Habitat structure influences the survival and predator–prey interactions of early juvenile red king crab Paralithodes camtschaticus

Abstract

Highly structured nursery habitats promote the survival of juvenile stages of many species by providing foraging opportunities and refuge from predators. Through integrated laboratory and field experiments, we demonstrate that nursery habitat structure affects survival and predator-prey interactions of red king crab Paralithodes camtschaticus. Crabs (< 1 yr old [Age 0]; 8 to 10 mm carapace length [CL]) preferred complex biogenic habitats formed by structural invertebrates and macroalgae over structural mimics and sand in the absence of predators in laboratory experiments, yet they associated with any available structural habitat when fish predators were present. Survival was higher in the presence of complex habitat for Age 0 crabs (5 to 7.5 mm CL) with Pacific cod Gadus macrocephalus predators in the laboratory and for Age 0 (4 to 8 mm CL) and Age 1 (16 to 28 mm CL) crabs with fish and invertebrate predators in the field. Crab activity and refuge response behavior varied with crab stage and habitat. Age 0 crabs were cryptic, avoiding predators by associating with habitat structure or remaining motionless in the absence of structure, and were less likely to respond to an attack. In contrast, Age 1 crabs were more likely to respond to an attacking predator and were less likely to remain motionless in the absence of structural refuge, suggesting an ontogenetic shift in behavior. Complex habitats, cryptic behavior, and direct defense improve juvenile red king crab survival against certain predators, including demersal fishes.

Effects of Ocean Acidification on Juvenile Red King Crab (Paralithodes camtschaticus) and Tanner Crab (Chionoecetes bairdi) Growth, Condition, Calcification, and Survival

“…Smaller crab are more vulnerable to predators [68] and do not satiate predators as quickly [29], and thus a decrease in growth rate is likely to reduce the survival of a cohort to maturity. Similarly, lower calcium content may make crabs easier prey for crushing predators.…”

Hide and seek: habitat-mediated interactions between European green crabs and native mud crabs in Atlantic Canada

“…A second mechanism to explain why juvenile green crab mortality levels were unaffected by habitat is the exact opposite; juvenile green crabs may lack the ability to effectively use complex habitat to escape predation. Long et al (2015) suggested that responding to predator presence by engaging in cryptic behavior (i.e., hiding in complex habitat) may be a learned behavior, and in some crab species, refuge-seeking behavior is known to develop with size and age (Johnson et al 2008;Stoner et al 2010;Pirtle et al 2012). Under this hypothesis, we might expect that 'naïve' juvenile mortality would indeed be similar across habitat types, while the mud crabs (already adults in our experiment) would be expected to be more experienced and have a greater affinity for hiding in complex environments.…”

Are fish associations with corals and sponges more than an affinity to structure? Evidence across two widely divergent ecosystems

“…However, the majority of studies examining mechanistic links for an association between structured habitats and demersal fish species have focused on their role as refuges from predation, especially for juvenile life history stages (Love et al 1991;Gotceitas et al 1995; Ryer D r a f t et al 2004;Auster 2005;Pirtle et al 2012). It is likely that multiple mechanisms may be resulting in observed associations between demersal fishes and structured habitat.…”