Publication Date:
2024-03-15
Description:
This paper reports for the first time upon the effects of increasing CO2 concentrations on a natural phytoplankton assemblage in a tropical estuary (the Godavari River Estuary in India). Two short-term (5-day) bottle experiments were conducted (with and without nutrient addition) during the pre-monsoon season when the partial pressure of CO2 in the surface water is quite low. The results reveal that the concentrations of total chlorophyll, the phytoplankton growth rate, the concentrations of particulate organic matter, the photosynthetic oxygen evolution rates, and the total bacterial count were higher under elevated CO2 treatments, as compared to ambient conditions (control). delta13C of particulate organic matter (POM) varied inversely with respect to CO2, indicating a clear signature of higher CO2 influx under the elevated CO2 levels. Whereas, delta13CPOM in the controls indicated the existence of an active bicarbonate transport system under limited CO2 supply. A considerable change in phytoplankton community structure was noticed, with marker pigment analysis by HPLC revealing that cyanobacteria were dominant over diatoms as CO2 concentrations increased. A mass balance calculation indicated that insufficient nutrients (N, P and Si) might have inhibited diatomgrowth compared to cyanobacteria, regardless of increased CO2 supply. The present study suggests that CO2 concentration and nutrient supply could have significant effects on phytoplankton physiology and community composition for natural phytoplankton communities in this region. However, this work was conducted during a non-discharge period (nutrient-limited conditions) and the responses of phytoplankton to increasing CO2 might not necessarily be the same during other seasons with high physicochemical variability. Further investigation is therefore needed.
Keywords:
Alkaline phosphatase activity, normalized to particulate organic carbon; Alkaline phosphatase activity, normalized to particulate organic carbon, standard deviation; Alkalinity, total; Alkalinity, total, standard deviation; Aragonite saturation state; Bacteria; Bacteria, abundance, standard deviation; Bicarbonate ion; Biomass/Abundance/Elemental composition; Bottles or small containers/Aquaria (〈20 L); Brackish waters; Calcite saturation state; Calculated; Calculated using CO2SYS; Calculated using seacarb after Nisumaa et al. (2010); Carbon, inorganic, dissolved; Carbon, inorganic, dissolved, standard deviation; Carbon, organic, particulate; Carbon, organic, particulate, standard deviation; Carbon/Nitrogen ratio; Carbon/Nitrogen ratio, standard deviation; Carbonate ion; Carbonate system computation flag; Carbon dioxide; Carbon dioxide, partial pressure, standard deviation; Chlorophyll a; Chlorophyll a, standard deviation; Chlorophyll a/particulate organic carbon ratio; Chlorophyll a/particulate organic carbon ratio, standard deviation; Coulometric titration; Dissolved inorganic nitrogen, standard deviation; Entire community; EPOCA; EUR-OCEANS; European network of excellence for Ocean Ecosystems Analysis; European Project on Ocean Acidification; Fluorescent microscope; Fucoxanthin/chlorophyll a ratio; Fucoxanthin/chlorophyll a ratio, standard devitation; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Growth/Morphology; Growth rate; Growth rate, standard deviation; Indian Ocean; Isotope ratio mass spectrometry; Laboratory experiment; Mass spectrometry; Nitrogen, inorganic, dissolved; Nitrogen, organic, particulate; OA-ICC; Ocean Acidification International Coordination Centre; Partial pressure of carbon dioxide (water) at sea surface temperature (wet air); Particulate organic nitrogen, standard deviation; Pelagos; pH; pH, standard deviation; Phosphorus, inorganic, dissolved; Phosphorus, inorganic, dissolved, standard deviation; Photosynthetic oxygen evolution, per particulate organic carbon; Photosynthetic oxygen evolution, per particulate organic carbon, standard deviation; Primary production/Photosynthesis; Salinity; Salinity, standard deviation; Silicate; Silicate, standard deviation; Spectrophotometry; Temperature, standard deviation; Temperature, water; Titration potentiometric, 794 Basic Titrino (Metrohm); Tropical; Zeaxanthin/Fucoxanthin ratio; Zeaxanthin/Fucoxanthin ratio, standard devitation; δ13C; δ13C, standard deviation
Type:
Dataset
Format:
text/tab-separated-values, 351 data points
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