Hydrological seasonality and nutrient stoichiometry control dissolved organic matter characterization in a headwater stream.

Dissolved organic matter (DOM) is a diverse and highly complex mixture of organic macromolecules, and thus plays a central role in aquatic ecosystems. However, responses of components and sources of DOM to hydrological processes and trophic levels (nutrient stoichiometric ratios) are poorly understood, particularly in monsoonal headwater streams of Asia that are vulnerable to catchment physical characteristics. In this study, the excitation - emission matrix florescence spectroscopy coupled with parallel factor analysis (EEM-PARAFAC) was used to explore the DOM characters in a headwater stream, where seasonal rainfalls and nutrient levels vary largely.

Mapping risk factors to climate change impacts using traditional ecological knowledge to support adaptation planning with a Native American Tribe in Louisiana.

Indigenous communities are often on the front-lines of climate change, and for tribes such as the Pointe-au-Chien Indian Tribe (PACIT) that make their homes and livelihoods in the dynamic landscapes of Coastal Louisiana (USA), sea-level rise, subsidence, and land loss are very real reminders of why they must continue to hone their adaptive capacity that has evolved over many generations and continues to evolve as the pace of change quickens. PACIT members have an inherited wisdom about their surrounding environment and continue to build on that body of observational knowledge that is passed from generation to generation to sustain themselves in this dynamic landscape. This knowledge is woven through their culture and is sometimes referred to as traditional ecological knowledge (TEK).

Insights from barium variability in a Siderastrea siderea coral in the northwestern Gulf of Mexico.

Coral Ba/Ca is a proxy for seawater barium concentration that varies with upwelling, terrigenous input, and marine productivity whereas coral Sr/Ca varies with temperature. We examine monthly coral Ba/Ca and Sr/Ca before and during offshore oil exploration in a Siderastrea siderea coral from West Flower Garden Bank located on the continental shelf edge in the Gulf of Mexico. Coral Ba/Ca variations lack pulses driven by upwelling or river outflow and are not in sync with coral Sr/Ca that exhibit a different seasonal pattern.

Hot spot of CH production and diffusive flux in rivers with high urbanization.

Rivers and streams play a central role in global carbon budget, but our knowledge is limited on the magnitude and extent of urbanization influence on riverine methane (CH) dynamics. In this study, we investigated dissolved CH (dCH) concentration and CH diffusive fluxes in 27 river segments of two 4-order and three 3-order tributary rivers to the Yangtze River in China, which drained land areas with varied urbanization intensities. We found that urban development was the key factor responsible for high fluvial dCH concentration and diffusive flux, exceeding the influence of agricultural farming, and these headwater rivers were over-saturated in CH with respect to atmospheric equilibrium.

Challenges and opportunities for sustaining coastal wetlands and oyster reefs in the southeastern United States.

Formed at the confluence of marine and fresh waters, estuaries experience both the seaside pressures of rising sea levels and increasing storm severity, and watershed and precipitation changes that are shifting the quality and quantity of freshwater and sediments delivered from upstream sources. Boating, shoreline hardening, harvesting pressure, and other signatures of human activity are also increasing as populations swell in coastal regions. Given this shifting landscape of pressures, the factors most threatening to estuary health and stability are often uncertain.

Finding voices in the floods of Freedom Hill: innovating solutions in Princeville, North Carolina.

Princeville, NC, is the oldest town chartered by Blacks in America. Founded as Freedom Hill in 1865 and incorporated as Princeville in 1885, the town continues to be predominantly African American today. Built on the unwanted and flood-prone lands adjacent to the Tar River, Princeville has flooded multiple times throughout its history, including after Hurricane Floyd in 1999 and Hurricane Matthew in 2016.

Coastal resilience surges as living shorelines reduce lateral erosion of salt marshes.

A growing suite of research has demonstrated that nature-based shoreline stabilization methods can increase resilience of coastal ecosystems by improving their capacity to return to predisturbance states. Previous work suggests that during hurricanes, living shorelines promote vertical accretion and experience less damage than traditional shoreline stabilization alternatives. Nevertheless, there is limited research looking at the impacts of major storm events on living shorelines and most studies have investigated a small number of sites.

Cross species multi-omics reveals cell wall sequestration and elevated global transcript abundance as mechanisms of boron tolerance in plants.

Boron toxicity is a world-wide problem for crops, yet we have a limited understanding of the genetic responses and adaptive mechanisms to this stress in plants. We employed a cross-species comparison between boron stress-sensitive Arabidopsis thaliana and its boron stress-tolerant extremophyte relative Schrenkiella parvula, and a multi-omics approach integrating genomics, transcriptomics, metabolomics and ionomics to assess plant responses and adaptations to boron stress. Schrenkiella parvula maintains lower concentrations of total boron and free boric acid than Arabidopsis when grown with excess boron.

Ocean planning for species on the move provides substantial benefits and requires few trade-offs.

Societies increasingly use multisector ocean planning as a tool to mitigate conflicts over space in the sea, but such plans can be highly sensitive to species redistribution driven by climate change or other factors. A key uncertainty is whether planning ahead for future species redistributions imposes high opportunity costs and sharp trade-offs against current ocean plans. Here, we use more than 10,000 projections for marine animals around North America to test the impact of climate-driven species redistributions on the ability of ocean plans to meet their goals.

Geometry and Topology of Estuary and Braided River Channel Networks Automatically Extracted From Topographic Data.

