Coccolithus pelagicus
Classification
Domain; Phylum; Class; Order; family [Others may be used. Use NCBI link to find]
Species
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NCBI: Taxonomy |
Genus species
Description and Significance
Describe the appearance, habitat, etc. of the organism, and why you think it is important.
Genome Structure
Describe the size and content of the genome. How many chromosomes? Circular or linear? Other interesting features? What is known about its sequence?
Cell Structure, Metabolism and Life Cycle
Interesting features of cell structure; how it gains energy; what important molecules it produces.
Habitat
C. pelagicus is found in Arctic and Subarctic cold waters across the North Atlantic and North Pacific (Mcintyre and Bé, 1967) with a minimal temperature of -1.7°C and an optimal temperature of 8°C (Baumann et al, 2000). However, coccospheres from this species have been reported in the Mediterraean (Daniels, 2015) and in New Zealand (Nishida, 1979). It is a major calcite producer in its North Atlantic range despite being less abundant than other calcifiers such as E. huxleyi (Daniels, 2015). C. pelagicus rarely dominates the phytoplanktonic community and has relatively low abundance (Poulton et al, 2006, 2007) but blooms have been reported in shallow waters with concentrations up to 106 cells per L (Milliman, 1980).
Biogeochemical relevance
Biological Carbon Pump
Phytoplankton are predominant contributors to Earth’s photosynthetic activity and form the base of the trophic network of marine ecosystems as primary producers. Photosynthesis and chemosynthesis are the major sources of all organic carbon on Earth. Through carbon fixation, phytoplankton have a critical impact on CO2 concentration. Coccolithophores fix inorganic CO2 into particulate organic carbon (POC) and thus have an impact on the PIC/POC ratio. As organic carbon flows to the deep ocean as particles, it is mainly remineralized before it reaches the depth of 1000 meters considered necessary for sequestration (Sanders et al, 2014).
Carbonate pump
There are three main components of dissolved inorganic carbon (DIC) in seawater: a carbon dioxide-carbonic acid pool (CO2 + H2CO3) at equilibrium, carbonate (CO3) and bicarbonate (HCO3-).
In addition to carbon fixation through photosynthesis, clalcifiers such as C. pelagicus produce CaCO3 shells that participate in fixing CO2 into (PIC). The inorganic carbon cycle participates in reducing the DIC concentration at the surface of oceans (Falkowski et al, ) and is a major actor in the flow of particulate carbon to the deep ocean.
The PIC to POC ratio, driven by the rates of calcification and photosynthesis, determines whether calcifiers act as a source of CO2, or a sink. The immediate consequence of calcification is a production of CO2 resulting from the assimilation of bicarbonate (HCO3-) ions. However, over longer geological periods, the effects of calcification in ocean waters are of a carbon sink.
Ocean Acidification and Warming
Carbonate and bicarbonate account for a major control of the pH of seawater through the CO2 to HCO3- and CO32- equilibrium. Calcification rate experiments suggest that impacts of seawater acidification are species-specific (Gafar et al, 2019). Thus, the structure of phytoplanktonic communities is expected to change in an acidifying ocean.
Experimental approaches have showed that high seawater temperatures increase the requirements of micro-nutrients such as phosphorus (P) and decrease the PIC/POC ratio by 40-60% (Gerecht et al, 2014). Temperature-challenged cells grew more calcite plates malformations (Gerecht et al, 2014).
Increased temperature experiments on calcification rates and growth have showed conflicting results and further research is needed to investigate the consequences of Ocean Warming on C. pelagicus.
References
Author
Page authored by _____, student of Prof. Jay Lennon at IndianaUniversity.
