| The Caspian sea is a limited and brackish water that 724 species and 566 species microbenthos distributed in Caspian sea .In Iranian water of Caspian sea, the Hydrology and hydrobiology studies was started from late decade 1980. The study area was Caspian Sea at Guilan province on the 30 transect and 4 depths. Distribution of macrobenthic biomass had not a large changes for many years. During study of autumn 1995 to summer 1996 on 9 transect and 4 depths (10, 20, 50, 100 meter) the biomass was various from 1.69 to 65.45 gr/m2. The groups of Pseudocumidae, Amphipoda, Tubificidae, Chironomidae, Amphatridae, Nereidae, Cardidae and Scrobiculidae were studied. Generally the highest biomass was shown in a small region with biomass of higher than 18 gr/m2. The biomass was larger in 10 meter than another depths and the biomass had not the significant difference in all season. The study of meiofuna showed that Bivalva, Foraminofera, Nematoda, Ostracoda, Copopoda were dominate from 12 identified groups. The Foraminefera and Bivalva were the most abundant groups. There was a significant difference between average abundance of meiofouna at 4 depths, That 20 meter had the most average that it decreased in 50 and 100 meter depths. The average abundance of meiofouna varied from 825 to 29315 ind./cm2 in 100 and 20 meter respectively while the frequency of meiofouna was various from 80 to 133382 ind./10cm2. The most frequency was shown in small part of the west study area with higher than 3000 ind./10cm2 however the most frequency percentage had been seen with frequency of lower than 150 ind./cm2. Results of substrate characteristics studies showed that the organic matter was the most in 50 meter and it was the lowest at 10 meter depth. Fig. 4 shows the distribution of T.O.M. in study area that the most surface belong to 4-8 % organic matter, however a large surface of study area have belong to organic matter percentage of higher than 12 > % .The silt percentage was the most than other grain size (1, 0.5, 0.25, 0.076 mm) in all of depths and percentage of grain size for different depths for 0.076 mm size was more in 10 meter than other depths. The comparison of macrobenthic biomass distribution maps with fish catch data showed a positive relation. Also the overlapping of meiofauna abundant map on organic matter and grain size maps showed that the most abundant of meiofauna was in 4-8 % organic matter and there was a negative relation between meiofauna and silt values. |
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