Variation in the tidal migratory behaviour and rhythmic light-responsiveness in the shore crab,Carcinus maenas

Abstract

The distribution of shore crabs, Carcinus maenas (L.), within the intertidal and shallow subtidal zones of a rocky shore in the Menai Strait, North Wales, was recorded regularly by diving throughout the tidal cycle. Samples were also obtained by searching the shore during low tide and by collecting crabs in baited pots. It was found that the smaller individuals (<35 mm carapace width) in the population tend to remain within the intertidal throughout the tidal cycle whilst others, mainly the red-coloured adults, appear to remain permanently below low-water mark. The remainder of the population, predominantly green males larger than 35 mm carapace width, migrate upshore with the flood tide and downshore again with the ebb. The behaviour of C. maenas on the shore appears to be affected, at least in part, by a tidally rhythmic pattern of responsiveness to directional light which is seen in freshly collected crabs in the laboratory.

Methyl farnesoate couples environmental changes to testicular development in the crabCarcinus maenas

“…As ESA increases MF levels, and MF treatment alone can stimulate testicular growth, it seems likely that MF couples ESA to gonad Finally, our present data show that environmental factors, such as temperature and salinity, can affect MF levels and thereby stimulate testicular growth. During the summer, green-phase animals are abundant in estuaries (Crothers, 1968; Hunter and Naylor, 1993;Warman et al, 1993), where the water is likely to be brackish and warmer. Thus, it seems likely that green-phase crabs will have a larger TI at the end of this season.…”

“…During the summer, green-phase animals are abundant in estuaries (Crothers, 1968;Hunter and Naylor, 1993;Warman et al, 1993), where the water is likely to be brackish and warmer. Thus, it seems likely that green-phase crabs will have a larger TI at the end of this season.…”

“…Red-phase animals tend to live in deeper water along open shores where the water is cooler and is closer to full-strength seawater. By contrast, green-phase crabs migrate into inlets and estuaries during high tide during the summer (Crothers, 1968;Hunter and Naylor, 1993;Warman et al, 1993). Thus, green-phase animals are more likely to experience higher water temperatures and brackish water during the summer compared with red-phase crabs.…”

Quantifying Tidal Movements of the Shore Crab Carcinus maenas on to Complex Epibenthic Bivalve Habitats

“…This resulted in negative estimates for the abundance on bivalve beds. One of the reasons for these negative abundance estimates is the behavior of juvenile crabs, which do not show tidal migration behavior and remain in the high intertidal zone (Crothers 1968;Hunter and Naylor 1993;Warman et al 1993). However, negative abundances were also observed for adult crabs.…”

“…It is native to coasts of Europe and North Africa and has successfully invaded many coastal areas worldwide (Carlton and Cohen 2003). While juvenile crabs remain in the high intertidal zone, with particularly high densities reported from complex biogenic structures like bivalve beds and seagrass meadows (Klein Breteler 1976a;Reise 1985;Thiel and Dernedde 1994;Moksnes 2002), adults tend to perform vertical tidal migrations, foraging in the intertidal during high tide and withdrawing to the subtidal zone during low tide (Crothers 1968;Hunter and Naylor 1993;Warman et al 1993). Shore crabs are opportunistic feeders, with a preference for molluscan prey (Ropes 1968;Elner 1981;Raffaelli et al 1989), and are capable of having drastic impacts on the stocks of commercial bivalve species (Ropes 1968;Walton et al 2002;Murray et al 2007).…”