University of Maryland Center for Environmental Science

Non-grain production of cropland (NGPCL) is a common consequence of rapid urbanization, but excessive NGPCL threatens food security and sustainable cropland use. However, the evolutionary processes and mechanisms of different NGPCL types remain largely unknown, compromising the scientific basis for NGPCL management. Thus, taking rapidly urbanized Deqing as the study area, this research constructed an NGPCL theoretical framework from the perspective of agricultural location, classified NGPCL types using Landsat images, random forest algorithm and Google Earth Engine, and revealed their spatiotemporal changes and different influencing factors through the Multinomial Logit Regression model, and provided targeted zoning and categorized policy suggestions. Our constructed theoretical framework modeled NGPCL by the complex interactions among geographical location, natural conditions, socioeconomic levels, and policy forces. From 2000 to 2022, NGPCL in Deqing County had a high degree and significantly increased from 68.65% to 89.19%. Pond farming and horticultural crops increased by 4046.46 ha (38.0%) and 1307 ha (27.1%), while tree planting slightly decreased by 54 ha (−2.5%). However, these NGPCL expansions resulted in a drastic decrease of 5299 ha (−65.5%) in grain crops plantation. Different NGPCL types showed varied spatial distribution characteristics and differentiated driving mechanism. Horticultural crops depended on geographical location and socioeconomic factors and were widely planted near towns and roads with high population density and economic strength. Pond farming mainly extended along the eastern flat rivers and relied on resource endowment. Tree planting was closely related to the natural condition and was concentrated in the sparsely populated mountainous areas. The NGPCL is the result of balancing various factors, and under conditions of extremely scarce cropland resources, the Chinese government needs to strike a reasonable threshold for non-grain production and propose targeted policies of zoning classification to prevent excessive NGPCL from threatening grain yield security.

The ecosystem response to anthropogenic nitrogen (N) loading in estuarine systems is determined by hydrodynamics, biogeochemical transformation rates, and other system-specific characteristics. Historically, San Francisco (SF) Bay has been an outlier from other estuaries with an unusual resistance to eutrophication, despite having extremely high rates of nitrogen loading. Recent increases in phytoplankton biomass and an unprecedented harmful algal bloom, however, have increased the urgency to understand rates and drivers of nitrogen removal in the system. To assess benthic N cycling rates, we conducted seasonal measurements across nine sites in South and Lower South SF Bay, the two sub-embayments with the highest rates of area-normalized N loading, to determine the rates and potential drivers of denitrification and dissimilatory nitrate reduction to ammonium (DNRA). Denitrification rates averaged 60.6 ± 8.1 µmol m ⁻² h ⁻¹ and were primarily coupled to nitrification. Denitrification rates were positively correlated with DNRA rates and % clay. DNRA rates ranged from 0 to 20 µmol m ⁻² h ⁻¹ and on an annual basis averaged ~ 10% of total benthic nitrate reduction, with a negative correlation to % clay content in the surface sediment. The measured denitrification rates account for the removal of, on average, 14% of N loaded annually to South SF Bay, leaving a sizeable portion for alternate fates (e.g., recycling, export, or burial) and potential for substantial temporal and spatial variability (1–79%). This identifies the relative importance of sediment denitrification in ecosystems characterized by high nutrients and low productivity.

Tiny unicellular cyanobacteria or picocyanobacteria (0.5–3 µm) are important due to their ecological significance. Chesapeake Bay is a temperate estuary that contains abundant and diverse picocyanobacteria. Studies of Chesapeake Bay picocyanobacteria in the past 20 years led to the finding of new members of subcluster 5.2 Synechococcus . They laid the foundation for revealing the ecophysiology, biogeography, genomics, and molecular evolution of picocyanobacterial in the Chesapeake Bay and other coastal estuaries. The Bay picocyanobacteria are known to better tolerate the changes in temperature, salinity, and heavy metals compared to their coastal and open-ocean counterparts. Many picocyanobacteria isolated from the Bay contain rich toxin–antitoxin (TA) genes, suggesting that the TA system may provide them with a genetic advance to cope with variable estuarine environments. Distinct winter and summer picocyanobacteria are present in the Bay, suggesting a dynamic seasonal shift of the picocyanobacterial community in the temperate estuary. While the Bay contains subcluster 5.2 Synechococcus , it also contains freshwater Synechococcus , Cyanobium, and marine Synechococcus due to river influx and the ocean’s tidal influence. Some Chesapeake Bay picocyanobacterial clades were found in the Bering Sea and Chukchi Sea, showing a link between the Bay and polar picocyanobacteria. Genomic sequences of estuarine picocyanobacteria provide new insight into the taxonomy and evolution of freshwater, estuarine, and marine unicellular cyanobacteria. Estuaries connect freshwater and marine ecosystems. This overview attempts to extend what we learned from Chesapeake Bay picocyanobacteria to picocyanobacteria in freshwater and marine waters.

