Kihansi spray wetlands under mitigation measures and its implication to the biodiversity of the resultant ecosystems

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Research Paper 01/10/2014
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Kihansi spray wetlands under mitigation measures and its implication to the biodiversity of the resultant ecosystems

Severinus J. Mutagwaba, Jasson R.M. John
J. Bio. Env. Sci.5( 4), 204-213, October 2014.
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Originally, the Kihansi River Falls produced sprays that created microhabitat with high humidity and low temperatures. These microhabitats were the only habitats for Kihansi Spray Toad (KST) Nectophyrinoides asperginis, while adjacent forest supported other endemic species. However, in 1999 the Kihansi Hydropower Project diverted over 90% of the water from Kihansi River to the reservoir resulting into population crash of some wetland dependent species due to dryness. In 2001, artificial sprinklers were installed in three spray wetlands within the Kihansi Gorge (KG) to mitigate effects especially for KST, which unfortunately were declared extinct in the wild in 2009. Wetlands and forest microclimate under these mitigation measures were examined from 2010 to 2012 using data loggers set and left in the study sites to record temperature and humidity. Data were then downloaded and analysed. Temperature and relative humidity (RH) showed variation according to location and time but remained within tolerable limits for KST survival (16-21°C;60-100%) with varying mean differences at – 0.860°C (2010), -0.585°C (2011), and 0.274°C (2012) and RH (±9.576%) between 2010 and 2012. Temperatures were significantly higher in adjacent forest than in wetlands and vice versa for RH suggesting that species outside the artificially maintained wetlands currently experience considerable dryness. This indicates that, the collapse or terminating artificial sprinklers may cause immediate negative effects to the ecosystem, and especially the endemic species. Thus, a long-term monitoring program and expansion of the artificial sprinklers are recommended for the healthier KG ecosystem.


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