International Journal of Molecular Ecology and Conservation, 2025, Vol.15, No.4, 163-174 http://ecoevopublisher.com/index.php/ijmec 1 67 However, even after the whale bones have almost completely decomposed, there may still be mineralized bone fragments slightly above the seabed left, serving as "micro-reefs" to continue providing habitats for deep-sea creatures until they are eventually buried by sediments or completely decomposed. The oligotrophic stage marks the end of a whale's life cycle, with energy output approaching its conclusion, but its impact on deep-sea organisms may persist for many years. Some researchers speculate that during the history of frequent whaling, a large number of whale bones sank to the seabed and might have continuously provided a hard substrate habitat for the deep sea, which to some extent connected the deep-sea sedimentary environment with the reef environment (Smith et al., 2019). 4 The Driving Mechanisms of Community Succession 4.1 Nutrient decomposition and material circulation Whale fall ecological succession is initially driven by huge nutrient pulses. The high amount of organic matter carried by whale carcasses is a huge energy input for the deep sea, and its rapid decomposition and circulation affect every stage of community dynamics. During the meat accumulation stage, large scavengers convert the organic matter in the whale body into their own biomass and metabolic products by consuming whale meat. Some nutrients are deposited in the form of feces and debris and enriched in the local environment (Zhou et al., 2020). Subsequently, in the opportunistic stage, small benthic invertebrates consume a large amount of organic debris and decays in the sediment, accelerating the mineralization and burial of organic matter (Li et al., 2022). At the chemoenergetic stage, the material cycle mode changes from direct decomposition to chemical synthesis: anaerobic bacteria decompose whalbonite lipids to produce H_2S, etc. Reducing compounds are utilized by chemoenergetic autotrophic bacteria to fix inorganic carbon into organic matter, which is then consumed by higher-level consumers, achieving a unique chemoenergetic food chain (Silva et al., 2021). Therefore, whale fall has established a combined cycle system of "heterotrophic and autotrophic". This cycle greatly enhances the local productivity of the deep sea, causing a "short circuit" in the deep-sea carbon cycle - a large amount of carbon rapidly settles and is permanently stored in deep-sea biomass and sedimentary reservoirs (Tulloch et al., 2018; Li et al., 2022; Pearson et al., 2023). 4.2 The fundamental role of microbial communities in ecological succession Microorganisms are the fundamental driving force of the material cycle in whale landing and play a key role at each stage. During the meat accumulation and opportunistic stages, aerobic heterotrophic bacteria multiply in large numbers on the surface of whale meat and in eutrophic deposits, accelerating the decomposition and spoilage of organic matter. These bacteria not only directly degrade complex organic matter, but also provide delicious bacterial membranes and residues for subsequent consumers (such as small worms, crustaceans), thereby promoting the forward development of community succession (Li et al., 2022). As the sedimentary environment tends to be anaerobic, a series of anaerobic microorganisms and chemoautotrophic bacteria make their appearance in the chemoenergy stage. In addition, microorganisms further participate in community building by symbiosis with animals. For example, the Gram-negative heterotrophic bacteria symbiotic in the bone-eating worm Osedax can assist it in dissolving whale bones to obtain nutrients (Shimabukuro and Sumida, 2019); Chemoautotrophic bacteria symbiotic to the gills of mussels and clams provide the main source of nutrition for the hosts (Silva et al., 2021). These symbiotic relationships enable the invertebrates on the whale landing to fully utilize the microbial products to thrive. The succession of microbial communities is closely linked to the changes in the whale landing environment. For instance, in whale fall sediments, heterotrophic bacteria such as Bacteroidetes and Firmicutes dominated in the early stage of eutrophication, while sulfur-oxidizing bacterial communities such as Campylobacteria emerged with the increase of H_2S (Li et al., 2022). 4.3 Interspecies interactions (Competition, Symbiosis, predation) The dynamic succession of whale fall communities is accompanied by rich interspecific interactions, including competition, symbiosis and predation, etc. Competition: In nutrient-rich whale landing environments, different species may compete for the same resources. Predation: The predation relationship runs through all stages of a
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