Horseshoe Lake is a former meander of the Avon River, which eventually became cut off. Following the earthquakes, it has become generally wetter.
We visited this site in July (2017). Below is some of what we saw.
We used a microscope (20-40 x magnification) to look at some of the water. There were lots of creatures, though most were still very small, and most were very active. The two photographed below are both tiny crustaceans.
The surface of the water was virtually covered with azolla and duckweed.
Azolla is a fern that contains a cyanobacteria, which converts atmospheric nitrogen into a form the azolla can use. In return, the azolla provides the cyanobacteria with carbohydrates.
Rushes have a type of tissue within their stems called aerenchyma. It has large gaps, that allow gas diffusion to occur within the plants, thereby enabling the movement of oxygen and carbon dioxide (which are required for respiration and photosynthesis).
Great soft-rush (Juncus pallidus).
Our thanks to NatureWatch for their help with identifications.