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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?
 Pacific
• Largest, deepest
 Atlantic
• Second largest
 Indian
• Mainly in Southern Hemisphere
 Arctic
• Smallest, shallowest, ice-covered
Average Ocean Depth
Why are the oceans important?
1.
2.
Influence weather
Lungs of the planet
•
•
3.
Take CO2 out of the
atmosphere and replace it
with O2
Supply 70% O2 humans
breathe!
Sustain life
Ocean life
Largest life
Smallest life
Microscopic Bacteria
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
Intertidal
Abyssal
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
Hydrothermal vent
Coral Reef
Zone: Benthic
 Hydrothermal Vents
• Discovered in 1977 by
submersible Alvin
• Were gushing hot mineralrich 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
Rain and snow
• Headwaters and mountain
streams swiflty flow
• Increases DO levels
• Lack nutrients; low productivity
Lake
Glacier
Rapids
Waterfall
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
Tributary
Flood plain
Transition Zone
Three aquatic life zones
 Floodplain zone
• Friction from water modifies
land
• High temperatures
• Low DO
• High productivity
• Murky water
• Erosion
Floodplain Zone
Oxbow lake
Salt marsh
Delta
Deposited
sediment
Ocean
Sediment
Water
Rain and snow
Lake
Glacier
Rapids
Waterfall
Tributary
Flood plain
Oxbow lake
Salt marsh
Delta
Deposited
sediment
Ocean
Source Zone
Transition Zone
Floodplain Zone
Sediment
Water
Stepped Art
Fig. 8-17, p. 176
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
Your Turn!
 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)
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