Limnological Determinants of Periphytic Algae Assemblage on Macrophyte in the Humic Freshwater Ecosystem of Eniong River, Itu Nigeria
Essien, Imedimfon I. *
Department of Botany and Ecological Studies, Faculty of Biological Science, University of Uyo, Uyo, Nigeria.
Udo, Ekaete D.
Department of Botany and Ecological Studies, Faculty of Biological Science, University of Uyo, Uyo, Nigeria.
Asuquo, Terrance J.
Department of Botany and Ecological Studies, Faculty of Biological Science, University of Uyo, Uyo, Nigeria.
Onyegbule, Chiemeka L.
Department of Botany and Ecological Studies, Faculty of Biological Science, University of Uyo, Uyo, Nigeria.
*Author to whom correspondence should be addressed.
Abstract
Aims: This research evaluate how limnological parameters influence the composition and distribution of periphytic algal communities in the Eniong River, a humic freshwater ecosystem in Itu, Nigeria.
Study Design: A stratified random sampling design was employed to ensure comprehensive coverage of the river ecosystem. The river was divided into four zones based on geomorphological characteristics and land use patterns and four representative sampling stations were selected for analysis.
Place and Duration of Study: The study was conducted along the Eniong River in Itu, Nigeria, during the wet season from April to October 2024 and a dry season from November 2023 to March 2024 to capture the influence of nutrient runoff and anthropogenic activities on water quality.
Methodology: Periphytic algae were collected manually from submerged surfaces of aquatic macrophytes using a standardized scraping technique, with samples preserved in Lugol’s iodine solution. Algal identification was carried out under a compound microscope using established taxonomic keys while Limnological variables were conducted based on standard methods as described in APHA. A total of 48 species were identified
Results: Physicochemical conditions indicated significant eutrophication and heavy metal stress. The pH ranged from 6.15 to 6.715, slightly below the upper limit of recommended standards, while water temperature remained consistently around 26 °C. Although conductivity and TDS were low, the system displayed very low alkalinity and hardness, rendering it vulnerable to pH fluctuations and metal toxicity. Nutrient concentrations were alarmingly high, with nitrate and phosphate levels far exceeding WHO and NESREA limits, driving eutrophication. Concurrently, elevated levels of heavy metals (chromium, lead, iron, nickel, and cadmium) were observed. These combined stressors favored the proliferation of opportunistic, eutrophication- and metal-tolerant periphytic algae such as Closterium moniliferum and Fragilaria javanica while more sensitive taxa were notably absent.
Conclusion: The findings underscore the critical role of multivariate limnological factors in shaping algal assemblages and highlight the potential of periphytic algae as bioindicators for assessing ecosystem health in tropical freshwater environments.
Keywords: Periphytic algae, limnology, black water, diversity, pollution