Linking Land-use, Water Body Type and Water Quality in Southern New Zealand
- 838 Downloads
Land-use and vegetation cover have been linked to the nutrient levels (nitrogen, phosphorus) of surface waters in several countries. However, the links generally relate to streams and rivers, or to specific types of standing water, for example shallow lakes in a geologically defined region. We measured physical variables and nutrient chemistry of 45 water bodies representative of the wide range of lentic wetland environments (swamps, riverine wetlands, estuaries, reservoirs, shallow lakes, deep lakes) in Otago, New Zealand, and related these to catchment variables and land-use in order to assess the potential influence of catchment modification on water quality of these diverse wetlands. Catchment boundaries and land cover were derived from maps using ArcView GIS software. Our predictions that concentrations of nutrients and other components of water quality would correlate positively with the nature and intensity of catchment modification were confirmed in multivariate analyses. Physical and chemical measures were positively related to the extent of modification in the catchment (percentage of the catchment in pasture, planted forest, scrub and urban areas), and negatively related to lack of catchment modification (more of the catchment in bare ground, tussock grassland and indigenous forest). The strong negative correlations between nutrient concentrations, suspended sediment, water colour and the percentage of tussock cover in the catchment imply that increased conversion of the␣native tussock grassland to pastoral farming in␣Otago will increase nutrient concentrations and␣reduce water quality of the diverse lentic ecosystems.
KeywordsWetlands Catchment Land cover Phosphorus Nitrogen Agriculture Eutrophication Drainage basin Lakes
Unable to display preview. Download preview PDF.
We thank Chris Arbuckle for help with GIS, Carleen Mitchell for nutrient analyses, Jo Bishop, Nathan Whitmore and Catherine Hall for field assistance, and Marc Schallenberg for technical advice. LG was supported by a University of Otago Postgraduate Scholarship.
- Elliott S, Sorrell B, (2002) Lake Managers’ handbook, land–water interactions. Ministry for the Environment, Wellington, New ZealandGoogle Scholar
- Huryn AD, Burns CW, Allibone R, Patrick B, Scott D (2003) Inland waters and wetlands. In: Darby J, Fordyce RE, Mark A, Probert K, Townsend C (eds) The natural history of Southern New Zealand. Otago University Press, Dunedin, New Zealand, pp 237–265Google Scholar
- Moss B (1998) Ecology of Fresh Waters: man and medium, past to future, 3rd ed. Blackwell Science, Oxford, UKGoogle Scholar
- Newsome PFJ (1987) Vegetation cover of New Zealand. Water and soil miscellaneous publication No. 112, Wellington, New ZealandGoogle Scholar
- Prepas EE, Planas D, Gibson JJ, Vitt DH, Prowse TD Dinsmore WP, Halsey LA, McEachern PM, Paquet S, Scrimgeour GJ, Tonn WM, Paszkowski CA, Wolfstein K (2001) Landscape variables influencing nutrients and phytoplankton communities in Boreal Plain lakes of northern Alberta: a comparison of wetland- and upland-dominated catchments. Can J Fish Aquat Sci 58:1286–1299CrossRefGoogle Scholar
- Rasmussen JB, Godbout L, Schallenberg M (1989) The humic content of lake water and its relationship to watershed and lake morphometry. Limnol Oceanogr 34:1097–1103Google Scholar
- SPSS (2000) SPSS for Windows, Version 10.1.0. 2000. SPSS IncGoogle Scholar
- ter Braak CJF, Šmilauer P (1998) CANOCO reference manual and user’s guide to Canoco for Windows. Centre for Biometry, Wageningen, The NetherlandsGoogle Scholar
- Thompson RM, Townsend CR (1998) The effects of land use on stream community attributes. Taieri Catchment Symposium, Ecology Research Group, University of Otago, Occasional paper 1:44–45. Dunedin, New ZealandGoogle Scholar
- Townsend CR, Niyogi D, Riley RH, Koren M (2001) Land-use impacts on streams. Unpublished fact sheet available as PDF on website of Ecology Research Group, University of Otago, Dunedin. www.otago.ac.nz/erg/freshwater/Google Scholar
- Wetzel RG, Likens GE (1991) Limnological analyses, 2nd ed. Springer-Verlag, New YorkGoogle Scholar