Back to Search
Start Over
Phytoplankton nutrient use and CO 2 dynamics responding to long-term changes in riverine N and P availability.
- Source :
-
Water research [Water Res] 2021 Sep 15; Vol. 203, pp. 117510. Date of Electronic Publication: 2021 Aug 03. - Publication Year :
- 2021
-
Abstract
- Long-term trends in riverine nutrient availability have rarely been linked to both phytoplankton composition and functioning. To explore how the changing availability of N and P affects not only phytoplankton abundance and composition but also the resource use efficiency of N, P, and CO <subscript>2</subscript> , a 25-year time series of water quality in the lower Han River, Korea, was combined with additional measurements of riverine dissolved organic carbon (DOC) and CO <subscript>2</subscript> . Despite persistent eutrophication, recent decreases in P relative to N have been steep in the lowest reach, increasing the annual mean mass ratio of N to P (N/P) from 24 (1994-2015) to 65 (2016-2018). While Chl a and cyanobacterial abundance exhibited overall positive and inverse relationships with P concentrations and N/P, respectively, severe harmful algal blooms (HABs) concurred with short-term increases in P and temperature. Microcystis often dominated HABs at low N/P that usually favors N-fixing cyanobacteria such as Anabaena. In the middle and lower reaches, phytoplanktonic P use efficiency was typically lower at low N/P. V-shaped relationships between N/P and CO <subscript>2</subscript> concentrations, together with longitudinal upward shifts in the inverse relationship between Chl a and CO <subscript>2</subscript> , implied that eutrophication-enhanced phytoplankton biomass could turn into a significant source of CO <subscript>2.</subscript> after passing a threshold. The combined results suggest that cyanobacterial dominance co-limited by P availability and temperature can lower planktonic P use efficiency, while enhancing riverine CO <subscript>2</subscript> emissions at low N/P ratios.<br /> (Copyright © 2021. Published by Elsevier Ltd.)
Details
- Language :
- English
- ISSN :
- 1879-2448
- Volume :
- 203
- Database :
- MEDLINE
- Journal :
- Water research
- Publication Type :
- Academic Journal
- Accession number :
- 34375930
- Full Text :
- https://doi.org/10.1016/j.watres.2021.117510