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Hi everyone
Just sharing with you the results of our environmental monitoring for January, 2023.
Many thanks to Kim, Helen, Ross and Brian for their assistance.
This monitoring consist of Water Quality, Chemical Analysis and Macroinvertebrate sampling.
January threw up a few differing considerations which deserve some attention:
In the saltwater section of the Coomera River the salinity was the highest yet recorded, approaching 40 ppt or mg/L if you prefer. This means now that for several months in a row the salinity results have been quite high, as a result of a lack of rainfall to flush the waterways and dilute the saltwater. In observing the effects of this, the numbers of fish bait fish in the Coomera River have noticeably increased, although I am unaware if angler effort has extracted any more fish than normal. It was interesting to see on public media yesterday a 1270mm barramundi caught in the Nerang River – nice fish.
The Macroinvertebrate results are technically better than the experience of sampling would indicate. When we consider that a SIGNAL score of 6 or more is healthy, almost all sites reached this score, if only barely. However the problem lay in the numbers of animals observed, and the number of species observed; both being poor when measured against the normal results from the waterways. For example in Yaun Creek there were 15 different species recorded yet only 30 animals in total counted. In other words some species had only one representative in the stream sample. A good sample has some 200 individual animals.
Part of the explanation lies in a lack of water flow which results in reduced dissolved oxygen and therefore less than ideal conditions for water dependent animals. Yet there was another unsettling observation in that there were very few breeding adults laying eggs apart from dragonflies and damselflies. Why there is a dearth of adult insects I have no idea and would love to hear from someone who does know.
The results of chemical analyses revealed that phosphates were recorded at significant levels and increased levels of ammonia nitrogen in a few cases. Phosphates are a sneaky chemical that derives directly from agriculture and gardens; people should be reminded from time to time that whatever goes on the garden ends up in the water. When there is no flushing rain it stays in the waterway and gives rise to unwanted algal and filamentous weeds growth which can rob the water of oxygen, particularly when it dies due to high water temperature and receding waters. Increased levels of ammonia nitrogen result from animal and human waste finding their way into the waterway. If you are out and about and observe pollution of that kind, best report it to CoGC who should take prompt action to determine the cause and eliminate that cause.
A final thought on cane toads. I regularly patrol my local area and remove toads; this year for the first time I have noted that the adults are in generally poor condition, which relates to a lack of food. Their food, because they feed at night, consist largely of insects including moths and beetles. When we return to the observation of lack of adult insects there may well be a correlation between that lack and the poor condition of predators. In any event there are less cane toads and more snakes. Food for thought.
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