Epipelic algal distribution in Ismailia Canal and the possible use of diatoms as bioindicators and a biomonitoring tool

Abstract

Ecology of Ismailia Canal and its branches were studied under a comprehensive program of the Freshwater and lakes Division, National Institute of Oceanography and Fisheries. Sixteen stations were selected quarterly in Ismailia Canal and its branches during 2011. Physical and chemical characters of water with surface sediment were sampled. Diatoms dominated the epipelon community, whereas chlorophyceae and cyanobacteria were rarely present. One hundred sixty-seven epipelic species were recorded. Diatoms were dominated by the centric diatoms Cyclotella spp. and Aulacoseira spp. Most frequent diatom species underwent multivariate analysis of TWINSAPN to clarify the classification of diatom species and CCA to correlate them to the most effective environmental parameters. Most species were positively affected by eutrophication, PO4 and NH4, and seasonal related factor, temperature, whereas some other species were negatively affected by pH and SiO2. Three diatom indices were applied to assess the ecological status of the studied area. Diatom species were tested as ecological bioindicators and four diatom taxa. Cocconeis placentula, Achnanthidium minutissimum, Fragilaria construens var. venter, Navicula atomus and Nitzschia gracilis satisfied the indicator selection criteria for some ecological parameters. Trophic Diatom Index (TDI), Eutrophication Pollution Index (EPI-D) and the Pampean Diatom Index (IDP) were applied. The results of the TDI revealed that the majority of the canal stations were in the acceptable ring but showed non-significant relation with the eutrophication parameters. Both IDP and EPI-D classified the stations of the canal and its branches in the high and good category of ecological status, respectively, which were not the real state in the canal and its branches as revealed by their correlation with the eutrophication parameters. The application of diatomic indices developed in foreign country cannot be applied in Egyptian environment and the development of indices based on the Egyptian ecoregions is very necessary.