The zooplankton community of Lake Abo Zaabal, a newly-formed mining lake in Cairo, Egypt

Abstract

Abo Zaabal Lake, a new mining lake at the outskirts of Cairo, receives domestic sewage from a nearby village. We examined its chemical and biological properties in order to develop a plan to improve its ecosystem services. The pH ranged between 7.8 and 8.5, salinity was 17 ppt and conductivity was 28 mS cm⁻¹, indicating brackish water. The pelagic zooplankton community comprised Rotifera (16%), Protozoa (Ciliophora and Rhizopoda) (18%) and Copepoda (16%). Cladocera were seldom recorded. Hexarthra, Brachionus and Rotaria were the dominant rotifer taxa. Several characteristics — including the community composition, the dominance of small ciliates and nauplii, the abundance of Cyanobacteria, and the absence of macrophytes — indicated that it is a severely eutrophic lake. To improve the water quality we recommend that: (1) domestic sewage inflow should be stopped so as to reduce nutrient loading into the basin; (2) the growth of rooted macrophytes should be encouraged so as to increase water transparency by reducing phytoplankton biomass through competition for nutrients; and (3) piscivorous fish should be introduced to control zooplanktivorous fish in the lake and thus promote the growth of large filter-feeding zooplankton.