A great deal of this topic revolves around the concept of SUSTAINABILITY Here s a good short introduction to what sustainability means. What can you do at home to make our world more sustainable?
Introduction to biodiversity Conservation biology is a goal-oriented science that seeks to counter the biodiversity crisis, the current rapid decrease in Earth s variety of life. Extinction is a natural phenomenon that has been occurring since life evolved on earth. The current rate of extinction is what underlies the biodiversity crisis. A high rate of species extinction is being caused by humans. Watch where you step. 3:30
Personal Grooming Products and Great Lakes Marine Life Could removing dead skin cells from your face each night mean doom for perch and other Great Lakes species? Cosmetics manufacturers use these micro beads, as abrasives in facial and body scrubs. They are too tiny for water treatment plants to filter, so they wash down the drain and into the Great Lakes. The biggest worry: fish or turtles or seagulls think of them as dinner; when eaten, the inert beads can deprive animals of nutrients from real food or lodge in their gut, blocking digestive systems. What would this do to a food web?
1. The three levels of biodiversity are genetic diversity, species diversity, and ecosystem diversity Fig. 55.1
Loss of species diversity. Much of the discussion of the biodiversity crisis centers on species diversity. The U.S. Endangered Species Act (ESA) defines an endangered species as one in danger of extinction throughout its range, and a threatened species as those likely to become endangered in the foreseeable future.
Here are a few examples of why conservation biologists are concerned about species loss. The IUCN reports that 13% of the known 9,040 bird species are threatened with extinction. That is 1,183 species!!! The Center for Plant Conservation estimates that 200 of the 20,000 known plant species in the U. S. have become extinct since records have been kept, and another 730 are endangered or threatened. About 20% of the known freshwater species of fish in the world have become extinct or are seriously threatened.
Loss of ecosystem diversity. The local extinction of one species, like a keystone predator, can affect an entire community. Some ecosystems are being erased from the Earth at an unbelievable pace. For example, an area the size of the state of West Virginia is lost from tropical forests each year.
Biodiversity is a crucial natural resource, and species that are threatened could provide crops, fibers, and medicines for human use. The loss of species also means the loss of genes. Fig. 55.3 Biodiversity represents the sum of all the genomes on Earth. Loss of genes = less adaptable.
3. The four major threats to biodiversity are habitat destruction, introduced species, overexploitation and food chain disruption Habitat destruction. By catastrophes or humans. Human alteration of habitat is the single greatest cause of habitat destruction, responsible for 73% of species designated extinct, endangered, or rare. About 93% of the world s coral reefs have been damaged by humans. How does cutting down a forest affect global warming?
3. Toxins can become concentrated in successive trophic levels of food webs Humans produce many toxic chemicals that are dumped into ecosystems. These substances are ingested and metabolized by the organisms in the ecosystems and can accumulate in the fatty tissues of animals. They accumulate because they are non-biodegradable. These toxins become more concentrated in successive trophic levels of a food web, a process called biological magnification. Stored energy molecules decrease, these increase.
Fig. 54.24 The pesticide DDT, before it was banned, showed this effect.
Fig. 54.25
1. Biological and geologic processes move nutrients between organic and inorganic compartments A general model of chemical cycling. There are four main reservoirs of elements and processes that transfer elements between reservoirs. Reservoirs are defined by two characteristics, whether it contains organic or inorganic materials, and whether or not the materials are directly usable by organisms.
Fig. 54.15
The water cycle is mostly a physical process (evaporation, condensation), but part is biological, right? Fig. 54.16
Did you get it right? Respiration and dehydration synthesis creates new water, and photosynthesis and hydrolysis breaks water molecules apart.
The carbon cycle fits the generalized scheme of biogeochemical cycles better than water. Fig. 54.17
The nitrogen cycle. You DON T need to know this for the EOC, but let s take a look. Nitrogen enters ecosystems through two natural pathways. Atmospheric deposition, where usable nitrogen is added to the soil by rain or dust. Nitrogen fixation, where certain prokaryotes convert N 2 to minerals that can be used to synthesize nitrogenous organic compounds like amino acids.
Fig. 54.18
Recent studies indicate that human activities have approximately doubled the worldwide supply of fixed nitrogen, due to the use of fertilizers, cultivation of legumes, and burning. This may increase the amount of nitrogen oxides in the atmosphere and contribute to atmospheric warming, depletion of ozone and possibly acid rain.
This may cause big problems in the future with the balance of this cycle, just as human burning of fossil fuels is causing problems related to the carbon cycle. Two more examples of human activity affecting the ecosystem in negative ways.
