| A | B |
|---|
| Limnetic zone | The well-lit, open surface waters of a lake farther from shore. |
| Mesotrophic | Lakes with moderate amounts of nutrients and phytoplankton productivity intermediate to oligotrophic and eutrophic systems. |
| Microclimate | Very fine scale variations of climate. |
| Neritic zone | The shallow regions of the ocean. |
| Oceanic zone | The region of water lying over deep areas beyond the contineental shelf. |
| Oligotrophic lake | A nutrient-poor, clean, deep lake with minimum phytoplankton. |
| Pelagic zone | The areas of open water in the ocean often reaching to very great depths. |
| Permafrost | A permanently frozen stratum below the artic tundra. |
| Photic zone | The narrow top slice of the ocean, where light permeates sufficiently for photosynthesis to occur. |
| Population | A group of individuals of one species that live in a particular geographic area. |
| Precautionary Principle | A guiding principle in making decisions about the environment. |
| Profundal zone | The deep aphotic region of a lake. |
| Thermocline | A narrow stratum of rapid temperature change in the ocean and in many temperature-zone lakes. |
| Tropics | Latitudes between 23.5 degrees north and south. |
| Turnover | The mixing of waters as a result of changing water-temperature profiles in a lake. |
| Wetland | An ecosystem intermediate between an aquatic one and a terrestrial one, soil may often be saturated with water. |
