Search for: All records

Building resilience to climate change in the Afrotropics hinges on accurately predicting the style and tempo of ecosystem responses. Paleoecological records offer valuable insights into vegetation dynamics, yet high-resolution data sets remain scarce in Africa. Here, we present a new radiocarbon-dated sediment core from Lake Tanganyika, capturing terrestrial ecosystem responses to hydroclimate variability and fire activity during the Common Era. Phytolith and macrocharcoal records reveal oscillations between grasslands and woodlands in the Zambezian miombo region, transitioning from “stable” to “unstable” states depending on fire disturbance levels. The expansion of grasslands was facilitated by reduced precipitation, increased fire activity, and ecosystem interactions. Our data sets provide new constraints regarding the timing and landscape responses within the Lake Tanganyika watershed to global hydroclimate changes, including the relatively dry Medieval climate anomaly (ca. 1000−1250 CE) and the two phases of the Little Ice Age. Cold and wet conditions, which favored tree encroachment, prevailed during the “early” Little Ice Age (ca. 1250−1530 CE), whereas drier conditions coupled with increased fire activity during the “main” Little Ice Age (ca. 1530−1850 CE) promoted the expansion of open grasslands. Significant changes in grassland-woodland communities were driven and modulated by hydroclimate and rapid ecosystem feedbacks. Fire activity served as both a disruptive force, facilitating the opening of landscapes and restricting the encroachment of trees, and a steadying control that promoted a grassland “stable state” in the tropical savannas surrounding Lake Tanganyika. Understanding shifting vegetation patterns throughout the Common Era offers valuable insights for developing biodiversity conservation strategies, sustainable land-use practices, and the maintenance of ecosystem services provided by miombo woodlands for millions of rural poor in the Lake Tanganyika basin. 

Abstract The significance of large tropical lakes as environmental reservoirs of Vibrio cholerae in cholera endemic countries has yet to be established. By combining large scale plankton sampling, microbial culture and ultrasensitive molecular methods, namely Droplet Digital PCR (ddPCR) and targeted genomics, the presence of Vibrio cholerae was investigated in a 96,600 L volume of surface water collected on a 322 nautical mile (596 km) transect in Lake Tanganyika. V. cholerae was detected and identified in a large area of the lake. In contrast, toxigenic strains of V. cholerae O1 or O139 were not detected in plankton samples possibly in relation to environmental conditions of the lake ecosystem, namely very low salinity compared to marine brackish and coastal environments. This represents to our knowledge, the largest environmental study to determine the role of tropical lakes as a reservoir of V. cholerae .