![]() There was a marginally significant increase in turbidity as agricultural land cover increased. Nitrate, ammonium, total and dissolved reactive phosphorus, and water column chlorophyll-a concentrations were greater in estuaries with higher urban land cover and total phosphorus concentrations were greater with higher agricultural land cover. ![]() Sites with greater freshwater influence had higher nutrient and faecal indicator bacteria concentrations, and turbidity, indicating that open coast and estuarine water quality is reduced predominantly via flows from the land. Previous literature had shown strong effects of agricultural and urban land cover on the quality of New Zealand's rivers, so we examined their effects on estuaries, while controlling for marine dilution and freshwater flushing. We compiled a coastal water quality database for New Zealand comprising 320 estuarine and coastal sites with records between 20. National-scale analyses of land cover effects on water quality can aid in directing environmental policy. In contrast, trends in nitrate-nitrogen in the exoticįorest and cool-dry/pastoral classes indicated worsening conditions. ![]() The pastoral and urban classes, possibly reflecting improved land Nitrogen, dissolved reactive phosphorus and total phosphorus in (2004–2013) indicated recent improvements in ammoniacal Visual clarity and Macroinvertebrate Community Index scoresĭecreased as proportions of catchments in high-intensityĪgricultural and urban land cover increased. Nutrient and Escherichia coli concentrations increased and Sites in the urban and pastoral classes had the poorest water Than in exotic forest and natural land-cover classes, and lowland ![]() State in urban and pastoral land-cover classes was poorer Using all sites and a subset of lowland river sites. Parallel state and trend analyses were carried out We assessed river water qualityĪnd biological state and trends using data from more than 900 ![]() River water quality, particularly in lowland catchments, is a matter ofĬoncern to the New Zealand public. ![]()
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