Transcript Aquatic Biodiversity

Aquatic Biodiversity
Chapter 8
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
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
Earth: The Watery Planet
• 71% Earth covered by
ocean
– 2.2% covered by
freshwater
What are Earth’s Major Oceans?
 Pacific
• Largest, deepest
 Atlantic
• Second largest
 Indian
• Mainly in Southern
Hemisphere
 Arctic
• Smallest, shallowest, icecovered
Average Ocean Depth
Pelagic
Intertidal
Abyssal
Benthic
Most Aquatic Species Live in Top,
Middle, or Bottom Layers of Water
• Plankton
– Phytoplankton
– Zooplankton
– Ultraplankton
• Nekton
• Benthos
• Decomposers
Measuring Primary Production
• Satellites measure
differences in sea
surface color
– Color = type of
producer
– Green color =
chlorophyll pigments
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
• Nutrient Availability – “Natural fertilizer”
– Zooplankton (fecal pellets, death) – leads to future
phytoplankton blooms
• Need bacteria to decompose waste
Phytoplankton: Season & Latitude
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
What is turbidity?
• Measure of the degree
to which the water
looses its transparency
– Due to the presence of
suspended particulates
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 is Dissolved Oxygen?
• Amount of gaseous oxygen (O2) dissolved in
an aqueous solution.
• Oxygen gets into water by:
– Diffusion from the surrounding air
– Aeration (rapid movement)
– Waste product of photosynthesis
Environmental Impact
• Should not exceed 110 %
• Concentrations above this level can be
harmful to aquatic life.
Gas Bubble Disease
• Fish in waters
containing excessive
dissolved gases
• Bubbles block the flow
of blood through blood
vessels causing death
• External bubbles
(emphysema)
– fins, skin and eyes
Environmental Impact
• As dissolved oxygen levels in water drop
below 5.0 mg/l, aquatic life is put under stress.
– The lower the concentration, the greater the
stress.
– Oxygen levels that remain below 1-2 mg/l for a
few hours can result in large fish kills.
Cultural Eutrophication Is Too
Much
of a Good Thing
• Cultural
eutrophication –
increase in nitrates
and phosphate
containing effluents
from various sources
in urban and
agricultural
communities
Eutrophication
• Nutrients are food for
algae, and water with high
amounts of nutrients can
produce algae in large
quantities.
• When these algae die,
bacteria decompose them,
and use up oxygen.
• DO concentrations can
drop too low for fish to
breathe, leading to fish kills.
Organic Wastes
• Remains of any living or
once-living organism
• Leaves, grass clippings,
dead plants or animals,
animal droppings, and
sewage
– Decomposed by bacteria;
these bacteria remove
dissolved oxygen from the
water when they breathe.
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
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
Stratification by temperature
• Epilimnion
• Hypolimnion
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
Water Resources
Chapter 13
Hydrologic Cycle
• Earth’s water supply:
– 97.2%
– 2.15%
– 0.62%
– 0.02%
– 0.001%
– World ocean
– Frozen in glaciers and ice caps
– Groundwater and soil moisture
– Streams and lakes
– Water vapor in the atmosphere
Hydrologic Cycle
• Water moves between the ocean, atmosphere, and land.
We Get Freshwater from
Groundwater and Surface Water
• Ground water: water
that percolates
downward through the
Earth until it collects in
an impenetrable layer
of rock
• Zone of saturation:
depth where Earth is
completely filled with
water
We Get Freshwater from
Groundwater and Surface Water
• Water table: top of
groundwater zone
• Aquifers: underground
caverns and porous
layers of sand, gravel,
or bedrock through
which groundwater
flows
– Natural recharge
– Lateral recharge
Natural Capital: Groundwater
System: Unconfined and Confined
Aquifer
Water Tables Fall When Groundwater Is
Withdrawn Faster Than It Is Replenished
• India, China, and the United States
– Three largest grain producers
– Overpumping aquifers for irrigation of crops
– Rate of pumping exceeds natural recharge
– Deeper wells increase pollution
• India and China
– Small farmers drilling tubewells
– Effect on water table
Water Tables Fall When Groundwater Is
Withdrawn Faster Than It Is Replenished
• Saudi Arabia
– As water-poor as it is oil-rich!
