental temperature, by way of alkenone unsaturation indices (e.g. U37K and U37K′). Alkenones are frequently found in brackish and saline lakes, however species effects confound temperature reconstructions when multiple alkenone-producing species with different temperature responses are present. Interestingly, available genetic data indicate that numerous freshwater lakes host a distinct phylotype of alkenone-producing haptophyte algae (the Group I or Greenland phylotype), providing evidence that species effects may be diminished in freshwater lakes. These findings encourage further investigation of alkenone paleotemperature proxies in freshwater systems. Here, we investigated lakes from northern Alaska (n=35) and show that alkenones commonly occurred in freshwater lakes, where they featured distinct distributions, characterized by dominant C37:4 alkenones and a series of tri-unsaturated alkenone isomers. The distributions were characteristic of Group I-type alkenone distributions previously identified in Greenland and North America. Our analysis of suspended particulate matter from Toolik Lake (68°38′N, 149°36′W) yielded the first in situ freshwater U37K calibration (U37K=0.021*T−0.68; r2=0.85; n=52; RMSE=±1.37°C). We explored the environmental significance of the tri-unsaturated isomers using our northern Alaskan lakes dataset in conjunction with new data from haptophyte cultures and Canadian surface sediments. Our results show that these temperature-sensitive isomers are biomarkers for the Group I phylotype and indicators of multiple-species effects. Together, these findings highlight freshwater lakes as valuable targets for continental alkenone-based paleotemperature reconstructions and demonstrate the significance of the recently discovered tri-unsaturated isomers.
Freshwater ecosystems underpin global water and food security, yet are some of the most endangered ecosystems in the world because they are particularly vulnerable to land management change and ...climate variability. The US National Research Council's guidance to NASA regarding missions for the coming decade includes a polar orbiting, global mapping hyperspectral satellite remote sensing mission, the Hyperspectral Infrared Imager (HyspIRI), to make quantitative measurements of ecosystem change. Traditionally, freshwater ecosystems have been challenging to measure with satellite remote sensing because they are small and spatially complex, require high fidelity spectroradiometry, and are best described with biophysical variables derived from high spectral resolution data. In this study, we evaluate the contribution of a hyperspectral global mapping satellite mission to measuring freshwater ecosystems. We demonstrate the need for such a mission, and evaluate the suitability and gaps, through an examination of the measurement resolution issues impacting freshwater ecosystem measurements (spatial, temporal, spectral and radiometric). These are exemplified through three case studies that use remote sensing to characterize a component of freshwater ecosystems that drive primary productivity. The high radiometric quality proposed for the HyspIRI mission makes it uniquely well designed for measuring freshwater ecosystems accurately at moderate to high spatial resolutions. The spatial and spectral resolutions of the HyspIRI mission are well suited for the retrieval of multiple biophysical variables, such as phycocyanin and chlorophyll-a. The effective temporal resolution is suitable for characterizing growing season wetland phenology in temperate regions, but may not be appropriate for tracking algal bloom dynamics, or ecosystem responses to extreme events in monsoonal regions. Global mapping missions provide the systematic, repeated measurements necessary to measure the drivers of freshwater biodiversity change. Archival global mapping missions with open access and free data policies increase end user uptake globally. Overall, an archival, hyperspectral global mapping mission uniquely meets the measurement requirements of multiple end users for freshwater ecosystem science and management.
•Freshwater ecosystems are under threat, but pose unique measurement challenges.•High fidelity, spectral and spatial resolutions needed for freshwater ecosystem measurements.•HyspIRI has unique observation capabilities for whole of ecosystem measurements.•HyspIRI will resolve a large portion of freshwater ecosystems at the seasonal time step.•An archival, global mapping mission with open access and free data is a key to end user uptake.
•Few broad-scale patterns are well-studied for aquatic macrophytes.•Local environmental predictors were important for freshwater plants at broad-scales.•Several knowledge gaps on macroecology of ...freshwater plants were identified.•Lack of lotic studies and databases of species traits and phylogeny were found.•Additional macroecological investigations on freshwater plants are clearly needed.
