Guanghui Fu’s research while affiliated with China Aerodynamics Research and Development Center 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.

Artificial reefs are widely recognized for their role in improving the ecological environment and creating protected habitats for marine organisms, ultimately enhancing biodiversity within the food web and fisheries resources. This study utilizes stable isotopes to analyze fish samples ranging from 3.4 to 1067 g in body mass, collected within the artificial reef area of Haizhou Bay. The objective is to determine if the δ15N-based fish body mass acts as a driving factor in shaping the food web structure. The results showed a certain level of overlap among all trophic guilds, suggesting that most trophic guilds within this region share similar living environments and feeding habits. The multiple linear regression showed a slight increasing trend between δ15N values and body mass. Furthermore, the predator–prey mass ratio (PPMR) was calculated to be 430:1 based on the δ15N–body mass relationship. This implies that larger reef fish within this artificial reef ecosystem tend to have higher δ15N values compared to smaller fish, indicating a shorter food chain in this ecosystem. In summary, this analysis provides valuable insights into the fish community structure within artificial reef ecosystems. Therefore, it is recommended that future studies focus on further characterizing the fish community structure using body mass information.

Abstract: Recent studies on microplastics (MPs) in marine ecosystems have focused on their bioaccumulation and biomagnification within food chains, emphasizing their potential health risks to humans. However, these bio-effects of MPs in marine ecosystems remain a contentious issue. Employing the "consumer–dietary source" tracking function in stable isotope analysis can enhance our comprehension of how MPs magnify in organisms. In our research conducted in the coastal waters of Haizhou Bay, Jiangsu, China, we examined two commercially important fish species, Larimichthys polyactis and Collichthys lucidus, through stable isotope analysis to investigate the accumulation of MPs in their dietary sources. Results revealed fiber, blue, and PET as the primary shapes, colors, and polymers of MPs in the region. C. lucidus displayed a broader isotopic niche and a higher propensity for MP accumulation than L. polyactis. Biomagnification analysis indicated that dominant MP shapes, colors, and polymers were magnified in both fish species, with MPs smaller than 3 mm exhibiting substantial biomagnification. Factors such as feeding strategies and habitat preferences may influence MP ingestion by fish. We conclude that a high proportion of dietary sources in fish does not necessarily equate to a high concentration of MPs. Neglecting the proportion of dietary sources might lead to underestimating MP biomagnification. Therefore, a multidimensional approach to exploring the biomagnification of MPs is essential to accurately grasp this unique pollutant's impact.

In the past two decades, there has been a growing interest in the ecological benefits and construction effects of marine ranching. As a result, the distribution of certain benthic fish species with limited swimming abilities is often used as a basis for assessment. This study focused on Chaeturichthys stigmatias in the Haizhou Bay marine ranching area of Jiangsu Province, China, and analyzed the seasonal variations in its population resources and the environmental factors influencing them. The findings revealed distinct seasonal changes in spatial distribution. During spring and autumn, the biomass of C. stigmatias was primarily concentrated in coastal waters (31.75 and 32.43 kg/km2), while during summer, it was mainly distributed in the northern waters of the marine ranching area (95.57 kg/km2). The generalized additive model (GAM) analysis identified the main environmental factors influencing changes in C. stigmatias biomass for each season. In spring, these factors included latitude, silicate (SiO3−–Si), phosphate (PO43––P), chlorophyll-a concentration (Chla), dissolved oxygen (DO), suspended matter (SS), and salinity. In summer, the main factors were biochemical oxygen demand (BOD5), DO, pH, Chla, chemical oxygen demand (COD), depth, and water temperature. In autumn, the main factors were Chla, COD, SiO3−–Si, BOD5, SS, depth, and water temperature. We find that Chla is consistently recognized as an environmental factor that influences the biomass of C. stigmatias. However, it is important to acknowledge that the effects of nutrients, DO, water temperature, and salinity should not be disregarded. To identify the key environmental factors impacting the biomass of C. stigmatias, it is necessary to consider the biological characteristics at different stages of its life history. Additionally, it is crucial to examine the potential interactive effects and dynamic relationships among various environmental parameters. This study aims to enhance our understanding of the ecological and physiological traits of C. stigmatias, provide guidance for population conservation efforts, and offer a scientific foundation for the management of fishery resources in marine ranching areas.

The debate surrounding "source" and "sink" of microplastics (MPs) in coastal water has persisted for decades. While the transportation of MPs is influenced by surface runoff and currents, the precise transport patterns remain inadequately defined. In this study, the typical coastal habitat – marine ranching in Haizhou Bay (Jiangsu Province, China) were selected as a case study to assess the ecological risk of MPs. An enhanced framework was employed to assess the entire community characteristics of MPs in various environmental compartments, including surface water (SW), middle water (MW), bottom water (BW), sea bottom sediment (SS), and intertidal sediment (IS). The results of the assessment showed a low risk in the water column and a high risk in the sediment. PERMANOVA based on size and polymer of MPs revealed significant differences between IS and other compartments (SW, MW, BW, and SS) (P<0.001). The co–occurrence network analysis for MP size indicated that most sites occupied central positions, while the analysis for MP polymer suggested that sites near the marine ranching area held more central positions, with sites in MW, BW, and SS being somewhat related to IS. Generalized additive model (GAM) demonstrated that MP concentration in the water correlated with Chla and nutrients, whereas MPs in sediment exhibited greater susceptibility to dissolved oxygen (DO) and salinity. We believe that except for the natural sedimentation and re–suspension of MPs in the vertical direction, MPs in bottom water may migrate to the surface water due to upwelling mediated by artificial reefs. Additionally, under the combined influence of surface runoff, currents, and tides, MPs may migrate horizontally, primarily occurring between middle and bottom water and sediments. The study recommends limiting and reducing wastewater and sewage discharge, as well as regulating fishing and aquaculture activities to control the sources and sinks of MPs in coastal water. Moreover, it advocates the implementation and strengthening of marine monitoring activities to gain a better understanding of the factors driving MP pollution in marine ranching area.

