aquatic biodiversity

Aquatic Biodiversity

Chapter 8

8.1

What is the General Nature of Aquatic

Systems?

Earth: The Watery Planet

71% Earth covered by ocean• 2.2% covered by

freshwater

What are Earth’s Major Oceans?

What are Earth’s Major Oceans?

PacificPacific• Largest, deepest

AtlanticAtlantic• Second largest

IndianIndian• Mainly in Southern

Hemisphere ArcticArctic• Smallest,

shallowest, ice-covered

Average Ocean Depth

Why are the oceans important?

1. Influence weather2. Lungs of the

planet• Take CO2 out of

the atmosphere and replace it with O2

• Supply 70% O2 humans breathe!

3. Sustain life

Ocean life

Smallest life

Microscopic Bacteria

Largest life

Blue Whale

How do humans impact ocean life?

80% of all Americans live within an hour’s drive from an ocean or the Great Lakes

8 of the 10 largest cities are in coastal environments

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

Biodiversity Important ecological

and economic services• Natural barriers

protecting coasts from erosion

• Provide habitats• Support fishing and

tourism businesses• Provide jobs• Studied and enjoyed

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

Degradation and decline• Coastal

development• Pollution• Overfishing• Warmer ocean

temperatures leading to coral bleaching• Increasing ocean

acidity

Aquatic life zones

Saltwater: marine • Oceans and

estuaries• Coastlands and

shorelines• Coral reefs• Mangrove forests

Freshwater• Lakes• Rivers and streams• Inland wetlands

Distribution of the World’s Major Saltwater and Freshwater Sources

8.2

Why Are Marine Aquatic Systems Important?

Oceans Provide Important Ecological and Economic Resources

Reservoirs of diversity in three major life zones• Coastal zone• Usually high NPP

• Open sea• Ocean bottom

Estuaries and Coastal Wetlands Are Highly Productive

Estuaries and coastal wetlands • River mouths• Inlets• Bays• Sounds• Salt marshes• Mangrove forests

Estuaries and Coastal Wetlands Are Highly Productive

Important ecological and economic services• Coastal aquatic systems

maintain water quality by filtering• Toxic pollutants• Excess plant nutrients• Sediments

• Absorb other pollutants • Provide food, timber,

fuel, and habitats• Reduce storm damage

and coast erosion

Estuaries and Coastal Wetlands Are Highly Productive

Seagrass Beds• Support a variety of

marine species• Stabilize shorelines• Reduce wave

impact

Some Components and Interactions in a Salt Marsh Ecosystem in a Temperate Area

Mangrove Forest in Daintree National Park in Queensland, Australia

Blue Planet Video Clip

Seasonal Seas 5:00-15:00

Most Aquatic Species Live in Top, Middle, or Bottom Layers of Water

Key factors in the distribution of organisms• Temperature• Dissolved oxygen

content• Availability of food• Availability of light

and nutrients needed for photosynthesis in the euphotic, or photic, zone

Pelagic

AbyssalIntertidal

Benthic

Zone: Intertidal Area between high tide and low tide• Sometimes covered, sometimes exposed

Very tough habitat to live in!• Subjected to drying and submersion• Temperature extremes• Pull of the waves• Sea and land predators

