9/29/2014

1

Chapter 6Major Ecosystems of the World

Overview of Chapter 6

PART 1

Earth’s Major Biomes

PART 2

Aquatic Ecosystems

Freshwater ecosystems

Estuaries

Marine Ecosystems

Interaction of Life Zones and Humans

Part 2: Aquatic Ecosystems

Fundamental Division:

Saltwater (Marine)

Freshwater

Aquatic ecosystems also affected by

Dissolved oxygen

Light penetration

Water chemistry (pH, salinity, etc.)

Water currents

9/29/2014

2

Aquatic Ecosystems

Three main categories of aquatic organisms

Plankton - free floating

Nekton - strong swimming

Benthos - bottom dwelling

Plankton Nekton Benthos

Freshwater Ecosystems

Include:

Rivers and streams

Lakes and ponds

Marshes and swamps

Represent 2% of earth’s surface

Assist in recycling water back to the oceans

Rivers and Streams

9/29/2014

3

Lakes and Ponds

Body of freshwater that does not flow

Three zones

Littoral

Limnetic

Profundal

Experience thermal stratification (depending on depth)

Lakes and Ponds

Littoral Zone - shallow water area along the shore

Limnetic Zone - open water beyond the littoral zone

Profundal Zone - beneath the limnetic zone of deep lakes

Lakes and Ponds

Littoral ZoneLimnetic Zone

9/29/2014

4

Thermal Stratification

Temperature changes sharply with depth

Thermocline

Temperature transition between warmer surface water and colder water at depth

Only present in warm months

Fall Turnover

Fall Turnover

Summer Winter

Echo Lake, California

9/29/2014

5

Marshes and Swamps

Lands covered by shallow, fresh water for at least part of the year

Historically filled in for development

Process called “Reclamation”

Current law recognizes their ecosystem services and ecological value

Flood protection, water purification, nesting habitat, etc.

Marshes and SwampsNapa-Sonoma Marsh

Marshes and SwampsNapa-Sonoma Marsh (Restoration)

9/29/2014

6

Marshes and SwampsNapa-Sonoma Marsh (After Restoration)

Estuaries

Where freshwater and saltwater mix

Highly variable environment

Temperature, salinity, depth of light penetration

Highly productive Nutrients transported

from land

High level of light

penetrates shallow water

Plants provide

photosynthetic carpet

Estuaries

San Francisco Bay (Estuary)

Largest estuary on west coast of United States

9/29/2014

7

Marine Ecosystems

Subdivided into life zones

Intertidal zone – land/sea interface

Benthic zone – sea bottom

Pelagic environment – open ocean

Tide pools Open ocean

Benthic Zone

Ocean floor, extending from tidal zone to deep sea trenches

Sediment is mostly mud

Burrowing worms and clams

Deep benthos Shallow benthos

Productive Benthic Communities

Seagrass Beds

Present to depth of 10 m

Provide food and habitat to ecosystem

Kelp Forest

60 m long brown algae found off rocky shores

Large Biodiversity

Coral Reefs

Built from accumulated layers of CaCO3

Colonies of millions of tiny coral animals

Found in shallow warm water

Most diverse of all marine environments

9/29/2014

8

SeagrassBed

Kelp Forest

Productive Benthic Communities

Coral Reef

Human Impacts on the Ocean