text: A biomonitoring assessment requires a baseline dataset which, ideally, defines the environment in its natural or default state. This is then used for comparison against any subsequent measurements, in order to assess potential alterations or trends.
  In some cases, these datasets are used to create standardised tools for assessing water quality via biomonitoring data, such as the Specific Pollution Index (SPI) and South African Diatom Index (SADI).