Fishes in high-CO2, acidified oceans

Abstract

Research interest in CO 2 -driven ocean acidification has been centered on certain groups of calcifying marine organisms, but knowledge on the possible impacts of ocean acidification on fish is limited. Our survey of the existing literature on the effects of increased pCO 2 on fish (total of 116 papers) revealed that few studies were conducted under pCO 2 conditions relevant to the future scenarios of ocean acidification. Information is nearly absent on reproduction, early development, and behaviour of marine fish. The short experimental durations of these studies preclude forecasting of how mortality and growth of marine fish would be affected by future increases in seawater CO 2 . Fish have been shown to maintain their oxygen consumption under elevated pCO 2 conditions, in contrast to declines seen in several marine invertebrates, in spite of possible additional energetic costs incurred by higher pCO 2 . Impacts of prolonged CO 2 exposure on reproduction, early development, growth, and behaviour of marine fish are important areas that need urgent investigation. There is also a need to rapidly advance research into possible acclimation of marine fish to high pCO 2 environments, endocrine responses to prolonged CO 2 exposure, and indirect influences through food availability and quality on fish growth, survival and reproduction. Useful guidance could be gained from the rich literature on the effects of freshwater acidification.

Effects of climate change on fish reproduction and early life history stages

“…Sperm motility of the flounder, Limanda yokohamae, is arrested by mild increases in pCO 2 (Inaba et al 2003), but similar effects were not observed in 10 other species from a range of families (Inaba et al 2003) or in the Baltic cod, Gadus morhua (Frommel et al 2010). Sensitivity of fish eggs to elevated CO 2 varies markedly between species, but species tested to date typically have 24-h LC50 (lethal concentration resulting in 50% mortality) values well above 10 000 ppm CO 2 (Ishimatsu et al 2008). Furthermore, Munday et al (2009a) did not detect any effect of exposure to 1000 ppm CO 2 on the embryonic duration or survival of clownfish (Amphiprion percula) eggs.…”

“…In general, fishes appear to be more tolerant to increases in ambient CO 2 than many invertebrates (Ishimatsu et al 2008;Widdicombe and Spicer 2008), possibly because of their welldeveloped mechanisms for acid-base regulation (Pörtner et al 2004;Melzner et al 2009). However, very little is known about the effects that chronic exposure to levels of pCO 2 predicted to occur over the next 50-100 years (up to ,1000 ppm CO 2 ) might have on fish reproduction.…”

“…Ocean acidification and early life history stages Larval stages are predicted to be more sensitive to elevated pCO 2 than adults because they have a larger surface areato-volume ratio, and thus are more susceptible to changes in ambient conditions, and because they might have lessdeveloped mechanisms for acid-base balance compensation (Fabry et al 2008;Ishimatsu et al 2008;Melzner et al 2009). Acid-base balance in adult fish is mostly maintained by ion transport across the gills (Claiborne et al 2002).…”

“…Lacustrine habitats will experience a range of effects depending on lake inflows, water column structure and lake basin topography (Wahl and Löffler 2009). In addition to increases in temperature, elevations in atmospheric CO 2 mean that marine systems will also be affected by ocean acidification, which has the potential to directly influence reproduction and early life stages of marine species (Ishimatsu et al 2008), and to interact with the effects of temperature (Pörtner and Farrell 2008).…”

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

“…To date, calcifying phytoplankton and invertebrates such as corals and mollusks have received the most attention due to the potential impact of acidification on carbonate shell integrity and formation [3,4]. 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].…”