Larval behavior and dispersal mechanisms in shore crab larvae (Carcinus maenas): Local adaptations to different tidal environments?

Abstract

Using a combination of empirical and model studies we tested whether European shore crab larvae (Carcinus maenas) from environments with different tidal regimes in the North Sea area have different swimming behaviors, and whether this affects connectivity and settlement success of larvae. Laboratory studies demonstrated the presence of an inherited tidal migration rhythm in newly hatched crab larvae from the mesotidal Danish Wadden Sea, and field studies showed that postlarvae swam in surface water almost exclusively during flood tides, suggesting that larvae use selective tidal stream transport to control the dispersal process. In contrast, shore crab larvae from microtidal Skagerrak displayed a nocturnal vertical migration behavior that appeared to switch to a diurnal behavior at the end of the postlarval phase, indicating an adaptation to avoid visual predators and to use wind‐driven transport to reach shallow settlement areas. A biophysical model showed that tidal‐migrating larvae in the Wadden Sea had two times higher settlement success than larvae with a diel behavior. However, no differences in settlement success were found between the two larval behaviors in microtidal Skagerrak, where lower fitness is suggested for tidal‐migrating larvae due to higher predation mortality from visual predators. We suggest that the differences in inherited larval behavior in larvae from meso‐ and microtidal regions reflect local adaptations maintained through natural selection of successful recruits. Consistent with recent population genetic studies, modeled connectivity of shore crabs indicated an oceanographic dispersal barrier to gene flow in Eastern Wadden Sea that may facilitate such adaptations.

Larval Behavior and Longevity in the Cold-Water Coral Lophelia pertusa Indicate Potential for Long Distance Dispersal

“…While rapid progress is being made considering biophysical modeling, the biological data to accommodate these models are largely lacking (Davies and Guinotte, 2011;Hilário et al, 2015;Treml et al, 2015). Besides the importance of ocean currents and hydrodynamics at different scales, the species' life history traits and larval behavior significantly affect dispersal direction and distance (Shanks, 2009), and it is increasingly recognized that hydrodynamic models must include intrinsic larval properties and behavior to successfully predict dispersal routes and population connectivity (e.g., Siegel et al, 2003;Aiken et al, 2007;Cowen and Sponaugle, 2009;Moksnes et al, 2014;Fox et al, 2016). For deep-sea organisms, this knowledge is particularly challenging to obtain and biological data are scarce (Hilário et al, 2015).…”

“…For dispersal distance, PLD was most important. The vertical positioning of larvae in the water column critically affects both dispersal distance and connectivity (e.g., Fiksen et al, 2007;Paris et al, 2007;Corell et al, 2012;Moksnes et al, 2014;Fox et al, 2016), and for deep-sea organisms the effect of being transported in the surface layer compared to deeper layers can be dramatic (Fox et al, 2016).…”

Biogeographic, ontogenetic, and environmental variability in larval behaviour of American lobster Homarus americanus

“…Vertical swimming that places larvae in specific flow conditions (e.g. selective tidal stream transport; Miller & Morgan 2013, Moksnes et al 2014 or at different positions in the water column as a function of time of day (Cowen et al 2006), and/or ontogeny (Butler et al 2011), can strongly influence horizontal transport. Vertical swimming by meroplankton can therefore influence horizontal transport by exposing larvae to heterogeneous physical flow environments (Queiroga & Blanton 2005, Fiksen et al 2007, Leis 2007, Cowen & Sponaugle 2009) and temperatures, thus influencing both dispersal and development.…”

“…Larval fish studies link variability in swimming to latitudinal gradients among species (Leis et al 2013), but intra-specific variation in response to different environments remains unresolved (but see Guan et al 2008). Observations of larval shore crabs highlight intra-specific variation in swimming behaviour among different coastal (Pachygrapsus crassipes Miller & Morgan 2013) and tidal environments (Carcinus maenas Moksnes et al 2014), highlighting potential influence of intra-specific variation in behaviour on larval transport trajectories. For species with pelagic durations that span weeks to months, population differences in behaviour and dispersal can lead to genetic differences (Bertness & Gaines 1993, Stobutzki 1998) and potentially to local adaptation (Yamahira & Conover 2002, Moksnes et al 2014.…”

“…Observations of larval shore crabs highlight intra-specific variation in swimming behaviour among different coastal (Pachygrapsus crassipes Miller & Morgan 2013) and tidal environments (Carcinus maenas Moksnes et al 2014), highlighting potential influence of intra-specific variation in behaviour on larval transport trajectories. For species with pelagic durations that span weeks to months, population differences in behaviour and dispersal can lead to genetic differences (Bertness & Gaines 1993, Stobutzki 1998) and potentially to local adaptation (Yamahira & Conover 2002, Moksnes et al 2014. For example, variation in larval green crab (C. maenas) dispersal has been linked to heritability of migration rhythm within the context of variable tidal flow (Zeng & Naylor 1996a,b).…”