2.9: Major Aquatic Ecosystem
pg. 60
Key Concepts:
6. Terrestrial biomes and aquatic ecosystems are largely determined by their abiotic
characteristics.
Evidence of Learning: Students can …
- describe the differences between a freshwater and a marine ecosystem.
- explain the features that make an aquatic ecosystem most productive.
- describe the unique features of the intertidal zone
- explain the conditions that species living in intertidal zones must withstand.
- There are two types of Aquatic Ecosystems; Freshwater and Marine
- Freshwater; below 1% salt concentration
- Marine (Ocean); avg. of 3% salt concentration
Freshwater Ecosystems
Oligotrophic: a body of water that is low in nutrients.
Eutrophic: a body of water that is rich in nutrients.
- made up of moving bodies of water, such as; rivers, and streams, and stationary bodies
of water, such as; lakes, and ponds.
- Rivers and streams continuously supply areas down stream with fresh water from
upstream.
- Lakes and ponds are classified by nutrient levels as either oligotrophic or eutrophic.
- Oligotrophic bodies of water are low in nutrients.
- Eutrophic bodies of water are high in nutrients.
- Wetlands, such as; bogs and marshes are large shallow waters or saturate d soils.
They have a high nutrient level and support large populations of fish, amphibians, insects,
and birds.
Watershed
Watershed: the land area drained by a particular river; also called drainage basin.
- An area of land which water drains into single rivers or lakes is known as a watershed.
- If pollutants should enter the watershed upstream, the pollutants will filter downstream.
Figure 3: In a watershed, all surface water and groundwater flow downhill and collect
into the same river or lake.
Marine Ecosystems
- Greater than 70% of the Earth’s surface is covered in oceans
- This supports the biogeochemical cycle, water cycle.
- Marine algae help to remove carbon dioxide from the atmosphere and store it, while
releasing oxygen.
- Deep portions of the oceans are limited to support life, while the shallow areas are
highly diverse in organisms.
- Estuaries partially enclosed areas where fresh water mixes with marine water, such as a
river mouth. These areas support a large variety of organisms.
- The Worlds larges estuary is The Gulf of St. Lawrence.
- Mangrove is a community that occurs along tropical and semitropical sandy shorelines.
- Tree roots prevent shore erosion and creates habitat for life.
The Intertidal Zone
- Areas of ocean coast line fluctuate between being terrestrial and aquatic, as the tide
occurs.
- Tides occur four times a day, moving from high tide (aquatic), to low tide (terrestrial).
- Highest is 17 m difference and occurs in the Bay of Fundy.
- Unusual communities of organism live here. (Seaweeds, barnacles, sea stars, and
urchins)
Check Your Learning
Questions 1 – 7, page 62
Summary:
- Aquatic ecosystems can be freshwater (for example, lakes and streams) or marine (for
example, coral reefs and estuaries).
- The most productive aquatic ecosystems occur in relatively shallow, warm, and nutrient
rich waters.
- The abiotic conditions of intertidal zones continuously alternate between those of a
terrestrial and those of an aquatic ecosystem.
- Species living in the intertidal zone are able to survive highly variable abiotic
conditions.