Enhanced abundance of tintinnids under elevated CO2 level from coastal Bay of Bengal

Abstract

The role of microzooplankton (MZP) in the pelagic trophodynamics is highly significant, but the responses of marine MZP to increasing CO 2 levels are rather poorly understood. Hence the present study was undertaken to understand the responses of marine plankton to increasing CO 2 concentrations. Natural water samples from the coastal Bay of Bengal were incubated under the ambient condition and high CO 2 levels (703-711 latm) for 5 days in May and June 2010. A significant negative correlation was obtained between phytoplankton and MZP abundance which indicated that phytoplankton community structure can considerably be controlled by MZP in this region. The average relative abundances of tintinnids under elevated CO 2 levels were found to be significantly higher (68.65 ± 5.63% in May; 85.46 ± 9.56% in June) than observed in the ambient condition (35.68 ± 6.83% in May; 79 ± 5.36% in June). The observed dominance of small chain forming diatom species probably played a crucial role as they can be potentially grazed by tintinnids. This fact was strengthened by the observed high negative correlations between the relative abundance of major phytoplankton and tintinnids. Moreover, particulate organic carbon and total bacterial counts were also enhanced under elevated CO 2 level and can serve as additional food source for ciliates. The observed responses of tintinnids to increasing CO 2 might have multiple impacts on the energy transfer, nutrient and carbon cycling in the coastal water. The duration of the present study was relatively short and therefore further investigation on longer time scale needs to be done and might give us a better insight about phytoplankton and MZP species succession under elevated CO 2 level.

Effect of elevated CO<sub>2</sub> on organic matter pools and fluxes in a summer Baltic Sea plankton community

“…Biswas et al, 2012;Engel et al, 2005Engel et al, , 2008Engel et al, , 2014Feng et al, 2010;Hama et al, 2012;Hare et al, 2007;Hopkins et al, 2010;Hopkinson et al, 2010;Hoppe et al, 2013;Kim et al, 2006;Nielsen et al, 2010Nielsen et al, , 2011Richier et al, 2014;Rossoll et al, 2013;Schulz et al, 2008Tatters et al, 2013a, b;Yoshimura et al, 2010Yoshimura et al, , 2013Yoshimura et al, , 2014 vs. nutrientdepleted (e.g. Law et al, 2012;Lomas et al, 2012;Losh et al, 2012)).…”

Impact of river discharge on the coastal water pH and pCO2 levels during the Indian Ocean Dipole (IOD) years in the western Bay of Bengal

“…The increased acidification (or CO 2 enrichment) seems to have significant impact on calcification and marine primary production (Riebesell et al, 2000;Riebesell, 2004 and references there in). Recent microcosm experiments conducted in the coastal BoB revealed enhancement in the abundance of tintinnids under elevated CO 2 levels (Biswas et al, 2012). Therefore, changes in the acidity of coastal waters would have significant impact on the ecosystem functioning in this sensitive region and requires more careful evaluation in the future studies.…”

Organic matter production response to CO 2 increase in open subarctic plankton communities: Comparison of six microcosm experiments under iron-limited and -enriched bloom conditions

“…Although monoculture experiments provide a useful first step to estimate the potential impact of pCO 2 increase on phytoplankton, to include variables such as competing species and effects of predation, experiments using natural plankton communities are required (Dupont and Pörtner, 2013;Rost et al, 2008). While information on the impacts in coastal plankton communities has been increasing (Biswas et al, 2012;Engel et al, 2014;Riebesell et al, 2008;Rossoll et al, 2013), studies using open ocean plankton communities are still scarce. Due to its vast area, phytoplankton in open ocean systems are the dominant marine photosynthesizing organism and therefore control the marine biogeochemistry of C and nutrients and thus indirectly potentially climate conditions (Falkowski, 2012).…”