Mereelustikku

Mereelustikku is a Finnish term that refers to the marine biota—the total assemblage of living organisms in marine environments. It encompasses organisms across all taxonomic levels, from microorganisms to large mammals, and includes life in both pelagic and benthic zones of the sea.

In practice, mereelustikku covers primary producers such as phytoplankton and macroalgae, as well as consumers including zooplankton, fish, crustaceans, mollusks, and echinoderms. It also includes decomposers such as bacteria and fungi that play critical roles in nutrient recycling. The concept therefore spans a wide range of biological diversity and functional roles within marine ecosystems.

Habitats for mereelustikku are diverse, ranging from coastal environments like seagrass beds, kelp forests, and coral reefs to the open ocean and deep-sea habitats. The composition and distribution of marine life vary with depth, salinity, temperature, oxygen levels, and the availability of food. Regional differences reflect local oceanography, productivity, and habitat structure, yet many core processes, such as photosynthesis, predation, and decomposition, are shared across systems.

Ecologically, mereelustikku underpins energy flow, trophic dynamics, and nutrient cycling in the sea. It influences carbon sequestration, supports fisheries and other human livelihoods, and contributes to the overall resilience of marine ecosystems to change. Understanding its structure and function is essential for assessing ecosystem services and planning conservation.

Threats to mereelustikku include overfishing, pollution, habitat destruction, invasive species, and climate change, which alter species composition and ecosystem processes. Research methods range from traditional taxonomy and ecological surveys to modern approaches such as environmental DNA (eDNA) analysis and remote sensing, often guiding management and protection through marine protected areas and sustainable practices.