Broad-scale studies of species distributions and diversity have contributed to the emergence of general macroecological rules. These rules are typically founded on research using well-known terrestrial taxa as models and it is thus uncertain whether aquatic macrophytes follow these macroecological rules. Our purpose is to draw together available information from broad-scale research on aquatic macrophytes growing in lakes, ponds, wetlands, rivers and streams. We summarize how different macroecological rules fit the patterns shown by freshwater plants at various spatial scales. Finally, we outline future actions which should be taken to advance macroecological research on freshwater plants. Our review suggested that some macroecological patterns are relatively well-evidenced for aquatic macrophytes, whereas little information exists for others. We found, for example, that the species richness-latitude relationship follows a unimodal pattern, and species turnover prevails over species nestedness, whereas higher nestedness-related richness differences are found in low beta diversity regions. Contrary to terrestrial plants, climate or history seem not to be dominant determinants explaining these broad-scale patterns; instead local explanatory variables (e.g., water quality, such as alkalinity and nutrients, and hydromorphology) are often important for freshwater plants. We identified several knowledge gaps related, for example, to a smaller number of studies in lotic habitats, compared with lentic habitats, lack of spatially-adequate aquatic plant studies, deficiency of comprehensive species traits databases for aquatic macrophytes, and absence of a true phylogeny comprising most freshwater plant lineages. We hope this review will encourage the undertaking of additional macroecological investigations on freshwater plants across broad spatial and temporal scales.
We provide results of quantitative measurements and characterization for inland freshwater Lake Taihu from the Moderate Resolution Imaging Spectroradiometer (MODIS) on the satellite Aqua. China
's ...Lake Taihu, which is located in the Yangtze River delta in one of the world
's most urbanized and heavily populated areas, contains consistently highly turbid waters in addition to frequent large seasonal algae blooms in various lake regions. Thus, satellite data processing requires use of the shortwave infrared (SWIR) atmospheric correction algorithm. Specifically for Lake Taihu, an iterative SWIR-based atmospheric correction algorithm has been developed and proven to provide reasonably accurate water-leaving radiance spectra data. Using MODIS-Aqua measurements, the blue-green algae bloom in Lake Taihu in 2007 has been studied in detail, demonstrating the importance and usefulness of satellite water color remote sensing for effectively monitoring and managing a bloom event.
Seasonal and interannual variability, as well as spatial distributions, of lake water properties were studied and assessed using the MODIS-Aqua measurements from 2002 to 2008. Results show that overall waters in Lake Taihu are consistently highly turbid all year round, with the winter and summer as the most and least turbid seasons in the lake, respectively. Extremely turbid waters in the winter are primarily attributed to strong winter winds that lead to significant amounts of total suspended sediment (TSS) in the water column. In addition, MODIS-Aqua–measured water-leaving radiance at the blue band is consistently low in various bay regions in Lake Taihu, indicating high algae concentration in these regions. Climatological water property maps, including normalized water-leaving radiance spectra
nL
w
(λ), chlorophyll-a concentration, and water diffuse attenuation coefficient at the wavelength of 490
nm (
K
d
(490)), are derived from all MODIS-Aqua data from 2002 to 2008 for Lake Taihu, showing overall spatial distribution features for the lake water property.
► Satellite remote sensing of inland freshwater optical and biological properties. ► Improved water property products using the SWIR atmospheric correction algorithm. ► Quantitative characterization of water properties for China's inland Lake Taihu. ► Monitoring inland freshwater water quality using satellite measurements.
Parasites can be used as effective monitoring tools in environmental impact studies as they are able to accumulate certain pollutants (e.g. metals) at levels much higher than those of their ambient ...environment and of free-living sentinels. Thus, they provide valuable information not only about the chemical conditions of their and their hosts' environment but also deliver insights into the biological availability of allochthonous substances. While a large number of different freshwater parasites (mainly acanthocephalans and cestodes) were investigated in terms of pollutant bioaccumulation, studies based on marine host–parasites systems remain scarce. However, available data show that different marine parasite taxa such as nematodes, cestodes and acanthocephalans exhibit also an excellent metal accumulation capacity.
