Ocean Acidification Affects Hemocyte Physiology in the Tanner Crab (Chionoecetes bairdi)

Abstract

We used flow cytometry to determine if there would be a difference in hematology, selected immune functions, and hemocyte pH (pHi), under two different, future ocean acidification scenarios (pH = 7.50, 7.80) compared to current conditions (pH = 8.09) for Chionoecetes bairdi, Tanner crab. Hemocytes were analyzed after adult Tanner crabs were held for two years under continuous exposure to acidified ocean water. Total counts of hemocytes did not vary among control and experimental treatments; however, there were significantly greater number of dead, circulating hemocytes in crabs held at the lowest pH treatment. Phagocytosis of fluorescent microbeads by hemocytes was greatest at the lowest pH treatment. These results suggest that hemocytes were dying, likely by apoptosis, at a rate faster than upregulated phagocytosis was able to remove moribund cells from circulation at the lowest pH. Crab hemolymph pH (pHe) averaged 8.09 and did not vary among pH treatments. There was no significant difference in internal pH (pHi) within hyalinocytes among pH treatments and the mean pHi (7.26) was lower than the mean pHe. In contrast, there were significant differences among treatments in pHi of the semi-granular+granular cells. Control crabs had the highest mean semi-granular+granular pHi compared to the lowest pH treatment. As physiological hemocyte functions changed from ambient conditions, interactions with the number of eggs in the second clutch, percentage of viable eggs, and calcium concentration in the adult crab shell was observed. This suggested that the energetic costs of responding to ocean acidification and maintaining defense mechanisms in Tanner crab may divert energy from other physiological processes, such as reproduction.

Hemocyte responses of the thick shell mussel Mytilus coruscus exposed to nano-TiO 2 and seawater acidification

“…Fisher et al (2000) found a reduced concentration of hemocytes in the oyster Crassostrea virginica under long-term stress of petroleum hydrocarbon. Meseck et al (2016) indicated that ocean acidification also resulted in decreased THC of the crab Chionoecetes bairdi. Similarly, in the present study, THC decreased with nano-TiO 2 concentration increase and pH decrease.…”

Assessing the Impacts of Ocean Acidification on Adhesion and Shell Formation in the Barnacle Amphibalanus amphitrite

“…An alternative hypothesis is that reduced seawater pH led to differences in intracellular pH, which could alter the ability of cells to participate in the mineralization process. In another crustacean (the Tanner crab, Chionoecetes bairdi), a reduction in intracellular pH was observed in animals held at reduced pH, a response that was proposed to have implications on the shell formation process (Meseck et al, 2016). Direct assessments of intracellular pH in barnacles grown at reduced pH as well as further investigation into the role of cells in the shell formation process in barnacles would be helpful in evaluating these mechanisms.…”

Elevated pCO2 Affects Feeding Behavior and Acute Physiological Response of the Brown Crab Cancer pagurus

“…Studies of physiological responses of crabs exposed to elevated pCO 2 ( Pane and Barry, 2007 ; Spicer et al, 2007 ; Fehsenfeld et al, 2011 ) have identified a wide range of responses ( Kroeker et al, 2010 ). High CO 2 has been reported to negatively impact various physiological processes, including growth ( Walther et al, 2010 ), survival ( Melzner et al, 2009 ), development ( Walther et al, 2010 ; Schiffer et al, 2013 ), immune response ( Meseck et al, 2016 ), chemoreception ( de la Haye et al, 2012 ), and swimming performance ( Dissanayake and Ishimatsu, 2011 ). The most immediate physiological responses to ocean acidification (OA) in marine crustaceans are best described by acid–base adjustments ( Pane and Barry, 2007 ; Pörtner et al, 2010 ; Whiteley, 2011 ).…”