Biodiversity and potential socio-economic importance of Abandoned Quarry Sites in Abeokuta Area, Ogun State, Nigeria

Abstract

The study evaluated the biodiversity status of abandoned quarry pits in ‘Aro’ in Abeokuta, Ogun State in Nigeria. The site was 1800 m2 in area. A total of 80 pits were inundated in the area. Stratified sampling was used to select 30 pits, ranging from small to medium and large pits. Twenty-eight per cent of the inundated pits were selected. A total of 26 aquatic plants were identified. Nymphae lotus had the highest occurrence (90%) while others with least occurrence had 2.3%. The study area was a good location for game animals, thus, animal species such as weaver birds (Ploceus spp.), hawks (Eremopterix leucotis) and water ducks (Dendrocygna viduata) were found to occupy some of the niches. A socio-economic assessment of the inundated pits in the area revealed that pit users made financial gains from the biological resources of the pits when exchanged in
market places under direct use value of the resources. The biological resources entered into human preferences and, therefore, users generated income. Estimates from a small pit with stocking density of 791 fingerlings showed that N59,219 could be generated annually and in multiples if the pits are many. The management method excludes supplementary feeding in such pits but polyculture could be adopted with species such as Clarias gariepinus and Oreochromis niloticus. There were also indirect values (non-marketed resources) from the pits, including environmental functions such as recycling of nutrients and gases, aesthetic and water for domestic uses. These also require valuation to appreciate economic values of the pits.