This document provides an overview of key concepts in ecology, including: - Ecosystems are made up of biotic (living) and abiotic (non-living) factors that interact in complex ways. Nutrients cycle through ecosystems via producers, consumers, and decomposers. - Ecological pyramids illustrate the transfer of energy and biomass between trophic levels in an ecosystem, with higher levels containing fewer and smaller organisms due to energy losses between levels. - Symbiotic relationships between species include mutualism, commensalism, and parasitism, with examples like cleaner fish and anemone crabs demonstrating mutualism.

20. Interactions in Ecosystems Activity Using the food web on the right, predict what might happen if a disease killed all the krill in the ecosystem. Which species would be affected, and how? Try drawing a new food web. 2 CHAPTER

25. ILLUSTATIVE EXAMPLES

40. Sample Energy Pyramid