Impact of elevated CO2 concentrations on the growth and ultrastructure of non-calcifying marine diatom (Chaetoceros gracilis F.Schütt)

Abstract

The impacts of different CO 2 concentrations on the growth, physiology and ultrastructure of noncalcifying microalga Chaetoceros gracilis F.Schu¨tt (Diatom) were studied. We incubated Ch. gracilis under different CO 2 concentrations, preindustrial and current ambient atmospheric concentrations (285 and 385 latm, respectively) or predicted year-2100 CO 2 levels (550, 750 and 1050 latm) in continuous culture conditions. The growth of Ch. gracilis measured as cell number was decreased by increasing the pCO 2 concentration from nowadays concentration (385 latm) to 1050 latm. The lowest percentage changes of oxidizable organic matter, nitrite, nitrate, phosphate and silicate were recorded at a higher pCO 2 (1050 latm), and this is in consistence with the lowest recorded cell number indicating unsuitable conditions for the growth of Ch. gracilis. The minimum cell numbers obtained at higher levels of CO 2 clearly demonstrate that, low improvement occurred when the carbon level was raised. This was confirmed by a highly negative correlation between cell number and carbon dioxide partial pressure (r = À0.742, p 6 0.05). On the other hand, highest growth rate at pCO 2 = 385 latm was also confirmed by the maximum uptake of nutrient salts (NO 3 = 68.96 lmol.l À1 , PO 4 = 29.75 lmol.l À1 , Si 2 O 3 = 36.99 lmol.l À1 ). Total protein, carbohydrate and lipid composition showed significant differences (p 6 0.05) at different carbon dioxide concentrations during the exponential growth phase (day 8). Transmission Electron Microscopy of Ch. gracilis showed enlargement of the cell, chloroplast damage, disorganization and disintegration of thylakoid membranes; cell lysis occurs at a higher CO 2 concentration (1050 latm). It is concluded from this regression equation and from the results that the growth of Ch. gracilis is expected to decrease by increasing pCO 2 and increasing ocean acidification.

Ocean acidification influences plant-animal interactions: The effect of Cocconeis scutellum parva on the sex reversal of Hippolyte inermis

“…The effect of CO 2 on the growth of diatoms is quite complex and, probably, depends on the particular physiology of each species. It has been shown that species can use different carbon sources, with some utilizing CO 2 as main carbon source, whereas others mostly drawing carbon from HCO 3 - [35]. Elevated CO 2 concentration did not cause significant differences in growth in diatoms such as Asterionella glacialis , Thalassiosira punctigera , Coscinodiscus wailesii , Phaeodactylum tricornutum [36–38].…”

“…Elevated CO 2 concentration did not cause significant differences in growth in diatoms such as Asterionella glacialis , Thalassiosira punctigera , Coscinodiscus wailesii , Phaeodactylum tricornutum [36–38]. In the case of Chaetoceros gracilis , the maximum number of cells was obtained at a carbon dioxide concentration of 385 μatm and a lower cell number was obtained at lower (control and 280 μatm) and higher levels of carbon dioxide (1,050 μatm) [35]. In other species, such as Thalassiosira weissflogii , algal density decreased with the decreasing pH [39] probably because, when the acidity is lower than a certain concentration, it will impair algal physiological functioning [40].…”

Macronutrient effect on biomass of Microalgae in biofuel production: A review

“…Typically, low CO 2 level is insufficient for microalgal growth, whereas high CO 2 level often exerts detrimental effect (35; 36; 37). Chloroplast damage and organelles disorder which in turn render cell lysis were observed in high CO 2 level (38). Many microalgae have evolved CO 2 concentrating mechanism (CCM) to enhance the efficiency of photosynthetic carbon fixation by raising the CO 2 level around carboxylating enzyme ribulose bisphosphate carboxylase/oxygenase (RuBisCO) which responsible for the first step of carbon dioxide fixation ( Figure 2).…”

INCREASING CARBON DIOXIDE CONCENTRATION AND TEMPERATURE ON GROWTH AND HISTOPATHOLOGY OF TROPIC MACROALGAE Halimeda sp

“…Hal tersebut terjadi karena pada konsentrasi 385 ppm CO 2 makroalga masih dapat melakukan proses fisiologi dengan baik karena kebutuhan akan kalsium karbonat masih normal, ketika terjadi kenaikan konsentrasi CO 2 maka terjadi disolusi karbonat yang berpengaruh terhadap lapisan utricle dalam thallus sehingga mengganggu proses fotosintesa dan respirasi apalagi dengan terjadinya peningkatan suhu maka kebutuhan komponen dan proses metabolik semakin bertambah sehingga kemampuan kloroplas dalam dinding sel semakin menurun pula (Dijoux et al, 2012). Hasil penelitian Khairy et al (2014) juga terjadi pada fitoplankton Chaetoceros gracilis mengalami kerusakan kloroplas, disintegrasi membran tilakoid, dan terjadinya sel lyses ketika terjadi peningkatan konsentrasi CO 2 550-1.050 ppm.…”

“…Selanjutnya penjelasan Barry (2011) bahwa konsekuensi dari tingginya konsentrasi CO 2 adalah menurunnya aktifitas enzim, terjadi inefisiensi fungsi seluler (seperti sintesa protein), terjadi depresi metabolik, bahkan pada organisme fitoplankton berpengaruh terhadap produksi pigmen sel 689 dan produktifitasnya. Selanjutnya hasil penelitian Khairy et al (2014) bahwa kandungan total protein, karbohidrat dan lipid pada fitoplankton Chaetoceros gracilis menurun pada konsentrasi 550-1.050 ppm CO 2 . Sejalan dengan penemuan Porzio et al (2013) bahwa ganggang laut menunjukkan respon yang berbeda terhadap pengasaman laut, yang mana pada penurunan pH tidak selalu mendukung organisme fotosintetik laut.…”