Impact of zooplankton grazing on phytoplankton in north temperate coastal lakes: changes along gradients in salinity and nutrients

Christensen, Inge
Pedersen, Lisbeth Kjæreby
Søndergaard, Martin
Lauridsen, Torben L.
Tserenpil, Sh.
Richardson, Katherine
Alves Amorım, Cıhelıo
Pacheco, Juan Pablo
Jeppesen, Erik
Zooplankton grazing at similar nutrient levels is generally regarded as lower in brackish than in freshwater lakes, but experimental evidence of this is lacking. Accordingly, we conducted short-term zooplankton grazing experiments in bottles with water from 12 Danish brackish lakes covering a large gradient in salinity (0.3-17.4 parts per thousand) and nutrient concentrations as well as with water from 24 mesocosms established in the same area with various salinities (0.5-12 parts per thousand), two nutrient levels and low fish density. Grazing was low in 11 of the 12 lakes, even when they were dominated by edible phytoplankton and nutrient addition led to a major increase in phytoplankton biomass. By contrast, grazing was significant in most of the mesocosms, particularly at high nutrient levels and salinities of 8 parts per thousand or below where Daphnia dominated. Moreover, grazing decreased the biomass of most phytoplankton taxa, except for a few (e.g. Ankyra at 0.5-2 parts per thousand and Ochromonas and Chaetoceros at 8 parts per thousand). Our results provide experimental support for potentially significant grazing by zooplankton on phytoplankton in brackish lakes up to a salinity of 8 parts per thousand at low fish density; however, grazing in summer was generally low in the majority of the lakes, which we attribute to high predation on zooplankton.


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Periphyton communities play an important role in shallow lakes and are controlled by direct forces such as temperature, light, nutrients, and invertebrate grazing, but also indirectly by planktivorous fish predation. We performed a pan-European lake mesocosm experiment on periphyton colonization covering five countries along a north/south geographical/temperature gradient (Estonia, Germany, Czech Republic, Turkey, and Greece). Periphyton biomass on artificial polypropylene strips exposed at 50 cm water dept...
Effects of Crucian Carp (Carassius auratus) on Water Quality in Aquatic Ecosystems: An Experimental Mesocosm Study
Huang, Yehui; Mei, Xueying; Rudstam, Lars G.; Taylor, William D.; Urabe, Jotaro; Jeppesen, Erik; Liu, Zhengwen; Zhang, Xiufeng (MDPI AG, 2020-5-19)
The presence of omnivorous fish is known to affect aquatic ecosystems, including water quality. The effect, however, depends on the species in question, and our knowledge is limited on the effect of omnivorous crucian carp (Carassius auratus), a common and often the most numerous fish species in eutrophic shallow lakes in China. We conducted a 70-day outdoor experiment in mesocosms with and without crucian carp to examine whether this species adversely affects water quality by increasing the levels of total...
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Özkan, Korhan; Johansson, Liselotte S.; Beklioğlu, Meryem (2010-02-01)
1. Recent experimental and field studies on temperate shallow lakes indicate that nitrogen may play a greater role in their functioning than previously thought. Several studies document that abundance and richness of submerged macrophytes, both central in shallow lake ecology, may decrease with increasing nitrogen loading, especially at high phosphorus levels. However, the role of nitrogen in warm lakes with fluctuating water regimes remains to be described in detail.
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Levi, Eti Ester; Beklioğlu, Meryem; Department of Biology (2016)
Current study provides further understanding of plant macrofossil and sedimentary pigment utilization in comparison with modern and historical environmental variables. Moreover, it contributes to investigations for determining suitable macrophyte-based indices (water framework directive-WFD) that can be employed in Turkey. In total 44 small and mostly shallow lakes, covering the whole latitudinal gradient at western half of Turkey were sampled with snap-shot sampling and from another set of three large lake...
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Yagbasan, Ozlem; Yazıcıgil, Hasan; Demir, Vahdettin (2017-08-01)
Variations in temperature and precipitation have direct impacts on the physical, chemical and biological characteristics of the shallow lakes. This paper examines the possible linkages between climate variables and the water levels of shallow interconnected Lakes Mogan and Eymir, located 20 km south of Ankara in Central Anatolia. The variations in the lakes' water levels during 1996-2015 are studied and the impacts of climate variables on the lake levels are assessed to address the long-term consequences. T...
Citation Formats
I. Christensen et al., “Impact of zooplankton grazing on phytoplankton in north temperate coastal lakes: changes along gradients in salinity and nutrients,” HYDROBIOLOGIA, pp. 0–0, 2022, Accessed: 00, 2023. [Online]. Available: