Ocean acidification effects on fish hearing

Abstract

Humans are rapidly changing the marine environment through a multitude of effects, including increased greenhouse gas emissions resulting in warmer and acidified oceans. Elevated CO 2 conditions can cause sensory deficits and altered behaviours in marine organisms, either directly by affecting end organ sensitivity or due to likely alterations in brain chemistry. Previous studies show that auditory-associated behaviours of larval and juvenile fishes can be affected by elevated CO 2 (1000 µatm). Here, using auditory evoked potentials (AEP) and micro-computer tomography (microCT) we show that raising juvenile snapper, Chrysophyrs auratus , under predicted future CO 2 conditions resulted in significant changes to their hearing ability. Specifically, snapper raised under elevated CO 2 conditions had a significant decrease in low frequency (less than 200 Hz) hearing sensitivity. MicroCT demonstrated that these elevated CO 2 snapper had sacculus otolith's that were significantly larger and had fluctuating asymmetry, which likely explains the difference in hearing sensitivity. We suggest that elevated CO 2 conditions have a dual effect on hearing, directly effecting the sensitivity of the hearing end organs and altering previously described hearing induced behaviours. This is the first time that predicted future CO 2 conditions have been empirically linked through modification of auditory anatomy to changes in fish hearing ability. Given the widespread and well-documented impact of elevated CO 2 on fish auditory anatomy, predictions of how fish life-history functions dependent on hearing may respond to climate change may need to be reassessed.

Climate Change Effects on North American Fish and Fisheries to Inform Adaptation Strategies

“…By the end of the century, ocean pH may decrease by 0.4 to 0.5 units (Raven et al 2005), which reduces the available carbonate needed to build coral reef structures (Hoegh‐Guldberg et al 2017). These changes in dissolved oxygen and CO 2 form the basis of ocean and coastal acidification, which can affect the survival, growth, reproduction, and calcification of marine organisms (Table 4; Kroeker et al 2010) and even auditory behavior (Radford et al 2021). These changes are further amplified by the diverse set of factors from human activities located along the nearshore environment or in rivers and streams that flow into estuaries (e.g., increases in eutrophication, impervious surfaces, and shoreline hardening; pollution, physiological disruptors, and agricultural run‐off; and general habitat degradation and fragmentation).…”

Ideas and perspectives: When ocean acidification experiments are not the same, repeatability is not tested

“…These influences include length of exposure, population-level genetic differences due to local adaptation, food availability, interactions with other stressors, seasonality, energy partitioning, life stage and the sex of the organisms used in experiments (e.g. Thomsen et al, 2012;Suckling et al, 2014;Sunday et al, 2014;Breitburg et al, 2015;Vargas et al, 2017;Ellis et al, 2017;Dahlke et al, 2018) as well as physico-chemical conditions (Riebesell et al, 2011).…”

“…Associated chemical changes include an increased concentration of bicarbonate ions and dissolved inorganic carbon and a decreased concentration of carbonate ions in the ocean and, unless compensated for, the body fluids of marine organisms. Although the chemistry of the carbonate system has been well-understood for decades, research on the biologi-cal and ecological implications of anthropogenic ocean acidification only began in earnest about 20 years ago (Gattuso and Hansson, 2011). A wide range of potential consequences have since been identified, with an early appreciation of the diverse vulnerability of plant and animal species (Kroeker et al, 2013;Wittmann and Pörtner, 2013).…”

Fisheries Volume 46 Number 9 September 2021

“…By the end of the century, ocean pH may decrease by 0.4 to 0.5 units (Raven et al 2005 ), which reduces the available carbonate needed to build coral reef structures (Hoegh-Guldberg et al 2017 ). These changes in dissolved oxygen and CO 2 form the basis of ocean and coastal acidifi cation, which can affect the survival, growth, reproduction, and calcifi cation of marine organisms (Table 4 ; Kroeker et al 2010 ) and even auditory behavior (Radford et al 2021 ). These changes are further amplifi ed by the diverse set of factors from human activities located along the nearshore environment or in rivers and streams that fl ow into estuaries (e.g., increases in eutrophication, impervious surfaces, and shoreline hardening; pollution, physiological disruptors, and agricultural run-off; and general habitat degradation and fragmentation).…”