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Ecosystem metabolism is a vital measurement for understanding the dynamics of aquatic environments. China has a range of aquatic resources and in the past two decades, there has been an increasing interest in ecosystem metabolism research. However, no studies have evaluated overall variation and environmental patterns which affect metabolism in China's vast range of aquatic systems. For this paper, we searched for articles with metabolism data for China's major rivers and coastal zones from 2000 to 2020. We identified 127 studies documenting ecosystem metabolism functions including primary production (PP), community respiration (CR) and net ecosystem production (NEP). Using path analysis, we documented relationships across a range of environmental parameters. Light availability affected riverine and coastal PP (<0.1–10.7 gC m−2 day−1), while riverine PP was also linked to precipitation, photosynthesis‐related biomass, and land‐use variables. Riverine and coastal CR ranged from 0.01 to 24.3 gC m−2 day−1 and was affected strongly by nutrient concentrations. Average NEP ranged from 2.9 to 9.2 gC m−2 day−1, suggesting the potential of some of the evaluated ecosystems to be CO2 sinks. Within this review, the large spatiotemporal range allows for a wide‐ranging understanding of the variation of metabolic processes which contribute to CO2 dynamics and the role of aquatic ecosystems in regional climate change. Additionally, by evaluating aquatic ecosystem metabolism across such a diverse range of environmental conditions this work provides a scientific basis for future assessments of ecological risks under the complex conditions of climate change. This article is categorized under:Science of Water > Water QualityScience of Water > Water and Environmental ChangeWater and Life > Nature of Freshwater Ecosystems [ABSTRACT FROM AUTHOR]

This study evaluated nutrient flux (nitrate (NO3−), ammonium (NH4+), phosphate (PO43−), and dissolved organic carbon (DOC) at the sediment-water interface and river ecosystem metabolism (REM) to investigate how these ecological functions vary in Beijing's urban waterways. Three tributaries of the River Beiyun were selected. Water quality varied across the study sites as each receives a mixture of wastewater treatment plant (WWTP) effluents and tributary inflows. A chamber technique was applied where water-specific nutrient concentrations were measured at two exposure times (3 and 10 min). Under the actions of physical and biological processes, NO3− and NH4+ flux was primarily controlled by equilibrium concentration and the N-cycle. However, bioabsorption appeared to regulate DOC flux. Specifically, NO3− flux ranged from −0.31 to +0.30 mg/(m2·s), NH4+ was −0.01 to +0.05 mg/(m2·s), PO43− was −0.01 to +0.01 mg/(m2·s), DOC was −0.04 to +0.13 mg/(m2·s). We applied the nighttime slope regression to estimate gross primary production (GPP) and ecosystem respiration (ER). Except in summer, net ecosystem production (GPP+ER) less than 0 indicated heterotrophic study reaches. Structural equation modelling revealed that nutrient dynamics and water temperature were the primary factors driving REM. Our study provides the needed systems-based understanding of vital ecological processes to improve in-stream management. [ABSTRACT FROM AUTHOR]

Raptors can be important components of urban ecosystems due to their role as apex predators, the presence of which may bring benefits to people. Urban environments may provide good quality habitats, and the raptors' ability to utilize resources found here can contribute to their success. However, urban environments are socio-ecological systems and such mechanisms shaping habitats and ecological resources therein are less understood. This paper explores how raptors utilize urban resources, and the socio-ecological processes influencing their quality and availability. It begins with a systematic mapping of the literature to summarize the utility of urban resources by raptors with European distributions. Eighteen species were documented in the literature successfully exploiting novel hunting and/or nesting opportunities in both green and built-up locations of urban areas. We discuss how these may be consequential of human activities, some of which intentionally provided as subsidies, and how their utility by raptors create opportunities for human-raptor interactions further shaping public perception and decisions which potentially affect the raptors. Finally, we demonstrate these concepts by drawing on our experience from an urban peregrine falcon (Falco peregrinus) conservation site in London, UK. The paper concludes with a call for urban raptor conservation and research to consider social and ecological aspects together, appropriately reflecting urban environments as socio-ecological systems. [ABSTRACT FROM AUTHOR]

Waterfalls are geomorphic features that often partition streams into discrete zones. Our study examined aquatic communities, litter decomposition and periphyton growth rates for above- and below-waterfall pools in Ulu Temburong National Park, Brunei. We observed higher fish densities in below-waterfall pools (0.24 fish m vs. 0.02 fish m in above-waterfall pools) and higher shrimp abundance in above-waterfall pools (eight shrimp/pool vs. less than one shrimp/pool in below-waterfall pools). However, macroinvertebrate densities (excluding shrimp) were similar among both pool types. Ambient periphyton was higher in below-waterfall pools in 2013 (4.3 vs. 2.8 g m in above-waterfall pools) and 2014 (4.8 vs. 3.4 g m in above-waterfall pools), while periphyton growth rates varied from 0.05 to 0.26 g m days and were significantly higher in below-waterfall pools in 2014. Leaf litter decomposition rates (0.001 to 0.024 days) did not differ between pool types, suggesting that neither shrimp nor fish densities had consistent impacts on this ecosystem function. Regardless, this research demonstrates the varied effects of biotic and abiotic factors on community structure and ecosystem function. Our results have highlighted the importance of discontinuities, such as waterfalls, in tropical streams. [ABSTRACT FROM AUTHOR]