Temperature effect on respiration and photosynthesis of the symbiont-bearing planktonic foraminifera Globigerinoides ruber , Orbulina universa , and Globigerinella siphonifera

Abstract

Respiration and photosynthesis of the planktonic foraminifera Globigerinoides ruber, Orbulina universa, and Globigerinella siphonifera and their symbiotic algae were calculated from measured dissolved oxygen gradients using microelectrodes, using different temperatures in dark and light (250 mmol photon m 22 s 21 ) conditions. At one temperature (24uC) the respiration rate increased as a power function of the foraminiferan organic carbon mass with a 0.57 6 0.18 exponent. The effect of temperature on respiration was quantified in two ways: by normalizing the rates to the organic carbon mass and by normalizing the observed rates to a constant temperature (24uC). This latter normalization was also used for photosynthesis. The respiration rates increase as a function of temperature for all species and can be described either with a Q 10 5 3.18 (60.27) or with an Arrhenius temperature of T A 5 10,293uK (6768uK). Similar calculations for net photosynthesis yielded a Q 10 5 2.68 (60.36) and a T A 5 8766uK (61203uK), and calculations for gross photosynthesis yielded a Q 10 5 2.76 (60.29) and a T A 5 9026uK (6926uK). For the species studied, the photosynthesis : respiration ratio varied from moderate for G. siphonifera (0.58) to very high (13) for O. universa. The high ratios indicate that photosynthesis is much higher than the carbon requirements for both foraminifera and symbiont growth. This excess carbon might be the source of organic exudates.

Modelling planktic foraminifer growth and distribution using an ecophysiological multi-species approach

“…universa G. sacculifer G. siphonifera G. ruber N. dutertrei G. bulloides N. incompta In a similar way, foraminifer respiration increases with temperature following an Arrhenius kinetics (Lombard et al, 2009a) and respiration can be defined as:…”

“…The model reproduces this process by using a Michaelis-Menten relationship as a function of the light availability. Warming also increases the photosynthesis rate following an Arrhenius kinetics (Lombard et al, 2009a). The combined effect of light intensity and temperature can thus be estimated as:…”

“…Photosynthesis only takes place during day length (dl, d −1 ) and we assume that only a fraction (% p ) of the symbiont photosynthesis potentially contributes to the growth of the foraminifer/symbiont complex (Lombard et al, 2009a). The weight increment W , which serves to calculate W f is calculated on a daily basis such as:…”

Factors Influencing Porosity in Planktonic Foraminifera

“…In this context, it is interesting to note that genetic-species of planktonic foraminifera are often found in distinct environments (i.e., different biomes or different depth habitats) (Huber et al, 1997;de Vargas et al, 2001;Darling & Wade, 2008;Morard et al, 2009;Quillévéré et al, 2011;Morard et al, 2013;Morard et al, 2016). While evidence for high heritability of wall thickness and porosity is lacking, both 325 porosity and wall thickness have been observed to vary with environmental conditions in culture and across environments gradients (this study; Colombo & Cita, 1980;Caron, 1987a-b;Bijma et al, 1990;Lea et al, 1999;Spero et al, 1997;Russell et al, 2004;Lombard et al, 2009;Kuroyanagi et al, 2013;Spero et al, 2015;Henehan et al, 2017). This raises the interesting possibility that some of the morphological differences between different genetic species are driven primarily by differences in the environment in which they occur, rather than by heritable genetic differences.…”

“…Similarly, temperature has a powerful effect on metabolism that can be characterized by the respiratory Q 10 relationship-the factor by which an organism's respiration rate increases with a ten-270 degree increase in temperature. Estimates for the respiratory Q 10 of symbiont-bearing planktonic foraminifera (specifically Globigerinoides ruber, Globigerinella siphonifera and Orbulina universa) are approximately 3.18 (Lombard et al, 2009). …”