The study of some trophic index in Anzali lagoon

Anzali wetland is one of the most important ecosystem in the southern Caspian Sea, acts as a special ecotone between different ecosystems; terrestrial, the Caspian Sea, brackish and fresh water environments. The hydro chemical and nutrients parameters were monthly studied in 10 locations of Anzali wetland for one year from May 2014. Trophic status index was calculated by different parameters including chlorophyll a, total phosphorus (TP), total nitrogen (TN) and transparency. Results showed that the annual average of total nitrogen, total phosphorus and dissolved oxygen were 1.023±0.523, 0.113± 0.105 and 8.71 ± 2.63 mgL-1 respectively. While no significant difference was observed in total nitrogen (P>0.05), total phosphorus showed a significant difference (P<0.05) among locations. Chlorophyll a varied between 0.6 to 330 (average 47.4 ± 65.0) µgL-1. EC varied between 254 and 14250 µm and had a significant difference among locations (p<0.05). The TN/TP was lower than 10 in Anzali wetland (except in western area) that show the limitation role of TP in eutrophication process. According to results while the western area and SiahKeshim are observed in eutrophic and super eutrophic status, the rest of regions are classified as hyper eutrophic status. Decrease of nutrient components from inlet rivers and to remove the aquatic plants in Anzali water bodies are recommended to control of eutrophication process in Anzali wetland.

Iranian Fisheries Science Research Institute

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