Temperature affects the morphology and calcification of Emiliania huxleyi strains
Rosas Navarro, Anaid (Universitat Autònoma de Barcelona. Institut de Ciència i Tecnologia Ambientals)
Langer, Gerald (The Marine Biological Association of the United Kingdom)
Ziveri, Patrizia (Universitat Autònoma de Barcelona. Departament de Biologia Animal, de Biologia Vegetal i d'Ecologia)

Data:	2016
Resum:	The global warming debate has sparked an unprecedented interest in temperature effects on coccolithophores. The calcification response to temperature changes reported in the literature, however, is ambiguous. The two main sources of this ambiguity are putatively differences in experimental setup and strain specificity. In this study we therefore compare three strains isolated in the North Pacific under identical experimental conditions. Three strains of Emiliania huxleyi type A were grown under non-limiting nutrient and light conditions, at 10, 15, 20 and 25°C. All three strains displayed similar growth rate versus temperature relationships, with an optimum at 20-25°C. Elemental production (particulate inorganic carbon (PIC), particulate organic carbon (POC), total particulate nitrogen (TPN)), coccolith mass, coccolith size, and width of the tube element cycle were positively correlated with temperature over the sub-optimum to optimum temperature range. The correlation between PIC production and coccolith mass/size supports the notion that coccolith mass can be used as a proxy for PIC production in sediment samples. Increasing PIC production was significantly positively correlated with the percentage of incomplete coccoliths in one strain only. Generally, coccoliths were heavier when PIC production was higher. This shows that incompleteness of coccoliths is not due to time shortage at high PIC production. Sub-optimal growth temperatures lead to an increase in the percentage of malformed coccoliths in a strain-specific fashion. Since in total only six strains have been tested thus far, it is presently difficult to say whether sub-optimal temperature is an important factor causing malformations in the field. The most important parameter in biogeochemical terms, the PIC : POC ratio, shows a minimum at optimum growth temperature in all investigated strains. This clarifies the ambiguous picture featuring in the literature, i. e. discrepancies between PIC: POC-temperature relationships reported in different studies using different strains and different experimental setups. In summary, global warming might cause a decline in coccolithophore's PIC contribution to the rain ratio, as well as improved fitness in some genotypes due to fewer coccolith malformations.
Ajuts:	European Commission 265103 European Commission 267931 Agència de Gestió d'Ajuts Universitaris i de Recerca 2014/SGR-1356 Ministerio de Economía y Competitividad MDM/2015-0552
Nota:	Unidad de excelencia María de Maeztu MdM-2015-0552
Drets:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, la comunicació pública de l'obra i la creació d'obres derivades, fins i tot amb finalitats comercials, sempre i quan es reconegui l'autoria de l'obra original.
Llengua:	Anglès
Document:	Article ; recerca ; Versió publicada
Publicat a:	Biogeosciences, Vol. 13,issue 10 (May 2016) , p. 2913-2926, ISSN 1726-4189

DOI: 10.5194/bg-13-2913-2016

14 p, 8.4 MB

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