Evaluating limnological condition of Anzali international wetland during 32 years period using nutrient parameters and TSI indices

Determining trophic condition of a wetland is an important step in scientific assessment of the aquatic ecosystem. High levels of nitrogen and phosphorus, is mainly the result of human activities in agriculture, industry, etc. Increasing levels of nutrients result in eutrophication of water ecosystems. Regarding the importance of Anzali international wetland, the present study conducted several models of Carlsons on trophic status of the wetland through 1985, 2007, 2014 and 2017. The evaluated stations include, Bandar Anzali under bridge, Sorkhankal, PirBazar, Siadarvishan, Nokhaleh, east of wetlands, Hendkhaleh, and west of wetland. The results of Analysis of Variance indicated significant difference (p<0.05) among values of the indicators listed in stations and different seasons. Assessment of trophy index (TSI) on total phosphorus (TP) and total nitrogen (TN) in order to reveal wetland condition determined oligotrophic and mesotrophic conditions in 1985 to acute hypertrophy in recent years. The results showed increase in the amounts of phosphorus and nitrogen during 1985 to 2017.