In recent years, the community structure of fishery resources in offshore waters has undergone significant changes, and the resources of traditional commercial fish have gradually declined; as a result, crustaceans have become the main catch. To prevent the loss of resources, it is necessary to carry out ecological stock enhancement and scientifically prevent and control the ecological risks of released species. In this study, based on the Ecopath with Ecosim model, the areas of marine ranching and adjacent waters in Haizhou Bay were used as a case study to construct a temporal dynamic model of Portunus trituberculatus, one of the typical crustacea released in offshore water of China. The ecological carrying capacity (ECC) of P. trituberculatus was assessed, and its impact on other functional groups and ecosystems was predicted. The results showed that the ECC of P. trituberculatus is 42.458 t·km−2, and the entire ecosystem would become imbalanced if this value is exceeded. Under the four simulation scenarios, each ecosystem indicator showed positive responses to different degrees, with total system respiration (R) and total system biomass (B) increasing by 244.66% and 236.90%, respectively. We believe that the maturity of the ecosystem in Haizhou Bay is not high, and the marine organisms are mostly in trophic levels Ⅱ to Ⅲ. Therefore, there is still room for the stock enhancement of P. trituberculatus. The model framework provides a method for assessing the ECC of P. trituberculatus in offshore water and offers a scientific reference and practical basis for stock enhancement activities, resource management, and fishing strategies for P. trituberculatus in the offshore waters of China.

Since the 20th century, as research on the fluctuating asymmetry (FA) of otoliths in sedentary fish has deepened in a gradual way, many scholars have focused on exploring the ability of their otolith FA to indicate different environmental pressures. In this study, a typical benthic fish – Cynoglossus joyneri from three artificial habitats (artificial reef area (ARA), oyster reef area (ORA) and kelp cultivation area (NCA)) and a natural habitat (natural area (NA)) of Haizhou Bay (Lianyungang, Jiangsu Province, China) was selected as the research object, of which four otolith characters (length, width, perimeter, and area) were used to detect FA based on the squared coefficient of asymmetry variation (CV2a). The results showed that the CV2a of otolith in C. joyneri tended to decrease as their body length increased. In terms of indicating environmental pressure, the CV2a of otolith length in NA was significantly higher than those in the other area (P<0.05); the CV2a of otolith width in NA was significantly higher than those in ARA and ORA (P<0.05), and those in NCA were significantly higher than those in ORA (P<0.05); and the CV2a of otolith area in NA was significantly higher than those in ARA (P<0.05), and those in NCA were significantly higher than those in ORA (P<0.05). Generally, the otolith FA of C. joyneri in artificial habitats has lower CV2a than that in natural habitats, indicating that the environmental pressure in artificial habitats is lower than that in natural habitats. We believe that C. joyneri can serve as an indicator species for environmental pressure between different habitats, which could be considered as a groundbreaking milestone in the study of otolith FA in fish. The findings not only advance the ability to assess environmental pressure in sedentary fish, which provide new insights into evaluating environmental pressure in artificial and natural habitats.

Artificial reef is regarded as an effective tool for restoring habitats and supporting the marine ecosystem. While the energy flow and material exchange in the food web of artificial reef ecosystem still remain vacant and should be further understood. In this study, stable isotopic characteristics (δ13C and δ15N) were used to identify the trophic niches and potential carbon sources of consumers (fish and invertebrates) in artificial reef areas and adjacent habitats in Haizhou Bay (the estuary area (EA), the aquaculture area (AA), the artificial reef area (AR), the natural area (NA) and the comprehensive effect area (CEA)) in spring and autumn. The results showed that the average δ13C for all consumers decreased from -16.99 ± 2.07‰ to -21.81 ± 1.66‰, and the average δ15N ranged from 11.37 ± 0.35‰ to 14.69 ± 0.64‰ in all seasons. A SIBER model revealed highly similar trophic niche among habitats in autumn, and lower overlap in spring. The SIMMR model showed that phytoplankton and sedimentary organic matter (SOM) were the major contributors to consumers, and particulate organic matter (POM) accounted for less contribution. In AA and NA phytoplankton and SOM generally contributed fairly equally to most fish, while single SOM sources were major contributors to nearly all the species in AR and CEA. Our findings reveal that ARs can serve as seascape mosaics to increase fish community diversity because of their high variation in the δ13C value and the trophic niches from EA to the NA. Preliminary multidisciplinary studies are needed for the mitigation of effects before any implementations deployed to the offshore waters that influence habitat connectivity, especially some habitat–specific migratory species.

The fluctuating asymmetry (FA) of fish otoliths can reflect the difference in the growth and development of fish in sea areas greatly affected by environmental pressure, thus enabling the assessment of different habitats. In this study, using 113 Collichthys lucidus samples collected from different functional areas (estuary area, aquaculture area, artificial reef area and natural area) in Haizhou Bay, the square coefficient of asymmetry variation (CV²a) of four characters (length, width, perimeter and area) of the left and right sagittal otoliths was calculated. The results showed that the CV²a value of otolith width was the lowest and that of otolith length was the highest. The CV²a value had no obvious regularity with increasing fish body length. In addition, the CV²a values of the four characteristics reached their lowest values in the artificial reef area, indicating that the construction of marine ranching dominated by artificial reefs may partly improve the aquatic environment in this functional area. We consider that the otolith FA of C. lucidus can be used as a characteristic of environmental stress between different areas/regions/habitats.