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No place for hardy nymphs to sport themselves

The stinking state of the Butler St channel.

The stinking state of the Butler St channel.

Story & photo Mary Gardner

The bright metallic blue-green dragonfly zigzags throughout the front garden. For the quarter hour I could track it, this insect never pauses. At the same time, the larger red dragonfly skips from one side of the garden to the other, spending most of the time poised on stiff green leaves. To think that these creatures spend from anywhere from one to three years as water insects in fresh streams, channels and waterways. Some Australian children used to call these underwater larvae ‘mud-eyes’. I wonder where 21st century children play. What chance have they to watch such creatures?

The proper name for ‘mud-eyes’ is nymph. These can be from 18 to 49 mm in length, with six legs. Under their heads are powerful jaws which they can stretch out in a flash, biting down on every other sort of water bug. Dragonfly nymphs are fierce predators, catching other animals such as the larvae of flies, mosquitoes, beetles and other species of nymphs. Although small, these monsters and their abilities were the original inspiration for characters in Pokemon.

Dragonfly nymphs are considered hardy. Biologists rank the sensitivities of water insects to varying water quality. The scale runs from 1 (tolerant of poor polluted conditions) to 10 (very sensitive and only found in clean, well oxygenated waters). The mud-eyes rank 4, rather tolerant. Other nymphs such as stone-flies with two tails rank as 10 and mayflies, with three tails, a 9. Damselfly nymphs and the likes of water striders and yabbies all rank as 3. Mosquito larvae as well as leeches, bloodworms and freshwater snails are 1, able to survive in some of the poorest conditions.

When certain types of water insects become rare or completely absent, the waterway is likely to be degraded and polluted in some serious way. This pattern of loss is seen throughout the world and biologists consider it as one of the key indicators of ecosystem health.

Such assessment of what are formally known as macro-invertebrates is part of the NSW EcoHealth Report Cards for waterways. Consider the Richmond, rated D- overall and its water quality F. Its macro-invertebrate assessment is D overall. But the upper Richmond freshwater rates a B- and the lower freshwater an F. Patterns within patterns. What does this mean for the children in different places, as they explore, turning over stones near the shores?

Still, from somewhere arrive the dragonflies. Each one clambered out of the freshwater, crawling up a rock or leaf there to crack open from its shell. Now transformed into elegant aerial hunters they seek mates as well as prey. When male finds willing female, he holds on tight, head to tail and they fly ‘tandem’. Males move their sperm packet close to their own head. When she arches her abdomen (often incorrectly called a ‘tail’) to his head, the pair creates a ‘circle’. Before donating their sperm packets, he removes all the others left by other males.

In some species, the male will guard their mate till she lays her eggs. She might drop them on leaves to be washed away by rain. She might stick her abdomen into the mud and lay eggs underground. She might fly over water, dipping her far end, shedding eggs and she skims the top layers of water.

One of the techno-world’s great ironies is that augmented reality Pokemon is only a game. I am not alone in thinking that our phones could be genuine tools in an augmented reality monitoring programme about our waterways. Imagine standing in a spot, checking your phone for its EcoHealth status and its history, updating this database with your own photos and findings.

 The augmented reality part might be a few years away yet. But the tools exist to create such phone apps that we can use to monitor our waterways. Such a database could help us now in Byron Bay. We’re wondering why the Belongil as well as the Butler St channel make such a stench and what actions may have led to a recent fish kill in the drains of West Byron.

From child’s play to hi-tech work, stories spoken, written and digitised, all on the wings of fierce bright dragonflies.


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