Azubuike V. Chukwuka

By Azubuike Victor Chukwuka and Ozekeke Ogbeide

The unregulated use of watersheds for agriculture negatively impacts the quality of river basins. In particular, the reduced quality of surface-waters, have been attributed to absence or poorly-decided riparian-buffer specifications in environmental laws. To demonstrate suitable buffer-width for protection of surface water, sediment and benthic fish populations, five riparian areas with different vegetation richness and buffer-width were selected within an organochlorine pesticide (OCP)-impacted watershed using the Normalized Differential Vegetation Index (NDVI) and multiple buffer analysis respectively. Mean OCP levels in surface water, sediment and fish sampled at each riparian stations showed site-specific differences with markedly higher levels of α-BHC, β-BHC, δ-BHC, p,p′-DDD and total pesticide residues at stations with least riparian cover. The principal component analysis further revealed more OCPs associating with sediment and fish from stations having smaller buffer-width and sparse riparian vegetation. Stations with wider buffer-width of at least 120 m provided greater protection to adjacent surface water and benthic fish populations. While this study recommends riparian buffer-widths for a typical tropical environment, further research which assesses other contaminant types in aquatic matrices adjacent to different riparian environments would be valuable and informative for regulatory guidance and strategic protection of ecosystem services.

Part of the book: River Basin Management

By Aina O. Adeogun and Azubuike V. Chukwuka

Lakes as essential ecosystems for diverse life forms, including humans, have suffered altered morphology with adverse effects on biodiversity including amphibians and amphibious species. Thus, it is imperative for effective conservation strategies to simultaneously consider lake morphology, landscape variables, and the role of keystone species as ecosystem engineers for biodiversity preservation. Keystone species, particularly birds and large-bodied predators, i.e., crocodylians, play a critical role in maintaining the health of lake ecosystems as ecosystem engineers, bringing about large-scale changes in lake morphology and hydrology that determine the abundance and survival of other species in the ecosystem. Conservation strategies should, therefore, prioritize the protection of these keystone species and their habitats. To balance the needs of human society with the protection of lake ecosystems and their biodiversity, conservation practices must involve stakeholder engagement, including government agencies, local communities, traditional ecological knowledge, and scientists. A multidisciplinary approach, incorporating ecological, hydrological, and social factors, is considered necessary for effective lake conservation. This approach will encompass the preservation of lake biodiversity and consider important variables such as lake morphology, landscape variables, and the role of keystone species as ecosystem engineers in providing insights for strategic conservation practices.

Part of the book: Science of Lakes