Nutrient attenuation in a shallow,gravel-bed river. II. Spatial and temporal changes in nitrogen dynamics and community metabolism期刊界 All Journals 搜尽天下杂志传播学术成果专业期刊搜索期刊信息化学术搜索

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Nutrient attenuation in a shallow,gravel-bed river. II. Spatial and temporal changes in nitrogen dynamics and community metabolism

Authors:	J Christopher Rutherford Roger G Young John M Quinn Robert J Wilcock

Institution:	1. National Institute of Water &2. Atmospheric Research, Napier, New Zealand kit.rutherford@niwa.co.nzhttps://orcid.org/0000-0003-3164-9550;4. Cawthron Institute, Nelson, New Zealand;5. NIWA, Hamilton, New Zealand

Abstract:	ABSTRACT Instream processes alter the concentration and bioavailability of nutrients as they are transported downstream. By relating primary production and periphyton composition to changes in nutrient concentration in a gravel-bed river this study made inferences about recycling and attenuation. Where dissolved inorganic nitrogen (DIN) was abundant, concentrations decreased linearly with distance but by less than required to meet the nitrogen demand of primary production. Where DIN was barely measurable photosynthesis was reduced but only by 50%. We infer that recycling sustained primary production even when DIN concentrations were negligibly small. One implication is that DIN removal underestimates attenuation. Further experimental research on recycling and improved modelling is required to better quantify the length of streams adversely affected by nutrients.

Keywords:	Nutrients nitrogen periphyton attenuation photosynthesis stoichiometry