Chunmei Gao’s research while affiliated with Shanghai Ocean University and other places

In recent years, there has been widespread attention to the toxic effects of microplastics (MPs) on marine mollusks. Therefore, we acclimated and cultured Pacific oysters (Crassostrea gigas) in a 140-liter container, incorporating two types of MPs into their feed: polymethyl methacrylate (PMMA) and polyvinyl chloride (PVC). The concentration of MPs in the water was maintained at 300 μg/L, 600 μg/L, and 900 μg/L, to observe the resulting oxidative stress, DNA damage, and metabolic disorders within their bodies. Under the interference of these pollutants, notable changes were observed in the antioxidant enzyme activities of C. gigas. Specifically, after 30 days of exposure to high concentrations of PMMA, the activity of superoxide dismutase (SOD) in the adductor muscle of C. gigas decreased by 59% compared to the control group, while the activity of catalase (CAT) increased by 67%. In terms of DNA damage, the expression level of NF- κB in the high concentration PMMA group after 30 days reached the highest value in the experimental groups: 2.46. Additionally, enrichment was noted in amino acid and pyrimidine metabolism pathways within the hepatopancreas of the C. gigas. Uridine and methylmalonic acid exhibited low expression levels, whereas glutamic acid and asparagine displayed high expression levels. This study provides fundamental toxicological data to elucidate and quantify the impacts of PMMA and PVC MPs on marine mollusks.

Marine ecosystems are facing numerous environmental challenges due to global climate change. In response to these challenges, the establishment and growth of marine ranching has emerged as a pivotal solution. Chlorophyll a concentration (Chla) is recognized as a valuable indicator for the ecological assessment of marine ranching. This study focused on the spatiotemporal distribution of Chla and its response to environmental factors according to the dataset in the marine ranching area of Haizhou Bay (Lianyungang, Jiangsu, China) from 2003 to 2022. The results showed that Chla had a significant cycle of summer > spring > autumn and was distributed evenly in the central area of the marine ranching. During interannual changes, Chla patches were centered in the central region during 2014, 2015, and 2016. The Chla patches predominantly focused on the eastern area in 2018-2019, shifting to the western area in 2020-2021. The generalized additive model (GAM) indicated that salinity, depth, temperature, biological oxygen demand (BOD5) and SiO3––Si were the main environmental factors affecting Chla during spring, summer and autumn. However, during El Niño events, salinity, depth, temperature, BOD5 and transparency became the main environmental factors. We concluded that salinity, depth and temperature consistently played a crucial role in determining Chla under various climate conditions, and SiO3––Si and transparency will no longer be an environmental factor limiting Chla. In addition, The effect of interannual variability on upwelling and vertical mixing of water layers may potentially alter the spatial distribution pattern of Chla. These findings can offer ideas into predicting the variation of Chla in marine ranching under global interannual events in the future. Furthermore, this can contribute to the comprehensive assessment of ecological benefits and the in-depth construction of marine ranching. Ultimately, it can provide essential data and scientific references for offshore ecological environment assessment and ecosystem restoration.

Plastic products are widely distributed worldwide and continue to have a negative impact on the environment and organisms. Intertidal regions, which interface between upland and marine ecosystems, are regions of high ecological importance and serve as repositories for a variety of plastic wastes. However, ecological risk assessments of microplastics (MPs) in these transitional environments are still scarce. In this study, the morphological characteristics and spatial distribution of MPs in the intertidal surface sediments of Haizhou Bay were analyzed, and an ecological risk assessment framework for MPs was developed. Overall, the average abundance of MPs in the sediments was 2.31±1.35 pieces/g dw. The size of the MPs was mainly less than 1 mm, and the main shape, color and polymer type of the MPs were mainly fibrous (58%), blue (30%), and PVC (22%), respectively. Cluster analyses showed that the sites could be well distinguished by size and polymer type but not by MP shape and color. According to the hazard scores, most of the sites in this area belonged to a risk level of IV, while the pollution loading index (PLI) showed that most of the sites belonged to a risk level of II. The ecological toxicity risk from the species–sensitive distribution (SSD) model showed that one–third of the sites had ecological MPs toxicity risks to marine organisms. We believe that normalized and standardized assessment methods should be implemented to monitor and manage the risk of MPs in the intertidal sediments. Particularly, the multiple dimensions, standard abundance of MPs, as well as MPs ingestion in the intertidal organisms, should be fully considered in the next step.