Evaluation of body appendage injuries to juvenile signal crayfish (Pacifastacus leniusculus): relationships and consequences

Abstract

Key-words:antennae, autotomy, intraspecific interaction, regeneration, walking leg Aggressive behaviour occurs frequently in crayfish and commonly results in injuries to body appendages. This study aimed to evaluate injuries to antennae, chelae, and walking legs of juvenile signal crayfish after seven months of rearing at high stocking density. We suggest that the high incidence of antennae injuries (66.8%) is related to their delicate structure and exposed position, which makes them vulnerable to damage. Chelae were more frequently injured (45.5%) than walking legs (7.8-23.6%). Considering the robustness of these structures and the scarcity of animals with both chelae missing and/or regenerating (4.9%), it seemed that injured animals were often killed by less injured ones. Antennae of crayfish with a single injured chela were more frequently injured on the side of the body with the damaged chela, and a similar pattern was observed for walking legs. Expanding on previous research reporting a negative relationship only between incidence of chela injury and crayfish size, we found this relationship to be significant for all evaluated appendages. We hypothesize that any injury and accompanying regeneration may have significant impact on subsequent injuries, overall growth, and reproductive success, and may result in death through cannibalism. RÉSUMÉ Évaluation des blessures aux appendices de juvéniles d'écrevisse signal (Pacifastacus leniusculus) : relations et conséquences Mots-clés :antenne, autotomie, interaction intraspécifique, régénération, pattes Le comportement agressif est fréquent chez l'écrevisse. Il aboutit souvent à des blessures aux appendices. Cette étude évalue les blessures aux antennes, pinces et pattes de juvéniles d'écrevisse signal après sept mois d'élevage à forte densité. Nous suggérons que la fréquence élevée des blessures aux antennes (66,8 %) est en relation avec leur structure fragile et leur position exposée, qui les rendent plus vulnérables aux blessures. Les pinces sont plus souvent endommagées (45,5 %) que les pattes (7,8-23,6 %). Considérant la robustesse de ces structures et la rareté des animaux auxquels les deux pinces manquent et/ou sont en régénération (4,9 %), il semble que les animaux blessés sont souvent tués par moins blessés qu'eux. Les antennes des écrevisses avec une seule pince blessée sont plus souvent blessées du même côté que celui de la pince endommagée et un schéma similaire est observé pour les pattes. En s'appuyant sur de précédentes recherches relatant une relation négative uniquement entre la fréquence des blessures aux pinces et la taille de l'écrevisse, nous trouvons cette relation également pour tous les appendices étudiés. Nous supposons que chaque blessure ou régénération liée peut avoir un impact significatif sur les dommages ultérieurs, croissance et succès reproductif et peut résulter en la mort par cannibalisme.

In a Pinch: Mechanisms Behind Potential Biotic Resistance Toward Two Invasive Crayfish by Native African Freshwater Crabs

“…Potamonautes perlatus had stronger right chela, whereas C. quadricarinatus and P. clarkii had stronger left chela. As claw length was not an effective predictor of strength it suggests a degree of ambidexterity between left and right chelae in all of these species as a response to likelihood of losing chelae during agonistic bouts (Kouba et al, 2011;Lele and Pârvulescu, 2019). The lack of strong morphometric predictors reinforces the concept of dishonest signaling in crayfish species (Wilson et al, 2007;Malavé et al, 2018).…”

Predation impact of common backswimmer (Notonecta glaucaL.) on juvenile narrow-clawed crayfish (Astacus leptodactylusEsch.)

“…A similar effect was observed by Hirvonen (1992) in the case of the effect of N. lutea on P. leniusculus. The result of the loss of chelipeds is the need for regeneration, which has a negative effect on the growth, survival, and also later on the ability to reproduce (Hirvonen, 1992;Kouba, Bu ri c, Policar & Koz ak, 2011;Koz ak et al, 2015;Savolainen, Ruohonen & Railo, 2004). According to Stein and Magnuson (1976) crayfish try to avoid direct contact with predatory insects, or use their chelipeds to defend themselves.…”

Crayfish in central and southern Ukraine with special focus on populations of indigenous crayfish Astacus pachypus (Rathke, 1837) and their conservation needs

“…As well as crayfish CPUE, density and sex ratio, crayfish individual total length (TL) and body weight (W) were determined using a tape with 1 mm increments and an electronic scale Mettler (model AE 200) with an accuracy 0.01 g, following Policar et al (). Moult phase determined following Reynolds (), crayfish health condition (evidence of disease, ectoparasites or commensals on the body surface) following Kozubíková‐Balcarová and Horká () and chelae injuries following Kouba, Buřič, Policar, and Kozák () were recorded for all thick‐clawed crayfish captured in the survey and those caught by crayfishermen and confiscated by the local Kherson state fishing inspectorate.…”