1. Ecosystems.
(10 pts) Provide a review of the process of succession and trends in biodiversity, productivity, and nutrient cycling.
Ecological succession refers to the process of gradual change of the ecosystems. This is attributed to the fact that habitats do not remain constant and they keep changing over time. Succession is divided into two; there is primary succession and secondary succession. Primary succession refers to changes which occur on an environment that has never been colonized before, for instance, quarrying on land that has never been quarried before. Secondary succession on the other hand involves environmental disturbance on a previously colonized but disturbed habitat.
Species living within a particular environment, the chemical nature as well as the physical nature of that particular habitat changes over time. This is because the processes carried out by those living organisms impact on the environment in various ways. In terms of environmental adaptation, each species is adapted to particular environmental conditions. If an organism is not well adapted to an environment, it is eliminated while the well adapted organisms colonize the environment. Succession within a habitat is wholesome and involves the whole community. It not only involves plants but also other microorganisms, animal species and plant species. Succession usually follows a given pattern and can be predicted. Communities in succession change from one sere to another. These seres are rather similar and thus may merge, forming a final community known as a climax community. Changes in an ecosystem are influenced by climate, microclimate, weather and soil type among other conditions.
Nutrient cycling involves the exchange of organic and inorganic matter back into the production of living matter. In an ecosystem, this process is regulated by food webs, through which organic matter is decomposed into organic materials.
2. Gaia.
- (15 pts) James Lovelock used the biogeochemical cycling of sulfur as an example of how life has moderated climate, particularly temperature on Earth. Summarize this process and (as illustrated by the Daisy model) the general trend in climate stability of Earth versus solar output (well, for at least for the past 600+ million years).
The biogeochemical cycle of sulfur outlines the events involving the movement of sulfur between minerals and living systems. The sulfur cycle comprises of both the terrestrial and the atmospheric portions. This process involves as series of steps:
- The cycle begins within the terrestrial portion with the weathering of rocks, thus releasing the stored sulfur.
- The released sulfur then comes into contact with air and is converted into sulfate.
- The formed sulfate is then taken up by plants and microorganisms, which convert it into organic forms. The sulfur is then moved through the food chain when animals consume these organic forms.
- When these organisms die and decompose, their consumed sulfur is then released into the atmosphere in the form of sulfate, while some accumulates in microorganisms. Other activities such as volcanic eruptions may also release sulfur into the atmosphere.
- Sulfur from the atmosphere then falls back to the earth and oceans in rainfall. Terrestrial runoff also deposits some sulfur into oceans. This sulfur gets into ocean communities and is transmitted through the food chain. Ocean sulfur may get back to the atmosphere through sea spray.
The daisy Model of climate stability versus solar output
As illustrated by the Daisy Model, the climate of the world originally was cool enough, favoring a number of species to thrive. The atmosphere was friendly enough and its constituents were the kinds that could absorb enough temperature from the sun and lose the excess energy. The black daisies which were dominant then, could absorb solar energy and freely let the excess get back to the atmosphere. With time however, the white daisies which have a reflective effect thrived and thus, reduced the temperatures of the daisy world drastically. With time, the solar intensity increased and killed all the white daisies, leading to high climatic temperatures of the daisy world.
- (10 pts) Apply the preceding summary to predict how sulfur enrichment of our atmosphere from fossil fuel burning has and will continue to alter our climate. A minimum of one of these opinion questions will be graded; there are more, below.
Introduction of gases among others over time may initially form the kind of atmosphere which reflects solar energy away, thus cool temperatures on the earth. With time, the intensity of the sun will increase accompanied by corresponding climatic change. It may get strong enough as to penetrate the introduced atmospheric sulfur, yet the excess energy cannot be lost. This will then result in global warming, which is already taking effect. As in the recent years, the solar output has increased and climatic temperatures considerably increased. Further enrichment of the atmosphere with sulfur may make the situation worse.
3. Habitat Destruction and Management
a. (15 pts) Provide a thorough review of the patterns of habitat destruction explored in lecture.
Terrestrial habitat destruction – this has been done mainly as a result of increase in population. The main activities that contribute to this include clearing of natural plantation for agricultural activities, mining, logging and urban sprawl. This has contributed to extinction of rare species of organisms across the world.
Aquatic ecosystem destruction – this has been donee mainly through pollution. This is by deposition of industrial effluents as well as other chemicals which are harmful to aquatic animal into water bodies. Overfishing has also resulted in marine ecosystem imbalance. Overexploitation of water bodies in terms of water use has also greatly contributed.
Coastal ecosystem destruction – these have been destroyed through costal land reclamation as well as destruction of coral reefs, overfishing, pollution and introduction of invasive species.
- (10 pts) Apply your summary to form your own opinion regarding whether these patterns are indicative of an over-utilization of our natural resources; i.e., a recipe for some form of local, regional, or global societal collapse (drastic or gradual). Note: These are “free” points so long as you explain your opinion and your reasoning for that opinion.
These habitat destruction patterns are indicative of overutilization of the available natural resources. This is because if people can for instance strike a balance between agriculture and fishing, the ecosystems will remain stable. Maintaining this balance, however, is rather difficult because, while the human population increases every other day, the sizes of the ecosystems remain the same. As such, overutilization of these available facilities is almost inevitable. The solution may only be in the improvisation of artificial facilities such as fish ponds, so as to minimize on the amount of damage caused.
- (15 pts) Explain why conservation organizations (public and private-non-profit) try to preserve or re-establish numerous large patches (of an ecosystem) with limited distance between them.
