The study of zooplankton population structure in Anzali wetland

Anzali wetland is one of the most important places for migratory fishes. Zooplankton organisms are the first consumers in the ecosystem. They are perfect food for the larvae of fishes. Six stations from different areas of wetland were examined for the study of zooplankton population during March 2011 to April 2012.  Sampling was done by tube (PVC) and passing through of 30 micron plankton net. The samples were identified and counted by inverted microscope.  According to the results, 60 Genus and 6 phylum (11, 31, 10, 2, 1, 1, 1, 2 genus of phylum Protozoa, Rotatoria, Arthropoda, Gastrotricha, Mollusca, Tardigrada, Nematoda, Porifera, Annelida) respectively were identified. The results showed that the maximum annual average density of zooplankton was observed with 2497 ± 687number per litre in Karkan station and the population was more in the summer than in other seasons. Density of Rotatoria, protozoa and superclass Copepoda   were 48%, 45% and 6% respectively. Results showed the population structure of zooplankton did not change much compared to past studies (due to improper environmental conditions), excluding Protozoa but the diversity of all zooplankton group is extremely declined. Kruskal Wallis test showed there was not significant difference between density of zooplankton in different stations, months and seasons (p>0.05), but significant differences were found between densities of   different zooplankton phylum  (p<0.05).