Lake Taupō long term monitoring programme 2013-2014
Report: TR 2015/31
Author: Dr M Gibbs (National Institute of Water & Atmospheric Research Ltd (NIWA))
About this report
In 1994, Waikato Regional Council initiated a long term programme to monitor Lake Taupo's water quality and the impact of land use changes within the lake’s catchment. This programme is conducted by NIWA with field assistance from the Department of Internal Affairs, Taupo Harbourmaster’s Office. This report presents the results from the 2013/14 monitoring period.
Some aspects of the water quality of the lake – including water clarity and concentrations of total phosphorus and algal chlorophyll – have remained broadly stable over the past 20 years. Other aspects have changed; in particular concentrations of total nitrogen have increased, particularly in recent years. The extent to which dissolved oxygen levels in the bottom waters decline during summer has also increased, although the reasons for this change are unclear – and do not appear to be linked to algal production within the lake. Despite these changes, the water quality of Lake Taupo is currently still excellent: nutrient concentrations are relatively low, as are those of the algae whose growth they support, and the water is generally clear and blue.
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Lake Taupō long term monitoring programme 2013-2014 [PDF, 6.9 MB]
| Contents | |
| Executive summary | |
| 1 | Introduction |
| 2 | Methods |
| 2.1 | Report contents |
| 2.2 | Statistical evaluation |
| 2.3 | "Trend" definition |
| 3 | Results and discussion |
| 3.1 | Temperature and dissolved oxygen |
| 3.2 | Net VHOD rate |
| 3.3 | Secchi depth |
| 3.4 | Phytoplankton |
| 3.5 | Deep chlorophyll maxima |
| 3.6 | Algal species abundance |
| 3.7 | Nutrients in the upper waters |
| 3.8 | Nutrient accumulation in the hypolimnion |
| 3.9 | Total mass accumulated |
| 3.10 | Net accumulation rate |
| 3.11 | Total N |
| 4 | Knowledge gaps |
| 5 | Summary |
| 6 | Acknowledgements |
| 7 | Glossary of abbreviations and terms |
| 8 | References |
| Appendix 1: Site map, sampling strategy and methods | |
| Appendix 2: The calculation of VHOD rates | |
| Appendix 3: Temperature and dissolved oxygen data | |
| Appendix 4: Nutrient data | |
| Appendix 5: Phytoplankton data | |
| Appendix 6: Historical data | |