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The biological and ecological integrity of marine ecosystems in the Pearl River Estuary (PRE) has been compromised due to overfishing and water pollution. Fishing moratorium and artificial reef construction have been implemented in Wanshan and Miaowan for resource protection and restoration. Therefore, food web structure and trophic pathways of Wanshan, Miaowan, and Wailingding in different temporal and spatial situation will be determined using the Ecopath model, as well as the keystone species affecting these ecosystems, which can provide a basis for fishery management. The results showed that the energy transfer efficiency of IV and V trophic levels (TL) was higher than that of II and III‐TL before and after fishing moratorium, and the energy transfer efficiency of artificial reefs II and III‐TL was only slightly higher than that of nonartificial reefs in Wanshan. In addition, the mean values of ecosystem property indicators (consumption, respiration flow, total system throughput, and total biomass) after the fishing moratorium were significantly higher than those before the fishing moratorium. The average value of the ecosystem attribute indicators (consumption, respiration flow, total system throughput, and total biomass) of artificial reefs is lower than those of nonartificial reef areas, which may be related to the differences in community composition between artificial reefs and non‐artificial reefs. Finally, Nemipterus japonicus and Gastrophysus spadiceus are keystone species that distinguish the Wanshan and Miaowan artificial reefs from other areas. Overall, the fishing moratorium has a positive effect on the short‐term restoration of fishery resources, mainly restoring short‐life cycle organisms. However, the construction of artificial reefs will be more conducive to the persistence of ecosystem restoration. In addition, reasonable proliferation, release and fishing of N. japonicus and G. spadiceus will be beneficial to the sustainable utilization of fishery resources. [ABSTRACT FROM AUTHOR]

• High connection between pelagic and benthic origin both in Wanshan Island and Wailingding Island with shallow waters. • Both fishes and macroinvertebrates are largely fueled by pelagic production in Wanshan Island. • Key environmental factors influencing the isotopic niches of fishes and macroinvertebrates were identified. Artificial reefs are frequently deployed in marine ecosystems to increase fishery yields and enhance the production of reef-associated fauna. However, information regarding trophic structures and pathways of faunal assemblages in artificial reef ecosystems in Pearl River Estuary were still in scare. To this end, we compared the abundances and isotopes of functional groups of fishes and macroinvertebrates in three offshore islands, including Wanshan Island with shallow artificial reefs, Miaowan Island with deep artificial reefs, and Wailingding Island with no reef. The results showed that high connection between pelagic and benthic origin in Wanshan and Wailingding Islands, with pelagic production dominating in Wanshan Island and benthic production dominating in Wailingding Island, respectively. The δ13C value of fishes was significantly lower in Wanshan Island compared to Miaowan Island and Wailingding Island, whilst the δ 15N value of macroinvertebrates was highest in Miaowan Island. Based on the trophic niches, Wanshan Island displayed higher trophic diversity and lower trophic redundancy in fish assemblages, while Miaowan Island was the same in macroinvertebrate assemblages. In addition, four key environmental indicators (i.e., salinity, pH, phosphate, and chemical oxygen demand) and five key environmental indicators (i.e., depth, dissolved oxygen, chlorophyll a , total phosphate, and transparency) were the best at explaining the niche variation of fishes and macroinvertebrates, respectively. Our findings provide an understanding of ecosystem functioning within and around the artificial reef systems to further enhance effective management. [ABSTRACT FROM AUTHOR]

Artificial reefs (ARs) are a preferred option for managers due to their distinctive hydrodynamic properties, which support a highly productive local ecosystem. However, the hydrodynamics characteristics of ARs in natural marine environments have not been conducted. Being the first to explore the spatiotemporal characteristic of flow fields around ARs along tidal cycles in marine environments, this study redefined the upwelling and downwelling of ARs, based on natural vertical velocities, and separated the upwelling into co-direction upwelling and re-direction upwelling, and the downwelling into co-direction downwelling and re-direction downwelling. This study simulated the flow field in the Wanshan ARs area of the Pearl River Estuary along the tidal cycles using the MIKE3-FM. Numerical simulations revealed that (1) co-direction upwelling and co-direction downwelling were the dominant components of the vertical flow field effects of ARs; (2) the areas sum of upwelling and downwelling were largest in the medium water column, with about 1.6 and 1.03 times as large as the bottom and surface water column, respectively, while the fluxes sum of the upwelling and downwelling were largest in bottom water column, with approximately 1.3 and 2.2 times larger than those in the middle and surface water columns; (3) the area and volume of the upwelling and downwelling gradually decreased along neap-spring tide, exhibited significantly negative correlations with current speeds; while the upwelling flux and downwelling flux gradually increased along neap-spring tide; exhibited a significantly positive correlation with current speed; (4) the effects of tide to upwelling and downwelling of AR are forced by the northward velocity of current speed, the net flux of upwelling and downwelling showed a significant positive correlation with the northward velocity of current speed (r = 0.94). These results could provide a reference for assessing the flow field effect of ARs and a guide for the configuration and management of ARs. • Redefined the upwelling and downwelling of ARs. • Areas and volumes of upwelling and downwelling of ARs decrease along neap-spring tide. • Fluxes of upwelling and downwelling of ARs increase along neap-spring tide. • Net flux of upwelling and downwelling positively correlate with current's v-velocity. [ABSTRACT FROM AUTHOR]

Deployment of artificial reefs (ARs) has become popular technique to create new hard-bottom habitats, increase biodiversity and richness for fisheries. We compared the faunal community structure and food web structure associated with before and after fishing moratorium between ARs and non-ARs in Wanshan Island, Pearl River Estuary using stable isotope techniques. Community composition showed higher differences between ARs and non-ARs. The range of δ13C and δ15N of different functional groups can distinguish the pelagic and benthic trophic pathways of the food web in reef-or-not area before and after fishing moratorium. The isotopic niches of entire faunal, as well as individual functional groups, overlapped less between ARs and non-ARs in Wanshan Island, which makes the isotopic functional indices non-equivalent. The total convex hull area (TA) of ARs was larger than that of non-ARs, indicating that nutrient pathways of ARs were more diverse. Overall, however, these results suggest that trophic structure was convergence between ARs and non-ARs, and differences before and after fishing moratorium, possibly due to seasonal differences. Finally, it was shown that the construction of ARs had a weak effect on the restoration of fishery resources in this area, which might be related to lack of further management, or even similar community composition to non-ARs areas. • The differences in community composition between artificial reef and non-artificial reef. • The value of niche overlap for artificial reef or not (16.14%) was greater than that before and after fishing moratorium (11.73%), indicating that the differentiation of niches was more obvious before and after fishing moratorium. • The analysis of the nutritional contribution of baseline consumers to high trophic consumers revealed that artificial reefs had no significant effect on the acquisition of high trophic prey. However, the implementation of the fishing moratorium resulted in a slight change in the feeding strategy. [ABSTRACT FROM AUTHOR]