Ocean Acidification-Induced Food Quality Deterioration Constrains Trophic Transfer

Abstract

Our present understanding of ocean acidification (OA) impacts on marine organisms caused by rapidly rising atmospheric carbon dioxide (CO2) concentration is almost entirely limited to single species responses. OA consequences for food web interactions are, however, still unknown. Indirect OA effects can be expected for consumers by changing the nutritional quality of their prey. We used a laboratory experiment to test potential OA effects on algal fatty acid (FA) composition and resulting copepod growth. We show that elevated CO2 significantly changed the FA concentration and composition of the diatom Thalassiosira pseudonana, which constrained growth and reproduction of the copepod Acartia tonsa. A significant decline in both total FAs (28.1 to 17.4 fg cell−1) and the ratio of long-chain polyunsaturated to saturated fatty acids (PUFA:SFA) of food algae cultured under elevated (750 µatm) compared to present day (380 µatm) pCO2 was directly translated to copepods. The proportion of total essential FAs declined almost tenfold in copepods and the contribution of saturated fatty acids (SFAs) tripled at high CO2. This rapid and reversible CO2-dependent shift in FA concentration and composition caused a decrease in both copepod somatic growth and egg production from 34 to 5 eggs female−1 day−1. Because the diatom-copepod link supports some of the most productive ecosystems in the world, our study demonstrates that OA can have far-reaching consequences for ocean food webs by changing the nutritional quality of essential macromolecules in primary producers that cascade up the food web.

Increased carbon dioxide availability alters phytoplankton stoichiometry and affects carbon cycling and growth of a marine planktonic herbivore

“…Therefore, all of the observed negative effects in the copepods here could be attributed to the direct changes in C content, rather than secondary biochemical changes in food quality. In contrast, the diatom Thalassiosira pseudonana contains less highly unsaturated fatty acids when grown under high pCO 2 conditions (Rossoll et al 2012). The authors also observed a decline in Fig.…”

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

“…in food availability, phytoplankton community structure, size classes and stoichiometry (Suffrian et al, 2008;Feng et al, 2009;Rossoll et al, 2012). On the other hand MZP are known for a direct pH sensitivity (Hinga, 2002;, and a drop in seawater pH as a result of increasing pCO 2 could directly affect the physiology of both autotrophic and heterotrophic protists by changing, e.g.…”

Synergism between elevated <i>p</i>CO<sub>2</sub> and temperature on the Antarctic sea ice diatom <i>Nitzschia lecointei</i>

“…For instance, Teoh et al (2004) reported a significant decrease in polyunsaturated fatty acids (PUFA) at temperatures above 4 • C in an Antarctic strain of Navicula sp. In addition, cellular fatty acid (FA) composition and nutrient stoichiometry can be directly related to the food quality transferred to higher trophic levels and may be negatively affected by ocean acidification (Riebesell et al, 2000;Rossoll et al, 2012;Schoo et al, 2013). However little is known about the combined effects of ocean acidification and warming on microalgal lipid FA composition.…”