Measures of heart and ventilatory rates in freely moving crayfish

The effects of tricaine mesylate on arthropods: crayfish, crab and Drosophila

Tricaine mesylate, also known as MS-222, was investigated to characterize its effects on sensory neurons, synaptic transmission at the neuromuscular junction, and heart rate in invertebrates. Three species were examined: Drosophila melanogaster, blue crab (Callinectes sapidus), and red swamp crayfish (Procambarus clarkii). Intracellular measures of action potentials in motor neurons of the crayfish demonstrated that MS-222 dampened the amplitude, suggesting that voltage-gated Na + channels are blocked by MS-222. This is likely the mechanism behind the reduced activity measured in sensory neurons and depressed synaptic transmission in all three species as well as reduced cardiac function in the larval Drosophila. To address public access to data, a group effort was used for analysis of given data sets, blind to the experimental design, to gauge analytical accuracy. The determination of a threshold in analysis for measuring extracellular recorded sensory events is critical and is not easily performed with commercial software.

Physiological and Behavioral Indicators to Measure Crustacean Welfare

Simple Summary

The purpose of this project was to determine how neural circuits were affected during warming by examining sensory neurons, the neuromuscular junction, and the cardiac function and behavior of the commercially important crustacean species, the red swamp crayfish (Procambarus clarkii). Various rates of heating at 1 °C/min, 12 °C/min, or 46 °C/min to 80 °C as well as placing crayfish directly in boiling water were examined. Sensory nerves and the neuromuscular junction will stop working at 44 °C within two minutes. The heart ceases functioning fastest (within 10 s) when placing the crayfish directly in boiling water, which is the quickest method to kill them while minimizing exposure to noxious stimuli.

Abstract

This project determined how neural circuits are affected during warming by examining sensory neurons, the neuromuscular junction, and the cardiac function and behavior of the commercially important crustacean species, the red swamp crayfish (Procambarus clarkii). Rapid inactivation of neural function in crustaceans prior to slaughter is important to limit exposure to noxious stimuli, thus improving animal welfare. This study demonstrated that as a crayfish is warmed at 1 °C/min, the heart beat stops at 44 °C. When temperature is rapidly increased, at 44 °C synaptic transmission at the neuromuscular junction ceases and primary sensory neurons stop functioning. Even though animals do not respond to stimuli after being warmed to 44 °C, if sensory neurons are returned to 20 °C saline after two minutes, they may regain function. Conversely, the neuromuscular junction does not regain function after two minutes in 44 °C saline. Examining behavior and heart rate while warming at 1 °C/min, 12 °C/min, or 46 °C/min to 80 °C indicated that at approximately 40 °C the heart rate is altered. Within 10 s at 80 °C, the heart stops with the highest heating rate. Directly placing crayfish in boiling water stopped the heart quickest, within 10 s, which likely represents denaturing of the tissue by heat. Using an impedance measure to detect a heartbeat may also be influenced by movements in the denaturing process of the tissue. A rapid increase in the temperature of the crayfish above 44 °C is key to limit its exposure to noxious stimuli.

Real-time monitoring of water quality using fish and crayfish as bio-indicators: a review

Water quality monitoring using fish and crayfish as bio-indicators requires an understanding of the state of pollution of waters, choice of bio-indicators, physiological and behavioral endpoints of fish and crayfish, and principles of the methodology and their potential applications. Here, we discuss telemetry, acoustic monitoring, vision-based monitoring, measures of ventilatory activity, electrocardiography, and fiber-optic plethysmography. Assessment of water quality must be based, not only on physicochemical characteristics of the current environment as determined by chemical analyses, but also on observations of the physiology and behavior of its inhabitants. Real-time biomonitoring is suggested as the most reliable method, since it incorporates living organisms into the system to serve as biosensors. The potential application of the methods discussed includes use at water treatment plants and water supply stations for prevention of hazardous toxicological events, and, for aquaculture, in ponds, lakes, and aquariums for monitoring growth, population size, and behavior traits.