Extinctions, Endangered Species, and Hope

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Transcript Extinctions, Endangered Species, and Hope

Topic 12
The Biodiversity Crisis
Why Should We Care About
Biodiversity?
 Use Value
Economic profits
Medicinal sources
Ecological services
 Nonuse Value
Aethetics
Enjoyment
Cultural inspiration
Ecosystem Services
 This is the idea that nature provides many services beyond economic
goods that are not accounted for:






Gas regulation
Water purification
Waste remediation
Nutrient cycling
Soil formation
Etc….
 Worth $16-54 trillion US dollars, on average $33 trillion (Costanza et al.
1997)
Biodiversity & ecosystem functioning
 Ecological communities with higher biological diversity are
more resilient* and stable** than those with low
biodiversity.
 Both species and functional diversity levels are important
factors in maintaining ecological communities.
 Species diversity: the number of different species it contains
(species richness) combined with the abundance of individuals
within each of those species (species evenness).
 Functional diversity: the number of different species performing
specific roles in the community (eg diversity of primary producers
or decomposers)
*Resiliency is the ability to recover from a disturbance.
**Stability refers to the maintenance of trophic levels and interspecific interactions.
Cenozoic
Era
Period
Millions of
years ago
Quaternary
Today
Bar width represents relative
number of living species
Extinction
Species and families
experiencing
mass extinction
Current extinction crisis
Tertiary
65
Extinction
Cretaceous
Mesozoic
Cretaceous
Jurassic
180
Extinction
Triassic
Triassic
250
Extinction
345
Extinction
Permian
Paleozoic
Carboniferous
Permian
Devonian
Devonian
Silurian
Ordovician
Cambrian
500
Extinction
Ordovician
Fig. 4-12, p. 93
The Biodiversity Crisis
Endangered & Threatened
Species
AT RISK
SPECIES
 Some species have
characteristics that
make them vulnerable
to ecological and
biological extinction.
Generalist and Specialist Species:
Broad and Narrow Niches
SPECIES GONE OR AT RISK
The International Union for the Conservation of
Nature and Natural Resources (IUCN) publishes
an annual Red List
They place species into 9 categories
The 2010 Red List contains 18,351 species at risk
for extinction out of 55,926 evaluated (33%).
SPECIES EXTINCTION
Species can become extinct:
Locally
Ecologically
Globally (biologically)
Global Extinction
Some animals have become
prematurely extinct because of human
activities.
Dodo
Steller’s sea cow
SPECIES AT RISK
 Percentage of various species types threatened with premature
extinction from human activities.
U.S. STATS
 Threatened species by broad taxonomic
grouping:
Mammals: 37
Birds: 74
Reptiles: 32
Amphibians: 56
Fishes: 177
Molluscs: 273
Other Invertebrates: 258
Plants: 245
U.S. FWS
Reasons for biodiversity loss
HIPPO
H:habitat destruction and degradation
 I: invasive species
P: population growth in humans
P: pollution
O: overexploitation
H: habitat degradation or loss
Terrestrial
 Deforestation
 Loss of grasslands
Aquatic and marine
 Benthic habitat loss
 Erosion
 Eutrophication
TROPICAL DEFORESTATION
Why Should We Care about
the Loss of Tropical Forests?
HABITAT LOSS, DEGRADATION, AND
FRAGMENTATION EXAMPLES
Commercial fishing
BEFORE
AFTER
I: invasive species
 Non-native species
 Not all exotics are invasive
Characteristics of invasives
 Many invasive species have qualities that make them
successful in novel environments
 Also depends on qualities of the habitats they are
introduced to
© US FWS
Zebra mussel
~2 months
ecological & economic damage
Zebra mussel impacts
 Negative
Decreased
populations of native
shellfish
Altered water
chemistry
Disruption of trophic
dynamics
 Positive
Increased water
clarity
Increased light
penetration into
water column
Increased
photosynthesis
Increased
populations of some
