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Macrobenthic bioturbation affects the environment, and variances in habitat, such as decreased dissolved oxygen concentration and increased ammonia concentration, affects the macrobenthic community. The relationship between macrobenthos and habitat factors may be a mutually causal relationship. The bottom-sowing culture for Manila clam Ruditapes philippinarum in many coastal countries plays an important role in coastal fisheries, and the relationship between Manila clam and other macrobenthos affects the ecological stability of the bottom-sowing culture zone. It is necessary to explore the relationship between them to manage the waters used for the bottom-sowing culture for Manila clam. In this study , from June to October 2021, the field investigation on macrobenthos including Manila clam and their habitat factors, such as particle size, nutrient content, redox potential, and organic matter content, in 21 experimental communities enclosed by bolting-silk net in Shuangdao Bay, Weihai, Shandong, China was conducted, during which macrobenthos functional groups were determined by feed sources and motor behavior. The results showed that Manila clam biomass was 7.215±0.984 g/m2 (calculated by dry soft tissue weight), and it was positively correlated with the biomass of macrobebthos functional groups B1, G1 and P1; water content in sediment; sulfide content in interstitial water; the Shanon-Wiener diversity index; Pielou’s evenness index and the W statistic of the ABC (Abundance-Biomass Comparison) curve (p< 0.05). Moreover, it was negatively correlated with sediment particulate size and HCl-NO3 content in sediment (p< 0.05). The action of Manila clam to habitats was the dominant role of the interaction between clam and habitat. Thus, the bottom-sowing culture for Manila clam does not decrease the macrobenthic community stability, and the invasion of other macrobenthos into the bottom-sowing culture zones for Manila clam may be accidental or inevitable. The results of our study suggest that the management of the bottom-sowing culture for Manila clam should be conducted from ecosystem level; i.e., fishing and aquaculture in the same waters are regarded as two components of an ecosystem; manage them together, rather than treat them separately.

The waves caused by typhoons pose a serious threat to offshore production activities, especially the sheltering ability of fishing ports. Numerical models are of great importance to forecast the waves generated by typhoons. In this study, the MIKE21 spectral wave model was combined with the Holland wind field model to simulate the wave characteristics of Kanmen Fishing Port (KFP) under the influence of the typhoon Lekima, and the berthing capacity of KFP was evaluated. The results showed that calculated significant wave height and wind speed were in good agreement with the observations, and the d trend evaluation considered the model performance to be excellent. The model results showed that the significant wave height near KFP was remarkably affected by the typhoon Lekima and the maximum significant wave height in the fishing port exceeded 2 m. When the typhoon Lekima was passing, the KFP with a total area of 3.92 km2 lost 45.2% of its berthing area, and 54.8% of the fishing port's permitted berthing area can only berth 1,348 vessels. When the typhoon was at level 16 (wind speed 52 m/s), 102 small-sized fishing vessels or 72 medium-sized fishing vessels or 44 large-sized fishing vessels would have no place to stay with each additional level (wind speed increased by 5 m/s).

The degradation of salt marsh plants due to human activities has accelerated in recent years, and this has decreased the ecological service functions of estuary wetlands and contributed to global climate change. In the threatened Red Beach area within the Liao River Estuary Wetland (LREW) of China, the factors that dominantly affect the distribution of salt marsh plants at large scale are unknown. Here, we used field observations and numerical simulation to identify factors influencing waterlogging stress and its role in the distribution of salt marsh plants (Suaeda heteroptera) in the LREW. Remote sensing image interpretation was then used to validate the results of the numerical simulation. Based on our field observations, the density of salt marsh plant communities may be highly sensitive to waterlogging. A hydrodynamic model was then used to reproduce the waterlogging distribution of the LREW. The distribution of the salt marsh plants was indirectly simulated by referencing the relationship between plant density responses to waterlogging. The simulation method proved consistent with remote sensing results. Our results show that the plant communities investigated here exhibited clear differences in density and inhabited environments based on waterlogging and soil salinity characteristics. S. heteroptera in the LREW can grow with 1.56–2.87 h/d of waterlogging. Our numerical model again confirmed this range and was consistent with field survey results. Based on these observations, drought tolerance and inundation tolerance determined the upper and lower boundaries of S. heteroptera distribution, respectively. Differences in waterlogging regimes that are suitable for growth resulted in a strip-shaped distribution of the salt marsh plants. Given the diverse threats posed by changing estuaries and coasts, our study provides a methodological framework for evaluating the distributions of salt marsh plants, in addition to baseline data to inform the protection and restoration of wetland plants.