by Jason Buchheim
Director, Odyssey Expeditions

The reason environmentalism and ecology get mixed up in the media is that the scientific basis of an endangered species problems come from studies ecologists have conducted determining the ecological relationship between the species and its deteriorating environmental conditions. The environmentalists use these studies as the backbone for reasons to protect and preserve our natural environments.

I. Living things do not exist as isolated individuals or groups of individuals. II. All organisms interact with others of their own species, with other species, and with the physical and chemical environments that surround them. III. All organisms have an effect on each other and their surroundings. 

No living organisms exists entirely by itself, it is a part of a community organisms which interact and have effect on each other and their environment.

Sun-original source of energy. Captured by autotrophs {from latin, self-food}, that's plants, the primary producers. The energy is stored as food, which drives the heterotrophs {latin, different-food}, the consumers. 

Trophic Levels Producers-the plants storing the energy as food. Herbivores-the animals which eat the plants. i.e., Cows, Parrotfish, Humans. Carnivores-the animals which eat the animals which ate the plants. i.e., Coyotes, Barracuda, Humans. Second Level Carnivores- the animals which ate the first level carnivores. i.e., Bears, Sharks, Humans. Third Level Carnivores- very rare Fourth Level Carnivores- some do exist Decomposers- break down the complex organic molecules of dead organisms from all trophic levels. Mostly Bacteria, also Hagfish, funguses, etc. 

In communities worldwide, the same trophic levels exist. The species constituting each level differs geographically, and in some areas each level may have a greater or fewer number of species constituting that level. Ecologically equivalent species replace each other geographically, the species structure is variable. The trophic structure, in contrast, is a constant. 

There once was a lady who swallowed a fly. I don't know why she swallowed the fly, I guess she will die. There once was a lady who swallowed a frog, she swallowed the frog to swallow the fly. I don't know why she swallowed the fly, I guess she will die. There once was a lady who swallowed a snake, she swallowed the snake to swallow the frog, she swallowed the frog to swallow the fly. I don't know why she swallowed the fly, I guess she will die. There once was a lady who swallowed Riki Tiki Tavi, need I go on, I bet she dies.

**Take home message: The closer our food source comes to the bottom trophic levels, the more Earth friendly we are. 

This is because much less grain would have to be grown if we ate cereal as our food source rather than steak. The cow supplying the steak must convert the energy from the grains into its own flesh, as well as support its body heat, walking around, and in general 'cowness'. Five to ten times as much grain must be grown if we are going to get our energy source from a grain fed cow then if we just ate the grain itself. Grain, and the land it is grown on, are not an unlimited resource. 

Pool- A major receiver of an element or compound. There is continuous movement of the element or compound in and out of the pool.  

Sink- A depository of an element or compound that is not recycled. A certain amount of the chemical passes in and is not recycled. A sink can become a limiting agent on the continued growth or health of an ecosystem, unless it can be tapped again. The retapping of a sink is usually through geological action such as movement or erosion. 

Two examples of biochemical cycles: 

A: Carbon Cycle 

Carbon is a vital element in all life systems, it is the basis of organic chemistry and is a major part of all sugars, proteins, fats, etc. Carbon Dioxide is abundant in water in the forms of carbonic acid and bicarbonate. Plants "fix" the carbon from the water into organic compounds through the process of photosynthesis. This carbon is transferred to animals by herbivory and predation. Respiration and bacterial action return the carbon to the pool. When carbon is deposited into the skeletons of corals or the shells of mollusks, it does not return to the pool. The coral skeletons and shells are a "sink". 

B: Nitrogen Cycle 

Nitrogen is also a major constituent in organic chemistry found in many of the basic amino acids and a required element in photosynthesis. Air is the major pool reserve of nitrogen, but in its raw form it is unusable to most organisms. Nitrogen must first be converted into a nitrogen compound, "fixing" by plants. This is done through a symbiotic relationship between bacteria and plants. Once the bacteria and plants have "fixed" the nitrogen, the nitrogen compounds are available for all the other organisms to use in their biological processes. Community Structure- General Ecology

Two general ecological success strategies have evolved for the continued propagation of species. These strategies are known as Equilibrium and Opportunistic, and they are most concerned with how frequently the species will face environmental disturbances.  

