The adverse effects of antibiotics on ecological health of aquatic environments is increasingly a social and scientific concern. Here we investigated the occurrence, distribution, and risk assessment of residual antibiotics in the main drinking water source (Baitiao River and Xuyan River) of Chengdu, China. Five commonly used antibiotics including sulfamethoxazole, tetracycline, roxithromycin, erythromycin, and chloramphenicol were tested in the two rivers with concentration ranging from less than limits of quantification to 3.62 ng L^-1. Among them, tetracycline was persistent in surface water and exhibited no significant differences along the flow direction of the two rivers. Compared to other rivers or surface waters in the world, the concentrations of the five antibiotics in present rivers were mainly below average levels. All the risk quotients of detected antibiotics in the rivers were lower than 0.001, suggesting that they were at a low level of ecological risk across trophic levels of aquatic organisms.

Influent, final effluent, biosolids, ultrafiltration membrane module inflow and outflow samples were collected in a tertiary wastewater treatment plant to enumerate and categorize anthropogenic particles, including microplastics in the 250 µm - 5 mm size fraction. Samples were digested with 50% hydrogen peroxide, filtered, and examined via microscopy at 40-50x magnification. Most (99%) anthropogenic particles were present in biosolids compared to final effluent (<1%), with fibres numerically dominating influent and final effluent, and fragments dominating biosolids and ultrafiltration inflow and outflow. Assessment of ultrafiltration (pore size = 0.02 µm) inflow and outflow before and after membrane deep cleaning and repair revealed high variability in source abundance and a general, yet non-significant reduction in particle counts in module permeate over 20 weeks. Removal techniques require assessment to explore effective options to mitigate the potential impacts, particularly to freshwater environments, of anthropogenic microparticle release. Our data reveal the utility of quantification and removal options for anthropogenic particles in wastewater treatment plants as they are conduits between municipal and industrial wastewater sources and freshwater and terrestrial receiving environments.

With an intensive increase in anthropogenic activities, plankton communities in coastal areas show deterioration, such as shifts from diatom-dominated to more dinoflagellates and cyanobacteria, and increasing gelatinous zooplankton. To further understand the dynamic changes in plankton communities under anthropogenic activities in coastal areas, a multi-annual survey comprising nine cruises in summer during 2012–2020 was conducted in Sishili Bay, China. The results showed that the phytoplankton community in Sishili Bay was mainly dominated by diatoms, with an abundance of 94.86%; copepods were the dominant taxa in the zooplankton community, accounting for 64.57% of the total abundance, followed by zooplankton larvae (24.74%) including bivalvia, copepoda nauplius, ophiopluteus, etc, whereas other taxonomic groups, such as cladocerans, tunicates, chaetoganatha, cnidarians, protozoa, mysidacea, and ctenophores only accounted for 10.69% of the total abundance. Noticeable changes were observed in the plankton community, accompanied by some signals of community deterioration: dinoflagellates presented an increasing trend compared with that in diatoms; zooplankton larvae and gelatinous organisms also displayed apparent increasing trends. Restriction of dissolved inorganic phosphorus (DIP) combined with an increase in total phosphorus was conducive to a proportional increase in dinoflagellates. Overall, these results suggest that sea reclamation and marine cage aquaculture have promoted an increase in gelatinous organisms. The observed juvenilization of zooplankton might be driven by a trophic cascade effect caused by an increase in carnivorous zooplankton. Overall, the present study highlights the importance of anthropogenic activities affecting plankton inter-annual changes and suggests that the nutrient structure and control of anthropogenic activities should be investigated in detail for the protection and restoration of marine ecological environments.

