Algal and riparian plant diversity and ecology of Bakingili Crater Lake in the Mount Cameroon National Park

Abstract

High altitude lakes, typically found in mountainous regions, are unique ecosystems supporting distinct biological communities. There is limited knowledge about the diversity and ecology of riparian plants growing in the Bakingili Crater Lake. The objectives of study were to assess the water quality of Bakingili Crater Lake and to determine the phytoplankton and riparian plant community structure of Bakingili Crater Lake.  Three sets of water samples were collected at the top 10 cm of the surface and at 3 m depth of the Lake using a van don water sampler. Phytoplankton and physicochemical parameters were determined in the laboratory using standard procedures and spectrophotometric methods. Inventory of riparian plants was done by delimiting two transects. In each transect, 2 plots of 10 m × 100 m each were demarcated. The Braun-Blanquet method was used for sampling herbaceous species. Tree frequency and diameter at breast height were recorded. Water pH was weakly acidic, 6.2 and 5.65 on the surface and depth respectively, with a low conductivity (0.02 µS/cm), with no significant difference at the bottom. A higher phytoplankton diversity was recorded for surface water (H’=1.58) than bottom water (H’=1.27). Cyanophyta was the most abundant taxon, with a relative dominance of 77% and 83% in surface and depth respectively. A total of 22 herbaceous species were identified. Shannon-Weiner’s diversity was 1.27, and species having the highest relative frequency included Cyperus atrovirdis (16.7%), Melanthera scandens (11.93%), Achyranthes aspera. var. sicula (7.7%) and Aframomum flavum6.84%). A low tree diversity of 0.67 was obtained, with the most abundant species being Tabernaemontana crassa Benth (35.42%) and Syzygium staudtii (Engl.) Mildbr (29.17%). Lake Bakingili is nutrient-poor and weakly acidic, driving a low phytoplankton abundance and diversity predominantly cyanobacteria which may have health implications on the tourists and wildlife in Mount Cameroon National Park.