Zone: Intertidal

Animals• Often burrow • Hard shells that can be sealed

to prevent water loss Plants• Cling to hard bottoms

Intertidal Creatures

High Tide

Low Tide

Video Clip

Blue Planet: Tidal Seas 5:00-18:00

Zone: Pelagic

Open ocean zone• Sub-divided by

depth or amount of sunlight

Zone: Pelagic

Epipelagic Zone• Photic zone• Plankton and

photosy thesis• Shallowest zone

Mesopelagic zone• Little light (twilight)• Plants cannot grow

Deep-pelagic• Aphotic

Pelagic Creatures

Pelagic Creatures Plankton (drifters) • Microscopic

organisms • Weak swimmers (at

mercy of currents)• Primary Producers

Nekton• Animals that can

swim well• Mostly vertebrates

Plankton and Primary Production

Gross primary productivity (GPP)• Rate at which an ecosystem’s producers

convert solar energy into chemical energy stored in their tissues

Net primary productivity (NPP)• Rate they create and store energy minus

the energy they use for homeostasis• Ecosystems and life zones differ in their

NPP

Zone: Abyssal

Midnight zone – no light penetrates

High pressure• Pressure at 10,000 = weight of 5

jumbo airliners

Zone: Abyssal Animal Adaptations• Withstand the dark,

the cold (near freezing), and the tremendous pressure

• Dark or nearly transparent in color

• Bioluminescent• Don’t move much,

and usually eat what falls from above

Zone: Benthic Zone ranging from the deepest part of the

ocean to the shore Organism diversity• Plants, anemones, sponges, fish, skates

and rays, octopus, mollusks, crabs, sea stars, corals and worms.

• Most are scavengers.

Zone: Benthic

Intertidal Benthic Coral Reef

Hydrothermal vent

Zone: Benthic Hydrothermal

Vents • Discovered in

1977 by submersible Alvin

• Were gushing hot mineral-rich water

Zone: Benthic Hydrothermal

Vents • Formed when cold

sea water seeps into cracks in Earth’s crust • Superheated by

the magma in the mantle. • Hot water with

dissolved minerals from the magma rises and spews out like an undersea geyser

Zone: Benthic Fantastic

communities of organisms that live by chemosynthesis

Thrive around these “black smokers”, using energy from chemical reactions with minerals in the water to live.

Hydrothermal Vent Video Clip

Your Turn

Your Turn: Cartoon Guide to Aquatic Ecosystems

8.3

How Have Human Activities Affected Marine

Ecosystems?

Human Activities Are Disrupting and Degrading Marine Systems

Major threats to marine systems • Coastal

development• Overfishing• Runoff of nonpoint

source pollution• Point source

pollution

Human Activities Are Disrupting and Degrading Marine Systems

Major threats to marine systems • Habitat destruction• Introduction of

invasive species• Climate change

from human activities

• Pollution of coastal wetlands and estuaries

Video Clip

Case Study: Chesapeake bay – An Estuary in Trouble

Class Bacillariophyceae

Diatoms• Most abundant

phytoplankton• Major oceanic

primary producer• Cell walls composed

of silica (glass-like)• Live alone or in

chains• Centric or pennate

shapes

Division Dinophyta

Dinoflagellates• Abundant in warm

surface H2O (tropics)

• Some symbiotic (zooxanthellae)• Live in coral, clams,

urchins, anemones• Give carbohydrates

& receive nutrients & shelter

Why Do Dinos. Produce Light?

Camouflage! When it senses a

predator (motion in H2O)• Attracts larger

predators that consumes the would-be Dino predator

Red Tides (Dinoflagellate Bloom)

Mass development of dinoflagellates discolor water

Often caused by excess nutrients• Enter ocean from

land (runoff)• Fertilizer, sewage

Red Tide Impacts Toxic to marine life:

accumulates in clams, mussels, scallops, fish, mammals• Death to some species;

biomagnification Human poisoning after

consumption (30 min.)• Symptoms:

• Paralytic: paralysis, asthma, heartattack (rare)

• Neurotoxic: tingling, paralysis, memory loss

• Diarrhetic: cramps, vomiting, diarrhea

Red Tide Impacts Toxic to marine life:

accumulates in clams, mussels, scallops, fish, mammals• Death to some species;

biomagnification Human poisoning after

consumption (30 min.)• Symptoms:

• Paralytic: paralysis, asthma, heartattack (rare)

• Neurotoxic: tingling, paralysis, memory loss

• Diarrhetic: cramps, vomiting, diarrhea

Red Tide Impacts

Measuring Primary Production

Satellites measure differences in sea surface color • Color = type of

producer• Green color =

chlorophyll pigments

Productivity Limitations

Eutrophication

Light Availability – depth, season, latitude• Little photosynthesis below 100m (330ft)• Phytoplankton productivity limited to photic

zone

Eutrophication

Light Availability – depth, season, latitude• Little photosynthesis below 100m (330ft)• Phytoplankton productivity limited to photic

zone

Eutrophication Nutrient Availability – “Natural fertilizer”

• Upwelling - aids primary production by bringing nutrients to surface• Nitrogen and Phosphorous

• Caused by winds blowing either parallel or offshore along a coastline

• Brings up cold nutrient-rich water

Eutrophication• Caused by winds blowing either parallel or offshore

along a coastline• Brings up cold nutrient-rich water

Eutrophication Nutrient Availability – “Natural fertilizer”• Zooplankton (fecal pellets, death) – leads to

future phytoplankton blooms• Need bacteria to decompose waste

Water temperature - diatoms like cool H2O

Phytoplankton: Season & Latitude

Phytoplankton vs. Zooplankton

Your Turn!

