The impact of deforestation and agriculture on aquatic ecosystems: Introduction

Impact of forest modification and agricultural practices on aquatic ecosystems

By

Okogwu Okechukwu I1 ; Ngonkeu Mangaptche Eddy Leonard2; Mochiah Moses Brandford3; Chima Uzoma Darlington 4 ; Bwala Richard Lema5 and Augustus Asmah 6

1 Applied Biology Department, Ebonyi State University, PMB 53, Abakaliki, Ebonyi State, Nigeria 2 Institute of Agricultural Research for Development PO Box 2067 Yaounde Cameroon 3 Crops Research Institute, P. O. Box 3785, Kumasi, Ghana 4 Department of Forestry & Wildlife Mgt., University of Port Harcourt, Nigeria 5 Environmental Division, National Institute for Freshwater Fisheries Research (NIFFR), P.M.B. 6006, New Bussa, Niger State, Nigeria. 6 Dept of Soil Science, School of Agriculture, University of Cape Coast, Ghana.

Introduction

Recent studies have shown that there is a direct link between land use and water quality. Deforestation exposes the land surface and contributes to soil erosion and nutrient leaching from soils into nearby rivers, lakes and ponds. Increased siltation of rivers and ponds may impact negatively on the quality of these ecosystems. Siltation decreases water depth leading to increase in water temperature, increase in water turbidty and a reduction in water clearity; such conditions will impair light penetration and as a consequence, reduce phytoplankton productivity. Reduced phytoplankton productivity is likely to have a cascading effect on zooplankton, fish productivity and diversity.

Forests especially riparian forests act as a buffer to rivers and other water bodies preventing sediments from contaminating them.Consequently,the replacement of natural forests with other land use types like farmlands, will undoubtedly lead to water quality detrioration, and may impact negatively on fish populations due to modified habitat conditions. Available information also shows that the impact of artificial fertilizers and pesticides on aquatic ecosystems are numerous, difficult to predict and ecosytem dependent. Most researchers have therefore, advocated the use of biofertilizers and biopesticides. Since these are biodegradable, it is believed that the impact on aquatic ecosytems may be minimal and easy to predict. However, there is a dearth of information on the comparative impact of artificial fertilizers and biofertilizers on one hand and artificial pesticides and biopesticides on the other hand accross a broad landscape scenerio. This study will be undertaken to evaluate the impact of deforestation and current agricultural practices on aquatic ecosystems in three countries within the West and central African Regions.