Scaling of Gill Metabolic Potential as a Function of Salinity in the Euryhaline Crab,Callinectes sapidusRathbun

Abstract

The body-size scaling pattern of enzymes that are important in energy metabolism was examined in gills of the blue crab as a function of acclimation salinity. We hypothesized that the higher surface-area-to-volume ratio of small crabs would impose a greater metabolic cost for hyperosmoregulation, leading to an increase in the capacity for ATP production in gills. Postmetamorphic crabs spanning a 2,500-fold range in body mass were examined following a 7-d exposure to a salinity of 35, 17, or 5 ppt. The posterior gills, which are the principal site of osmoregulatory ion pumping, generally had higher activities than the anterior gills, which are primarily used for gas exchange, and this discrepancy was greatest in small crabs. A significant effect of salinity was found only for the enzyme citrate synthase, where the activity was highest at the lowest salinity. Although most enzymes scaled negatively with body mass, the activity was independent of size over a 250-fold size range that encompassed the body masses of juvenile crabs but decreased abruptly in the adult crabs. These data suggest that ion pumping associated with osmoregulation may represent a greater energetic challenge in smaller crabs, and this is reflected in the relatively higher metabolic potential of the posterior gills. However, acclimation to different salinity regimes does not lead to dramatic global changes in the capacity for energy metabolism.

Gill area, permeability and Na+,K+-ATPase activity as a function of size and salinity in the blue crab,Callinectes sapidus

“…Crabs 5 g and less had uniformly high levels of gill Na 1 ,K 1 -ATPase (both in anterior and posterior gills), while those greater than 5 g had much lower levels. This pattern was also observed by our collaborators (Kinsey et al, 2003) in several metabolic enzymes in the gills of blue crabs. Arginine kinase from posterior gills and b-hydroxyacyl-CoA dehydrogenase from anterior and posterior gills also displayed uniformly high activities in small crabs with a dramatic decrease in activity in larger crabs.…”

Resilience of Oxygen Consumption Rates in the Juvenile Blue Crab Callinectes sapidus to Future Predicted Increases in Environmental Temperature and pCo2 in the Mesohaline Chesapeake Bay

“…The potential metabolic cost could be masked in the results from this study because of the remarkable ability of blue crabs to regulate their internal chemistry (Towle et al 1976, Henry & Kormanik 1985, Mangum et al 1985. It is also possible that the metabolic cost is constrained to only the gills in blue crabs, as has been observed in juvenile blue crabs exposed to an osmotic gradient in the study by Kinsey et al (2003). In that study, citrate synthase activity was significantly higher in the gill tissue of juvenile crabs exposed to low salinity than in the gill tissue of their adult counterparts, but no overall effect on the capacity for energy metabolism was observed.…”

Effects of Different Levels of Marine Snail Shells in the Diets of Juvenile Kuruma Shrimps Marsupenaeus japonicus as a Source of Calcium

“…Another possible factor associated with the resistance to the freshwater stress test is the shrimp's ability to use fatty acid as energy in their gills to facilitate ion pumping (Kinsey et al. ; Palacios and Racotta ). Previous research by Palacios and Racotta (), Palacios et al.…”

“…Another possible factor associated with the resistance to the freshwater stress test is the shrimp's ability to use fatty acid as energy in their gills to facilitate ion pumping (Kinsey et al 2003;Palacios and Racotta 2007). Previous research by Palacios and Racotta (2007), Palacios et al (2004), and Morris et al (1982) indicated that fatty acid content may affect water and ions permeability, which in turn can determine how shrimps respond to freshwater stress.…”