Replenishment of fish populations is threatened by ocean acidification

Abstract

There is increasing concern that ocean acidification, caused by the uptake of additional CO 2 at the ocean surface, could affect the functioning of marine ecosystems; however, the mechanisms by which population declines will occur have not been identified, especially for noncalcifying species such as fishes. Here, we use a combination of laboratory and field-based experiments to show that levels of dissolved CO 2 predicted to occur in the ocean this century alter the behavior of larval fish and dramatically decrease their survival during recruitment to adult populations. Altered behavior of larvae was detected at 700 ppm CO 2 , with many individuals becoming attracted to the smell of predators. At 850 ppm CO 2 , the ability to sense predators was completely impaired. Larvae exposed to elevated CO 2 were more active and exhibited riskier behavior in natural coral-reef habitat. As a result, they had 5–9 times higher mortality from predation than current-day controls, with mortality increasing with CO 2 concentration. Our results show that additional CO 2 absorbed into the ocean will reduce recruitment success and have far-reaching consequences for the sustainability of fish populations.

CO2-induced ocean acidification increases anxiety in Rockfish via alteration of GABAAreceptor functioning

“…By contrast, fish were initially believed to be safe from the effects of OA, as early studies demonstrated a lack of mortality under extremely high CO 2 levels (greater than 10 000 matm) [5]. However, an increasing body of evidence suggests that OA-relevant CO 2 /pH levels induce various sublethal effects in fish, including otolith over-growth [6,7], a shift in behavioural lateralization [8,9], alterations in olfaction that affect detection of cues from substrates, parents [10], prey [11] and predators [8,12,13], and impaired learning [9,14]. Because the gamma-aminobutyric acid type A (GABA A ) receptor antagonist, gabazine, restores proper discrimination of predator odour, learning of predatory cues [14] and behavioural lateralization in OA-exposed fish [8], at least some of the deleterious effects of OA in fish seem to be related to altered neurotransmitter function.…”

Ocean acidification alters the response of intertidal snails to a key sea star predator

“…Multiple species of fish, for example, fail to properly process waterborne cue information when confronted with the scent of predators [5,6]. Such impaired behaviours appear to originate from altered neurotransmitter and ion channel function under conditions of reduced seawater pH [7][8][9].…”

Assessing carbon dioxide removal through global and regional ocean alkalinization under high and low emission pathways

“…Potential impacts include changes in calcification, fecundity, organism growth and physiology, species composition and distributions, food web structure, and nutrient availability (Doney et al, 2012;Fabry et al, 2008;Iglesias-Rodriguez et al, 2008;Munday et al, 2009Munday et al, , 2010. Within this century, the impacts of ocean acidification will increase in proportion to emissions (Gattuso et al, 2015).…”