The Equilibrium success strategy is best suited for ecosystems with few environmental disturbances. The species which follow the equilibrium success strategy are usually the larger organisms. They have few reproductive periods per year, slow development, low death rate, are highly mobile, but they have low recruitment into and later colonization time of newly disturbed environments. As they survive in an environment for a long time, natural selection of the individuals can make the species highly adapted to their environment. In the oceans, these species are usually Lecithotrophic, with larger, fewer, more costly and less dispersed eggs. The problem with the equilibrium success strategy is when environmental stress or change does occur, its followers are not able to adapt to the stress through natural selection of the best suited individuals. The infrequent reproductive periods and slow development slows down the evolution process. The species may become extinct before it has had the opportunity to adapt to the new environment.  

The Opportunistic success strategy is best suited for ecosystems with frequent environmental disturbances. The opportunistic species are usually small compared to the equilibrium species. They have many reproductive periods, a fast development time, a high rate of recruitment into new environments, and are the first to colonize a freshly disturbed environment. These species also face high death rates, low mobility, and have small body sizes. The high rate of reproduction and development allows these species to quickly become better adapted to new environments. In the oceans, these species are usually Planktotrophic, with smaller, more numerous, easy to produce and highly dispersed eggs. The opportunistic species are the first to find and colonize a freshly disturbed environment and enjoy early success in the environment. With their high rate of evolution, they are able to continually survive in environments which face frequent environmental stresses. If the environment does not face another environmental stress for a long time after the opportunistic species have settled, then equilibrium species will usually gain the upper hand and soon crowd out the opportunistic species. Opportunistic species have much lower juvenile and adult death rates so they are the better competitors in a non-changing environment. As soon as there is environmental stress, the opportunistic species gain the upper hand, and the battle for species survival continues.

Leibig's Law of the Minimum Each species in a community has certain tolerances with respect to environmental factors. If the limit of tolerance is exceeded in some are by a given factor (i.e.. Temperature) the species will be absent in the community.  Each species requires a certain minimum amount of materials. If the concentrations of these necessities (i.e.. Nitrate) falls below the minimum then the species disappears. The above is true even if all other factors and substances are favorable for the species. 
**If you were living on the most beautiful sailboat in the world, full of the best food and drink available, and there were members of the opposite sex waiting on your every whim, you still could not survive if the sailboat had sunk to the bottom of the ocean and you had no scuba tank. Your minimum requirement would not be met, no air; the environment would be exceeding your bodily tolerances of relative humidity.

A species fundamental niche can be wide or narrow, meaning that it can have great latitude in what kind of actual environment it can exist in, or it can have very specific needs that the environment must posses in order for the species to exist in that environment. A Generalist has a very wide fundamental niche, and can exist in many different local environments. Generalists make great opportunistic species, as their widely dispersed eggs can settle and succeed in many of the new environments they may reach. A Specialist has a narrow fundamental niche. The number of environments a specialist can occupy is much lower than that of a generalist. Specialists are often equilibrium species; a long period without environmental disasters allows them to become very well adapted to a particular environment, which can enable them to out-compete the generalists in resource allocation as long as the environmental conditions remain constant. 

A generalist is a 'Jack of All Trades' and can do many things. 

A Specialist is an 'Airline Pilot' who can do one thing very well.

There is room and need in the world for both generalists and specialists.

Species structure in ecological communities can be measured by: 

Species Richness: the total number of species in a community. Species Diversity: combines into a single index a measure of both the number of species [Richness] and the distribution of the total number of individuals among the species [Evenness]. 

Richness= r= Total number of different species in a community  

Diversity= H'= - S Pi loge Pi i=1"for all species (species 1 through species S), multiply the relative proportion of that species (Pi) times the logarithm of Pi, then add the products together and change the sign"Evenness= J= H'/ H'max= H'/ loge S, max would be 1 [perfect evenness]

EQUILIBRIUM: Species composition in a community is usually in a state of equilibrium. 

I. High diversity is due to a large number of habitats and/or finely divided narrow niches maintained by various feedback mechanisms (i.e., Niche Diversification) 

II. Stable nature of the physical environment allows equilibrium to be maintained.

I. High species diversity is maintained through continual or gradual environmental change and disturbance. 

II. Promotes a changing species composition through the presence of many species that are not highly specialized.

I. Communities which experience very frequent disturbances that kill most or all of the resident species would tend to be colonized by only those few species that happen to have the ability to attain maturity and reproduce quickly before the next catastrophic event. 

II. Areas experiencing infrequent or small disturbances on long time intervals would also have low diversity; the most efficient competitors have had time to eliminate most or all other species and take over the community. 

