CONSERVATON BIOLOGYLecture06 – Spring 2015 Althoff - reference Chapters 6-10

THREATS TO BIODIVERSITYPart III

Ecosystem Degradation and Loss

• 1 of 5 major threats to biodiversity (others were/are mass extinctions & global change, extinction process, overexploitation, and invasive exotics)

• ___________degradation (HD) vs. ___________ degradation (ED): HDprocess by which habitat quality for a

given species is diminished. ED when alterations to the

ecosystem degrade or destroy habitat for many species that constitute that ecosystem.

Degradation vs. Loss

• Often a “fine line” between degradation and loss. Why?

A) difficult to _____________B) dynamics of extinction/colonization

processes and source-sink subpopulations• Probably “_________” phase if reproduction of one

or more species declining and/or at a minimum. A “loss” when no reproduction and no evidence of habitat or the ecosystem providing any critical life history requirement (ex. Breeding habitat vs. foraging habitat vs. wintering habitat, etc.)

the HUMAN footprint

MORE INFLUENCE LESS INFLUENCE

Source: Wildlife Conservation Society

Habitat Degradation vs. Loss• Keep in mind that what might be habitat degradation

or loss for one species might actually be a habitat gain or enhancement for another species (or group of species).

Ex. Small scale: cut a stand of oak-hickory down results in habitat loss for fox squirrels, yet

early successional habitat that results may benefit some butterfly species.

Ex. Endangered species example from the Everglades drain areas to concentratefood in residual pools for wood storks vs. no draining to extend wet periods to benefit snail kites

Wood Stork vs. Snail Kite

• How do we make those “habitat altering” decisions when both species are at risk?

?

Ecosystem destroying processes…. (a short list)

• Conversion of prairies to agricultural land (CRP & GRP in Farm Bill try to minimize such losses)

• Damming a river• Deforestation (prevalent in 3rd world countries)

• Draining a wetland (programs like WRP in the Farm Bill try to minimize such destruction)

• Highway construction (think 4-lanes or more!)

• Contamination• ____________ Development & Extraction….?• ____________…could they have downsides?• _______________…could they have downsides?

Wyoming Red Desert Region

Contamination

• Tends to be a “__________” process…• By definition = a substance (pollutant) that is where

we do not want it to be. This suggest they “______” from where we really want them.

• 3 main media can “move” contaminates/pollutants:a) _________ (abiotic)b) _________ (abiotic)c) _______________(biotic)

• There is overlap, in some instances, across the 3:For example, acid rain begins as air pollutantsand ends up contaminating a lake or causingincreased concentrations of heavy metals in living organisms

Air Pollution

• Nitrogen oxides, sulfur oxides nitric & sulfuric acids = acid rain

• Chlorofluorocarbons (CFSs) & halons affect ozone conc. reduced increase UV radiation levels at earth’s surface

• Ex. ___________ effects on 4 species of frogs in California

Air Pollution…con’t

• _______ often affected (some cases more dramatic than others (see Fig. 8.2 in Hunter and Gibbs)

• Many animal species negatively impacted: could be ______effects (as in they die from contact with the pollutant) or ______effects (they die off eventually because of negative impacts on plants community and/or their prey)

• Definitely air pollutants negatively impact _________—so much so that they are widely used to monitor air pollution

• Heavy metals contamination correlated withreduced reproductive success in

Belgium great tits

Water Pollution• Number of pollutants in water system is quite diverse:

mud and plant matterchemicals: nitrates, phosphates, etc.chemicals: dioxin, discarded Rx drugs, etc.`petro chemicals: oil, gas etc.

• ________ (easier to ID & control usually) sources _________ (harder to ID & control usually) sources

• Aquatic ecosystems _________, degraded on average than terrestrial ecosystems

• ___________________ more at-risk than marine ecosystem (latter too large to pollute entirely)

Water Pollution…con’t• Where monitored, much evidence of significant

degradation of wide-range of fauna• Example of The Rhine (one of Europe’s largest rivers)

(summarized in Hunter and Gibbs text, p156) 9 taxonomic groups showed decline in three

segments of the river:gastropoda (snails)lamellibranchiata (mussels)crustacea (crustaceans)heteroptera (true bugs)odonata (dragonflies)ephemeroptera (mayflies)plecoptera (stoneflies)trichoptera (caddisflies)

Pesticides

• Use to __________ with other organisms for earth’s resources

• Rodenticides, insecticides, herbicides, fungicides, etc.

• Estimates: _________ pesticide products in use with over _________ metric tons of use per year

• _____ all are problematic. Some breakdown quickly. Some are very species specific. Some are used over very small areas.

Pesticides…con’t

• Effects sometimes evident: corpses present after spraying, large areas “browning” (i.e. plants)

• Many impacts, however, are much less conspicuous :

a) impacts on hormone production:delayed sexual maturityaccelerated sexual maturityabnormal sex organs….”endocrine disruptors”….think DDT

b) passing up the food chain (to higher trophic levels) results in _________________(bioamplification)

Biomagnification

• A process whereby ___________________ (pesticides and PCBs) accumulate in the tissues of one species and pass from prey to predators, becoming more concentrated as they travel up the food chain.

• The fat soluble chemicals literally take years or even decades to break down

• Many of these (pesticides and PCBs) have been banned or sharply curtailed in use in developed countries (aka US, UK, etc.) but less-developed countries are still using these problematic chemicals in large quantities.

• ALL species probably vulnerable to this process

Pesticides

• Case study from Lake Kariba in Zimbabwe

• DDT• ___________

____________ (tigerfish, Nile crocodile, and reed cormorant) have high levels

• Parts per billion here

9500

1600

2500

1900

5000

34,200

<0.02%

DDT

Roads, Dams and Other Structures

• Landscapes criss-crossed with roads, railroads, fences, utility corridors (ROWs), and “marked” with buildings, dams, mines, parking lots, etc.

• Estimated at least ____ of land area directly with proximity “apron” that renders additional land and water habitats to lower quality

• Most of these either wipeout critical habitat OR present _________ to many species (think metapopulation dynamics)

• Roads provide an example of direct mortalities….usually affecting taxa like amphibians and small reptiles during movements to and from _______________

Roads as barriers….

• Impact on invertebrates illustrated by study of forest-dwelling carabid beetle (Abax ater)

• Lines represent movements of marked beetles between captures and recapture points.

• Source: Mader, H.J. 1984.

Animal habitat isolation by roads and agricultural fields. Biological Conservation 29:81-96.

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Earth, Fire, and Water

• Soil Erosion —estimated that human activities exceed the rate of “natural erosion” process by ________due to agriculture, livestock grazing, timberharvesting, road and building construction,etc.

• Fire Regimes—______ of regimes can reduce biodiversity as can _______ of prescribed burns

• Water Use—____% use for ___________, ____% for _________, and 7% for domestic purposes with 6% lost via evaporation from reservoirs… ecosystems losing this are obviously degraded

Other contributors to degradation include…

• Deforestation (probably #1 threat by humans currently to biodiversity)

• Desertification

• Draining, Dredging, Damming, etc.

• ________

• Fragmentation (more about that later)

In summary…• Lots of ways humans degrade and/or create loss of

ecosystems. • Often, it comes in the form of _______________

____________ such as:

accelerating soil erosiondecreasing

frequency of fire in ecosystems oraltering timing

removing too much water where it is needed

• Deforestation probably currently #1 for negatively affected biodiversity—especially ______________