Deciphering the water quality impacts of COVID-19 human mobility shifts in estuaries surrounding New York City

Stress in the City: Disentangling multi-stressor effects on an urbanized coral in a changing ocean

Reducing the negative impacts of global change on organismal physiology is a critical area of scientific investigation in the Anthropocene. Marine coastal ecosystems that exist downstream from urban centers are often subjected to excess nutrients, pathogens, and chemicals via runoff, which can harm organismal function, and may interact with climate change stress. To simultaneously investigate the individual and combined effects of locally-mediated (nutrient, bacterial) and globally-mediated (temperature) stressors on coral physiology, we conducted a multi-factor experiment utilizing the temperate, urban coral Astrangia poculata. Corals were incubated for 12 days with two levels of field-relevant nitrate concentrations at ambient (20 °C) and elevated (29 °C) temperatures, under fed or starved conditions. After 12 days, corals were challenged with an acute 4-h exposure to Escherichia coli, a known urban pathogen for A. poculata. Results show that the physiological impacts of E. coli exposure, nitrate, elevated temperatures, and starvation were interactive and nuanced. Elevated temperatures had the largest single factor impact, resulting in metabolic lethargy regardless of pathogen exposure, nitrate enrichment, or food level. However, corals under the combination of E. coli exposure, elevated nitrate, starvation, and high temperatures demonstrated metabolic hyperactivity, indicating energetic investment by hyper stressed corals in response to the pathogen. With this work, we move beyond pairwise interactions to demonstrate that the interactive effects of combined stressors may offer the key (and more realistic) answer to the fundamental question "How resilient will marine organisms be to locally-mediated stressors in an era of global change?"

The responses of physical, chemical, and microbiology components on the water quality of Cirebon's estuaries during pre and post-COVID-19 pandemic

The COVID-19 pandemic has led to significant societal disruptions, prompting the Indonesian government to implement various measures, including partial lockdowns or Community Activities Restrictions Enforcement (CARE), to curb the virus's spread. This research aims to assess the impact of various environmental parameters on Cirebon's estuaries, focusing on physical components (such as temperature, total solids [TS], and turbidity), chemical components (including pH, biochemical oxygen demand (BOD), dissolved oxygen (DO), nitrate, and phosphate), and microbiology components (specifically total coliforms). These comprehensive components have notably impacted environmental parameters during pre-, during, and post-COVID-19 pandemic based on the Water Quality Index (WQI) assessment in Cirebon's estuaries. In the port city of Cirebon, located on Java Island's northern coast, the water quality of three river estuaries Kesenden, Sukalila, and Kalijaga was analyzed before and after the CARE implementation. Water samples collected in 2019, 2020, 2022, and 2023 were evaluated against Class II water quality standards per Indonesian Government Regulation No. 22 of 2021. The assessment of WQI was determined using the National Sanitation Foundation Water Quality Index (NSF-WQI) technique revealing significant fluctuations and trends across various stations over the 2019-2023. In 2019, the water quality at Kesenden, Sukalila, and Kalijaga stations was recorded at 52.21, 56.40, and 53.36, respectively. By 2020, began of COVID 19, there was a noticeable decreasing of WQI, Sukalila sustained a "Moderate" classification with a WQI of 54.59, whereas Kesenden and Kalijaga witnessed declines with values recorded at 49.5 and 49.7, respectively. However, the peak-implementation of the CARE program in 2022 saw a drastic decline in water quality, with values dropping below the threshold in all observed stations, 23.97 in Kesenden, 23.10 in Sukalila, and 35.36 in Kalijaga. Meanwhile, the water quality in 2023 experienced increasing (remained in the poor category) with index values of 44.31, 35.14, and 42.0 at Kesenden, Sukalila, and Kalijaga, respectively. The findings underscore the complex interplay between human activities and environmental health, highlighting the need for sustainable practices and robust water management policies to mitigate the adverse effects of such disruptions. The results from the monitoring of ocean health pre- and post-the CARE implementation in the pandemic era have provided a unique opportunity to reflect on human behavior and its impact on the environment, emphasizing the importance of adopting pro-environmental behaviors to support sustainable development in the post-pandemic era. PRACTITIONER POINTS: The onset of the COVID-19 pandemic led to an improvement in water quality due to the reduction in industrial and human activities resulting CARE. The significant reduction in anthropogenic activities such as industry and transportation, which lead the improvement in DO, pH, and coliform because decreasing the phosphate, nitrate, turbidity, total solid, and BOD. The CARE program in 2022 and 2023, there was a marked decline in the water quality index across all monitoring stations in Cirebon. CARE period of reduced anthropogenic pressure offers valuable insights for policymakers to develop sustainable water management strategies to maintain and further improve water quality post-pandemic.

