Sustaining Aquatic Biodiversity
G. Tyler Miller’s
Living in the Environment
13th Edition
Chapter 24
Key Concepts
 Economic and ecological importance
 Effects of human activities
 Protecting and sustaining aquatic diversity
 Protecting and sustaining fisheries
 Protecting and restoring wetlands
Case Study: A Biological Roller
Coaster Ride in Lake Victoria
• Lake Victoria has lost its endemic fish
species to large introduced predatory
fish.
A Biological Roller Coaster Ride in
Lake Victoria
• Reasons for Lake Victoria’s loss of
biodiversity:
– Introduction of Nile perch.
– Loss of native cichlid species
– Lake experienced algal blooms from
nutrient runoff.
– Invasion of water hyacinth has blocked
sunlight and deprived oxygen.
– Nile perch is in decline because it has
eaten its own food supply.
AQUATIC BIODIVERSITY
• We know fairly little about the
biodiversity of the world’s marine and
freshwater systems.
• The world’s marine and freshwater
systems provide important ecological
and economic services.
The Importance of Aquatic Biodiversity
• The most
biologically
diverse habitats
include:
–
–
–
–
Coral reefs
Estuaries
Deep ocean floor
Highest near the
coast
– 25,000 known fish
species
The Importance of Aquatic Biodiversity:
Ecological and Economic
• Food Items
– 6% of total protein; 16% of
animal protein
• Many Chemicals
– Cosmetics
• from seaweed
– Medicines and Drugs
• Antibiotics and
anticancer drug,
adhesives, bone
reconstructive
materials
• seaweed, sponges,
mollusks, coral
barnacles, and other
fish
Human Impacts on Aquatic
Biodiversity
• Species loss and endangerment
• Marine habitat loss and degradation
• Freshwater habitat loss and
degradation
• Overfishing
• Nonnative species
• Pollution and global warming
Species Loss and Endangerment
•
•
•
•
Overfishing
Habitat destruction
Pollution
Freshwater species at greater risk
– Mussels, crayfish, amphibians, fish
Marine Habitat Loss and
Degradation
• 53% of coastal wetlands in US have
disappeared
– Agriculture
– Coastal development
• 58% of world’s coral reefs are threatened
– Coastal development
– Pollution
– Warmer ocean temperatures
• Two-thirds of US estuaries are at risk
from pollution
• 35% of world’s mangroves have
disappeared
Freshwater Habitat Loss and
Degradation
• The world has lost more than half of its
inland wetlands
– Agricultural and urban development
• 60% of the world’s larger rivers are
fragmented by dams, diversions, and
canals
• Flood control levees and dikes
– Alter and destroy aquatic habitats
– Disconnect rivers from their floodplains
– Eliminate wetlands and backwaters
(spawning areas)
Overfishing
• 75% of the world’s 200 commercially
valuable marine fish species are
overfished
• Overfishing leads to commercial
extinction
• Depletions and extinction of species
unintentionally caught as bycatch
Non-native Species
• Deliberate or accidental introduction into
coastal waters, lakes and wetlands
– purple loosestrife
– Asian swamp eel
– zebra mussle
• Displace or cause extinction of native
species
– 68% of fish extinctions
Pollution and Global Warming
• 44% comes from runoff from developed
coastal areas
• Major pollution threats • Global warming could
– Oil
– alter migration and
feeding patterns
– Acid deposition
– Plant nutrients
– increase ocean
temperature
– Toxic chemicals
– Coastal development
– raise sea levels
– Sediment and soil
erosion
PROTECTING AND SUSTAINING
MARINE BIODIVERSITY
• Six of the
world’s seven
major turtle
species are
threatened or
endangered
because o
human
activities.
Figure 12-4
Protect endangered and threatened
species
• Example: Sea turtle
– Turtle extrusion devices (TEDs)
Olive ridley
Loggerhead
Leatherback
Hawksbill
Australian
flatback
Black turtle
Green turtle
Kemp's
Ridley
Shrimp trawler
Turtle Extrusion
Device
Area enlarged right
Case Study: The Florida Manatee
and Water Hyacinths
• Manatee can eat unwanted
Water Hyacinths.
• Endangered due to:
– Habitat loss.
– Entanglement from
fishing lines and nets.
– Hit by speed boats.
– Stress from cold.
– Low reproductive rate
Case Study: Commercial
Whaling
• After many of the
world’s whale
species were
over-harvested,
commercial
whaling was
banned in 1960,
but the ban may
be overturned.
Commercial Whaling
• Despite ban, Japan,
Norway, and Iceland
kill about 1,300 whales
of certain species for
“scientific purposes”.
