Changes in hemolymph lactate and ammonia in the hermit crab Pagurus samuelis (Stimpson, 1857) (Decapoda: Anomura: Paguridae) during shallow burial

Increased sedimentation in intertidal areas may stem from anthropogenic sources such as coastal development and natural processes, including discharges by rivers, landslides, and floods. Furthermore, global climate change could eventually lead to environmental hypoxia altering the composition of intertidal communities when hypoxia events surpass the physiological tolerance of intertidal organisms. We measured hemolymph lactate and ammonia (NH₃ and NH₄⁺) in the hermit crab Pagurus samuelis (Stimpson, 1857) subjected to shallow burial events and found high lactate and ammonia, indicating a switch to anaerobic respiration. The likelihood of hermit crabs dying during burial increased 31% for every 10 mM increase in lactate. Lactate levels were generally raised by increasing temperature, burial depth, or burial duration. At 20 °C and 30 °C, more lactate was detected at 3 cm and 6 cm burial depths than in the control (0 cm). Lactate concentrations were higher at 3 cm burial depth after 6 h than after 2 h. Lactate concentrations were higher at 20 °C and 30 °C than at 5 °C at both 3 cm and 6 cm. A 10 μg ml^-1 rise in ammonia concentration was associated with increased probability of death by 21%. Ammonia concentrations were higher at 3 cm than at 6 cm, indicating a shift in ammonia production or excretion at 6 cm. Burial time did not impact ammonia production. Large numbers of hermit crabs survived up to 24 h following lactate (92.9%) and ammonium salt (83.3%) injections. These results provide evidence that neither lactate nor ammonia buildup are principal causes of death following shallow burial.