Assessment of Primary Parameters in Sawa Lake and Their Impact on Productivity

Abstract

Sawa Lake is one unique enclosed water system situated in southwest Iraq. The current study intends to track the change in water level and analyse the reasons and consequences of the shift in the lake’s physicochemical qualities and primary productivity. Monthly samples were taken from three study sites from February to July 2021. The study found that air and water temperatures increased and decreased at all sites, which were evaluated during the study period. The mean salinity values ranged from 85.92 to 19.67‰, with the highest value (52.20‰) occurring before the drought in February and the lowest value (19.67‰) occurring after the drought in July. The pH level ranged from 7.57 to 8.77. The current study’s nutrient concentration (nitrite, nitrate, and phosphate) was 1.04-19.91, 21.51-251.79, 0.26 - 2.37μg/L, respectively, and there was a reverse correlation between nitrite and nitrate with salinity. The productivity measured by the light and dark bottle method recorded the lowest level (0.25 mg/m3/h) before the drought, and the highest level (3.25 mg/m3/h) was observed after the drought period. Chlorophyll concentration decreased during a drought due to lowered nutrient inputs. These data demonstrate that primary productivity in the lake’s waters is relatively low. And, the drought for the lake occurred as a result of a series of reasons that were strongly influenced by human activities. Traditionally, groundwater is extracted for agricultural purposes in this region. Thus, the rate of groundwater flows into the lake decreases, which negatively affects the physical and chemical parameters and thus affects the productivity of the lake. One of the ways of management is to form a national campaign that adopts exceptional measures to meet the challenges related to groundwater by reformulating and developing water systems, in addition to the proposal to reduce the area of the lake basin industrially to one-third, because the water, even if it returns to flood the lake, does not return to the previous quantities. Thus, when the water quality will be good, it will create the appropriate conditions to increase the productivity of the lake.