International Journal of Marine Science, 2025, Vol.15, No.2, 65-74 http://www.aquapublisher.com/index.php/ijms 68 residual toxic substances have long endangered coral polyps and reef organisms, triggering a decline in diversity (Goldberg and Wilkinson, 2004; Madeira et al., 2020). Blast fishing reduces habitat heterogeneity by crushing coral substrates, hinders the recovery process of fish communities, and ultimately weakens their ecological functions (Goldberg and Wilkinson, 2004). Figure 1 Summary schematic demonstrating mean micronutrient (Ca, Mg, Fe, Zn, Mn, Cu) contribution by primary trophic guilds of coral reef fishes in ppm (Adopted from Van Wert et al., 2023) Image caption: To maintain the y-axis scale Ca, Mg, and Fe are represented as fractions of original values by 1000 (Ca) and 100 (Mg and Fe). The benthos is included below to contextualize the approximate quantity of nutrients that may disperse into the water column and land on benthos. Trophic guilds are represented by species within each guild(Adopted from Van Wert et al., 2023) The ecological effects of such destructive activities are exacerbated by the coupling of multiple stress factors. For example, the toxicity of cyanide is magnified under the condition of seawater warming, resulting in a sharp increase in fish mortality and an extended recovery period, and facing a higher risk in the context of climate warming (Madeira et al., 2020). Long-term illegal fishing leads to the loss of key functional groups, reducing the resilience of coral reefs and their ability to support fishery resources (Goldberg and Wilkinson, 2004). 4.2 The chain effect of bleaching driven by climate warming Bleaching events caused by Marine heatwaves are the core indirect threat to coral reef fish. Thermal stress leads to the large-scale death of corals and disintegrates the habitat base of reef-dwelling fish (Goldberg and Wilkinson, 2004; Cinner et al., 2009). The decline in coral coverage reduces structural heterogeneity, resulting in a decrease in fish community abundance and niche diversity (Wilson et al., 2010). Habitat degradation has a particularly significant impact on obligate species that rely on living corals, triggering changes in the composition of functional groups and the absence of key ecological processes. The synergistic effect of climate pressure and illegal fishing has intensified its harm. Cyanide exposure combined with high temperature significantly increases the mortality rate and predation vulnerability of fish, threatening the survival of populations (Madeira et al., 2020). The continuous degradation of coral reefs has led to a significant decline in their ecological service functions such as coastal protection and fishery support (Eddy et al., 2021). 4.3 The Superimposed effect of land-based pollution and tourism development Land-based pollutants (such as nutrient input, sediment deposition and sewage discharge) seriously threaten the health of corals. Pollutants deteriorate water quality, induce algal blooms, increase the risk of coral and fish diseases, and ultimately lead to the decline of biodiversity (Goldberg and Wilkinson, 2004). Tourism infrastructure projects have caused habitat fragmentation and physical damage. Coupled with human interference, the degradation of ecological functions has been exacerbated. Habitat fragmentation disrupts the connectivity of reef areas, hinders the migratory behavior of fish and the cross-regional transmission of energy and matter. Such disturbances form a superimposed effect with pollution and fishing pressure, resulting in the obstruction of core
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