– 70% of drinking water produced by removing
salt from seawater
– High evaporation rates
– Large pools and fountains
– Aquifer depletion and irrigation
Natural Capital Degradation: Irrigation in
Saudi Arabia Using an Aquifer
Case Study: Aquifer Depletion in the
United States
• Ogallala aquifer:
largest known aquifer
– Runs from South
Dakota to Texas
– One-time deposit of
liquid natural capital
– Irrigates the Great
Plains
Dams and Reservoirs
Is Building More Dams the Answer?
• Dam: structure built
across a river to control
the river’s water flow
• Reservoir: artificial lake
formed when a river is
dammed
– 800,000 worldwide
Advantages
•
•
•
•
Increase the reliable runoff available by 1/3
Reduce flooding
Grow crops in arid regions
Hydroelectricity
Disadvantages
• Displaced 40-80 million people from their
homes
• Flooded agriculturally profitable regions the
size of CA
• Impaired ecological services of rivers
• 1/5 loss of plant and animal species
• High evaporation and seepage rates
• Fill up with sediment within 50 years
– 85% of US reservoirs by 2020
Advantages and Disadvantages
Case Study: The Colorado River
Basin— An Overtapped Resource
• Four Major problems
– Colorado River basin has
very dry lands
– Modest flow of water for
its size
– Legal pacts allocated
more water for human
use than it can supply
– Amount of water flowing
to the mouth of the river
has dropped
Using Laws to Protect Drinking
Water Quality
• 1974: U.S. Safe Drinking Water Act
– Sets maximum contaminant levels for any pollutants
that affect human health
– 5.6 million Americans drink water that does not meet
EPA safety standards
• Health scientists: call for strengthening the law
– Banning all toxic lead in new plumbing
– Current laws allow fixtures with up to 10% lead to be
sold as “lead free”
Water Pollution Comes from Point
and Nonpoint Sources
• Water pollution
• Point sources
– Located at specific
places
– Easy to identify,
monitor, and regulate
– Examples?
Water Pollution Comes from Point
and Nonpoint Sources
• Nonpoint sources
– Broad, diffuse areas
– Difficult to identify
and control
– Expensive to clean up
– Examples
Water Pollution Comes from Point
and Nonpoint Sources
• Agriculture activities: leading cause of water
pollution
– Sediment eroded from the lands
– Fertilizers and pesticides
– Bacteria from livestock and
food processing wastes
• Industrial facilities: emit harmful organic and
inorganic chemicals
• Mining: erosion of sediments
Water Pollution Comes from Point
and Nonpoint Sources
• Other sources of water pollution
– Parking lots
• Grease, toxic metals, and sediments collect on
surfaces
• Prevent rain from soaking into ground
– Human-made materials
• E.g., plastics
Major Water Pollutants Have
Harmful Effects
• Infectious disease
organisms: contaminated
drinking water
• The World Health
Organization (WHO)
– 3 Million people die every
year, mostly under the age
of 5
– On average, diarrhea kills
a young child every 18
seconds
Streams Can Cleanse Themselves If
We Do Not Overload Them
• Biodegradation of wastes by bacteria takes time
– Depletes dissolved oxygen and creates Oxygen sag
curve
Groundwater Contamination from a Leaking
Gasoline Tank
Principal Sources of Groundwater Contamination in the
U.S.
Sewage Treatment Reduces
Water Pollution
• Wastewater or
sewage treatment
plants:
• Primary sewage
treatment
– Physical process –
screens and grit tank to
remove large floating
objects
Sewage Treatment Reduces
Water Pollution
• Wastewater or
sewage treatment
plants:
• Secondary sewage
treatment
– Biological process aerobic bacteria remove
90% of dissolved organic
waste
Sewage Treatment Reduces
Water Pollution
• Wastewater or
sewage treatment
plants:
• Tertiary or advance
sewage treatment
– Bleaching, chlorination
to remove nitrogen and
phosphates
– EXPENSIVE!
