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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
