Biogeography of the Freshwater Zooplanktonic Communities of Spain

Abstract

Recent surveys of Spanish freshwater zooplankton have shown that it has a clear Mediterranean character; furthermore the fauna of diaptomids (Crustacea: Copepoda) constitutes a differentiated Western Mediterranean region. The Iberian peninsula, lying outside the main area of glaciation and delimited by mountains and seas, accounts for a fragmentation and differentiation of popula- tions, acting as a rather isolated dead end in the dispersion of the species to the South and West. A good example is the differentiation of species and subspecies of several genera of diaptomids, such as Hemidiaptomus, Diaptomus and Mixo- diaptomus. A synthesis of 350 zooplanktonic communities is given, distinguishing three main types of freshwaters by their age and biota: (1) Steppic lagoons rich in ancient species, showing a West Europe-Asian distribution; (2) high mountain lakes with Western Mediterranean or Lusitanian species and typical boreo- Alpine species restricted to the Pyrenees; (3) reservoirs which have facilitated the expansion of species mainly from the South, but also from the North and have permitted the entrance of species not previously found in Spain.