Analyzing Plankton Data

8.4

Why Are Freshwater Ecosystems Important?

Water Stands in Some Freshwater Systems and Flows in Others

Standing (lentic) bodies of freshwater• Lakes• Ponds• Inland wetlands

Flowing (lotic) systems of freshwater• Streams• Rivers

Water Stands in Some Freshwater Systems and Flows in Others Formation of lakes

Four zones based on depth and distance from shore• Littoral zone – top layer near the shore• Limnetic zone – open sunlit layer away

from the shore; extends to depth penetrated by light

• Profundal zone – deep open water; too dark for photosynthesis

• Benthic zone – bottom of lake; mostly decomposers, detritus feeders and some fish

Stratification by depth/distance from shore

Distinct Zones of Life in a Fairly Deep Temperate Zone Lake

Stratification by temperature

Epilimnion

Hypolimnion

Some Lakes Have More Nutrients Than Others

Oligotrophic lakes• Low levels of nutrients and low NPP

Eutrophic lakes• High levels of nutrients and high NPP

Mesotrophic lakes

Cultural eutrophication leads to hypereutrophic lakes

The Effect of Nutrient Enrichment on a Lake

Three aquatic life zones

Source zone• Headwaters and

mountain streams swiflty flow

• Increases DO levels• Lack nutrients; low

productivity

Waterfall

LakeGlacier

Rain and snow

Rapids

Source Zone

Three aquatic life zones

Transition zone• Headwater streams

merge to form wider and warmer streams

• Gentle slopes• High turbidity• Less DO• Moderate

productivity

Transition Zone

Tributary Flood plain

Three aquatic life zones Floodplain zone • Friction from water

modifies land • High temperatures• Low DO• High productivity• Murky water• Erosion

Oxbow lakeSalt marsh DeltaDeposite

d sediment Ocea

n

WaterSedimentFloodplain

Zone

Waterfall

LakeGlacierRain and

snowRapids

Source Zone

Fig. 8-17, p. 176

Transition Zone

Tributary Flood plain

Oxbow lakeSalt marsh DeltaDeposite

d sediment Ocea

n

WaterSedimentFloodplain

Zone

Stepped Art

Freshwater Inland Wetlands Are Vital Sponges

Marshes

Swamps

Prairie potholes

Floodplains

Arctic tundra in summer

Freshwater Inland Wetlands Are Vital Sponges

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

Draw a graph that depicts the changes in water temperature levels in a lake through the four seasons!• One color to

represent epilimnion• One color to

represent hypolimnion

• Label lake overturn (upwelling events)

Draw a graph that depicts the changes in dissolved oxygen levels in a lake through the four seasons!• One color to

represent epilimnion• One color to

represent hypolimnion

• Label lake overturn (upwelling events)

Your Turn!

What is turbidity?

Measure of the degree to which the water looses its transparency • Due to the

presence of suspended particulates

What is turbidity?

The more total suspended solids in the water, the murkier it seems and the higher the turbidity

What causes turbidity?

There are various parameters influencing the cloudiness of the water. Some of these are:  • Phytoplankton   • Sediments from erosion  • Resuspended sediments from the bottom

(frequently stir up by bottom feeders like carp)  • Waste discharge  • Algae growth  • Urban runoff 

What are the consequences of high turbidity?

Suspended particles absorb heat from the sunlight• Turbid waters become warmer• Reduce the concentration of oxygen in the

water

What are the consequences of high turbidity?

The suspended particles scatter the light• Decrease the

photosynthetic activity of plants and algae

• Contributes to lowering the oxygen concentration even more