Palaeoenvironmental reconstruction of the recent history of Lake Chiuta Wetland, south Malawi

Abstract

Understanding the environmental trajectory over the recent (ca. 200 years) of shallow inland water bodies is key to sustainable management of the fisheries industry that is facing severe challenges. Paleolimnological techniques using multiple proxies provide valuable insights into the drivers and responses of these delicate systems currently threatened by environmental degradation and climatic extremes. Until the latter part of the 20^th Century, Lake Chiuta used to be an important ground for fisheries. The cause of the collapse of the fisheries industry is mostly assumed to be overfishing although there are pointers of water quality change and environmental degradation within the riparian catchment of the lake. This study used a multiple proxies such as LOI, grain size analyses and diatoms for mapping recent environmental changes of Lake Chiuta. Results of the study indicate that the lake is periodically affected by near decadal variability of climate in the short term but is on a medium to long term trajectory of declination affected by a shrinking lake and rapid incursion of marshland onto the open water. These may pose serious challenges not only to the fishery, but long term survival of the water body for other uses. It is recommended that integrated watershed management programs be used as a medium to long term solution to the water quality problems that impact the lake at various scales.

Keywords: Diatoms, Lake Chiuta, Marshland, Palaeolimnology