Species-specific phenological trends in shallow Pampean lakes (Argentina) zooplankton driven by contemporary climate change in the Southern Hemisphere.
Diovisalvi, N., Odriozola, M., Garcia de Souza, J., Rojas Molina, F., Fontanarrosa, M. S., Escaray, R., Bustingorry, J., Sanzano, P., Grosman, F. and Zagarese, H.
Instituto de Investigaciones Biotecnologicas-Instituto Tecnologico de Chascomus (IIB-INTECH) (CONICET-UNSAM), Chascomus, Buenos Aires, Argentina.
Laboratorio de Ecologia de Peces, Instituto de Limnologia "Dr. Raul A. Ringuelet" (ILPLA) (CONICET-UNLP), La Plata, Buenos Aires, Argentina.
Instituto Nacional de Limnologia (CONICET-UNL), Santa Fe, Argentina.
Facultad de Ciencias Veterinarias, Universidad Nacional del Centro de la Provincia de Buenos Aires (UNC), Tandil, Buenos Aires, Argentina.
The relationship between the timing of recurrent biological events and seasonal climatic patterns (i.e., phenology) is a crucial ecological process. Changes in phenology are increasingly linked to global climate change. However, current evidence of phenological responses to recent climate change is subjected to substantial regional and seasonal biases. Most available evidence on climate driven phenological changes comes from Northern Hemisphere (NH) ecosystems, and typically involve increases in spring and summer temperatures, which translate into earlier onsets of spring population developments. In the Argentine Pampa region, warming has occurred at a much slower pace than in the NH, and trends are mostly restricted to increases in the minimum temperatures. We used zooplankton abundance data from lake Chascomus (recorded every two weeks from 2005 to 2015) to evaluate potential changes in phenology. We adopted a sequential screening approach to identify taxa displaying phenological trends, and evaluated if such trends could be associated to observed long-term changes in water temperature. Two zooplankton species displayed significant later shifts in phenology metrics (end date of Brachionus havanaensis seasonal distribution: 31-day/decade, onset and end dates of Keratella americana seasonal distribution: 59-day/decade and 82-day/decade, respectively). The timing of the observed shift in B. havanaensis phenology was coincident with a warming trend in the May lake water temperature (4.7 degrees C per decade). Analysis of abundance vs. temperature patterns from six additional shallow Pampean lakes, and evaluation of previous experimental results, provided further evidence that the lake water warming trend in May was responsible for the delayed decline of B. havanaensis populations in autumn. This study is the first report of freshwater zooplankton phenology changes in the Southern Hemisphere (SH). This article is protected by copyright. All rights reserved.
Global Change Biology 24(11): 5137-5148 (2018)