تنوع و فراواني فصلي باسيلاريوفيتاي (دياتومه‌ها) پلانكتوني، در آب‌هاي ساحلي جنوب درياي خزر

Seasonal Diversity and Frequency of Planktonic Bacillariophyta (Diatoms) in Coastal Waters of the Southern Caspian Sea

اﯾﻦ ﺗﺤﻘﯿﻖ در ﺳﺎل 1395 ﺑﺎﻫﺪف ﺗﻌﯿﯿﻦ ﺗﻨﻮع زﯾﺴﺘﯽ دﯾﺎﺗﻮﻣﻪﻫﺎ در آبﻫﺎي ﺳﺎﺣﻠﯽ ﺳﺎري و ﺑﺎﺑﻠﺴﺮ، در دو ﺗﺮاﻧﺴﮑﺖ ﺧﻄﯽ و 8 اﯾﺴﺘﮕﺎه از ﻣﺼﺐ ﺗﺎ ﻋﻤﻖ 20 ﻣﺘﺮ اﻧﺠﺎم ﺷﺪ. ﭘﺲ از ﻧﻤﻮﻧﻪﺑﺮداري آب از اﯾﺴﺘﮕﺎهﻫﺎي ﻣﻮردﻧﻈﺮ و اﻧﺪازهﮔﯿﺮي ﻓﺎﮐﺘﻮرﻫﺎي دﻣﺎ، ﺷﻮري، اﺳﯿﺪﯾﺘﻪ و اﮐﺴﯿﮋن ﻣﺤﻠﻮل، دﯾﺎﺗﻮﻣﻪﻫﺎي ﻣﻮﺟﻮد در ﻧﻤﻮﻧﻪﻫﺎي آب، ﻣﻮردﺑﺮرﺳﯽ ﮐﯿﻔﯽ و ﮐﻤﯽ ﻗﺮار ﮔﺮﻓﺘﻨﺪ. ﺟﻬﺖ ارزﯾﺎﺑﯽ ﻏﻨﺎي ﮔﻮﻧﻪاي از ﺷﺎﺧﺺ ﻣﺎرﮔﺎﻟﻒ، ﭘﺮاﮐﻨﺪﮔﯽ از ﺷﺎﺧﺺ ﭘﯿﻠﻮ و ﺟﻬﺖ ارزﯾﺎﺑﯽ ﺗﻨﻮع زﯾﺴﺘﯽ از ﺷﺎﺧﺺ ﺷﺎﻧﻮن اﺳﺘﻔﺎده ﺷﺪ. از ﺑﯿﻦ ﻓﺎﮐﺘﻮرﻫﺎي ﻣﺤﯿﻄﯽ ﺗﻨﻬﺎ ﺷﻮري راﺑﻄﻪ ﻣﺴﺘﻘﯿﻢ ﺑﺎ ﺗﻨﻮع و ﻓﺮاواﻧﯽ دﯾﺎﺗﻮﻣﻪﻫﺎ ﻧﺸﺎن داد و ﺑﯿﺸﺘﺮﯾﻦ ﻣﯿﺰان ﺷﺎﺧﺺ ﺗﻨﻮع در ﻫﺮ دو ﻓﺼﻞ در ﻣﺼﺐ ﺑﺎﺑﻞ رود )0/79 ،1/20( ﻣﺤﺎﺳﺒﻪ ﮔﺮدﯾﺪ؛ ﻫﻤﭽﻨﯿﻦ ﻣﯿﺎﻧﮕﯿﻦ ﺷﺎﺧﺺ ﺗﻨﻮع دﯾﺎﺗﻮﻣﻪﻫﺎ، در ﻓﺼﻞ زﻣﺴﺘﺎن )0/62( ﺑﯿﺸﺘﺮ از ﻓﺼﻞ ﺗﺎﺑﺴﺘﺎن )0/41( ﺑﻮد. در اﯾﻦ ﻣﻄﺎﻟﻌﻪ 17 ﺟﻨﺲ از دﯾﺎﺗﻮﻣﻪﻫﺎ ﺷﻨﺎﺳﺎﯾﯽ و ﺷﻤﺎرش ﺷﺪﻧﺪ، ﻣﺤﺎﺳﺒﻪي ﻓﺮاواﻧﯽ ﺟﻨﺲﻫﺎي ﺷﻨﺎﺳﺎﯾﯽﺷﺪه ﻧﺸﺎن داد .Cyclotella sp در ﻫﺮ دو ﻓﺼﻞ ﺑﯿﺸﺘﺮﯾﻦ ﻓﺮاواﻧﯽ را داﺷﺘﻪ و .Surrirella sp ﮔﻮﻧﻪاي ﺑﻮد ﮐﻪ ﺗﻨﻬﺎ در اﯾﺴﺘﮕﺎهﻫﺎي ﻣﺼﺒﯽ ﻣﺸﺎﻫﺪه ﺷﺪ. ﻣﻄﺎﻟﻌﻪي ﺷﺎﺧﺺﻫﺎي اﮐﻮﻟﻮژﯾﮏ در اﯾﻦ ﭘﮋوﻫﺶ ﺣﺎﮐﯽ از وﺟﻮد ﻧﻮﻋﯽ آﺷﻔﺘﮕﯽ اﮐﻮﻟﻮژﯾﮑﯽ در ﻣﻨﻄﻘﻪ ﻣﻄﺎﻟﻌﺎﺗﯽ ﺑﻮده و در ﻣﻘﺎﯾﺴﻪ ﺑﺎ ﻣﻄﺎﻟﻌﺎت ﺳﺎلﻫﺎي ﮔﺬﺷﺘﻪ ﺷﺪت ﺑﯿﺸﺘﺮي از ﻋﺪم ﺳﻼﻣﺖ اﮐﻮﻟﻮژﯾﮑﯽ در ﻣﻨﻄﻘﻪ ﻣﺸﺎﻫﺪه ﮔﺮدﯾﺪ

This study aimed to investigate the biodiversity and abundance of diatoms in coastal waters of Sari and Babolsar on 2015, in two linear transects and 8 stations from estuary to 20 m depth. Sampling the water and measuring some environmental parameters such as temperature, salinity, acidity and dissolved oxygen, followed by evaluation of diatoms (Bacillariophyta) qualitatively and quantitatively. Margalef, Pielo and Shannon-wiener indices were used to assess richness, evenness and diversity of diatoms, respectively. There was no correlation between environmental parameters and diversity and abundance of diatoms, but only salinity; also, the mean of diatom diversity indices in both season was higher in Babolrood estuary (1.20 and 0.79). Also, the mean diversity indics of diatoms was higher in winter (0.62) than in summer (0.41). In this study, 17 genera of diatoms were identified and counted; and according the results, Cyclotella sp. was the most abundant diatom in both seasons, and Surrirella sp. was found only in estuaries. Ecological indices' assay showed that, this area is suffering of a kind of ecological disturbance, which indicated that the risk of ecological disturbance in the study area, is more serious than previous research.