Epiphytic Algae on Dominant Macrophytes in Lotic Ecosystems in the Eastern Flanks of Mount Cameroon

Aims: This study was designed to assess quantitative estimates of epiphyte biomass and diversity on the dominant macrophytes in two rivers in the Eastern flanks of Mount Cameroon.

Place and Duration of Study: Two sets of water samples were collected at the top 10cm of the rivers for nutrient and chlorophyll a determination. A single preliminary collection of algal epiphytes from partially submerged aquatic macrophytes was carried out from the littoral zone of Ndongo and Limbe rivers, between May and June 2023.

Methodology: The sedimentation technique was employed in the study. Three slides were prepared for each aquatic macrophyte sample for microscopic analysis. Identification was done by comparative morphology using relevant journals and textbooks.

Results: All variables related to water clarity (TSS, Phytoplankton Chl a, HC) assessed during the study were similar in both rivers. Water clarity based on HC values was below 6 mg/l implying both rivers were clear during the study period. Epiphytic algae identified were recorded from 4 main divisions, namely Bacillariophyta, Chlorophyta, Cyanophyta and Euglenophyta. The highest algal diversity in Ndongo was recorded from Commelina benghalensis (H=3.45) with 41 algal species identified. Justicia in Ndongo river had the lowest algal species richness (24) with an algal diversity of 2.91. Nymphaea had the highest algal diversity (H=3.36) and algal species richness (36) in Limbe river. Algal species richness was the same in the two other plant hosts Commelina benghalensis and Colocasia esculentus (29 species per host). The highest algal chlorophyll a was recorded on Nymphaea (621mg/g dry weight) and Commelina benghalensis (644mg/g) in Limbe and Ndongo respectively. Lowest epiphyte Chlorophyll a was recorded in Justicia secunda in Ndongo (607 mg/g).

Conclusion: All macrophytes studied harbored a large algal flora demonstrating their diverse ecological roles carried out in these rivers. Nymphaea lotus and Commelina benghalensis in Limbe and Ndongo rivers had the highest epiphytic algal biomass.