other organisms
Cane toad (Bufo marinus)
P: pollution
Terrestrial
 Acid deposition
 Toxic dump sites
 Litter
 Pesticides
 Inorganic fertilizers
 Tropospheric ozone
Aquatic and marine
 Cultural eutrophication
 Pollutant deposition and
leaching
 Litter
Pollutant Impacts: Litter
Pollutant Impacts: Nutrient loading
Pollution
 Each year pesticides are estimated to kill:
Kill about 1/5th of the U.S. honeybee colonies.
67 million birds.
6 -14 million fish.
 And to threaten 1/5th of the U.S.’s endangered
and threatened species.
Peregrine Falcons:
a success story
O: overexploitation
 Hunting
 Commercial fishing
OVEREXPLOITATION
Figure 11-16
Over-fishing:
About 75% of the world’s commercially
valuable marine fish species are over fished
or fished near their sustainable limits.
Big fish are becoming scarce.
Smaller fish are next.
30% of the fish that are caught are discarded.
Bycatch
Tragedy of the Commons
 Some resources are widely available and owned by no one (or
everyone, depending on your perspective).
 Many fisheries operate by the concept “if I don’t take it,
someone else will”.
(A) Trajectories of
collapsed fish and
invertebrate taxa over
the past 50 years
(diamonds, collapses
by year; triangles,
cumulative
collapses). Data are
shown for all (black),
species-poor (<500
species, blue), and
species-rich (>500
species, red) LMEs.
Regression lines are
best-fit power models
corrected for
temporal
autocorrelation.
(Worm et al 2006,
Figure 3A)
Local examples
Figure 1. Frequency distributions of maximum
known declines among marine fish populations
over periods of at least 10 years, shown
(a) for all 232 populations (the median decline of
83% is identified by a vertical line) and for 3
families:
(b) Clupeidae (n = 56, median decline = 91%;
includes Atlantic herring,
Clupea harengus);
(c) Gadidae (n = 70, median decline = 80%;
includes Atlantic cod, Gadus morhua, and
haddock,Melanogrammus aeglefinus); and
(d) Pleuronectidae (n = 30, median decline = 74%;
includes flatfishes such as flounder, sole, and
halibut).
Hutchings and Reynolds 2004
Fish farming
in cage
Trawl flap
Trawler
fishing
Spotter airplane
Sonar
Purse-seine fishing
Trawl
lines
Trawl bag
Long line
fishing
Fish
school
Drift-net fishing
Float Buoy
Lines with
hooks
Deep sea
aquaculture cage
Fish caught
by gills
Fig. 12-A, p. 255
Shark finning
Bycatch
Incidental capture of non-target
aquatic animals in fishing operations
(commercial or recreational)
Discards in US Fisheries (2002)
FISHERY
DISCARD
WEIGHT
(mt)
DISCARD
RATE
SPECIES
SEUS, G. of Mexico
shrimp trawls
507,845
4.39
Snappers, mackerel, Atlantic
croaker, crabs, porgies,
menhaden
Northeast groundfish
fishery
97,688
1.79
Spiny dogfish, skates,
butterfish, monkish, hake
West coast
groundfish fishery
23,297
0.88
Flatfish, skates, halibut,
whiting, sharks
Source: Harrington et al., 2005
Global Discards (1992-2001)
Source: Kelleher, 2005
Commercial whaling:
another tragedy of the commons
 1925-1975 1.5 million
whales killed
 8 of 11 major species
reduced to levels not
profitable to hunt any more
Commercial whaling
Current pop. sizes:
 Humpbacks 10,000
 Fin 56,000
 Minke 149,000
 Blue 10,000
Pre-exploitation pop. sizes:
 Humpbacks 240,000
 Fin 360,000
 Minke 265,000
 Blue 200,000
Roman & Palumbi 2003
International Policies
 International Convention for the Regulation of
Whaling, 1946 to regulate global whale
stocks (est.’d the IWC)
 Mission was to set sustainable quotas
 Moratorium 1986 (US ended commercial
whaling in 1970)
Commercial Whaling
Despite ban, Japan,
Norway, and Iceland kill
about 1,300 whales of
certain species (minke,
fin, humpback) for
“scientific purposes”.
Figure 12-5
Lake Victoria
Whooping cranes:
a fledgling success story
Whooping Crane Cons. Assoc.
 Current Whooping Crane population:
 Wild #: 407 (99 pairs)
 Captive #: 167 (34 pairs)
Source: Whooping Crane Conservation
Association
P: human population growth