A Novel Algicidal Bacterium, Microbulbifer sp. YX04, Triggered Oxidative Damage and Autophagic Cell Death in Phaeocystis globosa , Which Causes Harmful Algal Blooms

P. globosa is one of the most notorious harmful algal bloom (HAB)-causing species, which can secrete hemolytic toxins, frequently cause serious ecological pollution, and pose a health hazard to animals and humans. Hence, screening for bacteria with high algicidal activity against P. globosa and studies on the algicidal characteristics and mechanism will contribute to providing an ecofriendly microorganism-controlling agent for preventing the occurrence of algal blooms and reducing the harm of algal blooms to the environment.

Cyanopeptides Restriction and Degradation Co-mediate Microbiota Assembly During a Freshwater Cyanobacterial Harmful Algal Bloom (CyanoHAB)

Cyanobacterial harmful algal blooms (CyanoHABs) are globally intensifying and exacerbated by climate change and eutrophication. However, microbiota assembly mechanisms underlying CyanoHABs remain scenario specific and elusive. Especially, cyanopeptides, as a group of bioactive secondary metabolites of cyanobacteria, could affect microbiota assembly and ecosystem function. Here, the trajectory of cyanopeptides were followed and linked to microbiota during Microcystis-dominated CyanoHABs in lake Taihu, China. The most abundant cyanopeptide classes detected included microginin, spumigin, microcystin, nodularin and cyanopeptolin with total MC-LR-equivalent concentrations between 0.23 and 2051.54 ppb, of which cyanotoxins beyond microcystins (e.g., cyanostatin B and nodularin_R etc.) far exceeded reported organismal IC50 and negatively correlated with microbiota diversity, exerting potential collective eco-toxicities stronger than microcystins alone. The microbial communities were differentiated by size fraction and sampling date throughout CyanoHABs, and surprisingly, their variances were better explained by cyanopeptides (19-38%) than nutrients (0-16%). Cyanopeptides restriction (e.g., inhibition) and degradation are first quantitatively verified as the deterministic drivers governing community assembly, with stochastic processes being mediated by interplay between cyanopeptide dynamics and lake microbiota. This study presents an emerging paradigm in which cyanopeptides restriction and degradation co-mediate lake water microbiota assembly, unveiling new insights about the ecotoxicological significance of CyanoHABs to freshwater ecosystems.

Process evaluation of urban river replenished with reclaimed water from a wastewater treatment plant based on the risk of algal bloom and comprehensive acute toxicity

Municipal wastewater reuse has an important role to play with scarce water resources and serious water pollution. However, the impact of reclaimed water on the aquatic ecology and organisms of the receiving water needs to be assessed. This study investigated one ecological restoration project of an urban river replenished with reclaimed water, and evaluated the risk of algal bloom and acute biological toxicity in the river. Results showed that the concentrations of permanganate index and ammonia nitrogen in the river could stably remain below the standard values, the concentrations of total phosphorus were high and most of the monitoring values were between 0.42 and 0.86 mg/L. The content of chlorophyll a was relatively lower, ranging from 0.06 to 0.10 mg/m3. The maximum value of Fv/Fm was 0.42, which was lower than the algal bloom prediction threshold of 0.63. Moreover, the results of luminescence inhibition rate on luminescent bacteria showed that the reclaimed water did not cause significant biological toxicity to the aquatic ecology. The study suggested that implementing urban reclaimed water reuse projects requires a series of ecological purification and restoration technologies in the receiving water, which can effectively guarantee the stability of water quality and the safety of water ecological environment.

Ecological Potentiality of Plankton: A Perspective on Nutrition, Toxicity and Bio-Indication

The base of aquatic energy is initiated and concreted by plankton such as primary photosynthetic algae and consequently their immediate secondary grazers as zooplankton. The nutritional features of algae or phytoplankton are controlled by aquatic nutrients (e.g. nitrogen, phosphorus, silica and other essential minerals). Moreover, the biochemical content of zooplankton reflects their diet profiles (e.g. bacteria and algae). The promising and sustainable fisheries prospects are crucially subjective by nutritional quality and quantity of plankton (e.g. algal bloom). Additionally, both algae and zooplankton are efficient as auspicious biological tools for indicating the aquatic environments.