Biodegradation of Carcasses in Aquatic Biocoenoses

Drowning represents one of the most frequent causes of accidental death; however, many submerged remains remain unrecovered or unidentified due to the challenges associated with aquatic decomposition. This process differs substantially from decomposition on land and is influenced by a complex array of factors, including temperature, oxygen availability, depth, and the presence of necrophagous organisms. In aquatic environments, decomposition follows a nonlinear trajectory and can be either slowed — under hypoxic conditions or at low temperatures — or accelerated by the activity of scavenging organisms. In marine ecosystems, key contributors to soft tissue degradation include crustaceans (such as crabs, shrimp, and lobsters), fish, and other invertebrates (e.g., polychaete worms and mollusks). Their activity leads to rapid skeletonization. Subsequently, the remains are colonized by fouling organisms (including barnacles and bivalves) and undergo bioerosion by specialized species such as the bone-devouring worms of the genus Osedax. In freshwater environments, the main participants in the process are leeches, flatworms, insects, and crustaceans. Their sequential succession ensures complete recycling of organic material. The rate of decomposition is highly variable, ranging from several days to several months, complicating the estimation of the postmortem submersion interval. Biological indicators, such as the developmental stage of barnacles, are used to address this challenge.