Solutions: Primary and Secondary
Sewage Treatment
Septic Tanks…taking care of business at
home
• Rural and suburban areas
(25% US)
• Large drainage fields
• Pumped into settling tank
– Grease and oil rise to the top
– Solids fall to the bottom and
are decomposed by bacteria
• Must be removed every few
years
Solid and Hazardous Waste
Chapter 21
Core Case Study: “E-waste” An
Exploding Problem
• Shipped to other
countries
– 70% shipped to China
– 30% India and Africa
• International Basel
Convention
– Bans transferring
hazardous wastes from
developed countries to
developing countries
– US not involved…
We Throw Away Huge Amounts of Useful Things
and Hazardous Materials
• Solid waste
– Industrial solid – produced by mines agriculture, and
industries
– Municipal solid waste (MSW) – combined solid
waste produced by homes and workplaces
• Mostly paper and cardboard
• Buried in landfills or burned in incinerators
– Hazardous, toxic, waste – poisonous, dangerously
chemically reactive, corrosive, or flammable
•
•
•
•
Organic compounds
Toxic heavy metals
Radioactive waste
Hospital waste
US tragic trash history…
• Each day the average
American produces
more than 4.5 pounds
of MSW
There Are Two Types of Recycling
• Primary, closed-loop recycling – materials
are recycled into new products of the same
type
– Turning used aluminum can into recycled
aluminum can
• Secondary recycling – materials are
converted into different products
– Used tires can be shredded and turned into
rubberized road surfacing
Recycling Paper
• Paper mills use more water than any other
industry
– 3rd largest energy user and polluter
– Amount of paper thrown away in US is more than
all paper used in China
• Recycled paper
– Uses 64% less energy
– Produces 35% less water pollution and 74% less
air pollution
– No trees cut down!
Recycling Plastic
• Consists of various types of polymers
made by chemically linking molecules
produced by oil and natural gas
– 46 different types of plastics
– 4% in US is recycled
Burning Solid Waste Has
Advantages and Disadvantages
• Waste-to-energy
incinerators – burn
MSW to boil water to
make steam for heating
water or producing
energy
• 600 Globally
– Most in Great Britain
• 90% of MSW
– 98 in USA
• 16% of MSW
Burning Solid Waste Has
Advantages and Disadvantages
• Reduce the volume of
solid waste by 90%
• Pollute air
– Particulates, carbon
monoxide, toxic metals
– Toxic bottom ash that
must be disposed of safely
• Encourages trash
production; need huge
amounts of trash to be
economical
Solutions: A Waste-to-Energy
Incinerator with Pollution Controls
Burying Solid Waste Has
Advantages and Disadvantages
• Open dumps –fields or
holes in the ground where
garbage is deposited and
sometimes burned
• Sanitary landfills – solid
wastes are spread out in
thin layers
– Compacted and covered
daily with clay or plastic
foam
Sanitary Landfills
• EPA
– All landfills eventually
leak
– Expensive to clean up
– Hard to remove from
groundwater
• Department of Energy
– Radioactive materials
from nuclear weapons
dumped into regular
landfills
Solutions: State-of-the-Art Sanitary
Landfill
We Can Detoxify Hazardous
Wastes
• Collect and then detoxify
– Physical methods – use charcoal and resins
to filter out harmful solids; distill liquids
– Chemical methods – convert hazardous to
nonhazardous through chemical reactions
• Cyclodextrin molecular-sponge-type material; picks
up toxic chemicals as it is pumped through soil
We Can Detoxify Hazardous
Wastes
• Collect and then
detoxify
– Bioremediation –
bacteria, fungi, and
enzymes help to
destroy hazardous
compounds
• Wave of the future
• 1,000 different types of
bacterial and fungi
currently used
• Cheap but takes longer
to work
We Can Detoxify Hazardous
Wastes
• Collect and then
detoxify
– Phytoremediation –
using natural or
genetically engineered
plants to absorb, filter,
and remove
contaminants
We Can Store Some Forms of
Hazardous Waste
• Deep-well disposal –
liquid hazardous
wastes are pumped
through a pipe into
dry, porous rock
formations beneath
aquifers
– Theoretically
impermeable rock and
clay BUT diffuse into
aquifers
We Can Store Some Forms of
Hazardous Waste
• Surface
impoundments –
ponds, pits, or
lagoons containing
liners to store
hazardous waste
– Water evaporate and
wastes settle and
become more
concentrated on
bottom
We Can Store Some Forms of
Hazardous Waste
• Secure hazardous
landfills – liquid and
solid waste are put
into drums and buried
in monitored
environment
– Least used method
because it is
expensive
Case Study: Hazardous Waste
Regulation in the United States
• Laws encouraging the
cleanup of brownfields
– Abandoned industrial and
commercial sites
• Factories, junkyards, older
landfills, and gas stations
– Transformed into parks,
nature reserves, and
athletic fields
• 42,000 transformations!