Climate change can influence populations of monogamous species by affecting pair‐bond dynamics. This study examined the impact of climate on widowhood and divorce, and the subsequent effects on individual vital rates and life‐history outcomes over 54 years in a snow petrel (Pagodroma nivea) population. We found that environmental conditions can affect pair‐bond dynamics both directly and indirectly. Divorce was adaptive, occurring more frequently after breeding failure and leading to improved breeding success. Divorce probabilities also increased under severe climatic conditions, regardless of prior breeding success, supporting the ‘Habitat‐mediated’ mechanisms. Overall, pair‐bond disruptions reduced subsequent vital rates and lifetime outcomes. Climate forecasts from an Atmosphere–Ocean General Circulation Model projected increased male widowhood rates due to decreased sea ice negatively affecting female survival, despite considerable uncertainty. These findings highlight the importance of environmentally induced changes in demographic and pair‐bond disruption rates as crucial factors shaping demographic responses to climate change.

We explore the habitat use of Antarctic pack-ice seals by analyzing their occupancy patterns on pack-ice floes, employing a novel combination of segmented generalized linear regression and fine-scale (∼ 50 cm pixel resolution) sea ice feature extraction in satellite imagery. Our analysis of environmental factors identified ice floe size, fine-scale sea ice concentration and nearby marine topography as significantly correlated with seal haul out abundance. Further analysis between seal abundance and ice floe size identified pronounced shifts in the relationship between the number of seals hauled out and floe size, with a positive relationship up to approximately 50 m² that diminishes for larger floe sizes and largely plateaus after 500 m². These patterns provide information on pack-ice seal behavior and, when combined with methods to delineate individual ice floes, can yield predictions on the number of seals likely to be found in each satellite image scene. This work represents another step in the pipeline required to automate the survey of pack-ice seals using satellite imagery, a necessary step towards pan-Antarctic monitoring of these key marine predators.

Objective Extracting DNA is essential in wildlife genetic studies, and numerous methods are available. However, the process is costly and time-consuming for non-model organisms, including most wildlife species. Therefore, we optimized a cost-efficient protocol to extract DNA from the muscle tissue of White-tailed Deer using the DNAdvance kit (Beckman Coulter), a magnetic-bead-based approach. We devised a 3 × 3 factorial design using combinations of tissue mass (10 mg, 50 mg, or 100 mg) and reaction volume (25%, 33%, and 50% of the manufacturer's recommended volumes). DNA was extracted for N = 81 tissue sub-samples (9 replicates/treatment). Results Our target yield was 500 ng of genomic DNA per sample, sufficient for population genetic assessments. A combination of 50 mg tissue and 25% reaction volume yielded enough DNA at the lowest cost. The factorial design revealed that varying tissue mass and reagent volume significantly affected extracted DNA yield. Our study demonstrates that sufficient DNA can be extracted at 75% lower costs than the manufacturer's standard protocol. Other researchers can directly use our modified DNAdvance protocol to perform cost-effective DNA extractions.

