First record of Limnodrilus claparedeianus ratzel, 1868 (Annelida: Oligochaeta: tubificidae) from Anzali wetland, Guilan Province, Iran

Oligochaeta worms are important organisms in aquatic ecosystem. Their omnipresence makes them as an indicator of environmental changes and health of aquatic ecosystem. The members of the family Tubificidae and in particular, genus Limnodrilus are considered as the most tolerant oligochaets to aquatic pollution. Therefore identification and biological characteristics of this taxon are of great help to evaluate the ecosystem of water bodies. Limnodrilus claparedeianus were collected from Anzali Wetland with a grab of 0.04 m2 capacity at 13 stations from August 2012 through June 2013. Penis sheath was one of the main characteristics to identify them. Results showed their maximum and the minimum density in spring (601.27 ± 466.8346 Ind.m-2) and in autumn (156.12 ± 136.3 Ind.m-2) respectively which was significantly different (P<0.05). Comparative spatial distribution of L. claparedeianus among 13 stations revealed significant differences in the west stations (P<0.05). According to the results, correlation analysis did not exhibit any relation between abundance of L. claparedeianus and total organic matter, abundance of the species and percentage of silt in substrate sediment

Meiofauna and macrofauna community structure in relation with environmental factors at South of Caspian Sea

Biodiversity and distribution of benthic Meiobenthos in the sediments of the Southern Caspian Sea) Mazandaran) was studied in order to introduce and determine their relationship with the environmental factors. From 12 stations (ranging in depths 5, 10, 20 and 50 meters), sediment samples were gathered in four seasons (2012). Environmental factors of water near the bottom including temperature, salinity, dissolved Oxygen and pH were measured during sampling with CTD instrument(conductivity, temperature and Depth)    and the grain size and total organic matter percentage and calcium carbonate were measured in the laboratory. From the 4 group animals (Foraminfera, Crustacea, Worms and Mollusca), 40 species were identified belonging to 29 genera of 25 families belonging to meiofauna and 15 species belonging to 15 genera of 13 belonging to macrofauna. Among seven parameters evaluated, Pearson correlation showed that there is a negative correlation between density of meiobenthos, TOM and depth and there is not a correlation between macrofauna and environmental factors. However, according to the results of One Way ANOVA, the density of  meiofauna was significantly different from station, season and depth,  and macrofaunain was also significantly different from station and season (P<0.05). Maximum Shannon–Wiener index was observed in winter