r-strategy species	Species characterised by small body size, rapidly growing populations, high rates of dispersal, a single reproductive event, a high birthrate, and short generation time.
recruitment	The incorporation of young individuals to the adult population.
redox potential	This potential of a solution is a measure of the proportion of oxidized to reduced substances. In practice, the redox potential is measured in respect of a platinum electrode and is called the Eh. If electrons flow from the solution to the electrode, reducing conditions are said to exist in the solution and the potential (measured in volts) existing between the electrode and the solution. Oxidizing conditions are said to exist in the solution when electrons flow from the electrode to the solution and the voltage is given a positive sign.
reflectivity	The amount of light and energy that bounces off a surface relative to the amount of light and energy that struck the surface. A mirror is an example of an object with high reflectivity. The ocean has low reflectivity (also called Albedo).
remote sensing	The gathering of information from an object or surface without direct contact.
reproduction	The process of producing offspring. Sexual and asexual reproduction
reptile	Any of the cold-blooded vertebrates characterised by lungs, an outer covering of horny scales or plates, and young produced in eggs e.g, turtles, lizards, crocodiles, snakes.
respiration	1. The process in living organisms of taking in oxygen from the surroundings and giving out carbon dioxide 2. The chemical breakdown of complex organic substances that takes place in the cells and tissues of animals and plants, during which energy is released and carbon dioxide produced.
respiratory pigment	A molecule able to bind and transport oxygen efficiently, usually in a circulatory system.
restoration	Bringing to a former (often better) state
runoff	Water flowing across the land surface. It also refers to the water leaving an area of drainage. Also called overland flow.