Riparian Zone Retreatand Population Studies

Ross NelsonBiology 2Period 5

Virginia Opossum (Didelphis Virginiana)

• Virginia Opossum lives in North America and Central America

• The animals usually prefer to live in habitats near streams or swamps. They can be found in wet

areas or arid places

• Opossums are omnivores. Their diet consists of mainly insects and carrion. However, they also eat some fruits and grains too, when they’re in

season

• Opossums are generally preyed on by foxes, owls, coyotes, hawks, and of course, humans

• Opossums are important to the ecosystem. They are scavengers that eat trash and other foods that most animals don’t. They play the important role

of eating and being eaten

Factors which Affect Birth Rate of the Opossum

• Mates from January to July• Reproduces yearly• Mothers have from one to

thirteen babies. Although the average amount is six to seven for a litter

• Opossums generally carry their young around on their backs

• Usually live for the 18 months due to a high mortality rate from cars

Factors Which Affect the Death Rate of Opossum

• Opossums are preyed on by foxes, owls, coyotes, hawks, and humans. They don’t prey on any animals themselves

• The opossum generally lives 18 months. Their life spans are longer, but most are hit by cars before their natural deaths

• Humans love to harm opossums• Over population of the opossums

would most likely exhaust the animals’ food sources and kill it

Food ChainEarthworm

Crayfish OpossumRed Fox

Producer

Decomposer

First level consumer

Omnivore

Second level

consumer

Omnivore

Third level consumer

Carnivore

Food Web

Population Sampling Techniques

• Collecting a random group of organisms from a stream is one way that people estimate the quality of a stream. Another way is to measure the pH level and look for

phosphate and nitrate amounts. Dissolved oxygen in the water is another indication

• Using percentages one can find how many organisms there are compared to another species

Organisms Present

0

50

100

150

200

250

300

No. oforganisms

Class IClass IIClass III

• Only pollution tolerate organisms can live in polluted waters. What is in the water

tells you how good the stream is

• More organisms in the intolerant category means the

stream is healthy

• Murky water makes rocks slippery and ruins predator/prey relationships. It also clogs the

gills of fish

• The water wouldn’t be safe to drink if the water wasn’t

healthy. And there would be no fish to eat

Water Testing Data & Analysis

• pH of 7 is good. Nitrate and phosphate amount of zero is the best. And the amount of

dissolved oxygen is most optimal around 10

• The mine pool wasn’t of good quality because that its entire

purpose. It is a settling point for bad things in the water.

Marshes usually aren’t that nice of place so that’s why it was

bad

• Healthier organisms would be able to live near the stream.

The ones that couldn’t tolerate pollution would die near the

bad waters

• Too hot of water can kill and organism. Low turbidity benefits

predators and prey.

0

20

40

60

80

100

120

Nitrate

Oxygen

pH Phosphates

StreamMarshMine

Soil Testing & Analysis

0

2

4

6

8

10

12

14

16

18

20

pH Potash

Phosphorus

Nitrogen

Riparian

School Site

• pH describes how acidic or basic a sample of soil.

Potassium, phosphorus, and nitrogen are all chemicals that

are in the soil that aren’t supposed to be found in large

amounts

• The pH of the soil should be a standard level of 7. Potassium is supposed to be around 10 or

medium. While nitrogen and phosphorus shouldn’t even appear at all. In healthy soil

they would be absent

• When any of these things are out of order it can damage the soil. Making it bad for plants to grow in or cause over growth

Positive and Negative Factors

• My awesome opossum would die if it drank from the contaminated waters. That would be a very sad thing

to happen

• If the soil in the opossum’s habitat was bad then if would be difficult for plants to grow there. Without plants an ecosystem would fail and the opossum

might die. Not good!

• Cars are the most dangerous things for opossums. Each year opossum are brutally destroyed by tons of cars. More die than should. As they try to cross the

roads they are slaughtered, which is saddening

Conclusion

• I learned from all of this that one little problem can effect an entire ecosystem. AMD is not a good thing. It messes

with an entire stream and ruins the organisms’ lives

• I found the trip to Powdermill fun and informing. It let us have a first hand look at all of the organisms. That was the

most interesting part of the whole project

• AMD was the most intriguing thing we found out about. It is a tragic thing and it was cool to hear about the settling

pools and seeing the measures Saint Vincent has taken to fix the problem

Works Cited

http://www.fcps.edu/islandcreekes/ecology/virginia_opossum.htm

http://animaldiversity.ummz.umich.edu/site/accounts/information/Didelphis_virginiana.html

http://amrclearinghouse.org/