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
Definition adapted from Life on an Ocean Planet, NMEA, Santa Margarita, CA: 2010.

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
Photo: (accessed March 2011).

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)
Teacher’s Note: You can have the students tell you which organism is pelagic and which is benthic. The answers will fly in as you advance the presentation. You might want to remind students here of the difference between plankton and nekton.
Photo credits:
Top: Accessed: November 2010
Bottom: Accessed: November 2010
Crab: Benthic (benthos)

6. Pelagic and benthic zone divisions
Pelagic zone divisions (depth from surface)
Benthic zone divisions
(seafloor zones)
Supralittoral –shore above high tide
Epipelagic (0-200m)
Littoral – the intertidal zone (sometimes submerged and sometimes above water)
Mesopelagic (200-1,000m)
Sublittoral – seafloor of the continental shelf (from low tide to the shelf break)
Bathypelagic (1,000-4,000m)
Bathyl – seafloor of the continental slope to the deep ocean bottom
Abyssopelagic (4,000-6,000m
Abyssal – deep ocean bottom between the base of the slope and 6,000 m
Hadalpelagic (6,000-10,000m)
Hadal – the deepest zone, below 6,000m
Teacher’s Note: Refer your students to the student handout for this lesson for more information on ocean zones.

7. Pelagic and benthic zone divisions
high tide
200m
Low tide
epipelagic
1,000m
Littoral
mesopelagic
Bathyl
4,000m
bathylpelagic
Pelagic zone
Teacher’s Note: Refer your students to the student handout for this lesson for more information on ocean zones.
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
Teacher’s Note:
You may want to encourage students to think back to the lesson on the intertidal zone – what were some traits organisms needed to help them survive in this harsh environment?
Some answers include shells or exoskeletons for protection against crashing waves, mechanisms like tight, sealed shells to retain moisture during tide changes, and suction mechanisms like tube feet to help anchor organisms in place.

9. What is an ecosystem?
Beach
Coral Reef
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?
Intertidal (Splash zone)
Intertidal: Accessed: November 2010
Reef: Accessed: November 2010

10. Energy is transferred through ecosystems
Secondary
consumers eat primary consumers to get energy
Solar energy
is converted to chemical
energy by autotrophs
Teacher’s Note:
This slide gives a simple demonstration of a marine food web with phytoplankon as primary producers (autotrophs), krill as primary consumers and a baleen whale as a secondary consumer. Emphasize that when energy enters the system from the sun – it is never created or destroyed.
Krill: Accessed: November 2010
Whale: Accessed: November 2010
Phytoplankton: Accessed: November 2010
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. Important interactions
Photo: NOAA
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
Photo: NOAA Photo Library
Image ID: reef3097, NOAA's Coral Kingdom Collection Location: Mariana Islands, Guam Photographer: David Burdick
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