Ecological Studies of Epiphytic Microalgae and Epiphytic Zooplankton on Seaweeds of the Eastern Harbor, Alexandria, Egypt

A qualitative and quantitative study on the epiphytic microalgae and epiphytic zooplankton were conducted in order to follow up their community structures on seaweeds in relation to some physico-chemical variables in the coastal waters of the Eastern Harbor of Alexandria. Water and macroalgal samples were collected seasonally during two years successively: Winter, summer, autumn (2012) and spring (2013). The collected seaweeds were Ulva fasciata (green alga), Corallina mediterranea, Corallina officinalis, Gelidium sp., Pterocladiella capillacea, Hypnea musciformis and Grateloupia doryphora (red algae). The studied water quality parameters were pH, salinity, dissolved oxygen, oxidizable organic matter and nutrient salts. The abundance of epiphytes were significantly different between morphotypes (two-way ANOVA), p≤0.05; ranking the branched thalli as the first preference for microalgal epihytes, sheet-like thalli with a smooth surface as the second one, while the lowest rank was for the mucilaginous species. The same result was found for epiphytic zooplankton. The results of the statistics revealed insignificant seasonal variations in the epiphytic microalgae and very weak correlations between the abundance of microalgae and the physico-chemical parameters. In contrast, there were significant differences for epiphytic zooplanktonic seasonal variations. Whereas, the zooplankton count was correlated preferably with environmental water salinity, followed by nutrients.