High tolerance of microzooplankton to ocean acidification in an Arctic coastal plankton community

Abstract

Impacts of ocean acidification (OA) on marine biota have been observed in a wide range of marine systems. We used a mesocosm approach to study the response of a high Arctic coastal microzooplankton community during the post-bloom period in Kongsfjorden (Svalbard) to direct and indirect effects of high <i>p</i>CO₂/low pH. We found almost no direct effects of OA on microzooplankton composition and diversity. Both the relative shares of ciliates and heterotrophic dinoflagellates as well as the taxonomic composition of microzooplankton remained unaffected by changes in <i>p</i>CO₂/pH. Although the different <i>p</i>CO₂ treatments affected food availability and phytoplankton composition, no indirect effects (e.g. on the total carrying capacity and phenology of microzooplankton) could be observed. Our data point to a high tolerance of this Arctic microzooplankton community to changes in <i>p</i>CO₂/pH. Future studies on the impact of OA on plankton communities should include microzooplankton in order to test whether the observed low sensitivity to OA is typical for coastal communities where changes in seawater pH occur frequently

Low CO2 Sensitivity of Microzooplankton Communities in the Gullmar Fjord, Skagerrak: Evidence from a Long-Term Mesocosm Study

“…Previous mesocosm studies of comparable size from the Baltic Sea, the North Sea and the Arctic considered only shorter time spans. This might have masked effects of high CO 2 which are visible only under long-term exposure [15, 23, 24, 67]. Based on the results, MZP communities from coastal regions comparable to the study site are not expected to be strongly affected by end-of-century CO 2 levels.…”

“…Results from a laboratory study applying more realistic OA scenarios on a single MZP species showed no direct effect [13]. In support of that, most mesocosm studies with a CO 2 level expected for the end of the 21 st century also show no or only subtle effects on the MZP community composition and diversity [15, 23, 24]. This can be partly attributed to the high tolerance of coastal communities to frequently occurring habitat pH fluctuations [48, 49].…”

Alterations in microbial community composition with increasing &lt;i&gt;f&lt;/i&gt;CO&lt;sub&gt;2&lt;/sub&gt;: a mesocosm study in the eastern Baltic Sea

“…Viral lysis has been found to be as important as microzooplankton grazing to the mortality of natural bacterioplankton and phytoplankton (Weinbauer, 2004;Baudoux et al, 2006;Evans and Brussaard, 2012;Mojica et al, 2016). Thus far, most studies examining the effects of OA on microzooplankton abundance and/or grazing have found little or no direct effect (Suffrian et al, 2008;Rose et al, 2009;Aberle et al, 2013;Brussaard et al, 2013;Niehoff et al, 2013). To our knowledge, no viral lysis rates have been reported for natural phytoplankton communities under conditions of OA.…”

“…Hein and Sand-Jensen, 1997;Tortell et al, 2002;Leonardos and Geider, 2005;Engel et al, 2008;Feng et al, 2009;Eberlein et al, 2017). Certain cyanobacteria, including diazotrophs, demonstrate stimulated growth under conditions of elevated CO 2 (Qiu and Gao, 2002;Barcelos e Ramos et al, 2007;Dutkiewicz et al, 2015). However, no consistent trends have been found for Synechococcus (Schulz et al, 2017 and references therein).…”

Interaction effects of zooplankton and CO2 on phytoplankton communities and the deep chlorophyll maximum

“…We provide new evidence regarding the effect of CO 2 enrichment on zooplankton communities in a lake context. Previous work has shown either indirect negative effects via a change in phytoplankton biochemical or stoichiometric composition (Rossoll et al., ; Urabe et al., ), or neutral effects (Aberle et al., ; Niehoff, Knüppel, Daase, Czerny, & Boxhammer, ). Our study supports a neutral effect of CO 2 on crustacean zooplankton, but with the potential for indirect ones in the long term because of shifts in the phytoplankton communities (Sterner & Elser, ; Van De Waal, Verschoor, Verspagen, Van Donk, & Huisman, ).…”