روند فراغني شدن تالاب انزلي با استفاده از اطلاعات ده ساله 1371-1381

Eutrophication Trend ofAnzali Wetland Based on 1992-2002 Data

Anzali wetland is located between two different saline-freshwater body where constituted a unique ecosystem, internationally known as an important wetland and is registered as Ramsar site in 1975. Anzali wetland is under several stresses such as sea water level fluctuation, different human induced impact, exotic species and the eutrofication which are the causes of early destruction of wetland. Eutrofication or nutrient enrichment is a problem of wetlands, rivers, streams and lakes all over in the world. Hydrology of the watershed has profound effect on the eutrofication process of Anzali wetland which drains 52 % of its water through Siadarvishan river into central region, 44 % via Pirbazar, Komamrud river into eastern region and 4% by the other rivers. The water from eastern and central regions drains into Caspian sea faster than the western basin which has more retention time. The Eutrofication of Anzali wetland first reported at 1970 and approved by several other authors. Those reports were base on the biotic and abiotic parameters which describe Anzali wetland were eutroph between the years 1991 to 1995 but the evaluation based on the trophic index of phosphorous to nitrogen shows that most region of Anzali wetland reported to be mesotroph, In this survey we are going to use the available data from 1992 to 2002 to identify the change in over nutrient an enrichment of Anzali wetland at three periods by employing the trophic state index system.