Once upon a time the Waihoehoe Stream was not in pipes. All rain in Auckland flows to the sea. It may take centuries to get through groundwater. Some rain evaporates. Most rain runs downhill. It removes soil and rock. Small valleys form with low ridges. Auckland streams are small. They form a dense pattern like leaf veins. Waihoehoe Stream and other streams were great habitat for native fish. They love shady streams. These streams are close to productive estuaries. The Tamaki and Wairoa are such river valleys. They drowned at the end of the last Ice Age. Juveniles can feast there.
Many swamps once existed. Over forty-nine volcanoes spewed scoria and lava. This happened across the region. It showed reckless disregard for drainage patterns. Today, seeing this drainage pattern is difficult.
Streams can be called creeks. Creeks are tidal streams. They once were deep enough for coastal scows to anchor. ‘Drains’ and ‘ditches’ are re-channelled streams. This serves the convenience of landowners. ‘Waterway’ and ‘watercourse’ are handy terms. They describe any water from overland flow to an estuary. That’s the Waihoehoe Stream too.
Macroinvertebrates are important to stream health. Some are more sensitive than others to pollution. They are bugs. These bugs can be seen without a microscope. Many are larvae or juvenile stages of flying insects. Dragonflies and mayflies are examples. Sandflies and craneflies are too.
A healthy stream has clear cool water. It flows with various pools, riffles, and runs. Native bush covers the stream edges. It provides shade, food, and places for bugs to hide. Each bug type has a particular sensitivity. Chemical pollutants affect them. Sediment also matters. Increased water temperature is a factor. Decreased dissolved oxygen harms them. Increased nutrient levels are also bad.
We can identify the bugs in a Waihoehoe Stream sample. Then we can understand how healthy the stream is.
New Zealand has unique freshwater fish. About 39 species exist. Many are only found in this country. Besides native fish, other fish have been introduced. Trout and salmon are examples. Perch, catfish, and goldfish are too. Some introduced species are a nuisance. They negatively impact the environment. They harm native fauna. Gambusia outcompete native fish for food and habitat.
Sadly, New Zealand’s freshwater fish species are at risk. Their populations are declining. In some cases, they face extinction. Streams are directed into pipes. Streams are impacted by hydro dams. This changes the habitat for fish. They get less food and fewer places to hide. Pollution enters the Waihoehoe Stream. It comes from roadside drains. It comes from careless polluters. Exotic fish enter streams. They steal habitat and food. Sometimes they attack our native fish. Many native fish go to the sea to breed. Pipes and dams can restrict their movement.
But here’s what we can do. Don’t release exotic fish into the wild. Don’t drain wetlands or pipe streams. Remember stormwater drains lead directly to fish habitats. Report pollution to the Auckland Council. The number is (09) 3773107.
So remember the Waihoehoe Stream. It is more than just a waterway. It is a vital part of our ecosystem. It is a taonga that needs our care.