ABSTRACT
The most fundamental contrast within the biosphere is that between the environmental conditions and associated organisms of terrestrial and aquatic ecosystems. While the net primary productivity of aquatic ecosystems is only about half that from the land, aquatic animal production is over 3.5 times that from the land. Red and ultraviolet light are absorbed in the upper layers of clear ocean water; blue-green light penetrates to greatest depths. While the distribution of species of aquatic plants and animals is determined by their adaptation to salinity, that of primary productivity is influenced more by the nutrient status of the water. The efficiency of this form may well explain the overwhelming dominance of plant life by the phytoplankton in aquatic ecosystems. The majority of the aquatic herbivores are among the smallest of aquatic animals, of a size capable of capturing and ingesting phytoplankton efficiency.
