Structure and diversity of phytoplankton in Silver carp (Hypophthalmichthys molitrix) food content and resources central region of Mazandaran provinces

Subject Areas : Marine Biology

M. R. Akbari Lalehmarzi ¹ (Department of Natural Resources, Islamic Azad University, Savadkooh Branch, Iran)
B. Moghadasi ² (Department of Natural Resources, Islamic Azad University, Savadkooh Branch, Iran)
S. Farabi ³ (Caspian Sea Research Institute of Ecology, Sari, Iran)
A. Roohi ⁴ (Caspian Sea Research Institute of Ecology, Sari, Iran)
M. Shapoori ⁵ (Department of Natural Resources, Islamic Azad University, Savadkooh Branch, Iran)

Received: 2012-11-05 Accepted : 2014-05-08 Published : 2014-02-20

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Abstract :

Study of phytoplankton structure and silver carp (Hypophthalmichthys molitrix) feeding was conducted in three ponds in Esfandan, Mohammadabad and Arabmahaleh (Central of Mazandaran province) to identify different species of phytoplankton in water, using 2 liter Rotner bottle of mixed sample (surface, middle and bottom) from each station of Esfandan (4m), Mohammadabad (3 m) and Arabmahaleh (4 m) every 2 weeks. Fish gut contents were also investigated during the months of June, July and August in 2012. Phytoplankton samples were fixed with 4% formalin and transported to Caspian Sea Ecology Center Laboratory (Sari). A total of 50 phytoplankton species were determined from these 3 fish ponds, which belonged to Cyanobacteria (11 species), Chlorophyta (18 species), Bacillariophyta (19 species) and Euglenophyta (2 species). Laboratory analysis results indicated that phytoplankton species composition in Esfandan, Mohammadabad and Arabmahaleh were 44, 47 and 41 species, respectively. Most of the phytoplankton present in Esfandan belonged to Bacillariophyta (39%), Chlorophyta (37%), Cyanobacteria (19%) and Euglenophyta (5%), whereas the least belonged to Mohammadabad pond, Euglenophyta (4%), Chlorophyta (36%), Cyanobacteria (21%) and Bacillariophyta (39%), respectively. The average density of phytoplankton in the water was 2.4× 106± 0.3×106 ind/lit and 3.8±0.3 mg/lit that showed no significant different among phytoplankton ponds (P>0.05), but there was significant different in phytoplankton abundance between three months (P<0.05). Average percentage of phytoplankton groups at both the beginning and the end of the gut contents of silver carp, included: Chlorophyta (43/11 and 38/33), Bacillariophyta (28.78 and 26.67), Cyanobacteria (21.67 and 28.11) and Euglenophyta (6.44 and 7.00), respectively. Maximum phytoplankton concentration present at the beginning and the end of the intestine of the fed fish belonged to Chlorophyta with 77% and 66%, respectively. As a result, most of the silver carp fed on Chlorophyta and Bacillariophyta group