Experimental setup influences the cardiovascular responses of decapod crustaceans to environmental change

Abstract

The effects of different holding methods on heart rate (HR) changes in the green crab, Carcinus maenas (Linnaeus, 1758), were investigated. Green crabs were held in perforated plastic boxes (with or without a layer of sand) suspended above the bottom of the tank or strapped to a weighted plastic grate. The HR of green crabs classified as unrestrained (plastic box with or without sand) dropped more rapidly compared with restrained (hanging from band, strapped to grate) green crabs. Within 1 h, unrestrained green crabs exhibited periods of cardiac pausing accounting for between 8% and 14% of the hourly time. In contrast, restrained green crabs rarely exhibited cardiac pausing. When the green crabs were subjected to a temperature increase (10–30 °C), the HR of unrestrained green crabs reached higher levels than that of 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 green crabs declined to lower levels than that of the restrained animals. The restraining methods appeared to be more stressful for the green crabs that maintained elevated HRs and were less able to respond to environmental change compared with green crabs that could move freely within a small chamber. This suggests that even subtle changes in experimental design may alter physiological responses.

Non-invasive quantification of cardiac stroke volume in the edible crab Cancer pagurus

“…The crustacean cardiovascular system may respond differently to environmental triggers when animals are restrained in an experimental setup [11], which was necessary for present MRI experiments. This may impact the present results and limit their applicability.…”

“…It is speculated that these periodic fluctuations in cardiovascular activity may conserve energy over time [10]. Crustaceans are able to adjust their cardiac output through independently modulating HR and SV [11]. This is evidenced by constant stroke volumes with increasing heart rates above certain, species-specific temperature thresholds [12, 13].…”

Does physiological tolerance to acute hypoxia and salinity change explain ecological niche in two intertidal crab species?

“…However, analysis of continuous recordings in respirometry experiments showed that any initial elevations in oxygen consumption lasted less than 20 min (data not shown). Some authors have also utilized pauses in heart rate as an indicator of reduced stress in crabs (McGaw and Nancollas, 2017). In our study, the mean time of acardia onset in control crabs was 86 min (data not shown), suggesting that crabs settled relatively quickly into chambers.…”

Why Protect Decapod Crustaceans Used as Models in Biomedical Research and in Ecotoxicology? Ethical and Legislative Considerations

“…Physiological responses. Pain activates various physiological responses, such as modifications in heart rate, respiration and/or hormonal levels [ 17 , 73 , 82 , 83 ], and these are generally regarded as stress responses. Stress is a biological response that an animal exhibits to cope with a threat to its homeostasis [ 84 ].…”