Effects of anthropogenic activities on plant community structure and water quality along a peri-urban freshwater stream: The Bwitingi-Bwiteva water course, Cameroon

Abstract

InformationInland freshwater streams are increasingly exposed to anthropogenic pressures that affect their quality.This research aimed to determine the relationship between land use, water quality, plant and phytoplankton community structure.Water samples were collected in triplicate from six stations along the stream and subjected to ecological analyses, phytoplankton counts, bacteriological analyses as well as determination of physico-chemical characteristics.Data were analysed using the MINITAB Version 17 statistical package with ordination to establish relationships.The results showed that settlement, and agriculture have the greatest impact on the system.The physicochemical parameters recorded included water temperature (21.14-22.56o C), pH (6.52-7.53),conductivity (152.33-253.67μS/cm),nitrates (3.68-68.01ppm),dissolved oxygen (3.32 -5.17ppm), and phosphates (1.13-3.30ppm).Four of the six sites were highly degraded with no tree species, and the phytoplankton community structure at these sites also reflected disturbances.Disturbed sites were highly eutrophic (chlorophyll a > 10µg/L at 4 sites) and contaminated with human pathogenic bacteria.Total bacterial counts ranged from 3633 CFU at Site 3, with E. coli, Salmonella sp. and Shigella sp.measuring 513, 27 and 77 CFU, respectively, to 5510 CFU for total bacteria counts in Site 6, with E. coli, Salmonella sp. and Shigella sp.measuring 1631, 544 and 110 CFU.Less disturbed sites (Sites 1 and 2) had more trees and good water quality indicators.Total bacterial counts at Sites 1 and 2 were 12 CFU and 23 CFU respectively with no E. coli, Salmonella sp or Shigella sp.Existing conservation measures at the catchment sites were effective in preventing this level of contamination.A proper landscape planning is necessary in the Buea municipality to ensure that land use and development activities are compatible with the ecological integrity of the numerous streams and their watersheds.