Automatic extraction of channel networks from topography in systems with multiple interconnected channels, like braided rivers and estuaries, remains a major challenge in hydrology and geomorphology. Representing channelized systems as networks provides a mathematical framework for analyzing transport and geomorphology. In this paper, we introduce a mathematically rigorous methodology and software for extracting channel network topology and geometry from digital elevation models (DEMs) and analyze such channel networks in estuaries and braided rivers.

Are Groundwater Level Data Collected by Citizen Scientists Trustworthy? A Cautionary Tale.

Public participation in groundwater projects is increasing, however, the efficacy of the data collected in such studies, is not well-documented in the literature. In this study, the authors describe a citizen science project focused on measuring and recording groundwater levels in an aquifer and evaluate whether the groundwater data collected by the participants are trustworthy. A total of 31 participants were initially recruited to measure and record groundwater levels from 29 monitoring wells on a barrier island.

Voluntary Restoration: Mitigation's Silent Partner in the Quest to Reverse Coastal Wetland Loss in the USA.

Coastal ecosystems are under pressure from a vast array of anthropogenic stressors, including development and climate change, resulting in significant habitat losses globally Conservation policies are often implemented with the intent of reducing habitat loss. However, losses already incurred will require restoration if ecosystem functions and services are to be recovered. The United States has a long history of wetland loss and recognizes that averting loss requires a multi-pronged approach including mitigation for regulated activities and non-mitigation (voluntary herein) restoration.

Social Factors Key to Landscape-Scale Coastal Restoration: Lessons Learned from Three U.S. Case Studies.

In the United States, extensive investments have been made to restore the ecological function and services of coastal marine habitats. Despite a growing body of science supporting coastal restoration, few studies have addressed the suite of societally enabling conditions that helped facilitate successful restoration and recovery efforts that occurred at meaningful ecological (i.e.

Mangroves shelter coastal economic activity from cyclones.

Mangroves shelter coastlines during hazardous storm events with coastal communities experiencing mangrove deforestation are increasingly vulnerable to economic damages resulting from cyclones. To date, the benefits of mangroves in terms of protecting coastal areas have been estimated only through individual case studies of specific regions or countries. Using spatially referenced data and statistical methods, we track from 2000 to 2012 the impact of cyclones on economic activity in coastal regions inhabited by nearly 2,000 tropical and subtropical communities across 23 major mangrove-holding countries.

The revolution of crossdating in marine palaeoecology and palaeoclimatology.

Over the past century, the dendrochronology technique of crossdating has been widely used to generate a global network of tree-ring chronologies that serves as a leading indicator of environmental variability and change. Only recently, however, has this same approach been applied to growth increments in calcified structures of bivalves, fish and corals in the world's oceans. As in trees, these crossdated marine chronologies are well replicated, annually resolved and absolutely dated, providing uninterrupted multi-decadal to millennial histories of ocean palaeoclimatic and palaeoecological processes.

Daily pCO and CO flux variations in a subtropical mesotrophic shallow lake.

Carbon dioxide (CO) emissions from lakes have been proven to be an important component of the continental carbon balance, but most CO evasion estimates ignore daily variability of partial pressure of CO (pCO). To discern the variability of pCO and its effect on CO outgassing estimations, we conducted in-situ biweekly pCO measurements during daylight from November 2017 to June 2018 at 7:00, 10:00, 14:00, and 17:00 Central Standard Time of the United States (CST) in a subtropical shallow lake in Louisiana, USA. Daytime pCO varied largely from 154 to 1698 μatm with an average of 736 μatm, while daytime CO flux ranged from -43 to 284 mmol m h averaging at 44 mmol m h.

Spatial Distribution and Contamination Assessment of Surface Heavy Metals off the Western Guangdong Province and Northeastern Hainan Island.

Surface sediments collected from the continental shelf off the western Guangdong Province and northeastern Hainan Island are analyzed for selected heavy metals contents including Cd, Cr, Cu, Pb, Zn, and As to determine spatial distribution, potential ecological risks, and sources. In addition, some of the controlling factors of heavy metals distribution are also discussed. The average heavy metals contents decrease in the order of Zn > Cr > Pb > Cu > As > Cd.

Dissolved carbon transport in a river-lake continuum: A case study in a subtropical watershed, USA.

Rivers and lakes have been traditionally studied as separate entities for carbon transport. However, there is a gap in our knowledge of the connectivity of dissolved carbon in a river-lake continuum. In this study, we analyzed dissolved carbon along the Little River-Catahoula Lake in subtropical Louisiana, United States to assess carbon biogeochemistry in such a river-lake continuum.

Metals geochemistry and mass export from the Mississippi-Atchafalaya River system to the Northern Gulf of Mexico.

Discharging 680 km of freshwater annually to the Northern Gulf of Mexico (NGOM), the Mississippi-Atchafalaya River System (MARS) plays a significant role in transporting major and trace elements to the ocean. In this study, we analyzed total recoverable concentrations of thirty-one metals from water samples collected at five locations along the MARS during 2013-2016 to quantify their seasonal mass exports. The Atchafalaya River flows through a large swamp floodplain, allowing us to also test the hypothesis that floodplains function as a sink for metals.

Continuous Flow of Upper Labrador Sea Water around Cape Hatteras.

Six velocity sections straddling Cape Hatteras show a deep counterflow rounding the Cape wedged beneath the poleward flowing Gulf Stream and the continental slope. This counterflow is likely the upper part of the equatorward-flowing Deep Western Boundary Current (DWBC). Hydrographic data suggest that the equatorward flow sampled by the shipboard 38 kHz ADCP comprises the Upper Labrador Sea Water (ULSW) layer and top of the Classical Labrador Sea Water (CLSW) layer.