Impact of eutrophication on marine environment of Lebanese coastal waters

• Sami Lakkis ^1,2 and Raymonde Zeidane ²
• ¹ Section of Oceanography, Faculty of Sciences, Lebanese University,Beirut,Lebanon
• ² Laboratory of Plankton and Marine Ecology,NCMS / LNCSR, Batroun,Lebanon. Email: slakkis@ul.edu.lb
• The Regional Workshop on Marine Sciences & Natural Resources, HIMR, Tishreen Univ., Syria, 25-26 May 2004.

Abstract

Eutrophication is the most generic definition that applies to both fresh and marine waters. It is perhaps the oldest water quality problem created by mankind. It includes the process of enrichment of waters with plant nutrients, primarily nitrogen and phosphorus., that stimulate aquatic primary production and in its most serious manifestation lead to visible algal blooms, enhance benthic algal growth and to massive growth of submersed and floating macrophytes. Cases of eutrophication are frequent along the coast of Lebanon, particularly near Beirut area.Three stations were investigated during 2000-2001, two Beirut River and Saint Georges Bay in eutrophied and polluted waters and a third reference station, Jounieh Bay , in unspoiled area . During spring and early summer with the increase of seawater temperature and enrichment of water with nutrient input, namely nitrate and phosphate, eutrophication may create negative effects on Marine Environment. Sometimes these manifestations are accompanied by, or alternate with cycles of bacteria blooms and fungal development. The side effects may cause reduced water transparency, unsightliness and disturbance to the bathers impairing swimming recreation. Adhering algal material and high PH can cause dermatitis and conjunctivitis. Several toxic microalgae appeared in the water, among diatoms and dinoflagellates .The decaying organic material consumes and in serious cases depletes, the oxygen reserve of the water causing array of secondary problems such as: hypoxia in water layers and anoxia in the bottom, creating fish mortality, formation of corrosive and other nocive substances such as CO2, CH4,H2S,NH3, organoleptic substances, organic acids and toxins. Potential toxic phytoplankton developed and produced shellfish poisoning such as Paralytic Shellfish Poisoning (PSP), Amnesic Shellfish Poisoning (ASP),

Diarrhoeic Shellfish Poisonoing (DSP) in shellfish and killing fish toxins . Constituting a threat to public health. Controled eutrophication is necessary through permanent monitoring survey in order to avoid human health problems to swimmers on beaches and toxicity to consumers of contaminated seafood , particulerely shellfish.