The long-term response of lake nutrient and chlorophyll concentrations to changes in nutrient loading in Ireland's largest lake, Lough Neagh

Y McElarney, B Rippey, Claire Miller, Michelle Allen, Antony Unwin

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)
36 Downloads (Pure)

Abstract

The long-term response of chlorophyll-a (chl-a) to changing lake water nutrient concentrations and increasing water temperature was investigated in Lough Neagh, a large, hypereutrophic lake in Northern Ireland. Trends in external and internal nutrient loading and their relation to lake nutrient concentrations were also established. Lake water concentrations of total P (TP) have increased since the 1990s but were not correlated with catchment inputs, which showed no trend. The characteristics of internal loading of P have changed since the mid-1990s, with an earlier and larger mass of P released from the sediments each summer. Catchment inputs of total oxidised N (NOx) decreased from the peak value of 10,186T/yr in 1995 to 5,396T/yr in 2011, coinciding with a reduction in lake water concentrations. External inputs and lake concentrations of NOx were highly correlated (R=0.88). Water temperature increased approximately 1C and was a predictor of variation in chl-a from 1974 to 2012. After the peak chl-a concentration in 1993, dissolved inorganic N (DIN) also became an important predictor, accounting for almost half of the 44% variance explained by a hierarchical partition model. Decreasing log (DIN:TP) ratios suggest that N limitation of chl-a has become more important in the lake recently.

Original languageEnglish
Pages (from-to)47-60
Number of pages14
JournalBiology and Environment: Proceedings of the Royal Irish Academy
Volume121B
Issue number1
DOIs
Publication statusPublished - 29 Apr 2021

Bibliographical note

Funding Information:
This research was funded by the DAERA, Northern Ireland. The authors are grateful to all project and AFBI staff, past and present for their work on this long-term dataset. We are also grateful for the support of Wendy McKinley, Brenda Walker, Mary Gallagher, Paul Devine and Brian Ervine from DAERA NI. The authors wish to thank Prof. Bruce Osborne and two anonymous reviewers for their comments and sugges?tions which significantly improved this manuscript.

Funding Information:
This research was funded by the DAERA, Northern Ireland. The authors are grateful to all project and AFBI staff, past and present for their work on this long-term dataset.We are also grateful for the support of Wendy McKinley, Brenda Walker, Mary Gallagher, Paul Devine and Brian Ervine from DAERA NI.The authors wish to thank Prof. Bruce Osborne and two anonymous reviewers for their comments and suggestions which significantly improved this manuscript.

Publisher Copyright:
© The Author(s).

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