The foodweb of the Karapuzha reservoir ecosystem was constructed using modelling software Ecopath with Ecosim. This reservoir has a high biomass of primary producers that can support a fairly large fish biomass. Ecotrophic efficiency values of zoobenthos show that these primary consumers are heavily consumed. Hence at higher trophic levels flows are very low. The overall estimated fish biomass in the reservoir was 23.01 metric tonnes, with the carps having higher biomasses than other fish species. The trophic structure reveals that the reservoir can be split into four trophic levels. Flow from trophic levels I to II was 1123 t km^–2 whereas flows from level II into level III was just 257.8 t km^–2. Analysis of Lindeman's spine indicates that the foodweb of the Karapuzha reservoir is primarily a grazing food chain. The ascendancy of the Karapuzha reservoir is estimated at 24.5 percent, indicating a high overall maturity. This suggests that Karapuzha is immune to disturbance and a reasonably mature environment, although with a vulnerable foodweb. The large biomass of zooplankton and the TPP / TR value of 1.77 show that it is a healthy ecosystem but for overfishing, which is an area of concern. Stocking this reservoir with major carps (Catla catla, Labeo rohita and Cirrhinus mrigala) will help to properly use the primary production and also enhance energy flows. This will also help to improve the livelihood of the local tribal community who depend on fish catch from this reservoir.

Freshwater shorelines, including adjacent riparian habitats, are dynamic intersections between land and water that contribute to the maintenance of biodiversity in both realms. These areas are also affected by multiple stressors at local and global scales, from development to climate impacts. Despite increasing alterations to these areas, often to the detriment of connected ecosystems, and despite many regulations for residential and commercial development, there are no established thresholds across countries and governance levels for how much shoreline or riparian development is too much to maintain freshwater ecosystem function. The urgent need to identify thresholds for shoreline and riparian development in freshwater systems is complicated by a number of challenges, yet there is evidence that threshold effects occur after only a small area of a watershed is developed. Here, we summarize current information on development thresholds for shoreline and riparian areas of freshwater systems. We then discuss the inherent challenges in assigning numeric values to such a diverse set of ecosystems (spanning wetlands, lakes, streams, and more), including considerations such as temporal lags, spatial scales, and cumulative effects. We conclude with a call for research needed to overcome knowledge gaps that will enable practitioners to apply scientifically-robust thresholds to decisions regarding shoreline and riparian development. Doing so will benefit all actors by providing evidence to support shoreline policies and development guidelines that are inclusive of the aesthetic, recreational, and functional aspects of freshwater systems.

Cage aquaculture is quickly expanding in the African Great Lakes Region, with the potential of boosting fish output and acting as a source of food security, poverty reduction, job and wealth creation. However, the proliferation of fish cages in Lake Victoria has come along with sporadic fish kills especially in the shallow zones of the lake in specifically the months of September to November each year and whose documentation is key for future references in case such occurrences reoccur. This paper indicates and discusses results from a rapid assessment of recent fish kills in the years 2021 and 2022 and sheds some light on the possible causes of the fish kills using standard methods and proposes mitigation measures moving forward. Low dissolved oxygen levels (≤ 4.0 mg L^-1) instigated by increased eutrophication and upwelling are noted as the main causes of the fish kills. The application of good aquaculture practices for fish cage culture husbandry, application of guidelines as well as fast-tracking and enforcement of regulations will promote sustainable cage farming in such lacustrine systems.

The aim of this study was to investigate the effect of malachite green on the post-exposure filtration rate of Blood Clam, Barbatia virescens. Blood Clams were collected from the rocky coast and acclimated to laboratory conditions for 18 days. Bioassays were conducted wherein Blood Clams were exposed for 24 h to a clean medium (no malachite green), 0.06 mg l^-1 malachite green, 0.32 mg l^-1 malachite green, 5.06 mg l^-1 malachite green, and then to the same concentrations for 48 h. Filtration rate in all concentrations and malachite green-exposure durations were determined at 0.5, 1, 2, 3, 4, and 6 h. Blood Clams exposed for 24 h and 48 h to 0.32 and 5.06 mg l^-1 had significantly lower filtration rates than the control (p<0.05). Similarly, those exposed to 0.06 mg l^-1 for 48 h showed significant reduction in their filtration rates. The lower rate was associated with longer exposure to malachite green. In addition, Blood Clams exposed for 48 h were not able to improve their filtration rate, although they were transferred to a clean medium for 6 h. The green colouration on Blood Clams' muscles was also not eliminated. These findings suggest the ecological risk of malachite green to bivalves and its implications to the health of sessile coastal organisms.