Conservation Bio Test 1 Part 2

Habitat Degradation

Reduction in ecosystem quality, not necessarily habitat quantity, primary cause of biodiversity loss, directly linked to human population growth and human activities, pollution = most important source of degradation, the most effective conservation strategy is habitat preservation, which must be a bigger priority in the coming decades 

Tropical Deforestation

Remains the biggest problem, 7% of land but >50% of all species, 40% of tropical forest is in the Brazilian Amazon, 60% of tropical deforestation occurs in the Western hemisphere (i.e. Neotropics), half of that occurs in the Brazilian Amazon, largest relative amount of deforestation occurs in Asian forests = ca. 1.5% per year, extrapolation based on current rates = no primary tropical forest will exist outside reserves by 2050

Firewood and Charcoal

>2 billion people cook with wood and charcoal

Major Sources of Tropical Deforestation

Firewood and coal, shifting cultivation, commercial logging and agriculture, road construction

Tropical Montane and Deciduous Forests

Good for cattle and agriculture, easy to clear and burn, moderate rainfall, pleasant climate 

Temprate Grasslands

97% of tallgrass prairie destroyed since 1800

Wetlands

Large: everglades, marshes (bayou), riparian forests, small: vernal pools, springs, bogs 

Marine Coastal Habitats

Coral reefs and mangroves

Consequences of Degradation

Biodiversity loss, desertification, erosion, overgrazing

Biomagnification

Pesticides become concentrated in organisms at higher trophic levels 

DDT

Classic example of an insecticide

Insecticide Resistance

Artificial selection for immunity

Hyperdispersion

Pesticides appear in tissues of top predators far from the source, polar bears, marine mammals, etc. 

Atrazine

2^nd most widely used herbicide in US (after glyphosate), most common pesticide in drinking water, endocrine disruptor, banned in EU, approved by EPA (controversial) 

Neonicotinoids

Nicotine-like compounds, regulated in many countries, colony collapse disorder, European honeybee workers leave hive never return, many possible explanations 

Fipronil

Also implicated in CCD, neurotoxin, disrupts insect CNS, used as bait, long-acting, residual effect, especially good for killing social insects, cockroaches, and fleas, toxic to fish and some birds 

Point Sources

Localized discharges of pollutants, sewers, treatment plants, city storm drains 

Non-Point Sources

Cumulative effect of small amounts of contaminants collected from a large area, agricultural runoff 

Groundwater Contamination

Difficult to detect

Thermal Pollution

Industry, power plants

Hormones/Caffeine

Environmental estrogens may be causing precocious adolescence, caffeine is killing fish or something 

Eutrophication

Fertilization = high NPP – high respiration and anoxic decomposition (eventually), P often limits NPP (except in oceans) 

Air Pollution

Any chemical, physical, or biological agent that modifies atmospheric properties

Human Mortality

Focus on consequences for humans, also affects biodiversity, although we don't often think of it as habitat destruction, linked to heart disease, lung cancer, stroke, COPD, and pediatric lung infections, causes >3 million deaths annually, not getting better, prediction 6.6M deaths per year by 2050 

Lichen Air Pollution

N, S, heavy metals, etc., especially sensitive to N and S emissions, more N causes community shift from oligotrophic to eutrophic species, S deposition disrupts photosynthesis via acidification of tissues 

Tree Air Pollution

Acid Rain

Acid Rain

Industrial-scale output of NOx, NH3 and SOx, combine with H2O to make H2S, HNO3, NH4, and SO2, cars and agriculture produce 90% of N emissions, sulfuric and nitric acids significantly lower the pH of rainfall; kills trees 

Main S Producers

Coal plants, marine vessels (and other industrial scale diesel combustion), “bunker” fuel residual oil No.5 or No. 6 fuel oil, refinery dregs, high impurity content, must be preheated to 200F 

Degraded Soils

Affects ecosystem properties, slows decomposer microbe activity, metal toxicity, ongoing problem in the northeast and midwest US, but major improvement over two decades, pollution controls, cleaner fuels, industrial decline, increasing in China – high-sulfur coal 

Ozone

Reflects UV radiation in stratosphere, but also a pollutant, damaging to plants at moderate levels, ___ levels rising faster than CO2, ___ hole over Antarctica, Cl and Br in aerosols catalyze O3 breakdown 1970-2008 – hole in ozone grows 

Lead

Toxic metal, tetraethyl ____ was added to gasoline as anti-knock agent ca. 1920-1975, currently banned in most countries, still used in some (e.g. China, N. Korea), neurotoxin, exposure is correlated with violent crime rates following 20 yr lag