BACKGROUND In addition to the water watch testing conducted on the ecosystem student will take part in an investigation of the macro-invertebrate organisms and other life that exists in the chosen habitat. An indication of the health and productivity of a stream or water body can be analysed in a number of ways, the first being the testing of physio-chemical properties. The second can be found by analysing the living organisms that live in the system. Scientists have found that some macro invertebrates are more tolerant to pollutants than others, as a result of this the method of measuring water quality using SIGNAL scores has been developed. “If a stream is polluted , tolerant bugs will usually be found in larger number than intolerant ones” (Gooderham, J & Tsyrlin, E 2003) The SIGNAL method uses this ecological markers to obtain a result that is said to determine the health of the water body. SIGNAL stands for Stream Invertebrate Grade Number- Average Level and “by obtaining the SIGNAL grade one can calculate a score for the site and therefore form an objective opinion about it’s health” (Chessman, B.C. 2003) ASSESSMENT In this part of the field work students will use dip nets or waders to collect water sample that include sample of the macro-invertebrate species present in the water system; then students will sort the invertebrate samples into species (using the ice cube trays and spoons). To complete this assessment students will be required to fill out the attached worksheet DETERMINING THE HEALTH OF A WATER BODY Once students have sorted their samples into species students will then attempt to identify the species present using the Waterbug Book or classification sheets provided and if possible determine the corresponding SIGNAL score for each species.
Calculating SIGNAL score:
Step 1: Calculate the sum of the individual SIGNAL grades (count each species once, do not Include the abundance of each species)
Step 2: Divide the sum by the total number of different species collected.
SIGNAL score and water health:
Higher than 6: healthy ecosystem Between 5-6: mild pollution Between 4-5 moderate pollution Less than 4: severe pollution (Gooderham, J & Tsyrlin, E 2003)
In addition to the water watch testing conducted on the ecosystem student will take part in an investigation of the macro-invertebrate organisms and other life that exists in the chosen habitat.
An indication of the health and productivity of a stream or water body can be analysed in a number of ways, the first being the testing of physio-chemical properties. The second can be found by analysing the living organisms that live in the system.
Scientists have found that some macro invertebrates are more tolerant to pollutants than others, as a result of this the method of measuring water quality using SIGNAL scores has been developed. “If a stream is polluted , tolerant bugs will usually be found in larger number than intolerant ones” (Gooderham, J & Tsyrlin, E 2003)
The SIGNAL method uses this ecological markers to obtain a result that is said to determine the health of the water body. SIGNAL stands for Stream Invertebrate Grade Number- Average Level and “by obtaining the SIGNAL grade one can calculate a score for the site and therefore form an objective opinion about it’s health” (Chessman, B.C. 2003)
ASSESSMENT
In this part of the field work students will use dip nets or waders to collect water sample that include sample of the macro-invertebrate species present in the water system; then students will sort the invertebrate samples into species (using the ice cube trays and spoons).
To complete this assessment students will be required to fill out the attached worksheet DETERMINING THE HEALTH OF A WATER BODY
Once students have sorted their samples into species students will then attempt to identify the species present using the Waterbug Book or classification sheets provided and if possible determine the corresponding SIGNAL score for each species.
Calculating SIGNAL score:
Step 1: Calculate the sum of the individual SIGNAL grades (count each species once, do not
Include the abundance of each species)
Step 2: Divide the sum by the total number of different species collected.
SIGNAL score and water health:
Higher than 6: healthy ecosystem
Between 5-6: mild pollution
Between 4-5 moderate pollution
Less than 4: severe pollution
(Gooderham, J & Tsyrlin, E 2003)