Nutrient variations and environmental relationships of lakes and reservoirs before and after the COVID-19 epidemic public lockdown policy elimination: A nationwide comparative view in China

The continuous impact of COVID-19 on aquatic environments has attracted considerable attention, primarily focusing on short-term water quality effects during lockdown, while studies on changes following the lifting of restrictions are relatively limited. Following adjustments to China's pandemic public policy in December 2022, the effects on water quality and nutrient status in lakes and reservoirs remain unclear. In this study, we collected national environmental monitoring data comprising 15 indicators of water quality, meteorology, soil, and economic factors, from 86 lakes and reservoirs across China between March 2021 and December 2023. Total nitrogen (TN), total phosphorus (TP), the mass TN/TP ratio (TN/TP), and ammonia-nitrogen (NH3-N) were selected as representative nutrient indicators. The water quality index (WQI) and multivariate statistical techniques were employed to comprehensively assess national water quality and identify the drivers of nutrient variations in sub-regions. The results show that during the monitoring period from 2021 to 2023, Chinese national water quality consistently fell within the 'good (61-80)' or 'excellent (81-100)' categories, with the lowest water quality observed in the summer of each year. The summer of 2021 recorded the lowest WQI value among all seasons at 75.01. Following the elimination of the COVID-19 epidemic public lockdown policy, concentrations of TN, TP, and NH3-N declined. These findings indicate a general improvement in the water quality of lakes and reservoirs nationwide. Mantel test and multiple stepwise linear regression models revealed significant correlations between nutrients and human activity indicators in central, eastern, and northern China. In northern China, TP showed a significant positive correlation with GDP (0.2 < Mantel's r < 0.5, P < 0.05), with the beta value increasing from 0.27 to 0.38 after the elimination of the COVID-19 epidemic public lockdown policy. In these regions, the influence of rainfall, wind speed, NDVI, surface soil moisture, and water temperature on nutrients shifted from significant to insignificant effects after the elimination of the COVID-19 epidemic public lockdown policy, indicating that human activities have overshadowed natural factors. This study examines the water quality and nutrient status of lakes and reservoirs in China after the elimination of the COVID-19 epidemic public lockdown policy, highlighting the long-term impacts and spatial variations of the pandemic. These findings will inform environmental governance and promote sustainable water resource management in the post-pandemic era.

Driving factors of colored dissolved organic matter dynamics across a complex urbanized estuary

The role of estuaries in sourcing and transforming dissolved organic matter - the largest reservoir of organic carbon in the ocean - still presents many unknowns for coastal biogeochemical cycles, and is further complicated by increasing human pressures and a changing climate. Here, we examined the major drivers of colored dissolved organic matter (CDOM) dynamics in Long Island Sound (LIS), a heavily urbanized estuary of National Significance with a storied water quality past. A comprehensive new optical dataset, including measurements of CDOM absorption and fluorescence signatures, was integrated with biological and hydrological measurements to capture the spatiotemporal heterogeneities of LIS, including its urban-to-rural gradient, dynamic river mouths, and blue carbon ecosystems across seasons, following episodic storm events, and over five years. Results reveal longitudinal gradients in both DOM amount and quality. While carbon-rich and humic terrigenous DOM was dominant in the heavily riverine-influenced Central to Eastern LIS, an uncoupling between CDOM absorption (aCDOM) and dissolved organic carbon (DOC) concentration in Western LIS, and a stronger correlation with Chlorophyll-a, indicated increased autochthonous CDOM production. Closer to the New York City urban core, aCDOM was highly correlated to turbidity, consistent with increased wastewater influences. Fluorescence PARAFAC analysis provided strong evidence for seasonal processing of CDOM in LIS, related to increased summertime photochemical degradation of humic-like components and shoulder-season microbial processing. Riverine CDOM export was influenced by discharge amount, residence time, and coastal wetlands acting as additional sources of strongly humic and aromatic organic matter. These measurements allowed us to assess how hydrologic, biological, and anthropogenic processes impact DOM dynamics and, subsequently, biogeochemical variability and trophic status in this complex urbanized estuary, with implications for water quality management and policy. Results discussed here are applicable beyond LIS, as urbanized estuaries globally face similar hydrological and anthropogenic forcings.