Seasonal patterns of organic matter stoichiometry along a mountain catchment

DIAZ VILLANUEVA, V.; M. BASTIDAS NAVARRO; R. ALBARIÑO

HYDROBIOLOGIA

SPRINGER

Lugar: Berlin; Año: 2016 vol. 771

0018-8158

Organic matter (OM) nutrient content is expected to change from the upstream forested reaches to the open valley and these changes could depend on seasonal patterns. The aim of this study was to analyze OM carbon and nutrient (nitrogen and phosphorus) content, from a forested headwater to the open vegetation downstream reach. We sampled four sites along a mountain catchment over the course of one year and quantified fine particulate organic carbon (FPOC) in transport and dissolved organic carbon (DOC). Both FPOC and DOC concentration decreased downstream and changes in OM stoichiometry depended on the season. Stoichiometry of FPOM and DOM along the catchment was similar in autumn, with higher C:P and C:N ratios upstream, which could be associated with the relative importance of allochthonous versus autochthonous OM origin. Conversely in spring, C:N was very low in the forest sites. The mechanism by which organic N enters the aquatic system upstream remains unclear. This study also highlights the need to investigate the different possible origins of OM in streams and its stoichiometry.