Many coastal ecosystems have suffered from cultural eutrophication and dead zones. In the Chesapeake Bay, water quality degradation is manifested in low dissolved oxygen, poor water clarity, and decreased submerged aquatic vegetation acreage. This research combines long-term monitoring data, science-based assessment methods, and novel data analysis approaches (i.e., machine learning) toward understanding the geography, trajectories, and controls of water quality in the Chesapeake Bay, which provides an example for the assessment and management of complex coastal ecosystems. Results showed that the attainment of water quality standards has improved in both the deep zone and the shallow zone since 1985, but the shallow zone has improved more rapidly. In addition, the attainment trajectory has been affected by mainly external drivers (i.e., nutrient reductions) and, to a lesser extent, internal drivers (i.e., water temperature and stratification). Reductions in nutrient loads would improve attainment, whereas warming and stratification would decrease attainment. Furthermore, scenario analyses demonstrated the importance of managing both nitrogen and phosphorus loads. Overall, the deep zone and the shallow zone showed different trajectories and controls, emphasizing the importance of geographical targeting with management actions.

The Y‐organs (YOs) synthesize and secrete molting hormones, and thus regulate crustacean growth and reproduction. However, the YOs of the orange mud crab Scylla olivacea is yet to be described due to its minute size and ambiguous feature. This study describes the location, morphological characteristics, histology, and the changes of YOs at different molt stages, and examines in vitro ecdysteroid secreted by the YOs of S. olivacea . Mature male crabs (> 90 mm carapace width, CW) were used to identify the location of the YOs while male juveniles (50–65 mm CW) at three molt stages (intermoult, premoult, postmoult) were dissected for the characterization of 20‐Hydroxyecdysone (20E) levels. The yellowish‐white, compact, and oval‐shaped YOs are located in pairs at the anterior cephalothorax region, beneath the mandibular external adductor muscle, anterior to the branchial chamber space, and around the end of the nerve tract. The YOs index and YO's cell diameter increased from postmoult to premoult; YO's diameter increased only during premoult stage. Under electron microscopy, the YO's surface morphology is rough, bumpy, network‐like, and porous, with several lacunar system tubules. High concentrations of haemolymph 20E during premoult correlated with the changes in the characteristics of YOs at this stage. The presence of ecdysteroid in YOs was confirmed by high performance liquid chromatography (HPLC). The characteristics of the YOs of S. olivacea are similar to the YO descriptions of other brachyurans. The successful identification and characterization of YOs will spearhead future research on understanding its role in molt regulation of mud crabs, consequently contributing to the development and progress of crab culture and soft‐shell crab industries.

Spatial structure within populations promotes population stability and resilience through asynchronous responses among population sub-components (i.e., portfolio effect). In fishes, spatial structure frequently develops via early-life partial migration, leading to diversified nursery use. However, the portfolio effect depends on how adult recruitment from different nurseries exhibits asynchronous dynamics in response to climate variables, and whether nursery experiences carry over to adult demographics. For a three-decade span, we tested adult nursery recruitment and carryover effects associated with early-life partial migration in Hudson River striped bass. Early-life partial migration led to structured utilization of freshwater, brackish, and coastal nurseries, all of which recruited to the adult population. Adult recruitment from brackish nurseries increased with freshwater flow, while coastal nurseries produced more adults during severe winter years. First-year nursery experiences carried over to influence adult sex, but not growth. Most adult females utilized brackish nurseries in their first year, while adult males recruited from freshwater and brackish nurseries. Early-life partial migration led to diversified nursery use and influenced adult demographics, which buffered populations against perturbations.

Anaerobic oxidation of methane at the sulfate–methane transition in marine sediments is generally considered to be a near-perfect barrier against methane release from the seabed, but the mechanisms involved are not well understood. On the basis of a survey of Baltic Sea sediments we show that a highly variable amount (0–100%) of subseafloor methane leaks through the sulfate–methane transition. The diffusive methane flux to the sediment–water interface is often high, reaching over 2 mmol m⁻² d⁻¹. Even though anaerobic methane oxidation is thermodynamically and kinetically favoured where methane fluxes are high, there is no evidence of methane oxidation in concentration, isotope and modelling results. Cores that lacked anaerobic methane oxidation had high modelled organic matter mineralization rates, suggesting that a possible mechanism could be high electron donor availability due to elevated H2 concentrations, as has been predicted by laboratory studies. We show that methane leakage across the sulfate–methane transition is widespread in organic-rich marine sediments.

