Submerged plants as bio-indicators
Why use submerged plants as indicators?
Submerged plants have a number of advantages that favour their use as indicators of lake ecological condition.
- They are easy to observe and identify because of their size and are commonly found in lakes all year round.
- They are mostly rooted to the bed of lakes. This means they are non-mobile (they are not going to swim away like fish) and they are unable to flee rapid environmental changes.
- They are able to integrate long-term changes in environmental conditions. This means they provide a more stable measure of overall lake condition, rather than responding to seasonal or daily changes in water clarity and chemistry.
- They provide a focus on lake edges/margins (the littoral zone), where there is greatest public interaction and interest. These are the areas around a lake that are easy to see from shore and where most of our recreational activities (e.g. swimming) occur. The water quality and condition in these areas can be quite different to what is represented by water sampled from open water in the middle of a lake.
What plants are used as indicators in the LakeSPI method?
The LakeSPI method requires the identification of six key native plant community types and ten invasive plant species. Click plant names to learn more about them.
| LakeSPI native plants | LakeSPI invasive plants |
|---|---|
| 1. Turf community | 1. Ceratophyllum demersum |
| 2. Isoetes | 2. Hydrilla verticillata |
| 3. Native pondweeds | 3. Egeria densa |
| 4. Native milfoils | 4. Lagarosiphon major |
| 5. Charophyte species | 5. Vallisneria australis |
| 6. Charophyte meadows (>75% cover) | 6. Elodea canadensis |
| 7. Utricularia gibba | |
| 8. Potamogeton crispus | |
| 9. Ranunculus trichophyllus | |
| 10. Juncus bulbosus |
For more information on how LakeSPI reports on aquatic plants, see 'Reporting guidelines'.
Native submerged plants growing in Lake Waikaremoana. Credit: John Clayton
Invasive weed Lagarosiphon growing in Lake Tarawera. Credit: Rohan Wells