III. Only when the disturbances are intermediate in frequency does species diversity increase; enough time is available to permit establishment of a variety of slower growing and reproducing species, and the interval between disturbance events is short enough to avoid competitive exclusion. 

**Ample evidence exists for both schools of thought, depending on the particular environment and the methods used to investigate the models. 

** On a global scale, our biospheres richness and diversity indexes have started into a major downward trend as we loose many species to extinction and cover vast areas with monoculture crops [crops of the same species]. This has happened five previous times in the Earths history, and is known as a major extinction event, such as the way the dinosaurs departed. Models of Community Succession.

There are three major models as to how this community change takes place. 

Facilitation Model of Succession: Each community modifies the environment in turn making it suitable for the next community. Orderly change to the physical environment is known as Ecological Succession, and the terminal, persistent community is the Climax community. 
An example of this is in a pine forest, where an area has been opened up due to fire. The first trees to settle in the opening are the aspens, which can tolerate a lot of sunlight. As the aspens grow, they provide shade for the new pine trees, which don't tolerate direct sunlight well. As the pines grow, they will out compete the aspens for the sunlight as they grow taller then them, and soon there will be only pines.
Inhibition Model of Succession. No species is competitively superior, whichever species gets to a site first holds it against later settlers. The succession is not an orderly predictable process, and generally proceeds from short lived to long lived species. There is no climax community 

Tolerance Model of Succession. This model is intermediate between the other two. Early colonizing species are not necessary, any species can start succession. Community change occurs as species that are more tolerant, or more competitively superior, prevail. 

**Marine Environments tend to follow the second and third models. In many cases the initial occupier does not modify the environment to make it unsuitable for them and more suitable for subsequent organisms. They may even prevent the occupation of an area by more competitively superior organisms, and their is no climax community.

-Energy  
-Environment [Climate]  
-Interactions among component species  
-Tolerance limits on population ranges  

All systems on earth are limited by the amount of energy available from the sun. This is the greatest limitation of all.  

Limits on populations 

All species possess the reproductive potential to produce much larger populations than are observed under natural conditions. Given unlimited resources, a population could quickly grow to exponential proportions. Nature has control mechanisms so that if a population explosion occurs, it is quickly reduced. 

     POPULATION CONTROLS: I. Competition II. Predation III. Parasitism IV. Disease 

Competition: interaction among organisms for a necessary resource that exist in short supply. I. Intraspecific- among individuals of the same species II. Interspecific- among individuals of different species, usually two closely related species 
The organisms could be competing over light, food, nutrients, water, or space, etc. 

Options: 
A. Share limited resource, both individuals are hampered, which inhibits their growth, development, and reproduction. 
B. One excludes the other, controlling population. Competition Exclusion Principle: No two species with the same requirements can coexist in the same place at the same time. Complete competitors cannot coexist. This leads to niche diversification, where the competitors will diverge on their similar needs, a major factor in the formation of additional species. 

As population increases, competition increases as a limited resource becomes scarcer. Increased competition increases the stress on organisms, absorbing energy used for growth and reproduction, effectively limiting populations. Population Regulation

Predation: The consumption of one species by another. Consumer is the predator, victim the prey. 
I. Predator may be most important factor in regulating the #'s of prey species. Removal or the predator will have a marked effect on prey population, causing it to increase dramatically. 
i.e., The removal of coyotes from rangeland has been shown to dramatically increase the rodent population. The coyotes were the main predator limiting the rodents population; the rodents had an almost unlimited supply of food and quickly underwent a population explosion. 
II. Predator may have little effect on prey population. The predator was not the main factor limiting the preys population. The prey may be missing other elements in its environment that prevent a population explosion. 
In some communities, the existence of Keystone species has been shown. A keystone species is one of the most important species populations in a community; its affects are felt by most of the other populations in the community. Removal of the keystone species can cause great changes in the community structure even though most species are not the prey of the keystone species. An example of a keystone species is the seastar Pisaster ochraceus, which feeds on mussels. The removal of the seastar from the intertidal zone causes a population explosion in the mussels, which soon crowd out all the other species in the intertidal, lowering the overall species diversity.
Parasitism and Disease: As populations expands, the opportunity for parasitism and disease greatly increases as the organisms will be living closer together, polluting their local environment with waste and competing strongly over resources. They will become weakened and highly susceptible to the effects of parasitism and disease, lowering their populations. Little is known about the specifics of these effects in the marine environment, but we all know how it is affecting man.