To date, most studies focus on the ecological and environmental effects of land-based photovoltaic (PV) power plants, while there is a dearth of studies examining the impacts of water-based PV power plants. The effects of a fishery complementary PV power plant, a kind of water-based PV technology, on the near-surface meteorology and aquaculture water environment were investigated in coastal aquaculture ponds in southeast China. The results showed that PV prevented 89~93% of the solar radiation on the surface of the pond, resulting in an average reduction in water temperature of 1.5 °C and a substantial decrease in light intensity of 94%. Furthermore, it weakened the wind speed by 41~50% and elevated the surface air temperature by an average of 0.6 °C. In addition, PV power results in an impressive decrease in chlorophyll-α of 72~94% and a notable increase in dissolved oxygen (DO) concentrations of 8~24%. PV power also reduced the concentration of labile phosphate, active silicate, total nitrogen, total phosphorus, and total organic carbon. However, the PV power did not have a substantial influence on the concentrations of nitrate and ammonium. Our results highlight that fishery complementary PV power plants may be able to improve water quality and benefit shade-loving species.

Organic matter in the productive mangrove–estuary ecosystem plays an important role in global climate changes. In recent years, the eutrophication in such areas caused by anthropogenic inputs of sewage has been revealed, highlighting the need to understand its influence on organic matter. In this study, δ¹³C and δ¹⁵N were used to reveal the effects of sewage on organic matters in the Zhangjiang mangrove–estuary ecosystem. Our results indicate that sewage contributed the most of the total particulate organic matter (41%) in the Zhangjiang estuary, while mangrove plants contributed most of the soil organic matter (45%) in the neighboring Yunxiao mangrove. Phytoplankton was another important source of organic matter, accounting for about 21.8% and 49.8% of the particulate and soil organic matter, respectively. Sewage was also a major source of dissolved inorganic nitrogen, providing 28.9%, 12.2%, and 100% of the total NO₃⁻, NO₂⁻, and NH₄⁺ in the Zhangjiang estuary, respectively. This may be the major reason for the productive phytoplankton here, which contributed 21.8% and 49.8% of the total particulate and soil organic matter in the study area. Our results reveal the direct contribution and the potential effects of sewage on the contents and bioavailability of organic matter in mangrove–estuary ecosystems, providing new insights into understanding the response of coastal areas to the influence of human activities.

The decomposition of mangrove litter plays a crucial role in material circulation and energy flow within mangrove forests. Evaluating the decomposition-based variation in biogenic elements in litter is important for improving our understanding about their biogeochemical cycling in ecosystems. The main objective of this study was to examine the interaction effect during the decomposition process of mixed Kandelia obovata and Avicennia marina litter. Variations in C and N were also determined in the decomposing leaf litter mixtures. Our findings revealed that the decomposition rates were faster in summer than in winter, and increased with the proportion of A. marina litter. After 35 days of decomposition in summer, the remaining weights for different proportions of K. obovata (KO) and A. marina (AM) were 22.9% (KO:AM = 1:2), 27.2% (KO:AM = 1:1), and 31.2% (KO:AM = 2:1), respectively. Similarly, after 49 days of decomposition in winter, the remaining weights for the different KO:AM proportions were 27.7%, 35.4%, and 44.0%, respectively. Additionally, the decomposition of mixed K. obovata and A. marina litter had an influence on C content and N release dynamics. These results provide a scientific basis for understanding the decomposition of mixed mangrove litter and its implications for material circulation and energy flow within these ecosystems.

In this study, grey system theory is applied through the implementation of GM(1,1) modelling and Grey Relational Analysis (GRA) to forecast and evaluate sturgeon aquaculture production dynamics in Guizhou Province. The results demonstrate a marked temporal dependency in predictive efficacy, with GM(1,1) exhibiting a superior short-term forecasting performance that progressively diminishes with temporal extension. Utilizing 2018–2022 observational data, the GM(1,1) framework achieved Grade 2 precision (mean absolute percentage error, MAPE = 4.172%; 1% <$\overline{ ∆k}$ ≤ 5%), projecting sustained annual production growth. The decade-long forecast (2023–2032) yielded the following production estimates (×10³ tons): 32.3, 39.1, 47.3, 57.2, 69.2, 83.7, 101.2, 122.4, 148.1, and 179.2. GRA identified three principal determinants: the aquatic seed production value (X₉, r = 0.8336), freshwater fishery output (X₂, r = 0.8019), and per capita fisher income (X₅, r = 0.8003). Furthermore, technological promotion funding (X₆) and fishery workforce parameters (X₄), while demonstrating weaker correlations (r < 0.75), maintain critical roles in technological advancement and labour competency enhancement. This methodological framework provides empirical support for sustainable development strategies in Guizhou’s sturgeon aquaculture sector, emphasizing the necessity of temporal-scale considerations and multifactorial optimization in production management.

Estuary ecosystems serve as crucial connectors between terrestrial and marine environments, thus playing vital roles in maintaining the ecological balance of coastal marine ecosystems. In recent years, the eutrophication in estuaries caused by aquaculture sewage has been revealed, highlighting the necessity to understand its influence on the nutrient conditions and carbon storage of estuaries. In this study, δ¹⁵N and δ¹⁸O were used to indicate the contribution of aquaculture-derived sewage to dissolved inorganic nitrogen in Zhangjiang Estuary, and δ¹³C and C:N ratio were used to reveal its effects on the particulate organic matter. The major results are as follows: (1) Aquaculture water contributed 62~86% and 60~100% of the total nitrate and ammonium in Zhangjiang Estuary, respectively, and the drainage periods of the cultured species has a great influence on the content and composition of dissolved inorganic nitrogen. (2) Aquaculture water was also the major source of particulate organic matter (24~33% of the total content) here, most of which may be derived from crab ponds. (3) The imports of nutrients by aquaculture water may potentially regulate particulate organic matter in Zhangjiang Estuary by promoting the growth of phytoplankton and zooplankton. Our study revealed the coupling effects of aquaculture activities on the nitrogen and carbon storage in an estuarine ecosystem. It also indicates that isotopes may be efficient in the monitoring of a coastal environment, which may further aid the management of inshore cultivation.

Mangroves are characterized by high productivity, thus playing crucial roles in combating global climate change. In recent decades, the invasion of Spartina alterniflora has led to significant degradation of mangrove vegetation. Currently, the main restoration measure for such damaged mangroves is to remove the invasive S. alterniflora. Furthermore, monitoring of S. alterniflora regeneration after restoration is also of great significance. In this study, an indicator of the presence of S. alterniflora in the soil was measured using a stable isotopic mixing model and further used to predict the potential regeneration of S. alterniflora in the natural Zhangjiang Estuary mangrove forest and the artificially planted Quanzhou Bay mangrove forest. The key findings are as follows: (1) The regeneration of S. alterniflora was observed in the Quanzhou Bay mangrove forest after observing an increased indication of its underground biomass (from 2.5% to 10.6%). This was not observed in the Zhangjiang Estuary mangrove forest, indicating its higher resistance against S. alterniflora regeneration. (2) The removal of S. alterniflora affected the diversity of the soil microbes, possibly by regulating the available organic matter, thus further altering the levels of S. alterniflora regeneration after restoration. (3) The higher functional redundancy and co-occurrence of soil microbes in the natural ZJE mangrove forest may be one major reason for its higher resistance to S. alterniflora invasion/regeneration. This study reveals potential effects of soil microbial communities on the stability of mangrove wetlands, which may provide new insights for future research on mangrove restoration programs.