Species-specific effects of near-future CO2 on the respiratory performance of two tropical prey fish and their predator

Abstract

Ocean surface CO2 levels are increasing in line with rising atmospheric CO2 and could exceed 900 μatm by year 2100, with extremes above 2000 μatm in some coastal habitats. The imminent increase in ocean pCO2 is predicted to have negative consequences for marine fishes, including reduced aerobic performance, but variability among species could be expected. Understanding interspecific responses to ocean acidification is important for predicting the consequences of ocean acidification on communities and ecosystems. In the present study, the effects of exposure to near-future seawater CO2 (860 μatm) on resting (Ṁ O2rest) and maximum (Ṁ O2max) oxygen consumption rates were determined for three tropical coral reef fish species interlinked through predator-prey relationships: juvenile Pomacentrus moluccensis and P. amboinensis, and one of their predators: adult Pseudochromis fuscus. Contrary to predictions, one of the prey species, P. amboinensis, displayed a 28 – 39 % increase in Ṁ O2max after both an acute and four-day exposure to near-future CO2 seawater, while maintaining Ṁ O2rest. By contrast, the same treatment had no significant effects on Ṁ O2rest or Ṁ O2max of the other two species. However, acute exposure of P. amboinensis to 1400 and 2400 μatm CO2 resulted in Ṁ O2max returning to control values. Overall, the findings suggest that: (1) the metabolic costs of living in a near-future CO2 seawater environment were insignificant for the species examined at rest; (2) the ṀO2max response of tropical reef species to near-future CO2 seawater can be dependent on the severity of external hypercapnia; and (3) near-future ocean pCO2 may not be detrimental to aerobic scope of all fish species and it may even augment aerobic scope of some species. The present results also highlight that close phylogenetic relatedness and living in the same environment, does not necessarily imply similar physiological responses to near-future CO2.

Species-Specific Responses of Juvenile Rockfish to Elevated pCO2: From Behavior to Genomics

“…A decrease in aerobic scope mediated by a decrease in MMR under high p CO 2 has been observed in tropical cardinalfish [12]. In contrast, two other studies showed the opposite effect, with MMR increasing under high p CO 2 [37,38], potentially in response to other effects on respiratory physiology or behavior. These studies and a recent meta-analysis [21] highlight the taxonomic differences in the tolerances of teleost fishes to high p CO 2 .…”

Synergistic effects of acute warming and low pH on cellular stress responses of the gilthead seabream Sparus aurata

“…These patterns may reflect metabolic depression caused by CO 2 -induced acidosis which in turn, may reduce resistance to warming. Thus, a growing number of studies shows that the effect of increased CO 2 levels on aerobic performance varies dramatically among fish species, ranging from decreasing aerobic performance (Munday et al 2009) or no change in aerobic performance (Deigweiher et al 2008;MacKenzie et al 2003;Ishimatsu et al 2008) to increasing aerobic performance (Couturier et al 2013).…”

Molecular characterization of mudskipper (Boleophthalmus pectinirostris) hypoxia-inducible factor-1α (HIF-1α) and analysis of its function in monocytes/macrophages

“…Environmental hypoxia can modulate and compromise behavior and/or physiology, and manipulate the immune response in fish [2, 3]. Aquatic hypoxia induces changes in the fish immune system, involving cytokines, granulocytes, and macrophages [4–6].…”