2. Combustion of fossil fuels is the main cause of acid precipitation The burning of fossil fuels releases sulfur and nitrogen oxides that react with water in the atmosphere to produce sulfuric and nitric acids. Fig. 54.23a
These acids fall back to earth as acid precipitation, damaging ecosystems greatly. The acids can kill plants, and can kill aquatic organisms by changing the ph of the soil and water. Fig. 54.23b
4. Human activities may be causing climate change by increasing carbon dioxide concentration in the atmosphere Rising atmospheric CO 2. Since the Industrial Revolution, the concentration of CO 2 in the atmosphere has increased greatly as a result of burning fossil fuels. Normally, this carbon would stay locked up in coal and oil for a long time.
Measurements in 1958 read 316 ppm and increased to 400 ppm in May 2013, highest in a few million years Fig. 54.26
The greenhouse effect. Rising levels of atmospheric CO 2 and methane may have an impact on Earth s heat budget. When light energy hits the Earth, much of it is reflected off the surface. CO 2, methane and other gases cause the Earth to retain some of the energy that would ordinarily escape the atmosphere. This phenomenon is called the greenhouse effect. The Earth needs this heat, but too much could be disastrous.
Global warming. How will increasing levels of CO 2 in the atmosphere affect Earth? A doubling of CO 2 will cause a 2º C increase in the average temperature of Earth. Rising temperatures can cause polar ice cap melting, which can flood coastal areas. The distribution of organisms has already started to change. It is important that humans attempt to stabilize their use of fossil fuels.
5. Human activities are depleting the atmospheric ozone Life on earth is protected from the damaging affects of ultraviolet radiation (UV) by a layer of O 3, or ozone. Studies suggest that the ozone layer has been gradually thinning since 1975. Fig. 54.27a
The destruction of ozone probably results from the accumulation of chlorofluorocarbons, chemicals used in refrigeration and aerosol cans, and in certain manufacturing processes. The result of a reduction in the ozone layer may be increased levels of UV radiation that reach the surface of the Earth. This radiation has been linked to skin cancer and cataracts. So ozone up high is good, down low bad. But when it traps UV radiation, ozone up high also contributes to global warming!
The impact of human activity on the ozone layer is one more example of how much we are able to disrupt ecosystems and the entire biosphere. Are we entering the Anthropocene Era? 18 minutes if time. So what to do??? (9 min.)
Introduced (aka exotic, invasive) species. Introduced species are those that humans move from native locations to new geographic regions. The Nile perch was introduced into Lake Victoria as a food fish, but led to the extinction of several native species. Pythons? Fig. 57.7a
Overexploitation. This refers to the human harvesting of wild plants and animals at rates that exceed the ability of those populations to rebound. The great auk was overhunted and became extinct. Fig. 55.8
The African elephant has been overhunted and the populations have declined dramatically. The bluefin tuna is another example of an overharvested species. Fig. 55.9
3. Conserving species involves weighing conflicting demands Conservation biology highlights the relationship between science, technology and society. High profile organisms may be the most popular due to use as resources. Questions about human habitat needs also arise. The ecological role of the organisms must be addressed as well. And then there is the economy. Decisions must weigh the costs and benefits. EOC!
4. Restoring degraded areas is an increasingly important conservation effort Restoration ecology applies ecological principles in developing ways to return degraded areas to natural conditions. Biological communities can recover from many types of disturbances, through a series of restoration mechanisms that occur during ecological succession.
Fig. 55.21
Bioremediation is the use of living organisms to detoxify polluted ecosystems. Restoration ecologists use various types of organisms, like plants that absorb heavy metals, to remove many different types of toxins from ecosystems. Fig. 55.22
What does it all add up to? Too many people on earth for the amount of resources each person uses. It all boils down to how much fossil fuel has to be burnt for you to live the life you do. This is called your carbon footprint. Let s calculate here. Now some practice questions
Which of the following is NOT an example of sustainable development? A. Using one insect to control another that is consuming crops B. Planting crops that will grow in the shade to reduce deforestation C. Installing solar power cells to reduce the need to burn fossil fuels D. Using the slash-and-burn technique to clear land for farming
To reduce the use of fossil fuels, automobile makers are producing electric cars. Which of the following is an advantage of using cars that run on electricity instead of gasoline? A. Electric cars use batteries that are easy to recharge B. Electric cars cost less than gasoline-powered cars C. Electric cars do not release pollutants into the environment D. Electric cars are easier to operate than gasolinepowered cars
Which of these is the best reason for using wind farms to produce electrical power? A. The use of wind farms makes electricity less expensive B. The use of wind farms conserves nonrenewable fuels C. Wind farms have little environmental impact D. Wind farms are suitable for most locations
A power company wants to build a new electric power plant next to a river and use water from the river for cooling. Which of the following should be studied before deciding whether to let the company build the plant? A. The price of the high-voltage wires used to transmit electricity B. The effects of warmer water on the fish species that live in the river C. The power company s contributions to support local sports teams D. The efficiency of the generators that the company plans to build
Human activities that increase carbon dioxide in the atmosphere are likely to cause which of the following environmental changes? A. Tsunamis B. Decreased plant growth C. An ice age D. A higher sea level