Course Code: BIO308
Course Title: Habitat Ecology
Question: Discuss the distinguishing features that make the aquatic environment unique compared to the terrestrial one.
A habitat is defined as the physical and living surroundings of a species. There are two broad divisions of habitats. These are the:
• Terrestrial comprising the land and the atmosphere above it and the
• Aquatic this can be marine (salt water) and fresh water. However, a third component, which is an intermediary between the two, the brackish water, can also be considered. The marine environment has a high salinity, thus, up it about 34‰ with an example being the sea water. On the other hand, fresh water has a maximum salinity of 0.5‰ and examples include: lakes, streams and rivers. Brackish water’s salinity ranges between 0.5‰ -34‰. A typical example is the estuarine water body, whose salinity, though remains in that range, changes, depends on the relative amount of sea or fresh water flowing into it at a particular point in time.
Compared to the terrestrial environment, the aquatic environment is unique by virtue of the various features distinguishing it. Below is a discussion of some of these features.
Ricki Lewis in his work “Life” third edition stated that: “water saturated with oxygen contains only about one-thirtieth of the oxygen present in an equal volume of air, and the warmer or saltier the water, the less oxygen is present. Furthermore, oxygen takes about 300,000 times longer to replenish through water than air, so it takes longer to replenish oxygen used for cellular respiration.” This means that, to obtain the same amount of oxygen, an aquatic organism needs special structures, gill, and must have a lot greater volume of water pass over the respiratory surface than the volume of air for terrestrial dwellers. Again, because water is more dense and viscous than air, an aquatic dweller must use more energy to keep oxygen-rich water...