Lesson 21: Marine Ecosystems Marine Ecology

1. Lesson 21: Marine Ecosystems Marine Ecology

2. Life in the marine environment • We’ve learned a lot about the biology of different types of marine organisms • In marine science, it is important to understand why these creatures live where they do and how they interact with their environment • Today we will learn about marine ecology: the study of the relationship of marine organisms with each other and with the environment

3. Life in the marine environment • The ocean can be divided into zones based on depth (vertically) and distance from land (horizontally) • Different zones of the ocean have conditions that support different organisms • What is an ecosystem? • An ecosystem is a physically distinct area that contains a community of interacting organisms

4. Ocean zones and continental margins • Many ocean zones are defined based on continental margins. • To help you understand ocean zones, let’s first review continental Margins: • Continental Margin: Submerged area of continents. Include: • Continental Shelf (flat gradually sloping seafloor) from shoreline to ~ 200m; End of Shelf is called the Shelf Break • Continental Slope (steeply sloping seafloor) seaward of shelf break • Continental Rise (Moderately sloping seafloor) seaward of slope

5. Pelagic and benthic zones Photos: NOAA • One simple ocean zone classification is between the water and the ocean floor • The water is referred to as the pelagic zone • Organisms that swim through the water column are known as nekton • The ocean floor is referred to as the benthic zone • Organisms that live here are benthic organisms or benthos Shark: Pelagic (nekton) Crab: Benthic (benthos)

6. Pelagic and benthic zone divisions

7. Pelagic and benthic zone divisions high tide 200m Low tide epipelagic 1,000m Littoral mesopelagic Bathyl 4,000m bathylpelagic Pelagiczone Benthic zone Abyssal 6,000m abyssalpelagic hadalpelagic Hadal

8. Species evolve traits that help them survive in their environment • Species in different environments may evolve different lifestyles, behaviors and physical traits • Do you remember a few ways that intertidal organisms are adapted to their relatively harsh environment? • Species usually are not completely isolated from one another, but interact with other species that live in a shared environment

9. Coral Reef Beach Intertidal (Splash zone) What is an ecosystem? • Populations of different species interacting with one another in a shared environment form a community • An ecosystem is a distinct physical entity with unique abiotic (nonliving) conditions that is home to a community of interacting species • Can you think of some marine ecosystems you have learned about in earlier lessons, classes or elsewhere?

10. Energy is transferred through ecosystems Secondary consumers eat primary consumers to get energy Solar energy is converted to chemical energy by autotrophs Primary consumers eat primary producers to get energy Photos: NOAA

11. Life in ecosystems is interconnected • As you’ve probably already realized, the marine environment consists of many distinct ecosystems that contain unique organisms • How do you think life within ecosystems is interconnected? • Marine organisms form relationships with one another and share space and resources • As a result, an impact on a single species in an ecosystem can affect many other species in the same ecosystem

12. It is important to manage our natural resources in a way that reflects the interconnectedness of ecosystems and their components Ecosystem-based management (EBM) is a management approach that includes these interactions instead of considering single species or single issues at a time NOAA applies EBM in its management of marine resources Important interactions Photo: NOAA Management of ecosystems, like this bleached coral reef, requires looking beyond just the coral itself. Other important factors to study might include pollution, development, watershed management and interactions with other species.

13. Student activity: Ecosystem case study on an estuary • An estuary is a body of water that forms where freshwater from rivers and streams flows into the ocean and mixes with seawater to form a unique and productive ecosystem • One of our nation’s most valued ecosystems, the Chesapeake Bay, is an estuary • In fact, it is one of the largest estuaries in the world • In today’s exercise, you will analyze data about the blue crab to make inferences about the health of the Chesapeake Bay ecosystem