The littoral zone is the part of a sea, lake, or river that is close to the shore and extends from the high-water mark to the area where sunlight penetrates to the sediment, allowing aquatic plants to grow. This zone is critical for studying coastal processes, ecosystems, and the impact of human activities on nearshore environments.
Reference: Wetzel, R. G. (2001). “Limnology: Lake and River Ecosystems.” Academic Press.