Interactions in Ecosystems2CHAPTEREcosystems are made up of living things (biotic factors) and non-living things (abiotic factors), which are connected to each other in complex interrelationships.

Nutrients are cycled within an ecosystem. producers consumers decomposers producers

Interactions in EcosystemsEnergy flows through ecosystems. This energy comes from an outside source: the Sun.

Ecologists represent food and energy flows in food chain, food web, and pyramid diagrams.2CHAPTER

Interactions in EcosystemsActivityUsing 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.

You can find more information on food chains and webs on pages 3436 in the student book.2CHAPTER

Interactions in Ecosystems2Key IdeasLiving things are connected to each other in complex interrelationships.

Biotic and abiotic factors are responsible for shaping a community of living things.

Nutrients cycle within ecosystems.

Energy flows through ecosystems.CHAPTER

An ecosystem is made up of a community of organisms and the non-living environment.

The living components of the ecosystem are called biotic factors, which include plants, fish, invertebrates, and single-celled organisms.The non-living components, or abiotic factors, include the physical and chemical components in the environmenttemperature, wind, water, sunlight, and oxygen.Biotic and abiotic factors influence each other in an always changing balance called dynamic equilibrium.Biotic and Abiotic Factors in Ecosystems2.1VOCABULARYecologyorganismhabitatpopulationcommunityecosystembiospherebiotic factorabiotic factordynamic equilibriumlimiting factor

Ecological Roles and Relationships2.2VOCABULARYnutrientsproducerautotrophphytoplanktonconsumerheterotrophherbivoresprimary consumerzooplanktoncarnivoreomnivoredetrivoredecomposerbiodegradationpredationpredatorpreypredatorprey cycleAn ecosystem is a complex network of interactions.All organisms must take in water, food, and nutrients. Nutrients are elements and compounds that organisms need to live and grow.Organisms can be producers, consumers, herbivores, carnivores, or decomposers in ecosystems.Eventually nutrients cycle back into the ecosystem for the producers.

Symbiosis2.3VOCABULARYsymbiosismutualismcommensalismparasitismhostparasite

Symbiosis refers to any close relationship between two different species. There are three types of symbiotic relationships:

Mutualism is a relationship in which both species obtain some benefit from the interaction.

Commensalism is an interaction in which one organism benefits while the other is unaffected.

Parasitism occurs when one organism (the parasite) lives and feeds on, or in, the body of another organism (the host).