The biological availability of metals and their uptake routes in marine biota and parasites differ from those of freshwater organisms. We assume that a large part of metals and other pollutants are also taken up via the digestive system of the host. Therefore, in addition to environmental conditions the physiology of the host also plays an important role for the accumulation process. Additionally, we highlight some advantages in using parasites as accumulation indicators in marine ecosystems. As parasites occur ubiquitously in marine food webs, the monitoring of metals in their tissues can deliver information about the spatial and trophic distribution of pollutants. Accordingly, parasites as indicators offer an ecological assessment on a broader scale, in contrast to established free-living marine indicators, which are mostly benthic invertebrates and therefore limited in habitat distribution. Globally distributed parasite taxa, which are highly abundant in a large number of host species, are suggested as worldwide applicable sentinels.
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•This review summarizes the available data regarding the use of marine parasites as accumulation bioindicators•Published data on metal accumulation in marine parasites are discussed and linked to the requirements for sentinel species•Aspects concerning the uptake and biological availability of metals are thoroughly evaluated•Globally distributed parasites are suggested to be established as sentinels•The paper presents suggestions for future research
Procambarus clarkii is currently recorded from 16 European territories. On top of being a vector of crayfish plague, which is responsible for large-scale disappearance of native crayfish species, it ...causes severe impacts on diverse aquatic ecosystems, due to its rapid life cycle, dispersal capacities, burrowing activities and high population densities. The species has even been recently discovered in caves. This invasive crayfish is a polytrophic keystone species that can exert multiple pressures on ecosystems. Most studies deal with the decline of macrophytes and predation on several species (amphibians, molluscs, and macroinvertebrates), highlighting how this biodiversity loss leads to unbalanced food chains. At a management level, the species is considered as (a) a devastating digger of the water drainage systems in southern and central Europe, (b) an agricultural pest in Mediterranean territories, consuming, for example, young rice plants, and (c) a threat to the restoration of water bodies in north-western Europe. Indeed, among the high-risk species, P. clarkii consistently attained the highest risk rating. Its negative impacts on ecosystem services were evaluated. These may include the loss of provisioning services such as reductions in valued edible native species of regulatory and supporting services, inducing wide changes in ecological communities and increased costs to agriculture and water management. Finally, cultural services may be lost. The species fulfils the criteria of the Article 4(3) of Regulation (EU) No 1143/2014 of the European Parliament (species widely spread in Europe and impossible to eradicate in a cost-effective manner) and has been included in the “Union List”. Particularly, awareness of the ornamental trade through the internet must be reinforced within the European Community and import and trade regulations should be imposed to reduce the availability of this high-risk species.
As aquaculture becomes more important for feeding the growing world population, so too do the required natural resources needed to produce aquaculture feed. While there is potential to replace fish ...meal and fish oil with terrestrial feed ingredients, it is important to understand both the positive and negative implications of such a development. The use of feed with a large proportion of terrestrial feed may reduce the pressure on fisheries to provide feed for fish, but at the same time it may significantly increase the pressure on freshwater resources, due to water consumption and pollution in crop production for aquafeed. Here the green, blue and gray water footprint of cultured fish and crustaceans related to the production of commercial feed for the year 2008 has been determined for the major farmed species, representing 88% of total fed production. The green, blue and gray production-weighted average feed water footprints of fish and crustaceans fed commercial aquafeed are estimated at 1629m3/t, 179m3/t and 166m3/t, respectively. The estimated global total water footprint of commercial aquafeed was 31–35km3 in 2008. The top five contributors to the total water footprint of commercial feed are Nile tilapia, Grass carp, Whiteleg shrimp, Common carp and Atlantic salmon, which together have a water footprint of 18.2km3. An analysis of alternative diets revealed that the replacement of fish meal and fish oil with terrestrial feed ingredients may further increase pressure on freshwater resources. At the same time economic consumptive water productivity may be reduced, especially for carnivorous species. The results of the present study show that, for the aquaculture sector to grow sustainably, freshwater consumption and pollution due to aquafeed need to be taken into account.
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•The commercial feed-related water footprint of aquaculture has been determined.•Terrestrial alternatives for fish meal and fish oil increase the water footprint.•Economic water productivity may be reduced due to alternative feed formulations.•Future growth of the aquaculture sector increases pressure on freshwater resources.
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