Compared with other coral reef models, although the total biomass of the QICR ecosystem is relatively reduced, its total efficiency and total catch are higher than those reported by other models, indicating that the fishery resource exploitation efficiency in the study area is higher. In general, differences in ecosystem type influence ecological characteristics (
Heymans et al., 2011), however, TLc can indicate major differences in fishery protection between ecosystems (
Albouy et al., 2010). The TLc of the QICR model (2.62) is significantly lower than that for coral reefs in the Caribbean Sea (Cayos Cochinos Islands and Media Luna Archipelago), Galapagos Islands (Darwin and Wolf Islands), and Uvea Atoll, while those for Hawaii Island (2.59) and Nanwan Bay (2.40) are relatively close. According to the results of Nanwan Bay model,
Liu et al. (2009) suggests an overfished status would lead to the mean trophic level of the catch, matter cycling, and trophic transfer efficiency are extremely reduced. In addition, given that coral reefs are often overfished (
Mumby et al., 2006), climate change induced degradation will limit the ability of coral reefs to exert its ecosystem functions (
Dove et al., 2020). The reasons that TLc of the QICR model is also lower than values from the northern SCS (2.93) (
Chen and Qiu, 2010) are possibly that the combined effects of climate change (
Alva-Basurto and Arias-González, 2014) and fishing activities (
Pauly et al., 1998) have down the food web. On the one hand, climate change is a big one that one of the most important threats facing coral reefs on a global scale (
Lough, 2011), ocean acidification and ocean warming are two climate-related impacts to coral reefs. If large amounts of anthropogenic CO
2 from the atmosphere are dissolved in seawater that would causes the lowering of the ocean’s pH (ocean acidification) (
Hoegh-Guldberg et al., 2007). And ocean acidification reduces the calcium carbonate in the seawater, making it difficult for corals to form skeletons (
Anthony et al., 2008). The results of
Eyre et al. (
2018) showed that under the action of ocean acidification, it is expected that by circa 2050 CE, reef sediments globally will transition from net precipitation to net dissolution. In addition, ocean warming water caused by global warming would prompt corals to release the zooxanthellae, and then make corals experience different degrees of bleaching (
Gates, 1990), all of which would eventually lead to large-scale death of corals and the degradation of coral reef ecosystem (
Cook et al., 1990). According to the
Status of Coral Reefs of the World: 2020 report produced by the Global Coral Reef Monitoring Network, the total amount of corals in the world’s coral reefs gradually declined by 14% since 2009, which is more than all the coral currently living on Australia’s coral reefs. There are evidences that sea surface temperatures in the SCS increased in the last several decades since the middle of the twentieth century (
Jiao et al., 2015). On the other hand, “Fishing down the food web” refers to the decreasing of the catch size due to the depletion of previous catch size (
Pauly et al., 1998;
Pauly and Palomares, 2005), for example, excessive artisanal fishing pressure may be the main hindrance to develop ecosystem quality in the shelf slope area (
Karim et al., 2019). Except for overfishing, destructive fishing such as cyanide fishing and blast fishing are often considered one of the most destructive human activities on coral reef ecosystems (
Fox and Caldwell, 2006;
Mak et al., 2005). Of the more than 1 000 species of coral reef fish assessed by the International Union for Conservation of Nature, 8% of them are threatened with extinction (
Hixon and Randall, 2019). Consequently, anthropogenic activities can indirectly and/or directly act to homogenize and simplify ecosystems, by the climate change and fishing activities that aforementioned discussions, artificially favoring stress-tolerant species and forcing the ecosystem into an earlier successional state (
Williams et al., 2015).