T266 Limnogeology—Progress, Challenges, and Opportunities on Earth and Beyond: A Tribute to Beth Gierlowski-Kordesch (Posters)

Tuesday, 24 October 2017
9:00 AM - 6:30 PM
Halls 4EF

IMPACTS OF EXCESS SEDIMENT DISCHARGE FROM HILLSLOPE DEFORESTATION ON POPULATIONS OF OSTRACODES ON TWO PLATFORMS IN LAKE TANGANYIKA, TANZANIA

Paper number: T266-1
Program: Technical Sessions
Time: 9:00 AM – 6:30 PM

Authors

Abstract

Lake Tanganyika is a model system for depositional processes in fresh water lakes. It is the second deepest and second most diverse lake in the world. In addition, a large percentage of species present are endemic. Increasing deforestation on the edges of the lake are threatening habitats and diversity of the lake. During rainy seasons, newly exposed soils erode off hillsides into the lake and blanket the lake bed. Many ostracodes cannot survive in waters with high turbidity. How ostracode populations respond to increases in turbidity during wet seasons can impact organisms higher in the food web. Organisms that could be impacted are various cichlids who are important to both the people that live on the lake and to the aquarium industry. We have compared surficial death assemblages of ostracodes at two sites (a more deforested site near the Luiche R. delta platform and a less disturbed site near the Mahale Mountains platform) to understand the impact of deforestation within and between sites. Results show that the Mahale site has consistently higher abundances and species diversities of ostracodes than the Luiche R. site. These data show the highest species richness in the death assemblages of ostracodes at 9 meters to 20 meters depth at the Mahale Mountains platform site and at the Luiche platform site. At these depths, the Mahale Mountain site has an average of about 14 species with a maximum number of 20 species found and a minimum of 11 species. The Luiche site has an average of 11 species at these depths with a maximum of 20 species and a minimum of 0 species. Above and below these depths the species richness decline and ostracodes at both sites are either rare or absent in very shallow water (3m). A shift in assemblage and difference in species richness between the Luiche and Mahale site suggests that deforestation is impacting ostracode populations. In order to determine whether the impact of sedimentation is from the proximal hillslope or from up river we will look at distance from the closest river. The findings from this study synthesized with other ecologic and sedimentologic work will give insights into how conservation projects can be constructed to preserve the lake’s benthic ecosystems.

Geological Society of America Abstracts with Programs. Vol. 49, No. 6

doi: 10.1130/abs/2017AM-305838

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