Aquatic Biodiversity

Chapter 8

Core Case Study: Why Should We Care about Coral Reefs? (1)

Biodiversity

Formation

Important ecological and economic services• Moderate atmospheric temperatures

• Act as natural barriers protecting coasts from erosion

• Provide habitats

• Support fishing and tourism business

• Provide jobs and building materials

• Studied and enjoyed

Core Case Study: Why Should We Care about Coral Reefs? (2)

Degradation and decline• Coastal development• Pollution• Overfishing• Warmer ocean temperatures leading to coral

bleaching• Increasing ocean acidity

Key Concepts

What is the general nature of aquatic systems?

Why are marine aquatic systems important?

How have human activities affected marine ecosystems?

Why are freshwater ecosystems important?

How have human activities affected freshwater ecosystems?

8-1 What Is the General Nature of Aquatic Systems?

1) Most of the earth is covered with watera) Saltwater covers 71%b) Freshwater covers 2.2%

2) The global ocean is a single body of water, but divided into 4 large oceans

3) Aquatic life zone: water “biomes”a) saltwater or marineb) Freshwater

4) Aquatic species

a) Plankton: weakly swimming or free-floating1. Phytoplankton: plant like2. Zooplankton: animal like3. Ultraplankton: small photosynthetic bacteria

b) Nekton: Strong swimming consumersc) Benthos: bottom dwellersd) Decomposers: mostly bacteria,

break down material

5) Key factors determining type & number

a) Temperature

b) Dissolved oxygen

c) Food

d) Light & nutrients for PSN

6) Euphotic zone: area where PSN can occur, reduced by turbidity (cloudiness)

8-2 Why Are Marine Aquatic Systems Important? 1)

Important ecological and economic resources

Page 165

Fig. 8-6, p. 173

2) Reservoirs of diversitya) Coastal Zone: 1. Warm, nutrient rich shallow water

from high tide to continental shelf edge

2. Less than 10% of ocean, but 90% of marine species

b) Estuaries: Where rivers & ocean meetc) Coastal Wetland: coastal area

covered by water all or part of the year

d) Very productive because of nutrients from rivers & land, circulation of nutrients & sunlight

Fig. 8-7, p. 173

Fig. 8-8, p. 174

e) Seagrass beds:1. Consists of at least 60 species of plants growing underwater in shallow marine areas or estuaries.

2. Support a wide variety of marine species and help stabilize shorelines, & reduce wave impacts

f) Mangrove forests: 1. Tropical salt marsh (especially SE Asia)2. Include 69 different tree species3. Many important services (page 168)

Fig. 8-10, p. 175

3) Rocky and Sandy Shoresa) Intertidal Zone:1. area between High and low tide2. Must be able to survive extremes &

avoid being wasted out to seab) Rocky shores have pools & other

microhabitatsc) Barrier beach (sandy shore): Most

survive by burrowing, digging or tunneling in the sand, also home for many other organisms

d) Barrier islands form parallel to shore and protect from strong waves

Fig. 8-11, p. 176

4) Coral Reefs Are Amazing Centers of Biodiversitya) Provide homes for ¼ of all marine speciesb) Aquatic equivalent of the rain forest5) Open Sea & Ocean floor

a) Open Sea: Begins at the edge of the shelfb) 3 Zones

1. ) Euphotic: where light penetrates for PSN

2. Bathyal: dimly lit middle zone3. Abyssal: Dark, very cold area

6) Most animals in the abyssal zone feed on marine snow & are deposit or filter feeders (page 170)

Fig. 8-12, p. 177

8-3 How Have Human Activities Affected Marine Ecosystems?

Case Study: The Chesapeake Bay—an Estuary in Trouble page 172

Largest estuary in the US; polluted since 1960 Population increased Point and nonpoint sources raised pollution

Phosphate and nitrate levels too high Overfishing

1983: Chesapeake Bay Program

Update on recovery of the Bay

Should we introduce an Asian

oyster?

8-4 Why Are Freshwater Ecosystems Important?

1) Lentic: Standing water: lakes, ponds wetlands

2) Lotic: flowing, rivers and streams

3) Services Page 174

4) Lakes: natural bodies of standing water

5) Zones:a) Littoral: near the shore, shallow sunlit water, rooted plants can grow here, very diverseb) Limnetic: open sunlit surfacec) Profundal: deep, open water to dark for PSNd) Benthic: bottom area

Fig. 8-16, p. 182

6) Some Lakes Have More Nutrients Than Others

a) Oligotrophic: poorly nourished, usually have deep with steep banks, usually clear with small populations

b) Eutrophic: large supply of nutrients, usually shallow, have murky brown or green waterhigh NPP

c) Mesotrophic: between the 2 d) Cultural Eutrophication:

increasing the rate of eutrophication due to input from urban & agricultural areas

Stepped Art

Fig. 8-17, p. 182

7) Freshwater Streams and Rivers

a) Surface water, becomes runoff when it flows into streams

b) Watershed (drainage basin): land area that drains into a specific stream or river

c) River zones (page 176) 1. Source: Cold mountain water2. Transition: wider, deeper and warmer streams down gentler slopes3. Flood plain: even wider, flow over flat valley

Fig. 8-18, p. 183

Case Study: Dams, Deltas, Wetlands, Hurricanes, and New Orleans

Coastal deltas, mangrove forests, and coastal wetlands: natural protection against storms

Dams and levees reduce sediments in deltas: significance?

New Orleans, Louisiana, and Hurricane Katrina: August 29, 2005

Global warming, sea rise, and New Orleans

Fig. 8-19, p. 178

8) Freshwater Inland Wetlands Are Vital Sponges

a) Land covered with freshwater all or part of the time

b) Types1. Marsh: grass and reeds with few trees2. Swamps: mostly trees3. Prairie pothole: depression left by glaciers4. Flood plain: during rainy season5. Arctic tundra: during the summer

c) Highly productive & provide habitats for many species

d) Provide free ecological and economic services•Filter and degrade toxic wastes•Reduce flooding and erosion•Help to replenish streams and recharge groundwater aquifers

•Biodiversity•Food and timber•Recreation areas

8-5 How Have Human Activities Affected Freshwater Ecosystems?1) Dams & Canals fragment 40% of world’s

237 large rivers. Destroy habitats by reducing water flow, cause floods and increase damage by storms

2) Flood control levees & dikes: disconnect the rivers from flood plains, destroy habitats alter or reduce the functions of wetlands

3) Addition of pollutants by cities and farms

4) Draining or filling of wetlands for crops or buildings

Case Study: Inland Wetland Losses in the United States (page 179)

Loss of wetlands has led to• Increased flood and drought damage

Lost due to• Growing crops

• Mining

• Forestry

• Oil and gas extraction

• Building highways

• Urban development