Climate warming reduces fish production and benthic habitat in Lake Tanganyika, one of the most biodiverse freshwater ecosystems

Proceedings of the National Academy of Sciences
By: , and 

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Abstract

Warming climates are rapidly transforming lake ecosystems worldwide, but the breadth of changes in tropical lakes is poorly documented. Sustainable management of freshwater fisheries and biodiversity requires accounting for historical and ongoing stressors such as climate change and harvest intensity. This is problematic in tropical Africa, where records of ecosystem change are limited and local populations rely heavily on lakes for nutrition. Here, using a ∼1,500-y paleoecological record, we show that declines in fishery species and endemic molluscs began well before commercial fishing in Lake Tanganyika, Africa’s deepest and oldest lake. Paleoclimate and instrumental records demonstrate sustained warming in this lake during the last ∼150 y, which affects biota by strengthening and shallowing stratification of the water column. Reductions in lake mixing have depressed algal production and shrunk the oxygenated benthic habitat by 38% in our study areas, yielding fish and mollusc declines. Late-20th century fish fossil abundances at two of three sites were lower than at any other time in the last millennium and fell in concert with reduced diatom abundance and warming water. A negative correlation between lake temperature and fish and mollusc fossils over the last ∼500 y indicates that climate warming and intensifying stratification have almost certainly reduced potential fishery production, helping to explain ongoing declines in fish catches. Long-term declines of both benthic and pelagic species underscore the urgency of strategic efforts to sustain Lake Tanganyika’s extraordinary biodiversity and ecosystem services.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Climate warming reduces fish production and benthic habitat in Lake Tanganyika, one of the most biodiverse freshwater ecosystems
Series title Proceedings of the National Academy of Sciences
DOI 10.1073/pnas.1603237113
Volume 113
Issue 34
Year Published 2016
Language English
Publisher National Academy of Sciences
Contributing office(s) Pacific Coastal and Marine Science Center
Description 6 p.
First page 9563
Last page 9568
Country Burundi, Democratic Republic of the Congo, Tanzania, Zambia
Other Geospatial Lake Tanganyika, Mahale Mountains National Park
Online Only (Y/N) N
Additional Online Files (Y/N) N