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

1 Citation (Scopus)
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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. 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 oxidized N (NOx) decreased from the peak value of 10,186 T/yr in 1995 to 5,396 T/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 1 C 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 half of the 42 % variance explained by a hierarchical partition model. Decreasing 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

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