Experimental set-up influences the cardiovascular responses of decapod crustaceans to environmental change.

The effects of different holding methods on heart rate (HR) changes in the green crab, Carcinus maenas (Linnaeus, 1758) were investigated. Crabs were held in perforated plastic boxes (with or without a layer of sand), suspended above the bottom of the tank or strapped to weighted plastic grate. The HR of crabs classified as unrestrained (plastic box with or without sand) dropped more rapidly compared with restrained (hanging from band, strapped to grate) crabs. Within 1 h unrestrained crabs exhibited periods of cardiac pausing accounting for between 8-14% of the hourly time. In contrast, restrained crabs rarely exhibited cardiac pausing. When the crabs were subjected to a temperature increase (10-30oC), the HR of unrestrained crabs reached higher levels than the restrained animals. The four restraining methods were also used to investigate cardiac responses to hypoxia. During progressive hypoxia (100-20% oxygen) the HR of unrestrained crabs declined to lower levels than the restrained animals. The restraining methods appeared to be more stressful for the crabs, which maintained elevated HRs and were less able to respond to environmental change compared to crabs that could move freely within a small chamber. This suggests that even subtle changes in experimental design may alter physiological responses.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author