Effects of temperature increase on the physiology and behavior of fiddler crabs

• Autor(a) principal: Vianna, Brunna da Silva [UNESP]
• Data de Publicação: 2020
• Outros Autores: Miyai, Caio Akira [UNESP], Augusto, Alessandra [UNESP], Costa, Tânia Marcia [UNESP]
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional da UNESP
• Texto Completo: http://dx.doi.org/10.1016/j.physbeh.2019.112765; http://hdl.handle.net/11449/199849
• topic: Climate warming; Ecophysiology; Leptuca spp.; Microhabitat selection; Thermoregulatory behavior; Waving display

Intertidal organisms rely on physiological and behavioral adjustments to maintain homeostasis under warm exposure. We examined the effects of the temperature increase related to climate warming on the physiology and behavior of two fiddler crab species: Leptuca uruguayensis, which inhabits mostly vegetated areas, and Leptuca leptodactyla, that inhabits unvegetated areas. We hypothesized that L. uruguayensis would be more sensitive to warming than L. leptodactyla. Crabs were exposed to different temperatures: 27 °C (control), 31 and 33 °C (+4 and +6 °C, respectively) for 15 days to evaluate their physiological responses (oxygen consumption, Q10, ammonia excretion and hepatosomatic index) and for 2 days to observe their behavioral responses (feeding rate and duration of burrow retreat). We also tested in situ the effect of air, surface, and body temperatures on the claw-waving display of both species. We found that species were affected differently by increasing temperature. Leptuca uruguayensis showed adaptation limit (Q10 <1), increasing oxygen consumption. Also, in comparison with control, L. uruguayensis decreased the ammonia excretion at 31 °C, but not at 33 °C, indicating a compensatory mechanism to cope with thermal stress. In contrast, L. leptodactyla was able to adjust its metabolic rate to temperature rise (Q10 ~3) and reduce ammonia excretion, suggesting changes in the energetic substrate and amino acid catabolism. Higher temperatures reduce the hepatosomatic index of both species, indicating increased use of energy reserve (although only the L. uruguayensis feeding rate was reduced). Furthermore, warmer temperatures increase the duration of burrow retreat in both species, potentially impacting social interactions, such as mating. Temperature increase did not affect the claw-waving display frequency, suggesting that other factors may affect this behavior, e.g., the presence of females and competitors. Specific behavioral (e.g., microhabitat selection) and morphological attributes (e.g., larger major claw) might benefit the thermoregulation of each crab species since no differences in body temperature were found between them in situ. Therefore, fiddler crabs that inhabit vegetated areas are more vulnerable to higher temperatures and may change its geographic range as a result of climate warming, while fiddler crabs that inhabit unvegetated areas are more tolerant to temperature rise and may have a competitive advantage under a temperature increase scenario.