اثرات مزمن و حاد كبالت و نيكل بر ميزان كلروفيل آ و كاروتنوئيد‌ها در ريز‌جلبك سبز ‌دريايي Nannochloropsis oculata

Chronic and acute effects of nickel and cobalt on chlorophyll a and carotenoids of marine micro algae Nannochloropsis oculata

ﻠﺒﮏﻫﺎ از ﺟﻤﻠﻪ آﺑﺰﯾﺎﻧﯽ ﻫﺴﺘﻨﺪ ﮐﻪ در دﻫﻪﻫﺎي اﺧﯿﺮ در ﻣﻌﺮض ﺷﺪﯾﺪ آﻟﻮدﮔﯽﻫﺎي رو ﺑﻪ اﻓﺰاﯾﺶ و ﻧﮕﺮانﮐﻨﻨﺪه اﮐﻮﺳﯿﺴﺘﻢﻫﺎي درﯾﺎﯾﯽ ﻗﺮار ﮔﺮﻓﺘﻪاﻧﺪ. ﻣﯿﺰان EC50 ﻧﯿﮑﻞ و ﮐﺒﺎﻟﺖ ﺑﺎ ﺗﻮﺟﻪ ﺑﻪ ﭘﺮوﺗﮑﻞ OECD 2011 از ﺟﻤﻠﻪ ﺗﺮﮐﯿﺒﺎﺗﯽ ﻫﺴﺘﻨﺪ ﮐﻪ اﻓﺰاﯾﺶ ﺑﯿﺶ از ﺣﺪ آنﻫﺎ در ﻣﺤﯿﻂﻫﺎي آﺑﯽ ﺳﺒﺐ ﺑﺮوز ﻣﺸﮑﻼﺗﯽ در ﺳﺎﺧﺘﺎر ﺟﻤﻌﯿﺖﻫﺎي ﺟﻠﺒﮑﯽ اﯾﻦ اﮐﻮﺳﯿﺴﺘﻢﻫﺎ ﺷﺪه اﺳﺖ. در اﯾﻦ ﺑﺮرﺳﯽ ﻣﯿﺰان ﻓﻠﺰات ﺳﻨﮕﯿﻦ، ﻣﯿﺰان ﮐﻠﺮوﻓﯿﻞ آ و ﮐﺎروﺗﻨﻮﺋﯿﺪ ﺟﻠﺒﮏ Nannochloropsis oculata ﺑﺮرﺳﯽ ﺷﺪه اﺳﺖ. در اﯾﻦ ﻣﻄﺎﻟﻌﻪ، اﺛﺮات ﻏﻠﻈﺖﻫﺎي ﻣﺨﺘﻠﻒ ﻧﯿﮑﻞ )15 ،12 ،8 ،6 ،4 ،3 ،1/5 ﻣﯿﻠﯽﮔﺮم ﺑﺮ ﻟﯿﺘﺮ( و ﮐﺒﺎﻟﺖ )10 ،8 ،6 ،5 ،3 ،2/5 ،1/5 ﻣﯿﻠﯽﮔﺮم ﺑﺮ ﻟﯿﺘﺮ( ﺑﻪ ﻣﺪت 72 ﺳﺎﻋﺖ ﺑﻪ ﻣﺪت 72 ﺳﺎﻋﺖ در ﺗﯿﺮﻣﺎه 1396ﺗﻌﯿﯿﻦ ﺷﺪ. ﻧﺘﺎﯾﺞ آزﻣﻮنﻫﺎي ﺣﺎد ﻧﺸﺎن داد ﻣﯿﺰان EC50 ﻧﯿﮑﻞ و ﮐﺒﺎﻟﺖ ﺑﻪ ﺗﺮﺗﯿﺐ 6/5 و 5/3 ﻣﯿﻠﯽﮔﺮم ﺑﺮ ﻟﯿﺘﺮ ﻣﯽﺑﺎﺷﺪ. ﺑﻪﻃﻮرﮐﻠﯽ، ﻧﺘﺎﯾﺞ اﯾﻦ ﺗﺤﻘﯿﻖ ﻧﺸﺎن داد ﮐﻪ ﻧﯿﮑﻞ در ﻏﻠﻈﺖﻫﺎي ﺑﺎﻻﺗﺮي ﻧﺴﺒﺖ ﺑﻪ ﮐﺒﺎﻟﺖ ﺑﺎﻋﺚ اﯾﺠﺎد ﺳﻤﯿﺖ ﻣﯽﺷﻮد. ﻫﻤﭽﻨﯿﻦ ﻓﻠﺰات ﺳﻨﮕﯿﻦ ﮐﺒﺎﻟﺖ و ﻧﯿﮑﻞ داراي اﺛﺮ ﺑﺎزدارﻧﺪﮔﯽ ﻗﺎﺑﻞ ﺗﻮﺟﻬﯽ ﺑﺮ رﺷﺪ و ﺗﻮﻟﯿﺪﻣﺜﻞ N.oculata ﺑﻮدﻧﺪ، اﻣﺎ ﺑﺮ ﻣﯿﺰان ﮐﺎروﺗﻨﻮﺋﯿﺪﻫﺎ ﺗﺎﺛﯿﺮ ﮐﻤﺘﺮي ﻣﺸﺎﻫﺪه ﺷﺪ.

Algae are among the aquatic organisms that are severely exposed to increasing levels of pollutants, which are becoming a concern in marine ecosystems. Heavy metals are among the compounds for which their increase in high levels causes problems in the structure of algae communities in aquatic ecosystems. In this study, the effect of different concentrations of Nickel (1.5, 3, 4, 6, 8, 12, 15 mg/l) and cobalt (1.5, 2, 3, 5, 6, 8, 10 mg/l) on chlorophyll a and the carotenoid level of microalga Nannochloropsis oculata was investigated for 72 hours. The EC50 of nickel and cobalt were determined according to the OECD 2011 protocol. The results of acute tests showed that EC50 of nickel and cobalt was 6.5 mg/l and 5.3 mg/l, respectively. Overall, the results of this study showed that nickel caused toxicity in higher concentrations compared to cobalt. Furthermore, nickel and cobalt heavy metals significantly inhibited the growth and reproduction of N. oculata. However, these heavy metals had lower effect on ceratoid contents.