Natural Changes in Ecosystems

Could this ever turn into this?

Succession Process where there is a change in the species of a community over time Extremely gradual

Organisms present at one stage change the environment in some way Create soil Change soil conditions This change makes it possible for some species to move in Process repeats until new environment is formed

2 types of succession… #1: Primary Succession Gradual growth of organisms in an area that was previously empty Ex. volcanic islands, lava flows, rocks left by glaciers

Pioneer species First organisms that appear in an area As they grow, they alter the conditions of the area Ex. Create soil Changes allow new plants and animals to grow and survive Ex. Lichens Break down rocks into soil – allows other plants to start to grow

Surtsey Island Volcanic island Pioneer species were bacteria and mosses Other organisms – sandworts, grasses, flies, birds http://www.youtube.com/watch?v=rzE6BNNLew0 http://www.youtube.com/watch?v=YxuttSOtqNE

Succession Timeline 6 environments Put in order of succession 9 organisms In which environment do they fit?

Climax community Stable community of a diverse number of species that is not easily replaced by other communities

Succession in a Wetland

#2: Secondary Succession Gradual growth of organisms in an area that previously had a number of organisms Ex. Regeneration of a burned forest

Artificial succession Farmer ploughs his field Field is now bare Pioneer species are introduced when crop seeds are planted Climax community forms when crop starts to grow

Pollution

When a substance is added to the environment at a fast rate Substance can not be broken down or stored in a non-damaging form Is cycled through the environment Natural substances (eg. carbon dioxide) can also become pollutants when the amount is too high

Acid Rain Occurs when pollutants containing sulfur and nitrogen are found at high levels in the air Ex. From burning fossil fuels Pollutants mix with water vapor creating acid rain

What is an acid? pH scale measures acidity 0-6 = acid 7 = neutral (pure water) 8-14 = basic (opposite of acid) Acid rain has a pH below 5.6

Effects of acid rain

http://www.pbslearningmedia.org/asset/lsps07_int_acidlake/

1908 vs. 1969

Pollution & the Food Web

Biomagnification Tag Krill – eat plankton Fish – eat zooplankton Seal – eat small fish Orca – eat seal Did our game accurately model a food chain?

Pink tokens were not food Mercury that had entered the environment If you had 30% or higher, you did not survive Where could the mercury have come from? Which organism had the highest levels of mercury? Why? What other top level carnivores could we substitute for the orca?

Biomagnification Example Occurs when pollutants enter food web and magnify (build up) in higher level consumers Example Pollutants are stored in organisms in the same way that food energy is stored

Examples PCBs (polychlorinated biphenyl) Found in paints & plastic packaging materials Break down slowly in the environment Remains in ground and water

Used in old thermometers, gold mining Mercury Used in old thermometers, gold mining Dissolves in water http://www.usgs.gov/themes/factsheet/146-00/

DDT Pesticide used to kill insects in the 1940s-1960s

Bio-Indicator Species A species that indicates whether or not the ecosystem is healthy and balanced Ex. Wolves, Falcons, Frogs

Keystone Species Species that hold the ecological balance together in an ecosystem Maintain the structure and integrity of the community