Comparison of enzyme activities linked to acid–base regulation in a deep-sea and a sublittoral decapod crab species

Abstract

When compared to the sublittoral Dungeness crab Cancer magister, the deep-sea Tanner crab Chionoecetes tanneri exhibited lower activities of enzymes involved in some of the processes essential for efficient acid -base regulation. Tissue enzymatic activities were compared between Dungeness crabs held in normoxia and Tanner crabs held in hypoxia -both treatments mimicking typical habitat oxygen levels. In the posterior gill, activities of all forms of ATPase and carbonic anhydrase (CA) were approximately 2-to 13.2-fold lower in Tanner crabs than in Dungeness crabs. CA activity in the heart and white muscle was also significantly lower in hypoxic deep-sea Tanner crabs, while ATPase activity in these 2 tissues was similar between the 2 treatments. Diagnostically, enzymatic activities were compared when both species were held in normoxic seawater, with additional significant differences found in specific white muscle ATPase fractions (amiloride-and N-ethylemaleimide [NEM]-sensitive ATPases) and tissue buffering (β) capacity. When both species were acclimated to normoxia, C. tanneri exhibited mass specific rates of oxygen consumption significantly lower (4.5-fold) than C. magister. Under short-term, strongly hypercapnic conditions (1% CO 2 ), the Dungeness crab displayed reduced (30 to 40%) branchial ATPase activities, while enzymatic activities in the Tanner crab gill, muscle and heart were refractive to short-term (24 h) hypercapnia, suggesting a minimal ability to tune branchial function to changing environmental conditions. These results support our hypothesis that the deep-sea Tanner crab has a reduced capacity for active transport of acid -base relevant ions, particularly at the gill, and is therefore at a marked disadvantage with respect to iono-and acid -base regulatory capacity. These results add to a growing database documenting the limited ability of deep-sea megafauna to compensate for internal acid -base disruptions associated with introduction of anthropogenic CO 2 into the deep sea.

Deep-water prawn Pandalus borealis displays a relatively high pH regulatory capacity in response to CO2-induced acidosis

“…Increasing the concentration of the Na + /K + -ATPase-specific inhibitor ouabain did not alter the results, suggesting that other ATPases may be highly active in the gills of P. borealis. The results of the present study and the findings of Pane et al (2008) may indicate that when exposed to environmental hyper capnia, decapod crustaceans can maintain pH e without increasing the activity of ion-transporting enzy mes above the basal metabolic level. However, the activity of other enzymes in volved in acid -base regulation, such as carbonic anhydrase, could be altered to increase acid -base regulation during hypercapnic exposure (Burnett et al 1981, Henry & Cameron 1983.…”

“…However, the effect of hypercapnic exposure on gill Na + /K + -ATPase activity in decapods has been poorly investigated. Pane et al (2008) found significantly decreased Na + /K + -ATPase activity in Dungeness crabs Cancer magister exposed to pCO 2 of 10 000 µatm for 24 h, and no change was found in the deep-sea crab Chionoecetes tanneri subjected to the same conditions. Using both microarray and quantitative PCR, Fehsenfeld et al 2011found only small changes in gene expression of proteins known to be important in osmoregulation and acid -base regulation, while other membrane proteins were differentially regulated in response to elevated seawater pCO 2 (3900 µatm) under low salinity conditions.…”

Impact of ocean acidification on metabolism and energetics during early life stages of the intertidal porcelain crab Petrolisthes cinctipes

“…However, the efficiency of crustacean buffering varies among species depending on their natural environment (Pane et al, 2008;Whiteley, 2011) and within life-history stages (Bouaricha et al, 1991). Thus, it is probable that early developmental stages of intertidal crustaceans vary in sensitivity to high CO 2 as a consequence of physiological adaptations to their respective environments, with larval stages expected to be most vulnerable to future ocean acidification.…”

Chasing the Future: How Will Ocean Change Affect Marine Life?

“…Each CT (7.6-liter RubberMaid Model 1530 water cooler) is equipped with a float valve to regulate seawater input, sensors (T, DO, pH), a gas input line connected to a diffuser stone, a 600-watt heater, and a drain with a distribution manifold that connects delivery rates according to pH and DO set points. The GCA has supported several studies evaluating the response of a variety of deep-sea animals to future deep-sea conditions (e.g., Pane and Barry, 2007;Pane et al, 2008;Kim et al, 2013a,b;Taylor et al, 2014;Hamilton et al, 2017).…”