First Records of Butterfly Diversity on Two Remote Islands on the Volta Lake of Ghana, the Largest Reservoir by Total Surface Area in the World

摘要

The construction of the Akosombo Dam in Ghana for hydroelectric energy led to the creation of many islands on the Volta Lake. The biological diversity on these islands is unknown and so a rapid assessment was conducted in January 2014 as part as a region wide assessment to determine the butterfly diversity on two of these islands, Biobio and Agbasiagba. Diversity indices were computed for both islands using the Shannon-Weiner index, Margalef’s index for richness and Whittaker’s index for comparison of diversity between the two islands. A total of eight hundred and eighty-one (881) individual butterflies representing forty-five (45) species belonging to eight (8) families were recorded during the study. Thirty-nine (39) species of butterflies were recorded on Biobio island whiles twenty-eight (28) species were recorded on Agbasiagba. This was expected as the larger islands are expected to support more species than smaller ones, with Biobio island being relatively bigger than Agbasiagba. The shared species of butterflies on both islands were twenty-two (22) representing 48.9% of the total species accumulated. Indicator species like Junonia oenone, Danaus chrysippus and Papilio demodocus were also recorded indicating the degraded floral quality of the Islands. Even though this survey has not found much, it serves as the first record of Butterflies on these Islands. A thorough assessment of these islands in a more suitable season is however being recommended.