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Estimate of Biomass and Secondary Production of Macrobenthos in Khore-e-Mousa
S. M. B. Nabavi, A. Savari, Gh. H. Vosoughi, A. R. Nikouy,
Volume 5, Issue 4 (1-2002)
Abstract

To estimate the biomass and secondary production of macrobenthos in Khore-e-Mousa creeks, 216 sediment samples were taken. The sampling period started in 1996 and terminated in 1997. A bimonthly sampling strategy was adopted. The samples were taken by Van-Veen grab (0.1 m2) from the beginning, middle and end of each creek (Khor). To estimate the biomass of the macrobenthos, the Crisp method (1984) was employed. The standing crop was expressed as dry weight and ash free dry weight. For the measurement of secondary production, a dominant crustacean species Apseudes sp. was used.

The results indicated a low biomass per unit area in Khore-e-Mousa creeks. Maximum and minimum amounts of the standing crop were found to be in June (33.5 g DW/m2) and December (2.19 g DW/m2), respectively. Amongst all creeks, Douragh creek displayed the highest (24.93 g DW/m2) and Beehad the lowest (2.24 g DW/m2) standing crops. During the study period, 1483 individuals of Apseudes sp. were collected and grouped into 5 age classes according to Bhattacharya (Sparre, 1989) method. The secondary production was estimated to be 0.08 g/m2 ash free dry weight (AFDW). The production/biomass ratio (P/B), therefore, is calculated as 0.08÷0.18=0.44. Considering the ecological efficiency, (transfer efficiency) of different trophic levels which is about 10%, the fish production is estimated to be 2430 tons in Khore-e-Mousa area.


Ecosystem Investigation of Zayanderood Dam Lake
E. Ebrahimi, M. Zare Shahraki, O. Farhadian, Y. Keivany,
Volume 23, Issue 4 (2-2020)
Abstract
Benthos play an important role in the transmission of primary production and organic material (detritus) accumulation of the substrate in the water ecosystems to the higher levels of food chain. Also, they are used as biological indicators to evaluate the effect of pollutants caused by human activities on water ecosystems. To evaluate the benthic communities of Zayanderood Dam Lake, 4 sampling stations were selected on the lake; then, during the year 2014, seasonal sampling at each station was performed. The sampling was carried out by using the sediment sampler instrument with the dimensions of (20 cm × 20 cm). The average temperature of surface and deep water in the Zayanderood Dam Lake during the study was estimated to be 15.6 ± 2.4 and 8.9 ± 1.8°C, respectively. The average concentration of dissolved oxygen in the surface and deep water was varied from 10.3 ± 0.6 to 8.1 ± 0.7 mg/L, respectively. Totally, 2165 samples of benthos were collected and identified in the Zayanderood Dam Lake, belonging to 3 classes, 6 orders and 5 families. The maximum number of samples belonged to Tubifex, Naididae and Chironomidae genera. The dominant genus was Tubifex in all stages. According to this study, therefore, it seems that the structure of substrate, the amount of nutrients, grazing pressure and hydrostatic pressure are the most important environmental factors that can affect benthic community in the Zayanderood Dam Lake.

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