Role of food partitioning in structuring the zooplankton community in mountain lakes.
Trophic-niche differentiation is often cited as a main factor in structuring zooplankton assemblages, although field evidence for this is rarely presented. The study was based on a survey of 29 Pyrenean lakes with altitudes ranging between 1,875 and 2,990 m carried out during July and August 2000. Because of the oligotrophic nature of these lakes, we aimed to confirm that food partitioning is a major factor in shaping zooplankton assemblages. We analysed the amino acid composition of six cladocera and seven copepod species. A discriminant analysis showed that each species could be distinguished according to its amino acid composition. A negative relationship between amino acid differentiation and co-occurrence among the cladocera and cyclopoid copepod was observed. In contrast, calanoids did not show any relationship and were characterised by a high amino acid differentiation between species. As the differences in the amino acid composition among zooplankton species indicate distinct food sources, the relationship found indicates that trophic-niche differentiation plays a key role in determining the assemblage of these zooplankton communities. Therefore exploitative competition, either at present or in the past by driving co-evolutionary histories, has been a significant factor in structuring the cladocera and cyclopoid communities in these oligotrophic lakes.
Guisande
C
C
Facultad de Ciencias, Universidad de Vigo, Lagoas-Marcosende, 36200 Vigo, Spain. castor@uvigo.es
Bartumeus
F
F
Ventura
M
M
Catalan
J
J
D000531:Altitude; D000596:Amino Acids / Q000032:analysis*; D000818:Animals; D005075:Biological Evolution; D033361:Cladocera / Q000737:chemistry*; D033342:Copepoda / Q000737:chemistry*; D020387:Food Chain; D011157:Population Dynamics; D014881:Water Supply; D015048:Zooplankton
D000596:Amino Acids