Horseshoe Lake Reserve, Trip #44

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Horseshoe Lake is a former meander of the Avon River, which eventually became cut off. Following the earthquakes, it has become generally wetter.

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Water covered with azolla and duckweed, lined with rushes, sedges and toetoe.
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Searching the water.

We visited this site in July (2017). Below is some of what we saw.


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A catepillar, probably of a moth or butterfly (Order Lepidoptera).
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Ground cricket (Subfamily Nemobiinae).

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.

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Clam shrimp (Order Diplostraca).
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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.

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Azolla rubra.
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Azolla rubra and duckweed (Lemna minor).
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Water milfoil (Myriophyllum triphyllum).

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).

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Pukio (Carex secta).
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Harakeke (Phormium tenax).
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Cabbage tree (Cordyline australis).

Our thanks to NatureWatch for their help with identifications.


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