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2. A natural or human-caused event that changes a biological community and usually removes organisms from it. Disturbances, such as fires and storms, play a pivotal role in structuring many communities.
4. A narrow stratum of abrupt temperature change in the ocean and in many temperate-zone lakes.
6. Nonliving; referring to the physical and chemical properties of an environment.
8. The open-water component of aquatic biomes.
10. The part of an ocean or lake beneath the photic zone, where light does not penetrate sufficiently for photosynthesis to occur.
13. A plot of the temperature and precipitation in a particular region.
15. The bottom surface of an aquatic environment.
16. The communities of organisms living in the benthic zone of an aquatic biome.
17. The uppermost layer of vegetation in a terrestrial biome.

1. The study of how organisms interact with each other and their environment.
3. The part of the ocean’s benthic zone between 2,000 and 6,000 m deep.
4. The mixing of waters as a result of changing water-temperature profiles in a lake.
5. Pertaining to the living factors—the organisms—in an environment.
7. The long-term prevailing weather conditions at a given place.
9. The transition from one type of habitat or ecosystem to another, such as the transition from a forest to a grassland.
11. The narrow top layer of an ocean or lake, where light penetrates sufficiently for photosynthesis to occur.
12. Dead organic matter.
14. Climate patterns on a very fine scale, such as the specific climatic conditions underneath a log.