Topic 12The Biodiversity Crisis

Why Should We Care About Biodiversity?

Use ValueEconomic profitsMedicinal sourcesEcological services

Nonuse ValueAetheticsEnjoymentCultural 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.

Fig. 4-12, p. 93

Tertiary

Bar width represents relative number of living speciesEra Period

Species and families experiencing

mass extinction

Millions ofyears ago

Ordovician

Devonian

500

345

Cambrian

Ordovician

Silurian

Devonian

Extinction

Extinction

Pal

eozo

icM

eso

zoic

Cen

ozo

ic

Triassic

Permian

Carboniferous

Permian

Current extinction crisis

Cretaceous

Extinction

Extinction

Triassic

Jurassic

Cretaceous

250

180

65Extinction

ExtinctionQuaternary Today

The Biodiversity Crisis

Endangered & Threatened Species

Some species have characteristics that make them vulnerable to ecological and biological extinction.

AT RISK SPECIES

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: LocallyEcologicallyGlobally (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. STATSThreatened species by broad taxonomic

grouping:Mammals: 37Birds: 74Reptiles: 32Amphibians: 56Fishes: 177Molluscs: 273Other Invertebrates: 258Plants: 245

U.S. FWS

Reasons for biodiversity loss

H:habitat destruction and degradation

I: invasive species

P: population growth in humansP: pollution

O: overexploitation

HIPPO

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 speciesNon-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

ecological & economic damage

~2 months

Zebra mussel impacts

NegativeDecreased

populations of native shellfish

Altered water chemistry

Disruption of trophic dynamics

PositiveIncreased water

clarityIncreased 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

HuntingCommercial fishing

OVEREXPLOITATION

Figure 11-16Figure 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

Fig. 12-A, p. 255

Fish farming in cage

Trawler fishing

Spotter airplane

Sonar

Trawl flap

Trawl lines

Purse-seine fishing

Trawl bagFish school

Drift-net fishingLong line fishing

Lines with hooks

Fish caught by gills

Deep sea aquaculture cage

Float Buoy

Shark finning

Bycatch

Incidental capture of non-target Incidental capture of non-target aquatic animals in fishing operations aquatic animals in fishing operations (commercial or recreational)(commercial or recreational)

Discards in US Fisheries (2002)

Source: Harrington et al., 2005

FISHERYFISHERY DISCARD DISCARD WEIGHT WEIGHT (mt)(mt)

DISCARD DISCARD RATERATE

SPECIESSPECIES

SEUS, G. of Mexico SEUS, G. of Mexico shrimp trawlsshrimp trawls

507,845507,845 4.394.39 Snappers, mackerel, Atlantic Snappers, mackerel, Atlantic croaker, crabs, porgies, croaker, crabs, porgies, menhadenmenhaden

Northeast groundfish Northeast groundfish fisheryfishery

97,68897,688 1.791.79 Spiny dogfish, skates, Spiny dogfish, skates, butterfish, monkish, hakebutterfish, monkish, hake

West coast West coast groundfish fisherygroundfish fishery

23,29723,297 0.880.88 Flatfish, skates, halibut, Flatfish, skates, halibut, whiting, sharkswhiting, sharks

Global Discards (1992-2001)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 whalingCurrent pop. sizes: Humpbacks 10,000 Fin 56,000 Minke 149,000 Blue 10,000

Pre-exploitation pop. sizes:Humpbacks 240,000Fin 360,000Minke 265,000Blue 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 quotasMoratorium 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 12-5Figure 12-5

Lake Victoria

Whooping cranes: a fledgling success story

Current Whooping Crane population: Wild #: 407 (99 pairs) Captive #: 167 (34 pairs)

Source: Whooping Crane ConservationAssociation

Whooping Crane Cons. Assoc.

P: human population growth