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- Title
Growth responses of the calcite-loricated freshwater phytoflagellate Phacotus lenticularis (Chlorophyta) to the CaCO3 saturation state and meteorological changes.
- Authors
Gruenert, Uta; Raeder, Uta
- Abstract
The pelagic phytoflagellate Phacotus lenticularis creates a shell of highly symmetrical calcite crystals at its outer extracellular layer and thereby constitutes a significant source of calcite in temperate alkaline lakes worldwide. Responses of P. lenticularis to a changing lake environment therefore have potential implications for the calcium carbonate flux in lakes. How meteorological variability in interaction with the CaCO3 saturation state may influence the abundance and phenology of P. lenticularis has not been investigated so far. We measured, biweekly to daily, algal abundance, CaCO3 saturation, pH, water temperature and nutrient status in three hard-water lakes that varied in lake morphology and wind exposure. Our data provide evidence that increasing supersaturation of CaCO3 mediates the onset of P. lenticularis exponential growth and stimulates seasonal peak development. However, total cell concentration in the lake water appears to be independent of the CaCO3 saturation state and was the highest in the most wind exposed lake. Phacotus lenticularis abundance and epilimnetic CaCO3 supersaturation were significantly positively correlated at a time lag of about 1 day. Wind caused an immediate decline in epilimnetic pH followed by a decline in CaCO3 saturation about 2 days later. Solar irradiance positively affected both pH and water temperature, but water temperature changes were insufficient to produce a significant CaCO3 saturation response. We conclude that the CaCO3 saturation state is a determinant factor driving the timing of P. lenticularis peaks in alkaline lakes.
- Subjects
PHYTOFLAGELLATES; CALCIUM carbonate; CALCITE crystals; ALKALI lakes; WATER temperature; WATER hardness; FRESHWATER ecology
- Publication
Journal of Plankton Research, 2014, Vol 36, Issue 3, p630
- ISSN
0142-7873
- Publication type
Article
- DOI
10.1093/plankt/fbu006