The North Pacific spiny dogfish is known to tolerate a narrow range of salinities; whilst this species has been found in salinities of less than 25‰ in the wild, this low salinity cannot be tolerated for long. This is in contrast to certain other elasmobranch species such as the blue shark (Prionace glauca) which has been known to infiltrate river systems for extended periods of time.
Elasmobranch species moving between salt water and fresh water can experience changes in the concentration of Na+, Cl- and urea in their plasma, the pH of their blood and the volume of body water as they attempt to readjust to their new environment.
In this study, the researchers exposed S. suckleyi to dilute saltwater at a salinity of 21‰, in order to assess the time taken to acclimatise and the physiological effects this hyposmotic solution had.
They found that the concentration of plasma Na+, Cl- and urea dropped, and the body weight of the experimental animals increased - most likely owing to an influx of water. Whilst S. suckleyi was able to begin to balance the Na+ and Cl- concentrations, possibly by active transport, steady states in the concentration of plasma urea was not achieved and it is hypothesised that this is the key limiting factor for the survival of the North Pacific spiny dogfish in low saline environments.
Whilst it appears as though this species can tolerate an environment of 21‰ for a short period of time, the ability to regulate key body processed in a lowered salt environment would appear to restrict the long term survival of this species in water of this salinity.
Samuel C. Guffey, Greg G. Goss, Time course of the acute response of the North Pacific spiny dogfish shark (Squalus suckleyi) to low salinity. Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology. Volume 171, May 2014, Pages 9-15.
Elasmobranch species moving between salt water and fresh water can experience changes in the concentration of Na+, Cl- and urea in their plasma, the pH of their blood and the volume of body water as they attempt to readjust to their new environment.
In this study, the researchers exposed S. suckleyi to dilute saltwater at a salinity of 21‰, in order to assess the time taken to acclimatise and the physiological effects this hyposmotic solution had.
They found that the concentration of plasma Na+, Cl- and urea dropped, and the body weight of the experimental animals increased - most likely owing to an influx of water. Whilst S. suckleyi was able to begin to balance the Na+ and Cl- concentrations, possibly by active transport, steady states in the concentration of plasma urea was not achieved and it is hypothesised that this is the key limiting factor for the survival of the North Pacific spiny dogfish in low saline environments.
Whilst it appears as though this species can tolerate an environment of 21‰ for a short period of time, the ability to regulate key body processed in a lowered salt environment would appear to restrict the long term survival of this species in water of this salinity.
Samuel C. Guffey, Greg G. Goss, Time course of the acute response of the North Pacific spiny dogfish shark (Squalus suckleyi) to low salinity. Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology. Volume 171, May 2014, Pages 9-15.
No comments:
Post a Comment