Daily activity rhythms, chronotypes, and risk-taking behavior in the signal crayfish

Using crayfish behavior assay as a simple and sensitive model to evaluate potential adverse effects of water pollution: Emphasis on antidepressants

The freshwater crayfish, Procambarus clarkii is an excellent aquatic animal model that is highly adaptable and tolerant. P. clarkii is widely used as a toxicity model to study various pharmaceutical exposure. This animal model has complex behavioral traits and is considered sensitive to environmental changes, making it an excellent candidate to study psychoactive drugs based on a behavioral approach. However, up to now, most behavioral studies on crayfish use manual observation and scoring that require panelists. In this study, we aim to develop an automation pipeline to analyze crayfish behavior automatically. We use a deep-learning approach to label body parts in multiple crayfish, and based on the trajectory results, the intra- or inter-individual crayfish were calculated. Reliable and fast results of several behavior endpoints in multiple crayfish were retrieved. We then validated the detection performance of numerous crayfish in specific gender groups (male-male and female-female). Based on the result, the male crayfish displayed significantly higher aggression than females. We also tested the antidepressant exposure on this animal model to evaluate the psychoactive effects of this drug. As male crayfish display more distinct agonistic behavior than females, we exposed them to sertraline (SRT) 1 ppb for 7 and 14 days. It was revealed that sertraline was able to alter several behavioral endpoints in crayfish. Significant increases in extend claw ratio, total distance moved, average speed, and rapid movement were displayed in sertraline-exposed crayfish but decreased interaction time and longest interaction time. In addition, SRT 14 days exposure could atler the aggressiveness and bold behavior In the present method, DeepLabCut (DLC) has been utilized to analyze the locomotion behavior of multiple crayfish. This established method provides rapid and accurate ecotoxicity measurements using freshwater crayfish, which beneficient and applicable for environmental research.

Personality, density and habitat drive the dispersal of invasive crayfish

There is increasing evidence that personality traits may drive dispersal patterns of animals, including invasive species. We investigated, using the widespread signal crayfish Pacifastacus leniusculus as a model invasive species, whether effects of personality traits on dispersal were independent of, or affected by, other factors including population density, habitat, crayfish size, sex and limb loss, along an invasion gradient. Behavioural traits (boldness, activity, exploration, willingness to climb) of 310 individually marked signal crayfish were measured at fully-established, newly-established and invasion front sites of two upland streams. After a period at liberty, recaptured crayfish were reassessed for behavioural traits (newly-established, invasion front). Dispersal distance and direction of crayfish movement, local population density, fine-scale habitat characteristics and crayfish size, sex and limb loss were also measured. Individual crayfish exhibited consistency in behavioural traits over time which formed a behavioural syndrome. Dispersal was both positively and negatively affected by personality traits, positively by local population density and negatively by refuge availability. No effect of size, sex and limb loss was recorded. Personality played a role in promoting dispersal but population density and local habitat complexity were also important determinants. Predicting biological invasion in animals is likely to require better integration of these processes.