Publication Date:
2021-07-16
Description:
This study has been carried out in waters of Bushehr province in the Persian Gulf covering Nayband bay to Bahregansar between 26° 45 N to 30° 00 N and 49° 45 E to 52° 45 E, 15 main and 5 sub- stations, by R/V Ferdows 1 in winter 2004, summer 2004 and winter 2005. The physico - chemical parameters, nutrients (silicate, phosphate, nitrate and nitrite), phyto, zooplanktons, sediments and macrobenthoses were collected from water layers and sea bottom, and then analysed. The parameters were compared and evaluated with the results of the previous work, conducted in the same area. Termocline, halocline, oxycline and picnocline layers were formed in summer. These clins disappeared due to water column mixing in winter. The values of temperature, conductivity and pH in summer were higher than those of in winter, while the salinity and density values of surface and subsurface layers in winter were higher than those of in summer. The temperature and conductivity have been decreased from surface to depth, from coastal rigions to offshore and from southern waters to northwern waters, while salinity, density and turbidity have been increased. The dissolved oxygen is decreased by increasing the values of temperature, salinity and depth and it is observed that D.O. has increased in correlation with chlorophyl a in mean and subsurface layers. The pH was rather decreased from surface to depth while turbidity was increased. Orthosilicate (Si_SiO44), nitrate (N_NO3), and nitrite (N_NO2 ) concentration have increased from surface to depth while orthophostate (P_PO43) decreased. Among the phytoplanktons, Dinophycea had most abundance in winter 2004 and Diatoms had most abundance, variety and distribution in summer 2004 and winter 2005. Among the zooplanktons, Copeopda had most abundance, variety and distribution. The intensity of phytoplanktons in summer was more than those in winter; it decreased from surface to depth and from coastal rigions to offshore, at first increased and then gradually decreases. Intensity of zooplanktons in summer was more than those in winter and decreased from surface layers to depth and from coastal waters to offshore. The abundance of benthoses in summer was more than that in winter while their biomass in winter was more than that in summer. The abundance decreased from southern to northwern waters, but the rate of decrease in biomass was more than that of abundance. The mainly texture of sediments was loamy or muddy and the grain size in southeastern and northwestern areas were coarser than those in middle area. Compared with the previous study, the trend of physico chemical, silicate, nitrate and nitrite were the same but in spite of the past, the values of pH in summer were more than those in winter and also phosphate concentration had been decreased frome surface layer to depth. The overall trends of phyto and zooplanktons densities are almost similar to previous observation, but cyanophyceae significantly decreased, in comparison with spring and summer abundance. It is also observed that the zooplanktons average density has been in reverse order compared to previous observations. Average concentration of phosphate in the entire region was seven times more than that of the former study and its maximum value has rised more than 26 times in the petroleum and gas industries areas. On the other hand, the abundance and diversity of phyto and zooplanktons and also the ratio of biomass to abundance of benthoses were decreased.
Keywords:
Ecology
;
Iran
;
Persian Gulf
;
Bushehr Region
;
Nayband
;
Bahregansar
;
Hydrology
;
Hydrobiology
;
Nutrients
;
Phytoplankton
;
Zooplankton
;
Sediments
;
Macrobenthose
;
Temperature
;
Dissolved oxygen
;
Chlorophyll a
;
pH
;
Diatoms
;
Copeopda
;
Depth
;
Monitoring
Repository Name:
AquaDocs
Type:
monograph
Format:
application/pdf
Format:
application/pdf
Format:
177
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