Prolonged SDA and reduced digestive efficiency under elevated CO2 may explain reduced growth in Atlantic cod (Gadus morhua)

Changes to Intestinal Transport Physiology and Carbonate Production at Various CO2Levels in a Marine Teleost, the Gulf Toadfish (Opsanus beta)

“…Carbon dioxide levels utilized in this study were admittedly high compared to what would be seen in the environment, even under the most drastic climate change scenarios (Meehl et al 2007). However, in certain coastal and upwelling areas, CO 2 levels occasionally meet or exceed these predictions (Feely et al 2008;Thomsen et al 2010;Melzner et al 2013), and fish in high-density aquaculture settings regularly experience high levels of CO 2 (Tirsgaard et al 2015). Few studies have examined impacts of hypercarbia on osmoregulatory processes (Brauner et al 2000;Shaughnessy et al 2015), despite the fact that the maintenance of homeostasis involves the exchange of Na 1 and Cl 2 and/or HCO 3 2 and H 1 .…”

“…However, the intestine is known to be responsive to changes in plasma HCO 3 2 (Taylor et al 2010;Heuer et al 2012) and appears to counteract measures employed at the gill to retain HCO 3 2 during elevated CO 2 , at least during short-term exposures (Perry et al 2010;Heuer et al 2012). In addition, hypercarbia has recently been demonstrated to prolong specific dynamic action (Tirsgaard et al 2015). Most patterns of acid and base flux in the intestine have been studied in the context of osmoregulation by manipulating environmental salinity (Genz et al 2008 Gilmour et al 2012), since this organ is critical for osmotic homeostasis.…”

“…Although the gill is rightfully well studied as the dominant organ responsible for regulating acid-base disturbances during hypercarbia in marine teleosts, it is nonetheless surprising that the intestine has received relatively little attention, since the secretion of HCO 3 2 through the intestine appears to be linked to digestion, osmoregulation, and acid-base balance in the multifunctional gut of marine teleosts. While some information is available on how the marine fish intestine responds to hypercarbia (Perry et al 2010;Heuer et al 2012;Tseng et al 2013;Esbaugh et al 2015;Tirsgaard et al 2015), most in vivo work on transport mechanisms is restricted to two species that were investigated at two CO 2 tensions that differ by 25-fold. The abundant gulf toadfish has served as a model for study of the marine fish intestine and more specifically for investigation of bicarbonate secretory pathways, anchoring findings from this study to a rich body of previous literature.…”

Aquatic acidification: a mechanism underpinning maintained oxygen transport and performance in fish experiencing elevated carbon dioxide conditions

“…Specifically, both the diffusion distance of the respiratory epithelium and the permeability of the gas through the epithelium can impact gas exchange (Perry et al, 2009). Esbaugh et al (2016) suggest that, when fish are exposed to hypercapnic Couturier et al, 2013;Di Santo, 2015Esbaugh et al, 2016;Gräns et al, 2014;Green and Jutfelt, 2014;Hamilton et al, 2017;McKenzie et al, 2003;Melzner et al, 2009;Methling et al, 2013;Munday et al, 2009;Nadler et al, 2016;Ou et al, 2015;Rummer et al, 2013a;Tirsgaard et al, 2015).…”

The effect of diet, temperature and intermittent low oxygen on the metabolism of rainbow trout

“…Diurnal fluctuations in DO due to photosynthesis, increasing temperature and varying water exchange in net cages or flow through systems are probably one of the most pronounced water-quality changes most farmed fish endure (6)(7)(8) . Low DO levels are likely to occur during intensive fish VO 2 associated with feed ingestion and digestion (9)(10)(11)(12) . In addition, partial DO depletion or intermittent hypoxia can be amplified at night when phytoplanktons switch from photosynthesis to respiration (13) .…”