Spatial and seasonal pattern of macrozoobenthic assemblages and the congruence in water quality bioassessment using different taxa in artificial Mingzhu Lake in Shanghai

The spatial and seasonal pattern of macrozoobenthic structure and its relationship with environmental factors were studied from July 2006 to April 2008 in Mingzhu Lake,Chongming Island,Shanghai at the Changjiang River mouth.The congruences in water quality bioassessment based on diversity and biotic indices and using different taxonomic categories were also explored to find the best assessment method of water quality for the lake.All major structural characteristics of macrozoobenthic community,including species composition,abundance,biomass and four biomass-based diversity indices(Shannon's diversity,Simpson's diversity,Pielou's evenness and Simpson's evenness index) fluctuated significantly in season but in space.The above four abundance-based diversity indices plus abundance-based Margalef's richness index did not display significant spatial variations;and significant seasonal differences were found in three indices only.Water temperature was the key environmental factor responsible for macrozoobenthic spatio-temporal distribution patterns.Water quality assessed by Shannon's index(H_a') and biological pollution index(BPI) rather than the other four biotic indices were consistent with those by trophic state index(TSI).Results from chironomids and oligochaetes did not always agree to those from the whole community when H_a' or Hilsenhoff biotic index was applied to bioassessment.Therefore,combining multiple indices and avoiding a single taxonomic category to assess water quality are strongly recommended and in Mingzhu Lake using a mixture of H_a' and BPI will ensure the most effective investigation of water quality.Our results also show that the main structural characteristics of macrozoobenthic communities in the small lake may display consistent spatial patterns.

Nano polystyrene microplastics could accumulate in Nile tilapia(Oreochromis niloticus):Negatively impacts on the intestinal and liver health through water exposure

Microplastics(MPs)have become a significant concern for their potential toxicity.However,the correlation between the size of plastic particles and their toxicity remains inconclusive.Here,we investigate the toxic effects of different sizes(80 nm,800 nm,8μm and 80μm)polystyrene MPs(PS-MPs)on the model organism Nile tilapia(Oreochromis niloticus).The results of bioluminescent imaging indicate that the 80 nm PS-MPs are more likely to invade the body.H&E staining shows severe damage on the intestinal villi and distinct hepatic steatosis in the 80 nm group.Ed U labeling shows that the proliferation activity of intestinal and liver cells reduces significantly in the 80 nm group.The gut microbiome analysis shows a severe imbalance of gut microbiota homeostasis in the 80 nm group.The analysis of liver transcriptomics and metabolomics shows that the liver lipid metabolism is disordered in the 80 nm group.In conclusion,this study confirms that the 80 nm PS-MPs are more likely to induce intestinal and liver toxicity.All the above lay the foundation for further study on the pathological damage of MPs to other organisms.

Macro-evolutionary patterns of East Asian opsariichthyin-xenocyprinin-cultrin fishes related to the formation of river and river-lake environments under monsoon climate

Although the East Asian monsoon is believed to be an important driver for the origin and evolution of the biotas in this region,the association has rarely been rigorously tested.Here,using phylogenetic comparative methods and analyses of key innovations of adaptive traits,we investigated evolutionary patterns of the East Asian cyprinid opsariichthyin-xenocyprinin-cultrin clade;the dominant species in lakes and rivers,which are the typical productions of monsoon climate.Our molecular phylogenetic analyses revealed the relationships as(Opsariichthystribe t(((Oxygaster-tribe t Aphyocypris-tribe)t Metzia-tribe)t(Paralaubuca-tribe t(Squaliobarbus-tribe t(Hypophthalmichthys-tribe t(xenocyprinins t cultrins)))))).Based on Bayesian relaxed-clock methods,we found that origins of the Squaliobarbus-and Hypophthalmichthys-tribes bearing the key adaptation of riverine spawning with drifting eggs occurred 22.5 and 21.1 Mya,respectively.These times are consistent with the Early Miocene origin of major rivers(e.g.,Yangtze River)and the appearance of the East Asian monsoon climate.Diversification of the cultrins,characterized by spawning of adhesive eggs as well as swimming and feeding in lentic waters,were estimated to have evolved 16.6 to 0.2 Mya.This period covers three phases of enhancement of the East Asian monsoon from the Middle Miocene to the Pliocene(around 15–13,10–7,and 3.5 Mya).The habitats of these cultrins and their evolution also suggest the appearance and development of a lake-river environment during those periods.Therefore,our results suggest close relationships between the evolution of these fishes and geological events in East Asia.Further,they provide knowledge that may help facilitate future conservation strategies such as the maintenance of high river flows during dam construction and operation.