The river walk team would like to inform the readers how we conduct the so called Mini SASS (South African Scoring System) that we are always referring to. It is a form of bio monitoring and gives an indication of river health. The mini SASS was derived and down scaled from a full SASS that contains over 90 micro-invertebrates, to only 13 groups or classes, for easy identification. Each invertebrate has a score relative to its pollution sensitivity. Thus the higher the score, the less tolerant it is and the lower the score the more tolerant it is to pollution.
What we do is: We choose a rocky area with rapids and allow ourselves 15 minutes on the clock. Armed with our catching cups we hop from rock to rock disturbing the silt, turning over stones and shaking the vegetation along the banks to capture the invertebrates that live in the water. We then identify them, classify them into the different classes, add up the score and then divide it by the number of groups that they fall under.
Today was not an eventful day for the walking half of the team, as the other half were canoeing the restricted stretch we spoke of on Mayday 15.
Upon doing our mini SASS we caught:
a) Minnow mayflies which score – 5
b) Stout crawlers which score -11 under the group “other mayflies”
c) Cased caddis flies which score 9
d) Creeping water bugs and water striders that score 5 under the group “Bugs and Beetles”
e) Mosquito larva which scores 2 under the group “True Flies”
Adding these numbers we got a total of 32, which we divide by 5 (no. of groups) which leads to an average score of 6.4. Such a score means the river has been moderately modified and is in fair condition. We also did Nitrate/Nitrite and PH tests that both came out normal.
Submitted by: Penz Malinga