We describe the long-term (1981-2008) dynamics of several physico-chemical and biological variables and how their changes may have influenced zooplankton structure in Lake Maggiore (Italy). Data was available for the 1981-1992 and 1995-2008 periods. Standardized time-series for temperature and total phosphorus (TP), chlorophyll-a, phytoplankton density (cel m-3), and cell size (μm3), as well as zooplankton structure (Copepoda, Cladocera, and Rotifera density, ind m-3) were smoothed using penalized B-splines and analyzed using Functional Principal Components (FPCs) to assess their dominant modes of variation. The first four FPCs explained 55% of 1981-1992 and 65% of 1995-2008 overall variation. Results showed that temperature fluctuated during the study period, particularly during 1988-1992 with a general tendency to increase. TP showed a declining trend with some reversions in the pattern observed in the years 1992, 1999, and 2000. Phytoplankton estimators and chlorophyll-a concentration showed a variable trend along the study period. Zooplankton groups also had a variable trend along the study period with a general increase in density of large carnivorous (mainly Bythotrephes longimanus) and a decrease of large herbivorous (mainly Daphnia), and a similar increase in the ratio of raptorial to microphagous rotifers. Our results suggest that the lake experienced a strong trophic change associated with oligotrophication, followed by pronounced climate-induced changes during the latter period. TP concentration was strongly associated with changes in abundance of some zooplankton taxa

Arfe, A., Quatto, P., Zambon, A., Macisaac, H., Manca, M. (2019). Long-term changes in the zooplankton community of Lake Maggiore in response to multiple stressors: A functional principal components analysis. WATER, 11(5) [10.3390/w11050962].

Long-term changes in the zooplankton community of Lake Maggiore in response to multiple stressors: A functional principal components analysis

Quatto, P;Zambon, A;
2019

Abstract

We describe the long-term (1981-2008) dynamics of several physico-chemical and biological variables and how their changes may have influenced zooplankton structure in Lake Maggiore (Italy). Data was available for the 1981-1992 and 1995-2008 periods. Standardized time-series for temperature and total phosphorus (TP), chlorophyll-a, phytoplankton density (cel m-3), and cell size (μm3), as well as zooplankton structure (Copepoda, Cladocera, and Rotifera density, ind m-3) were smoothed using penalized B-splines and analyzed using Functional Principal Components (FPCs) to assess their dominant modes of variation. The first four FPCs explained 55% of 1981-1992 and 65% of 1995-2008 overall variation. Results showed that temperature fluctuated during the study period, particularly during 1988-1992 with a general tendency to increase. TP showed a declining trend with some reversions in the pattern observed in the years 1992, 1999, and 2000. Phytoplankton estimators and chlorophyll-a concentration showed a variable trend along the study period. Zooplankton groups also had a variable trend along the study period with a general increase in density of large carnivorous (mainly Bythotrephes longimanus) and a decrease of large herbivorous (mainly Daphnia), and a similar increase in the ratio of raptorial to microphagous rotifers. Our results suggest that the lake experienced a strong trophic change associated with oligotrophication, followed by pronounced climate-induced changes during the latter period. TP concentration was strongly associated with changes in abundance of some zooplankton taxa
Articolo in rivista - Articolo scientifico
B-Splines smoothing; Functional Data Analysis; Limnology; Monitoring ecological dynamics; Oligotrophication; Phytoplankton; Zooplankton
English
2019
11
5
962
partially_open
Arfe, A., Quatto, P., Zambon, A., Macisaac, H., Manca, M. (2019). Long-term changes in the zooplankton community of Lake Maggiore in response to multiple stressors: A functional principal components analysis. WATER, 11(5) [10.3390/w11050962].
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