Irradiance and pH affect coccolithophore community composition on a transect between the North Sea and the Arctic Ocean

Abstract

Little is known about the distribution of coccolithophores in Arctic regions, or the reasons why they are absent from certain locations but thrive in others. Factors thought to affect coccolithophore distribution include nutrients, salinity, temperature and light, as well as carbonate chemistry parameters. Here we present data collected in summer 2008 along a transect between the North Sea and Svalbard (Arctic). Coccolithophore abundance and diversity were measured and compared with a set of environmental variables that included macronutrients, salinity, temperature, irradiance, pH and Ω calcite . Eighteen coccolithophore species were found in the southern North Sea where coccolithophores were previously thought to be absent. In the ice-covered region north of Svalbard, coccolithophores were scarce and dominated by the family Papposphaeraceae. A multivariate approach showed that changes in pH and mixed layer irradiance explained most of the variation in coccolithophore distribution and community composition (Spearman's r S = 0.62). Differences between the Svalbard population and those from other regions were mostly explained by pH (r S = 0.45), whereas mixed layer irradiance explained most of the variation between the North Sea, Norwegian Sea and Arctic water assemblages (r S = 0.40). Estimates of cell specific calcification rates showed that species composition can considerably affect community calcification. Consequently, future ocean acidification (changes in pH) and stratification due to global warming (changes in mixed layer irradiance) may influence pelagic calcification by inducing changes in the species composition of coccolithophore communities.KEY WORDS: Coccolithophore · Emiliania huxleyi · Arctic Ocean · pH · Irradiance · Ocean acidification Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 431: [25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43] 2011 concentrations and light conditions (Bopp et al. 2001, Sarmiento et al. 2004, as well as ocean acidification (Orr et al. 2005). Extensive experimental and field research on Emiliania huxleyi, the most common cocco litho phore, indicates that calcification in this species depends strongly on irradiance and is stimulated by nutrient stress, even though cells grow well under high nutrient concentrations and low irradiance (see review by Zondervan 2007). However, elevated pCO 2 levels have varying effects on the calcifying ability of different E. huxleyi strains (Riebesell et al. 2000, Iglesias-Rodriguez et al. 2008, Langer et al. 2009) and different coccolithophore species (Langer et al. 2006). Moreover, effects of simultaneous changes in multiple environmental variables are diverse. For example, light saturation for E. huxleyi growth depends on temperature (Paasche 2001, Zondervan 2007 whereas the sensitivity of E. huxleyi calcification and organic C fixation to elevated pCO 2 depend on their replete or depleted nutrient status (Sciandra et al. 2003, Delille et al. 2005, E...

Environmental drivers of coccolithophore abundance and calcification across Drake Passage (Southern Ocean)

“…Paasche, 2002), and there is now a growing number of field studies examining its eco-physiology (e.g. Harley et al, 2010;Poulton et al, 2010Poulton et al, , 2011Poulton et al, , 2013Poulton et al, , 2014Charalampopoulou et al, 2011;Young et al, 2014).…”

“…In natural coccolithophore populations, bulk community rates of calcite production (CP) are influenced by both cell numbers (a product of growth and mortality of the population) and variability in the rate of calcification per cell (a function of environmental conditions and species composition) (Poulton et al, 2010Charalampopoulou et al, 2011). Cellular rates of calcification are dependent on both the calcite content of individual coccoliths and the rate of coccolith production.…”

“…Cellular rates of calcification are dependent on both the calcite content of individual coccoliths and the rate of coccolith production. Rather than examining bulk CP and comparing it to environmental factors, a more appropriate approach is to consider cellular levels of calcification in the form of cell-normalised rates (cell-CF), which when normalised to coccolith calcite content allow an estimate of coccolith production rates (Poulton et al, 2010(Poulton et al, , 2013Charalampopoulou et al, 2011). The calcite content of individual coccoliths is determined by their volume/shape and distal shield length (DSL) (Young and Ziveri, 2000).…”

“…temperature, salinity, nutrients, irradiance and carbonate chemistry parameters). In order to examine changes in calcification, we made estimates of cellular coccolith production rates (Poulton et al, 2010(Poulton et al, , 2013Charalampopoulou et al, 2011) from cell-CF and estimates of coccolith calcite content using biometric A. Charalampopoulou et al: Coccolithophores across Drake Passage 5919 measurements Young et al, 2014;Jin et al, 2016).…”

Net primary productivity estimates and environmental variables in the Arctic Ocean: An assessment of coupled physical-biogeochemical models

“…This database consisted of the ARCSS-PP data set , available at NOAA/National Oceanographic Data Center (NODC) (http://www.nodc.noaa. gov/cgi-bin/OAS/prd/accession/details/ 63065), and more recent international polar research activities such as CASES (2004) [Brugel et al, 2009;Tremblay et al, 2011], ArcticNet ( -2008( ) (M. Gosselin, personal communication, 2014, K-PORT (2007K-PORT ( , 2008, and 2010) (S. H. Lee, personal communication, 2014), CFL (2008) [Mundy et al, 2009;Sallon et al, 2011], ICE-CHASER (2008 [Charalampopoulou et al, 2011], JOIS (2009 [Yun et al, 2012], RUSALCA (2009) [Arrigo et al, 2014]. These recent data were primarily collected in the Pacificsector of the Arctic Ocean ( Figure 1c).…”