– Although meat is still
sold commercially.
Key Concepts
 Economic and ecological importance
 Effects of human activities
 Protecting and sustaining aquatic diversity
 Protecting and sustaining fisheries
 Protecting and restoring wetlands
Protecting and Sustaining Marine
Biodiversity
• Identifying and protecting endangered
and threatened species
– Sea turtles
• Turtle extrusion devices (TEDs)
• National and International laws and
treaties
• CITES - Convention on International Trade and
Endangered Species
• Global Treaty on Migratory Species
• US Marine Mammal Protection Act
• US Endangered Species Act
• US Whale Conservation and Protection Act
• International Convention on Biological Diversity
Protecting and Sustaining Marine
Biodiversity
• Establish marine protected areas
– Coastal nations have sovereignty over
waters and seabeds up to 12 miles
offshore
– Jurisdiction over their Exclusive
Economic Zone extends 200 miles
offshore
• Integrated coastal management
– community based attempt to develop
and use coastal resources sustainably
Protecting and Sustaining Marine
Biodiversity
• Regulating and preventing ocean
pollution
• Sustaining management of marine
fisheries
Managing and Sustaining the
World’s Marine Fisheries
• Fishery regulation
– Set, monitor, and enforce fishery catch limits
below estimated MSY (maximum sustained yield)
– Divide up fishing quotas
– Require selective gear
– Improve monitoring and enforcement
• Economic approached
– Reduce or eliminate subsidies
– Impose fees for harvesting fish and shellfish from
public managed offshore waters
– Certify sustainable fisheries
Managing and Sustaining the
World’s Marine Fisheries
• Bycatch reduction
–
–
–
–
–
Wider mesh fish nets
Extrusion devices
Observers on boats
Multiple species licensing
Laws prohibiting throwing edible and
marketable fish back to sea
Managing and Sustaining the
World’s Marine Fisheries
• Protected areas
– Establish no-fishing marine areas
– Protect marine habitats that are in good
condition and disregard potentially hopeless
cases
– Strengthen commitment to marine biodiversity
protection
• Non-native invasions
– Kill organisms in ship ballast water
– Develop filters and traps
– Require ships to dump ballast water beyond 200
mile limit
Managing and Sustaining the
World’s Marine Fisheries
• Consumer information
– Use labeling to identify fish that have been
harvested sustainably
• Aquaculture
– Restrict location of fish farms to reduce
loss of mangrove forests
– Enact and enforce stricter pollution
regulations
– Increase productions of herbivorous
aquaculture fish species
Protecting, Sustaining, and
Restoring Wetlands
• Regulations
– federal permit required
• Mitigation banking
– allows destruction of existing wetlands if an equal area of
they same type of wetland is created or restored
• Land use planning
– steer agriculture and mining away from wetlands
• Wetland restoration
– often has limited success
• Control of invasive species
– purple loosestrife
Restoring the Florida Everglades
• Natural flow of the
Everglades has been
diverted or disrupted.
• Farmers planted vast
agricultural land to
sugarcane and vegetables.
• Established Everglades
National Park. Became the
most endangered park.
• Massive plumbing and land
development projects cut
off water flow
Restoring the Florida Everglades
• 1990 began the world’s
largest ecological
restoration project.
– restore he curving flow of
more than half of the
Kissimmee River.
– remove 400 km of canals and
levees
– create artificial marshes in
previous farmland
– add land adjacent to
Everglades National Park
– create network of artificial
marshes
– create 18 large reservoirs
– capture much of the water
flowing out to sea and return it
to the Everglades
Protecting, Sustaining, and
Restoring Wetlands
Protecting, Sustaining, and
Restoring Lakes
 Pollution
 Cultural
eutrophication
 Water levels
 Invasive species
Zebra mussel
Protecting, Sustaining, and
Restoring Rivers
 Pollution
 Disruption of
water flow
 Loss of
biodiversity
 Invasive
species
Protecting, Sustaining, and
Restoring Rivers

Disruption of water flow
119 dams,
19 hydroelectric dams
Salmon population
dropped 94%

Salmon Restoration
Project
upstream hatcheries
fish ladders
transport juveniles
around dams
turning off turbines
PROTECTING, SUSTAINING, AND
RESTORING LAKES AND RIVERS
• We can help sustain freshwater fisheries by
building and protecting populations of
desirable species, preventing over-fishing,
and decreasing populations of less
desirable species.
• A federal law helps protect a tiny fraction of
U.S. wild and scenic rivers from dams and
other forms of development.
– National Wild and Scenic Rivers Act
(1968).