| 1. |
- Moksnes, Per-Olav, 1965, et al.
(författare)
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Larval behavior and dispersal mechanisms in shore crab larvae: Local adaptations to different tidal environments?
- 2014
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Ingår i: Limnology and Oceanography. - : Wiley. - 0024-3590. ; 59:2, s. 588-602
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Tidskriftsartikel (refereegranskat)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.
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| 2. |
- Moksnes, Per-Olav, et al.
(författare)
-
Larval behavior and dispersal mechanisms in shore crab larvae : Local adaptations to different tidal environments?
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Recent studies indicate that local adaptations may occur in marine populations over relatively small geographic areas despite high dispersal potential if strong environmental gradients are present. Here we assess if local adaptations in larval behavior can develop in response to tidal gradients by studying the shore crab Carcinus maenas in the North Sea area using a combination of empirical and model studies. Specific aims of the study was to assess if shore crab larvae from different tidal environments have different swimming behaviors, and if these behaviors affect connectivity and recruitment success of the larvae. Field and laboratory studies demonstrated that newly hatched shore crab larvae from mesotidal Danish Wadden Sea displayed an inherited vertical migration rhythm with a circatidal periodicity, and 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 switched to a diurnal behavior at the end of the larval phase, indicating an adaptation to avoid visual predators and to use wind-driven transport to reach shallow settlement areas. Results from a biophysical model showed that larval swimming behavior had a dominant role for the dispersal process and the recruitment success in the study area, and demonstrated that modeled tidal-migrating larvae in Wadden Sea had 2x higher recruitment success than larvae with a diel behavior. However, in microtidal Skagerrak no differences in recruitment success was found between the two larval behaviors. Lower fitness is suggested for tidal-migrating larvae in microtidal regions due to a predicted higher predation mortality. Consistent with recent population genetic studies, connectivity analyses indicated an oceanographic dispersal barrier in Eastern Wadden Sea that will restrict gene-flow between the two areas, and allow local adaptations in larval behavior.
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