ABSTRACT
Ecology is the study of interactions between organisms, and between organisms and their environments. The Greek root of the term ecology (oikos = a house; logos = discourse) applies very well to terrestrial ecosystems, because although dispersal and migration are inherent, a large part of their components (e.g. trees, bushes, grass) do not move around (hence house). In contrast, oceanic ecosystems are literally fluid; a large portion of the biota is microscopic and suspended (= plankton) in water, and therefore governed by its properties. In all ecosystems, most of the energy follows two lines: grazing foodchains (animals eat plants; carnivores count for little) and detritus foodchains (small animals, fungi and bacteria eat anything dead, returning nutrients to the environment). On land, movement of matter and energy generally operate locally; but in the sea, the mobile nature of marine ecosystems, and the huge scale of ocean volume, mean that the larger transport distances of ecosystem components are a critical aspect of their operation. Habitats on land are easy to picture, because you can walk amongst and touch them. In the sea, much is microscopic, and everything lies out of sight beneath the waves in a 3D space so large that appreciating the processes is more difficult.
