Abundance, diversity and distribution of Macrophytes in lotic wetlands: A case study on Sironga and Kapkatet Wetlands, Kenya

Abstract

Wetland macrophytes provide important ecological and social-economic values. However, the recent increase in anthropogenic influences has compromised the ecological integrity of most lotic wetlands, which has ultimately threatened their structure and functioning, causing degradation and loss of macrophytes. This study was aimed at assessing the biodiversity, distribution and abundance of macrophytes in Sironga and Kapkatet wetlands with respect to various anthropogenic activities.  Sampling was conducted for a period of six months, covering both dry and wet seasons from February – July 2019. Macrophytes were identified using identification keys and diversity indices such as the Shannon-Wiener, Simpson’s, and Species evenness were used to determine macrophyte diversities. The numbers of different macrophytes species was enumerated from five randomly sampled line transects along the water ways and another fifteen also randomly distributed on the wetlands on a monthly basis. There were three main lifeforms of aquatic macrophytes found in both Sironga and Kapaktet wetlands namely, emerged, submerged and floating, which were dominated by Centella asciatica and Cyperus sp. and the floating macrophytes, Potamogeton schwenfurthii dominated Kapaktet wetland. The study found that macrophyte distribution, abundance and biodiversity were highly affected by predominant economic activities resulting to wetland conversion, nutrient influxes and unsustainable exploitation of macrophytes. We recommend a further study focusing on effects of sedimentation resulting from unsustainable agricultural practices on water quality and macrophytes diversity, distribution and abundance, the effects of changing land-use practices and how different environmental agencies can be involved in the advocacy, conservation and management of the riverine wetlands.