This is majorly to safeguard the species within a given ecosystem. If only one kind of an ecosystem exists in an area, the members may be forced to over exploit it. Besides, should one ecosystem be threatened for one reason or another, the species living within it can find refuge in the next ecosystem. This kind of conservation is also done to strike a balance between ecosystems in a given region.
- (5 pts) Apply your summary (c) to develop a general opinion regarding whether such preservation efforts are worthwhile, given that they inevitably mean some reduction in agricultural production. Note: These are “free” points so long as you explain your opinion and your reasoning for that opinion.
These efforts are worthwhile. Without such management, human beings may end up destroying all ecosystems, leading to drastic environmental implications. Besides, agricultural production can still be done on the available land. Other methods of agricultural production such as the introduction of genetically modified organisms, which mature within a shorter period of time, can be used in place of the natural organisms that take rather long on agricultural lands before harvest.
Resource exhaustion
- (15 pts) Provide a thorough review of the patterns of resource exhaustion explored in lecture
Resource exhaustion refers to the utilization of resources faster than they can be replenished. There are many patterns or rather many causes of resource depletion. These include:
Deforestation – this involves the cutting down of trees or burning down of natural forests.
Erosion – this is caused by a number of factors among which are poor agricultural practices which eventually result in poor quality of soil.
Slash and burn agricultural practices conducted in many countries where agriculture is practiced.
Over exploitation of oil and other minerals, which is done at a rate that does not allow the ore to regenerate the minerals.
Extreme reclamation of wetlands, which are usually considered useless, yet they contain very important plants among other organisms.
Overpopulation within limited areas of land
- (10 pts) Apply your summary to form your own opinion regarding whether these patterns are indicative of an over-utilization of our natural resources; i.e., a recipe for some form of local, regional, or global societal collapse (drastic or gradual). Note: These are “free” points so long as you explain your opinion and your reasoning for that opinion.
Deforestation, extreme reclamation of wetlands, over exploitation of oil and other minerals as well as slash and burn agricultural practices are indicative of overutilization of our natural resources. Overpopulation within small regions too is an indicator of the same. This is because the people within those limited regions have to scramble for the few resources which are available. The high rate at which resources such as forests and minerals are getting depleted is also a clear indication of poor resource utilization and management.
5. Invasive species
a. (20 pts) Provide a thorough review of the impacts invasive species have had on North American ecosystems, including the traits that promote invasive ability and at least one example of each trait.
Invasive species are organisms which do not belong where they have been intentionally or accidentally brought by human beings. Others invade regions to which they are not suited on their own. These species may lead to degradation of habitats and destruction of the native species.
These invasive species have got a range of traits that enable them to survive in new invaded ecosystems. These traits include:
Close association with humans such as the rhinoceros beetle
Ability to survive on a wide range of food types such as the Zebra Mussels
Tolerance to a wide range of environmental conditions for example B.Tectorum plant species that can withstand frequent fires
Fast growth
Rapid reproduction
High dispersal ability
The ability to alter growth form to suit current conditions
- (10 pts) Look up recent estimates of the cost invasive species have had on the US and worldwide. Use this information and your summary (a) to form your own opinion regarding whether laws should be enacted to restrict the rights of US citizens to purchase, transport, sell, or release exotic species. Keep in mind that such laws will have their own economic impacts as well as an infringement on the liberty of US citizens. Which price is worse? Note: These are “free” points so long as you explain your opinion and your reasoning for that opinion.
In my opinion, laws should be enacted to restrict the rights of US citizens to purchase, transport, sell or release exotic species. This should be done by a department that comprises of experts who are well versed with knowledge on plant and animal species, as well as their effects on new ecosystems. It is important that such a restriction is enacted to ensure the local systems are not threatened. Once the laws have been enacted, the citizens should be educated on the importance of maintaining organisms that are native to their ecosystems. They should also be educated on the importance of having their exotic species approved before getting into their native ecosystems. Information on the massive negative impacts that these exotic species may have on their various ecosystems should also be given, so that they do not feel that their liberty is infringed upon.
6. Pollution.
(20 pts) Visit the website for either ‘Physicians for Social Responsibility’ (http://www.psr.org/) or the ‘EPA’ (http://www2.epa.gov/learn-issues/learn-about-chemicals-and-toxics) and look up a toxin. Report the following:
- What is the toxin?
mercury
- Why did you choose this toxin?
Because it is a commonly available toxin that affects a number of people; and has adverse effects on its victims.
- Is it a carcinogen, teratogen, or endocrine disrupter (or more than one category)?
Mercury is a carcinogen, teratogen as well as an endocrine disrupter.
- What forms of industry produce the toxin?
Cosmetic manufacturing industries
Fluorescent bulb and battery industry
Pharmaceutical industries
- Where in the environment or in what product(s) is the toxin most likely encountered?
In medical devices such as thermometers and blood pressure instruments
In fluorescent light bulbs and batteries
In laboratory chemicals, vaccine preservatives, pharmaceuticals and dental amalgams
In barometers, hydrometers and certain flame sensors.
- Is it a chronic or acute toxin?
Mercury is both an acute and chronic toxin depending on the levels of exposure.
vii. Is the toxin biomagnified? Also summarize the concept of biomagnification.
Mercury is biomagnified. Biomagnifications refers to the concentration of a substance within an organism, beyond the concentration of that substance in its diet. This happens when a substance cannot be broken down by environmental processes, when the concentration of the substance increases progressively as it moves up the food chain and when organisms have no internal degradation or excretion of the substance.
