CONTRIBUTION TO THE KNOWLEDGE OF THE BATHYMETRY AND THE SPATIAL DISTRIBUTION OF N, P, K OF THE MUD OF LAKE OUBEIRA (EXTREME NE ALGERIAN)

Alayat Hacène, Mouissi Samia, Satouh Rachida
Laboratory agriculture and ecosystem functioning, University of El Tarf, El Tarf 36000, Algeria

Abstract

Lakes around the Mediterranean, and particularly those of North Africa, have degradation qualitative and quantitative, resulting from natural constraints (precipitation, runoff, siltation) and anthropogenic (withdrawals, discharges). This degradation has consequences on the structure and functioning of ecosystems. The Oubeira Lake which is the subject of this study is located in the NE of Algeria. This extremely precious environmental indicator, with an area of 21.73 km2, may disappear because of the bulkiness of the water by the vegetation (yellow water lily, Meriophyle, chestnut of water…), discharges of waste water from smaller surrounding communities, the pumping of water during low water period (speculative crops) and fire in the watershed, which lead to a development of soils and increases erosion. These actions have effects on some physico-chemical properties of the water (temperature, conductivity, pH, turbidity,...) and mud (levels of nitrogen, phosphorus, potassium, calcium…). Samples of mud were made along a twenty vertical, distributed along six transects. The results covering  all the stretch of water, shallow, show the mudding of the lake and a sandy texture of the mud along the east bank, a clay texture in the center and a sandy loam trend for the rest of the lake . Chemical analysis proved a significant contribution to identify high levels of nitrogen, potassium and phophorus and the accumulation in the center of the lake of these elements, which are responsible for degradation of the aquatic ecosystem, by the proliferation of aquatic vegetation. The correlations between the different parameters of the mud and water are lost and can not be determine with precision, the equations that govern the relationship between elements dissolved in mud.

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