title: Distribution of leukocytes as indicators of stress in the Australian swellshark, Cephaloscyllium laticeps.
abstract: Differential leukocyte counts were taken of blood smears collected from laboratory stressed adult Australian swellsharks Cephaloscyllium laticeps. We calculated the granulocyte (combined count of heterophils and neutrophils) to lymphocyte (G/L) ratio to use as a new physiological indicator of stress for sharks. Animals were captured and stressed using commercial fishing gear (monofilament gillnet and mid-water longline) in a laboratory setting, with blood samples collected prior to capture and at predetermined intervals during a subsequent 72 h recovery period. There was a significant increase in the G/L ratio of 291.14 +/- 54.13% at 72 h post-capture during recovery from the 6-h gillnet capture plus 15-mintue air exposure. Six hours of longline capture plus 15 min of air exposure also evoked a significant increase in the G/L ratio of 490.32 +/- 294.25% (24 h post-capture) and 590.53 +/- 277.65% (72 h post-capture). There was no significant change in the G/L ratio for control sharks that did not undergo capture stress but that experienced an identical blood-sampling regime as captured animals. Our study presents findings of stress-induced changes in leukocyte distribution within the peripheral blood of a shark species brought on by lymphopenia (decrease in lymphocytes) and granulocytosis (increase in granulocytes), and confirms this as a useful measure of the relatively rapid onset of stress in these animals.
authors.affiliation: School of Biological Sciences, Monash University, Clayton, VIC 3800, Australia.
authors.forename: Jason Adrian
authors.initials: JA
authors.lastname: Van Rijn
authors.forename: Richard D
authors.initials: RD
authors.lastname: Reina
mesh_terms: D000818:Animals; D001315:Australia; D005398:Fisheries / Q000379:methods*; D006098:Granulocytes / Q000166:cytology; D006234:Handling, Psychological; D007958:Leukocyte Count; D007962:Leukocytes / Q000166:cytology / Q000502:physiology*; D012754:Sharks / Q000276:immunology*; D013312:Stress, Physiological / Q000502:physiology*; D013997:Time Factors