Practise IB Biology SL D4.2 through mesocosm, keystone-species and pollution questions that connect ecosystem evidence with stability and change.
Primary plant succession has been observed in sand dunes adjacent to the northern end of Lake Michigan, one of the Great Lakes in North America. The youngest sand dunes have beach grass (Ammophila breviligulata) and prairie bunch grass (Schizachyrium scoparium). The oldest dunes have coniferous trees (Pinus strobus and Pinus resinosa).
Outline how the type of stable ecosystem that will develop in an area can be predicted based on climate.
Beavers (Castor fiber) have been reintroduced into many European countries. They cut down trees and use them as a source of food as well as for building their homes and dams.
Beavers are a keystone species. Outline the importance of keystone species.
Studies show that species richness of large invertebrates increases in the presence of beavers. Suggest reasons why biodiversity is important in an ecosystem.
Outline two methods of restoration of natural processes in ecosystems by rewilding, other than reintroducing a keystone species.
1.
2.
Which is not essential in a viable mesocosm?
Light source
Autotroph
Saprotroph
Herbivore
Beavers (Castor fiber) have been reintroduced into many European countries. They cut down trees and use them as a source of food as well as for building their homes and dams.
Studies show that species richness of large invertebrates increases in the presence of beavers. Suggest reasons why biodiversity is important in an ecosystem.
The sea snail Nucella ostrina and the sea star Pisaster ochraceus are predators of the mussel Mytilus trossulus. The mussels live on rocks at the edge of the sea and feed on phytoplankton and zooplankton. The zooplankton feed on the phytoplankton.
Nucella ostrina
Pisaster ochraceus
Mytilus trossulus
Groups of 50 mussels were transplanted to an experimental area and protected from predation until the start of the experiment. Researchers then investigated the effect of the predators on the population of the mussels over a period of 60 days.
Sea stars along the pacific coast of the US are dying from "sea star wasting syndrome". Suggest the effect this will have on the ecosystem.
What directly causes oxygen levels to drop during eutrophication in aquatic ecosystems?
Increased photosynthesis by aquatic plants
Enhanced respiration by fish
More decomposition of organic matter by bacteria
Lower levels of nitrogen in the water
Explain the cause and consequences of biomagnification.
Data from the International Union for Conservation of Nature (IUCN) indicates that the population numbers of many mammal species are decreasing. The chart shows reasons for the decrease and the number of species in each category of danger.
Explain the impact of plastic waste on Laysan albatrosses (Phoebastria immutabilis).
Which action is part of the rewilding of ecosystems?
Applying fertilizer
Removal of apex predators
Reintroduction of keystone species
Restricting size for easier management