The document discusses the marine ecosystem and its various components. It describes the pelagic and benthic divisions of the marine environment. The pelagic division includes the neritic and oceanic zones, while the benthic division encompasses the littoral and deep-sea systems. It also discusses the five major kingdoms found in the ocean - Monera, Protista, Fungi, Metaphyta and Metazoa. Additionally, it examines the key components of the marine ecosystem including plankton organisms, zooplankton, nekton community, benthos organisms, coral reefs and mangrove swamps. Finally, it outlines some problems facing marine ecosystems such as natural and