Species Approach

When there are no more animals of a particular species left alive, that species is said to be extinct.

In the distant past, several species of animals became extinct through natural causes. There might have been a change in the climate of a particular region, and the plants or animals on which the species lived could have died out because of the change in the weather. Or one animal might have been destroyed by another that was stronger or faster.

But ever since human beings have been on Earth, and especially in the last hundred years, animal species have become extinct because of hunting, pollution, or the destruction of the places where they live.

So many animals are now in danger of extinction that a list is kept in a Red Book. unfortunately, the list gets longer every year.

Characteristics of animals prone to extinction

Endemic species

• Low reproductive rate
• Specialized niche
• Feeds at high trophic level
• Fixed migratory level
• Commercially valuable

Invasive species vs. Ecosystem

Invading species success because:

• High reproductive rate
• Wide life span
• High dispersion rate

The new ecosystem is adequate because there are not direct depredators, the climate conditions are the correct ones.

Disadvantages:

• You just focus your efforts in just one species
• Not holistic
• ‘Cause not all the variable are considered you could miss a higher priority
• Connections between species, biotic and abiotic factor cannot be ignored

Eutrophication

Too many nutrients, algae grows, there is no light, plants die, there is oxygen depletion

The primary causes for eutrophication are anthropogenic Detergents and fertilizer
However there is the case of natural causes.
Eutrophication will cause at the end the dead of many organisms in the body water, most of the times because the lack of oxygen.
This phenomena is specially harmful in slow moving water bodies.

How do we stop it?

• Controlling the runoff from crop fields and from urban areas
• Control the amount of fertilizers used in agricultural practices
• Develop buffer zones around body water. Growing plants around them. The plants will absorb the excess of nutrients
• Set water treatments on sewage sources.
• Oxygenize the water
• Drench the sediment off the water.

Indicator Species

Aquatic ecosystems
Oyster: They fed on organic material and pollutants in the water. They filter the water, removing the particles.
Vertebrate and invertebrate species: Found in rivers and streams. Can determine the grange pollution to kept in check.
Lilies: rivers, lakes, ponds and swamps. They absorb oxygen and sunlight. Indicate abundance of nutrients, which leads to eutrophication.

Mayfly larvae: Native specie that are adapted to live in certain biome. When its number decreases it is a very clear sign that the pollution levels are increasing. They reappear downstream as the effects of the discharge are diluted. This help to indicate the level of pollution in water.
Sludge Worm. Common in lakes and rivers. All fresh water ecosystems. They fed on the sediments and bacteria, hence a great population on them might indicate great pollution in the body water and oxygen-poor water. They indicate stagnant water unfit to drink.
Soil Indicator species
The plants that are found in certain soil might indicate the presence or absence of a specific substance.
Besides plants, there are many other indicators.
Birds eggs can be analyze to find out pesticide sin the soil.
Invertebrates:. Indicator species to identify the use of foreign soils, insecticides, pesticides, and other pollutants.
In Canada there are plans to use soil-living arthropods in order to quantify the pollution in the forests.
A good way to measure the healthiness of an ecosystem and to determine the presence of pollution is biodiversity. High biodiversity indicates a strong and healthy environment.

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Direct and Indirect Measurements

Direct sampling

• In situ. Actually, in the studied place.

Reliable and the best option because of the exact results gases
It is difficult to carry all of the instruments

• Ex situ. Off from the place where sample is established

Use of more methods and instruments, flexible
You cannot experiment instantly and so the sample could suffer some changes.
Shipping and handling is necessary.
When measuring pollution, direct measurements could be use to measure the concentration of:

• gases
• particulate matter
• pH
• dissolved oxygen
• biomass content
• salts
• conductivity
• turbidly

Most of the measurements are giving in units per area, or per
Indirect sample
These measurements are the ones where we measure one factor in order to study or get conclusions for other factor. They don’t really tell you the concentration, you need to interpret them.
Examples of it are

• Indicator species,  They define an specific area or a specific biome
• Biodiversity indexes
• Chromatography
• Spectroscopy

Rollin' to the "ecosystems"

Now, let's talk about the ecosystem. We already know what's a system so let's analyze the word.

ECOSYSTEM

First think that comes to mind, at least for me, is nature, animals, trees, bushes, sunny skies, dry lands or rainy days. Actually with this simple idea the definition of ecosystem can be got.

An ecosystem is the relation between biotic (living components) and abiotic (non-living components) factors in an environment.

Some examples of ecosystems

- A grassland

- A forest

- A pond

- The PrepaTec Cumbres and its surroundings.

In ecosystems matter and energy goes in and out, constantly.

Energy "goes through the system" while matter "circulates around" it.