Comparative Study of Metal Accumulation in Three Fish Species (Silurus asotus, Cyprinus carpio, and Carassius auratus auratus) from the Jinsha and Tuo Rivers Located Upstream of the Yangtze River, China.

The concentrations of lead, chromium, cadmium, arsenic, and mercury were analyzed in the muscle and liver (hepatopancreas) of three fish species (Silurus asotus, Cyprinus carpio, and Carassius auratus auratus) from the Jinsha and Tuo Rivers. The above mentioned metal concentrations in the muscles of the three fish species were below the permissible limits, indicating that these fishes are safe for human consumption. The concentration of mercury in the carnivorous fishes was higher than that in the omnivorous fishes. There was no significant difference in growth rate and the concentration of lead, chromium, cadmium, arsenic, and mercury among the fishes from Panzhihua and Fushun. In the two age groups, the concentration of mercury did not vary significantly with growth rate of fish. The relationship between heavy metal concentration and growth rate of fish varied with metal species, fish species, and fish tissue.

A bacteria-based index of biotic integrity assesses aquatic ecosystems effectively in rewetted long-term dry river channel after water replenishment.

Climate-induced droughts exert a significant influence on the connectivity of river systems. It is estimated that about 25% of the world's rivers ran dry before reaching the ocean due to climate change and human activities. Ecological water replenishment is an effective measure for restoring aquatic ecosystems damaged by drought. It is urgently needed to quantitatively assess the aquatic ecosystems in rewetted dry river channels after water replenishment. This study investigated the variations in phytoplankton, zooplankton, benthic macroinvertebrates, and benthic bacterial communities in the rewetted dry river channel of Yongding River after water replenishment. In comparison with the water column communities, the benthic macroinvertebrates were identified as limiting factors for ecological restoration in rewetted dry river channels. In the absence of a certain recovery time for benthic macroinvertebrates, the benthic bacterial-based index of biological integrity, especially calculated based on their intrinsic properties, can properly assess aquatic ecosystems in rewetted dry river channels.

Functional trait-based phytoplankton biomass and assemblage analyses in the pre-growing season for comprehensive algal bloom risk assessment.

Algal bloom (AB) risk assessment is critical for maintaining ecosystem health and human sustainability. Previous AB risk assessments have focused on the potential occurrence of ABs and related factors in the growing season, whereas their hazards, especially in the pre-growing season, have attracted less attention. Here, we performed a comprehensive AB risk assessment, including water trophic levels, phytoplankton biomass, functional trait-based assemblages, and related environmental factors, in the pre-growing season in Dongting Lake, China. Although mesotrophic water and low phytoplankton biomass suggested low AB potential, toxic taxa, which constituted 13.28% of the phytoplankton biomass, indicated non-negligible AB hazards. NH4+ and water temperature were key factors affecting phytoplankton motility and toxicity. Our study establishes a new paradigm for quantitative AB risk assessment, including both potential AB occurrence and hazards. We emphasize the importance of phytoplankton functional traits for early AB warning and NH4+ reduction for AB control in the pre-growing season.