SUMMARY 1. Charophytes have disappeared from several enriched lakes in Scania (southern Sweden) since the 1940s. Poor light conditions, rather than a toxic effect of phosphorus or negative impact of fish, are the most probable reason for this decline. 2. Small species of charophytes (shoot diameter 0.5–1.0 mm), which are able to form dense, low mats, still occur in eutrophic lakes with high phosphorus concentrations, but are restricted to areas of shallow water. In contrast, large species (shoot diameter 1–4 mm) have totally disappeared from the most turbid lakes. I suggest that these species are unable to grow in very shallow water because of damage by ice and wave action. 3. Maximum depth distribution (z e ) and Secchi depth ( D ) were measured in Scanian lakes for both charophytes and angiosperms and combined with data obtained from Chambers & Kalff (1985). According to the combined data, z c and D are closely correlated with each other for both angiosperms and charophytes. 4. The z c of charophytes is higher than z c of angiosperms in clear lakes but lower in turbid lakes. Higher z c of angiosperms in the most turbid lakes is explained by special adaptations of these species to poor light availability (shoot elongation, canopy formation, rapid growth during spring).
No takes yet. Share an insight, caveat, or question.
Irmgard Blindow (1992) studied this question.