PATTERNS OF ASPARTATE AMINOTRANSFERASE VARIATION IN RELATION TO POPULATION SIZE, FOUNDER EFFECT, AND PHYTOGEOGRAPHIC HISTORY IN Cypripedium calceolus; pp. 4–11

A CLASSIFICATION OF RIVER REACHES ON THE BASIS OF WATER QUALITY WITH REFERENCE TO STREAMS OF SAAREMAA ISLAND; pp. 12–26

A THREE-PARAMETER TROPHIC STATE INDEX FOR SMALL LAKES; pp. 27–39

TENDENCIES AND RELATIONSHIPS IN THE PELAGIC ENVIRONMENTANDPLANKTON COMMUNITY OF LAKE VÕRTSJÄRV IN 1964–1993; pp. 40–57

PLANKTON CHANGES IN ESTONIAN SMALL LAKES in 1951–1993; pp. 58–79

A REVIEW OF THE ESTONIAN DITOMYIIDAE, KEROPLATIDAE, AND DIADOCIDIIDAE (DIPTERA, NEMATOCERA); pp. 80–87

FISHES AND FISHERIES MANAGEMENT IN LAKE PEIPSI; pp. 88–93

ARCTO-ALPINE LEOTIALES AND OSTROPALES FROM THE MOUNTAINS OF SOUTH NORWAY; pp. 94–111