Disruption of ecosystem processes Flashcards
What two processes are fundamental to ecosystem functioning?
Energy flows: for example where primary producers at trophic level 1 convert sunlight into energy by photosynthesis and as energy is lost through respiration at each stage of the process, the amount of biomass at each trophic level decreases.
Nutrient cycling: circulation of chemical elements from the environment to organisms and back again to the environment.
As the world becomes globally connected, what becomes a threat to ecosystems.
The movement of species from one part of the world to another become a threat including alien or exotic species.
What features do alien/exotic species have?
- enhanced survival rates as they are more efficient competitors than native species
- lack any native predator
- not susceptible to indigenous diseases
What deliberate introductions of species did the UK have?
- Game species such as pheasants and rainbow trout
- Plant species for scenic purposes (rhododendron)
- The hedgehog was imported from the Scottish mainland to the Outer Hebrides to deal with a plague of garden slugs
What have been some accidental introductions of species?
- Some species arrive by ship (the zebra mussel arrived in North America from the Caspian Sea in ships’ ballast water or by clinging to the sides of ships.
- Air transport (introducing snakes to the Pacific Island of Guam)
Why has nutrient loading recently increased?
Due to increased human activities such as using chemical fertilisers and detergents.
How does nutrient loading have a negative impact on ecosystem processes?
Excess nitrates and phosphates are washed into rivers and lakes and this encourages algae growth leading to an algal bloom. This prevents sunlight reaching other water plants which then die. Bacteria break down the dead plants and use up the oxygen in the water leading to the lake becoming lifeless.
Give an example of a place where eutrophication is happening
The process is happening a lot in the Norfolk Broads but is happening in over three-quarters of the world’s lakes.
What are the knock-on effects of eutrophication?
It can lead to contaminated drinking water and some algal blooms are harmful and can contaminate fish and lead to gastrointestinal illness for humans. In particular, eutrophication is east African lakes is threatening colonies of flamingos and other wetland birds.
Which islands’ ecosystems are at severe threat?
The Galapagos Islands.
Why were a huge rang of alien species introduced from the Ecuadorian mainland?
As people were seeking to make a living from fishing and tourism.
Up to how many species are now considered ‘threatened’ in the Galapagos Islands?
Up to 60% of the 180 species of endemic plant.
How many insect species are at ‘high risk’?
55 out of the 490 introduced insect species and 43 species of other invertebrates.
How many vertebrate species are considered harmful?
13 out of the 18 detected.
What actions have been taken to preserve the unique biodiversity of the Galapagos?
Rodents and feral cats have been eradicated and stray dogs have been rounded up. The quinine tree has also been removed.
