Ocean Acidification Leads to Counterproductive Intestinal Base Loss in the Gulf Toadfish (Opsanus beta)

Abstract

Oceanic CO(2) has increased from 280 to 380 μatm since preindustrial times and is expected to reach 1,900 μatm by 2300. In addition, regional upwelling zones exhibit levels up to 2,300 μatm, making exploration at future global projected CO(2) levels ecologically relevant today. Recent work has demonstrated that CO(2) exposure as low as 1,000 μatm induces acidosis in toadfish (Opansus beta), leading to metabolic compensation by retention of blood HCO(3) in an effort to defend pH. Since increased serosal HCO(3) translates to increased HCO(3) rates in isolated intestinal tissue, we predicted that blood elevation of HCO(3) and Pco(2) during exposure to 1,900 μatm CO(2) would increase in vivo base secretion rates. Rectal fluid and CaCO(3) excretions were collected from toadfish exposed to 380 (control) and 1,900 μatm CO(2) for 72 h. Fluids were analyzed for pH, osmolality, ionic composition, and total CO(2). Precipitated CaCO(3) was analyzed for titratable alkalinity, Mg(2+), and Ca(2+) content. Fish exposed to 1,900 μatm CO(2) exhibited higher rectal base excretion rates, higher rectal fluid HCO(3) (mmol L(-1)), and lower fluid Cl(-) (mmol L(-1)) than controls, suggesting increased intestinal anion exchange as a result of the compensated respiratory acidosis. This study verifies that imminent projected CO(2) levels expected by the year 2300 lead to greater intestinal HCO(3) loss, a process that acts against compensation for a CO(2)-induced acidosis.

Trophic transfer of essential elements in the clownfish Amphiprion ocellaris in the context of ocean acidification

“…Indeed, dietary trace element absorption occurs mainly in the intestine [30,31], and in marine fish (drinking water species), the intestine is also involved in acid-base balance and the ionoregulation (with gills and kidney [32,33]). Hereto, even if previous studies provided evidence of disturbances caused by p CO 2 on these processes in the fish intestine [34,35], our results indicated that it does not affect dietary essential element transfer in clownfish.…”

The solubility of fish‐produced high magnesium calcite in seawater

“… Perry et al [2011] give XRD and Energy‐dispersion X‐Ray (EDX) of 11 different fish species in their supplemental material confirming that it is a high magnesium calcite with a maximum of 48.9 mol %. The magnesium content of the toadfish precipitates analyzed in the present study was found to be 47.9 mol % ± 0.7 (n = 8) [ Heuer et al , 2012]. Perry et al [2011, Figure 3] show that fish produced carbonates with ellipsoidal morphology, similar to the gulf toadfish, had a high Mg content of greater than 40 mol%.…”

“…After cleaning the precipitates were filtered through 0.45 μ m filter and dried. The magnesium and calcium content of the precipitates was determined after acid digestion by flame atomic adsorption spectrometry [ Heuer et al , 2012]. In brief, precipitates where sonicated using a rod sonicator in 10 ml deionized water, after which pH was lowered to 4.00 by addition of HCl under continuous gassing with N 2 .…”

Is warmer better? Decreased oxidative damage in notothenioid fish after long-term acclimation to multiple stressors

“…In addition to elevated sea surface temperature (SST), a growing body of literature has focused on the impacts ocean acidification will have on marine teleosts; however, the majority of these studies have focused primarily on tropical or temperate species (Melzner et al, 2009;Munday et al, 2009a;Munday et al, 2009b;Munday et al, 2010;Munday et al, 2011;Esbaugh et al, 2012;Heuer et al, 2012;Nowicki et al, 2012;Bignami et al, 2013;Chivers et al, 2014;Munday et al, 2014;Murray et al, 2014;Pope et al, 2014). Despite projections that indicate changes in SST and partial pressure of CO 2 (Ṗ CO2 ) in seawater will impact higher latitudes faster and to a greater Is warmer better?…”