AQUATIC VEGETATION OF NOVA-SCOTIAN LAKES DIFFERING IN ACIDITY AND TROPHIC STATUS

Aquatic macrophytes of the littoral zone were surveyed in 21 Nova Scot ian lakes, and macrophyte composition was interpreted in relation to c hemical and physical characteristics. The lake set included both nutri ent-enriched and acidified lakes, and consequently had a wide range of water chemistry variables, notably pH (3.7-8.3) and total phosphorus (0.003-6.0 mg l(-1)). Using canonical correspondence analysis, we rela ted differences in vegetation among lakes to 14 water chemistry and th ree physical variables. Alkalinity, total phosphorus, and total nitrog en were most strongly correlated with differences in vegetation betwee n heavily enriched, moderately enriched and non-enriched lakes. Intere stingly, macrophyte composition was not strongly correlated with pH. E ven in a subset of lakes consisting of moderately enriched and non-enr iched lakes, alkalinity, total phosphorus and total nitrogen remained strongly correlated with vegetation differences. By contrast, vegetati on differences among non-enriched lakes correlated most strongly with substrate slope, lake area, calcium, and alkalinity.