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Radbourne2020_Article_TheInfluenceOfClimateChangeOnT.pdf (1.61 MB)

The influence of climate change on the restoration trajectory of a nutrient-rich deep lake

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posted on 2019-10-24, 11:43 authored by Alan D Radbourne, David RyvesDavid Ryves, Genevieve Madgwick, Nicholas John AndersonNicholas John Anderson
Nutrient reduction in impacted lowland freshwater systems is ecologically and culturally important. Gaining a greater insight into how lakes respond to lowering nutrient loads and how climate-driven physical limnology affects present and future cycling of available nutrients is important for ecosystem resource management. This study examines the nutrient decline in a hypereutrophic freshwater lake (Rostherne Mere, Cheshire, UK) 25 years after sewage effluent diversion, a uniquely long-term analysis of a recovering nutrient-rich deep lake. Using nutrient, phytoplankton, climate and catchment hydrological monitoring, the contemporary lake system is compared to previous studies from 1990 to 2002. Nutrient change since point source load diversion showed annual average and maximum phosphorus (P) concentrations decreased significantly for the first 10 years (1992: ~ 600 µg P L−1; 2002: ~ 200 µg P L−1), but have since stabilised due to a substantial legacy sediment P internal load. Dissolved inorganic nitrogen (DIN) concentrations have not substantially changed since diversion, resulting in the alteration of the DIN/SRP ratio from a system characterised by N limitation (N:P ~ 5), to one predominantly P limited (N:P > 20). Nutrient changes over this time are shown to drive ecological change, especially in the cyanobacterial and algal communities. Furthermore, very high-resolution monitoring of lake inflow and outflow (every 5 min during 2016) shows that water residence time at this lake is significantly shorter than previously estimated (~ 0.8 years compared to previous estimates of ~ 1.6–2.4 years). Together with long-term data demonstrating that the stratification period at Rostherne Mere has increased by 40 days over the last ~ 50 years (due to later autumnal mixing), we show that a rapid rate of epilimnetic flushing together with a long stratification period substantially reduces the available epilimnetic P during the summer cyanobacterial bloom. This is of growing importance for many such lakes, given widespread climate-driven lengthening of stratification and a national trend of decreasing summer rainfall (decreasing seasonal flushing) but more intense summer storm events (resulting in short-term flushing events).

Funding

Natural Environment Research Council (NERC) [Grant Number NE/L002493/1]

Research studentship award from Central England NERC Training Alliance (CENTA)

History

School

  • Social Sciences

Department

  • Geography and Environment

Published in

Ecosystems

Volume

23

Pages

859 - 872

Publisher

Springer

Version

  • VoR (Version of Record)

Rights holder

© The Authors

Publisher statement

This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.

Acceptance date

2019-09-02

Publication date

2019-09-20

Copyright date

2019

ISSN

1432-9840

eISSN

1435-0629

Language

  • en

Depositor

Dr Dave Ryves. Deposit date: 23 October 2019

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