Evaluation of chemical Water Quality and Macro Invertebrates Biodiversity in the Obili Aquaculture Unit –Yaounde (Cameroon)

by

TANGEM LUCAS LEKU (+237674930502, tangemlucasleku@gmail.com)

Professional Master of Engineering in Fisheries and Aquatic Sciences, Option Aquaculture and Master of Science in HYDROBIOLOGY AND ENVIRONMENT, LABORATORY OF HYDROBIOLOGY AND ENVIRONMENT,

DEPARTMENT OF ANIMAL BIOLOGY AND PHYSIOLOGY, FACULTY OF SCIENCE, UNIVERSITY OF YAOUNDE I.

TANGEM LUCAS LEKU, OMGBA MARIE THÉRÈSE VIVIANE, MPOMEZOK CHILLY VANESSA GABY, NYAMA JOSEPH, TAMPONO IDEDOU CHRISTELLE.

MINISTRY OF LIVESTOCK, FISHERIES AND ANIMAL INDUSTRIES

YAOUNDE, CAMEROON.

Abstract

The study evaluated water quality and macroinvertebrate biodiversity in four (04) fish ponds at the Obili Aquaculture Unit, Centre Region of Cameroon, from June 2022 to November 2022. Monthly sampling was carried out, measuring physico-chemical parameters according to Rodier’s guidelines and collecting benthic macroinvertebrates using a multihabitat approach. Results indicated poorly oxygenated, slightly acidic water conditions, which are unfavorable for aquatic species production, along with low levels of organic pollution indicators such as nitrates, orthophosphates, and nitrites. A total of 532 macroinvertebrates were identified, spanning two phyla, two classes, six orders, and ten families. Insects dominated the community, comprising 51.7% relative abundance across four orders and eight families, followed by Gastropoda, which accounted for 48.3% relative abundance across two orders and two families. Spatial-temporal analysis revealed the presence of pollution-tolerant taxa, including Lestidae, Thiaridae, and Lymnaeidae, indicating excessive organic pollution. Diversity indices (Shannon-Weaver and Pielou’s equitability) reflected low taxa diversity, caused by unfavorable conditions for pollution-sensitive species. Hilsenhoff’s Biotic Index confirmed significant organic pollution across all ponds. The Global Biotic Numeric Index (GBNI) indicated poor water quality in the fish ponds, while Sörensen’s similarity coefficient (>50%) showed high similarity among ponds.

. Finally, the study suggests promoting macroinvertebrate cultivation as a viable alternative to fishmeal in aquaculture feed.

Key words: Biodiversity, Benthic Macroinvertebrates, Water quality, Fish ponds, Obili.

Fish diversity in the Obili Aquaculture Unit (Centre Region) and relationship to organoleptic properties of the ecosystem

by

TANGEM LUCAS LEKU (+237674930502, tangemlucasleku@gmail.com)

TANGEM LUCAS LEKU, OMGBA MARIE THÉRÈSE VIVIANE, MPOMEZOK CHILLY VANESSA GABY, NYAMA JOSEPH, TAMPONO IDEDOU CHRISTELLE.

MINISTRY OF LIVESTOCK, FISHERIES AND ANIMAL INDUSTRIES

YAOUNDE, CAMEROON.

Abstract

The study evaluated water quality and fish biodiversity in four fish ponds at the Obili Aquaculture Unit, located in the Centre Region of Cameroon, from June to November 2022. Monthly sampling was carried out, with physico-chemical parameters measured following Rodier’s guidelines. A multihabitat approach was used for fish capture, employing nets to sample and count fish, which allowed estimation of total fish populations in each pond. Results indicated poorly oxygenated and slightly acidic water conditions, unfavorable for aquatic species production, along with low levels of organic pollution indicators such as nitrates, orthophosphates, and nitrites. The African catfish, identifiable by barbels, absence of scales, a single long dorsal fin, and dark grey coloration with a white ventral side, was present in all ponds. Pond 4 was stocked at a density of 20 catfish per square meter, corresponding to an estimated 8,000 catfish, while only a few Tilapia were observed there. Oreochromis niloticus, an omnivorous grazer feeding on phytoplankton, periphyton, aquatic plants, small invertebrates, benthic fauna, detritus, and associated bacterial films, outnumbered catfish in the other ponds. Catfish stocking was aimed at controlling tilapia populations. The Global Biological Normalized Index (GBNI) indicated poor water quality across the ponds, whereas Sørensen’s similarity coefficient (exceeding 50%) demonstrated good biological similarity among the ponds. Finally, the study suggests promoting macroinvertebrate cultivation as a viable alternative to fishmeal in aquaculture feed.

Key words: Biodiversity, fish, water quality, fish ponds, Obili.