Modified habitat

A habitat is an environment or place where animals normally live.

Mahinga kai are found in streams, lakes, rivers, estuaries and the sea at different stages of their life cycle. Mahinga kai require habitat to live, and their requirements vary depending on the type and life stage of species. Rocky boulders, sand banks, and vegetated margins are all parts of a stream that is important mahinga kai habitat. A waterway with a diverse range of habitats is likely to have a greater number of mahinga kai species present in a range of age groups (i.e., both juveniles and adults).

When we alter the habitat available in a waterway, we can significantly impact the species that live there. The way we use the land around a waterway, or when we discharge wastewater into a waterway - can potentially modify important mahinga kai habitats. Examples of these modifications include altering stream characteristics such as the bottom substrate, the water margins, stream bank, surrounding riparian vegetation, water flow, or by increasing the amount of nutrients and sediments going into a waterway, through inappropriate land use practices.

How mahinga kai respond to these changes depends on the species and how their particular habitat, behaviour (competition and predation), and food supply change. However, simplification of habitat usually results in a decrease in the number of mahinga kai present. One of the most important features we can maintain to ensure mahinga kai habitat is protected and enhanced is the riparian vegetation around the water margins.

Potential impacts of modified habitat on water quality and mahinga kai

  • Loss of breeding and feeding habitat.
  • Increases in erosion and sedimentation (sands and silts) or excessive scouring, which reduces water quality and visibility.
  • Increases in nutrients and contaminants.
  • Loss of riparian vegetation for shade and water temperature control, and reduced inputs of wood and leaf litter, which provide cover and food.
  • Changes in water flow, currents, and velocity.