D4.2 Stability and Change*

requirements for a stable ecosystem

A steady supply of energy (sunlight)

Recycling of nutrients (nothing leaving the system) ○

Genetic diversity

Appropriate climatic variables

stable definition

ability of ecosystem to maintain itself despite disturbance/change

issues for stability

Disruptions interfering with stability:

Removal of materials from the ecosystem

Erosion leads to nutrient loss ○ Eutrophication

Removal of species e.g. hunting

tipping point

critical threshold that, when crossed, leads

to large and often irreversible changes in the climate system.

example of tipping point

The Brazilian tropical rainforests may soon be at a tipping point for

climate change.

tipping point positive feedback

Cutting trees down = less trees

less trees = less transpiration less transpiration = less cloud cover

less cloud cover = less rain

less rain=loss of trees

cutting tree = stimuli

mesocosm definition

ny indoor experimental system that examines the natural environment

under controlled conditions. In this way mesocosm studies provide a link between field surveys and highly controlled laboratory experiments.

IV of mesocosm

water amount

pH of soil

phosphorus amount

etc biotic factors

field surveys show

corrleation

not causation

DV of mesocosm

biodiversity indicator

simpson index

(higher - higher biodiversity)

aim of mesocosm

study how it contributes to sustainability

pros of mesocosm

highly controlled

time cost efficient

how to improve experiemnt (mesocosm)

lid concealed

keep other variable constant

keystone species

species whose activity has a

disproportionate effect on the ecosystem.

● Species diversity is lost if the keystone species is lost.

example key stone specie

P. orchraceus (Starfish)

top down control

prevent mussels taking over

- decrease biodiversity if decrease starfish

example 2 keystone species

Beavers

- more - increase biodiversity

build dams - create wetlands

changes distribution of many species

rewilding

reintroduce of key stone species

saving ecosystem by autotroph

biosequestration

keep carbon in object for an extended period of time

eg lime stone - keeps carbon

sustinable harvest ways

not catching baby fish so they can reproduce

keep existing plants and seeds available to regenrate

sustainbale agriculture

meet the current needs of food production while preserving the natural environment and farmland for future generations.

factors affecting sustainability

pollution eg fertilizers affecting soil

carbon footprint - climate change

eutrophication definition

process in which a water body becomes overly

enriched with nutrients, leading to plentiful algal growth.

eutrophication process

Phosphates and nitrates (often from fertilizers) enter an aquatic

ecosystem.

An algal bloom forms on the surface of the lake, which prevents sunlight reaching plants on the bottom of the lake.

Fish and other organisms die due to low oxygen levels, leading to a reduction of biodiversity in the ecosystem.

biomagnification

unable to digest hence being consumed by next trophic level

bioaccumulation

more concentrated (substances) along trophic level

intoxicated

biomagnification ddt example

DDT was used to kill insect pests.

Some insects survived, but DDT was found in their fat tissue, and it

didn’t break down.

Insects are eaten by fish, which are

eaten by ospreys.

● High concentrations of DDT

accumulated in the tissues of ospreys, as they eat many fish containing DDT

biomagnification mercury example

Mercury was released into Minamata Bay, and was converted to methylmercury by bacteria.

Methylmercury was absorbed by plankton which were then eaten by

fish.

● The residents of Minamata

consumed fish. High concentrations of methyl- mercury in people caused neurological problems, now known as

Minamata disease.

Microplastics

oth macroplastic and microplastic debris is ingested by marine animals, which mistake the debris for food.

Plastics may damage the stomach of animals or cause them to stop

feeding. Macroplastics – large visible debris

●

(more than 1 mm across).

● Microplastics – produced by the

physical breakdown of macroplastics

(less than 1 mm across).

rewilding

restore degraded ecosystems back to their natural

state. Reintroduction of keystone

species such as wolves into Yellowstone National Park. Re-establishing the connectivity of habitats over large areas through wildlife corridors.