Publikationsdatum:
2011-04-02
Beschreibung:
The mean body size of limnetic cladocerans decreases from cold temperate to tropical regions, in both the northern and the southern hemisphere. This size shift has been attributed to both direct (e.g. physiological) or indirect (especially increased predation) impacts. To provide further information on the role of predation, we compiled results from several studies of subtropical Uruguayan lakes using three different approaches: (i) field observations from two lakes with contrasting fish abundance, Lakes Rivera and Rodó, (ii) fish exclusion experiments conducted in in-lake mesocosms in three lakes, and (iii) analyses of the Daphnia egg bank in the surface sediment of eighteen lakes. When fish predation pressure was low due to fish kills in Lake Rivera, large-bodied Daphnia appeared. In contrast, small-sized cladocerans were abundant in Lake Rodó, which exhibited a typical high abundance of fish. Likewise, relatively large cladocerans (e.g. Daphnia and Simocephalus ) appeared in fishless mesocosms after only 2 weeks, most likely hatched from resting egg banks stored in the surface sediment, but their abundance declined again after fish stocking. Moreover, field studies showed that 9 out of 18 Uruguayan shallow lakes had resting eggs of Daphnia in their surface sediment despite that this genus was only recorded in three of the lakes in summer water samples, indicating that Daphnia might be able to build up populations at low risk of predation. Our results show that medium and large-sized zooplankton can occur in subtropical lakes when fish predation is removed. The evidence provided here collectively confirms the hypothesis that predation, rather than high-temperature induced physiological constraints, is the key factor determining the dominance of small-sized zooplankton in warm lakes. Content Type Journal Article Pages 1-15 DOI 10.1007/s10750-011-0645-0 Authors Carlos Iglesias, National Environmental Research Institute, Aarhus University, Vejlsøvej 25, 8600 Silkeborg, Denmark Néstor Mazzeo, Grupo de Ecología y Rehabilitación de Sistemas Acuáticos, Centro Universitario Regional Este-Facultad de Ciencias, Universidad de la República, Maldonado, Uruguay Mariana Meerhoff, National Environmental Research Institute, Aarhus University, Vejlsøvej 25, 8600 Silkeborg, Denmark Gissell Lacerot, Sección Limnología, Facultad de Ciencias, Universidad de la República, Iguá 4225, CP 11400 Montevideo, Uruguay Juan M. Clemente, Grupo de Ecología y Rehabilitación de Sistemas Acuáticos, Centro Universitario Regional Este-Facultad de Ciencias, Universidad de la República, Maldonado, Uruguay Flavio Scasso, Sección Limnología, Facultad de Ciencias, Universidad de la República, Iguá 4225, CP 11400 Montevideo, Uruguay Carla Kruk, Sección Limnología, Facultad de Ciencias, Universidad de la República, Iguá 4225, CP 11400 Montevideo, Uruguay Guillermo Goyenola, Grupo de Ecología y Rehabilitación de Sistemas Acuáticos, Centro Universitario Regional Este-Facultad de Ciencias, Universidad de la República, Maldonado, Uruguay Javier García-Alonso, Sección Limnología, Facultad de Ciencias, Universidad de la República, Iguá 4225, CP 11400 Montevideo, Uruguay Susanne L. Amsinck, National Environmental Research Institute, Aarhus University, Vejlsøvej 25, 8600 Silkeborg, Denmark Juan C. Paggi, Instituto Nacional de Limnología-CONICET, Universidad Nacional del Litoral. Ciudad Universitaria. Paraje “El Pozo”, CP 3000 Santa Fé, Argentina Susana José de Paggi, Instituto Nacional de Limnología-CONICET, Universidad Nacional del Litoral. Ciudad Universitaria. Paraje “El Pozo”, CP 3000 Santa Fé, Argentina Erik Jeppesen, National Environmental Research Institute, Aarhus University, Vejlsøvej 25, 8600 Silkeborg, Denmark Journal Hydrobiologia Online ISSN 1573-5117 Print ISSN 0018-8158
Print ISSN:
0018-8158
Digitale ISSN:
1573-5117
Thema:
Biologie
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