Functional groups (FGs) represent a classification scheme designed to study the ecological adaptations of phytoplankton. However, FG dynamics studies in phytoplankton are often conducted independent of taxonomic studies, so the factors influencing community dynamics have not been sufficiently investigated or compared between the two classification systems. In this study, we compared the intricate relationship between taxonomic and FG compositions in North China lakes and delve into the key environmental drivers shaping phytoplankton community dynamics. This investigation revealed that taxonomic and FG classifications exhibit high qualitative and quantitative similarities in the community structure. Environmental drivers had a stronger influence on the FG structure than taxonomic composition, indicating that the FG classification does not result in the loss of ecological information regarding the community structure, even with the reduced number of grouping units. Indeed, it was evident that FGs contained a larger quantity of ecological information. These conclusions were further verified using lakes in eastern China. Additionally, we found that climatic–geographical factors usually exerted indirect influences, by altering water chemistry, while water chemical factors had more direct and stronger influences. The combined effects of both types of environmental factors had a greater impact on the phytoplankton FG structure than on taxonomic composition. In conclusion, we believe that an in‐depth study of FGs will better focus on the ecological characteristics of phytoplankton, while also avoiding the need for extensive species identification.

The Arctic Ocean has experienced significant sea ice loss over recent decades, shifting towards a thinner and more mobile seasonal ice regime. However, the impacts of these transformations on the upper ocean dynamics of the biologically productive Pacific Arctic continental shelves remain underexplored. Here, we quantified the summer upper mixed layer depth and analyzed its interannual to decadal evolution with sea ice and atmospheric forcing, using hydrographic observations and model reanalysis from 1996 to 2021. Before 2006, a shoaling summer mixed layer was associated with sea ice loss and surface warming. After 2007, however, the upper mixed layer reversed to a generally deepening trend due to markedly lengthened open water duration, enhanced wind-induced mixing, and reduced ice meltwater input. Our findings reveal a shift in the primary drivers of upper ocean dynamics, with surface buoyancy flux dominant initially, followed by a shift to wind forcing despite continued sea ice decline. These changes in upper ocean structure and forcing mechanisms may have substantial implications for the marine ecosystem, potentially contributing to unusual fall phytoplankton blooms and intensified ocean acidification observed in the past decade.

The study of projected rainfall data across multiple future scenarios is a key factor in developing sustainable water resource management plans. This paper presents an analysis of projected rainfall series in the Sabah and Sarawak region, Malaysia, against the bias-corrected GCM simulated rainfall data. Three Shared Socioeconomic Pathways (SSP) of SSP126, SSP245, and SSP585 were used to retrieve rainfall simulations of three Global Climate Models (GCMs) of Access-CM2, HadGEM, and UKESM1. The SSPs provide different pathways through which they can affect the rainfall trend. This investigation helps to illustrate the complex interactions between socio-economic developments and climatic changes, underlining the need for adaptive strategies in regional planning. The GCM outputs were downscaled using the quantile-based bias correction method for the future projections. The annual and monthly rainfall data were divided into two periods of 2021–2055 and 2056–2090 for detailed analysis of the future rainfall in the study area. This division allows for a clearer understanding of short-term versus long-term climatic impacts. The non-parametric Mann–Kendall (MK) test and the Sen’s Slope estimator were used to study the trend in the rainfall series. The rainfall data simulated using the Access-CM2 and the HadGEM showed a negative trend, while it was positive in the UKESM1 simulations. Generally, a positive trend in the projected rainfall series was observed. The rainfall series and the rainfall variability index (RVI) chart were plotted to compare the rainfall series of all the SSPs. The drought Severity-Duration-Frequency analysis for the return periods of 2-year, 5-years, 10-year, 20-year, and 50-year was also developed based on the RVI, to estimate the temporal trend of drought severity. These analyses are crucial for preparing effective drought management and mitigation strategies. Results demonstrated that as the drought duration increases its intensity and severity increases as well.

The widespread use of polymers across various industries has led to significant microplastic pollution in marine environments, with millions of tons of microplastics being released annually. This study examines the contribution of coatings particles released from commercial ships, to marine microplastic pollution. Key sources of these microplastics include the weathering and abrasion of coatings during ship maintenance activities. Marine coatings, which are rich in polymers such as polyurethanes and epoxies, are released into the ocean through processes like normal wear and tear, damage, in-water cleaning, and removal of old paint layers. Our research indicates that the global shipping sector could be a substantial contributor to microplastic pollution, potentially releasing thousands of tons annually. Predictive modeling identifies bulk carriers as the largest contributors, followed by tankers, containerships, and cargo vessels. This study also finds that manual biofouling cleaning by divers generates more microplastics than cleaning using mechanized in-water cleaning (IWC) systems with debris capture. Mitigation strategies, such as alternative cleaning methods and improved waste capture and processing, are proposed, but their effectiveness remains uncertain due to implementation challenges. A multidisciplinary approach and coordinated global efforts are essential to develop effective strategies for reducing microplastic pollution from ship coatings and protecting marine ecosystems.

Particles, including aggregates, fecal pellets, and inorganic matter, modulate the transport of carbon and nutrients through estuarine environments. Particles’ size, mass, and density influence their trajectories and ability to transport carbon and other elements. In the Chesapeake Bay, particles fuel the emergence of a seasonal oxygen-deficient zone, with their origin and trajectories being shaped by their characteristics. However, the variability of particle characteristics has not previously been characterized across the length of the Chesapeake Bay, particularly in and around the oxygen-deficient zone. In this study, we measured of the size, abundance, and mass of suspended particles along the Chesapeake Bay during a major deoxygenation event. We demonstrate that particles in the anoxic region have a sandwich structure, with higher particle abundance and mass in the oxic overlying waters and in the deep nepheloid layer, than in the pelagic anoxic zone. These particles in the anoxic zone appear to have similar size properties as particles elsewhere. Stratified water above the oxygen minimum zone may keep particles from the productive top layer from mixing into this region, and our results suggest that this lack of mixing isolates the anoxic zone and limits the amount of reductant entering this environment. Particles in the less saline northern end of the Bay were less massive relative to size than particles farther south, suggesting differences in origin and physical makeup of these particles.

Navigating uncertainty is a critical challenge in all fields of science, especially when translating knowledge into real-world policies or management decisions. However, the wide variance in concepts and definitions of uncertainty across scientific fields hinders effective communication. As a microcosm of diverse fields within Earth Science, NASA’s Carbon Monitoring System (CMS) provides a useful crucible in which to identify cross-cutting concepts of uncertainty. The CMS convened the Uncertainty Working Group (UWG), a group of specialists across disciplines, to evaluate and synthesize efforts to characterize uncertainty in CMS projects. This paper represents efforts by the UWG to build a heuristic framework designed to evaluate data products and communicate uncertainty to both scientific and non-scientific end users. We consider four pillars of uncertainty: origins, severity, stochasticity versus incomplete knowledge, and spatial and temporal autocorrelation. Using a common vocabulary and a generalized workflow, the framework introduces a graphical heuristic accompanied by a narrative, exemplified through contrasting case studies. Envisioned as a versatile tool, this framework provides clarity in reporting uncertainty, guiding users and tempering expectations. Beyond CMS, it stands as a simple yet powerful means to communicate uncertainty across diverse scientific communities.

Phytoplankton have a high potential for CO2 capture and conversion. Besidesbeing a vital food source at the base of oceanic and freshwater food webs, microalgae provide acritical platform for producing chemicals and consumer products. Enhanced nutrient levels,elevated CO2, and rising temperatures increase the frequency of algal blooms, which often havenegative effects such as fish mortalities, loss of flora and fauna, and the production of algaltoxins. Harmful algal blooms (HABs) produce toxins that pose major challenges to waterquality, ecosystem function, human health, tourism, and the food web. These toxins havecomplex chemical structures and possess a wide range of biological properties with potentialapplications as new therapeutics. This review presents a balanced and comprehensiveassessment of the roles of algal blooms in generating fixed carbon for the food chain,sequestering carbon, and their unique secondary metabolites. The structural complexity ofthese metabolites has had an unprecedented impact on structure elucidation technologies andtotal synthesis, which are highlighted throughout this review. In addition, the influence ofbiogeochemical environmental perturbations on algal blooms and their influence on biospheric environments is discussed. Lastly, wesummarize work on management strategies and technologies for the control and treatment of HABs