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- Title
Settlement behavior of the megalopa and the early juveniles of Portunus trituberculatus (Miers, 1876) (Brachyura: Portunidae) under laboratory conditions.
- Authors
Satoshi Takeshima; Shigeki Dan; Takaaki Kaneko; Masakazu Ashidate; Katsuyuki Hamasaki
- Abstract
Megalopae and early juveniles of Portunus trituberculatus (Miers, 1876), a commercially important species, are known to utilize drifting seaweeds before transition to benthic habitats, but little is understood about this settlement behavior. Clinging and burying behavior of P. trituberculatus was investigated during nighttime and daylight by culturing megalopae and first to fifth crab stages in tanks with different bottom substrates (polyethylene, gravel, or sand) and an attachment substrate (artificial seaweed) in the water column. Clinging behavior on the artificial seaweed was observed for all growth stages. The proportions of individuals that exhibited clinging behavior increased from megalopae to the first crab stage, peaked in second and third crab stages, and declined through the fourth and fifth crab stages in all treatment groups. The proportion of crab stages that buried in the substrate was much higher in daytime than in nighttime (P < 0.001). For daytime observations, the burying rates linearly increased from first or second to fifth crab stages and were higher in tanks provided with sand as opposed to gravel. Our results suggest that early juvenile crabs utilize drifting seaweeds as a vehicle, and they voluntarily shift to benthos after the fourth crab stage when the risk of predation is reduced, as first to third crab stages are known to be vulnerable to predation by benthic fishes. The juveniles of P. trituberculatus thus appear to "hitchhike" drifting seaweeds before final settlement on the bottom. The present study supports the idea that hitchhiking behavior could be an important transport mechanism leading to settlement by larval and juvenile stages in decapod crustaceans.
- Subjects
CRAB fisheries; MARINE algae as feed; CRAB ecology; CRAB culture; BENTHIC ecology
- Publication
Journal of Crustacean Biology, 2017, Vol 37, Issue 6, p667
- ISSN
0278-0372
- Publication type
Article
- DOI
10.1093/jcbiol/rux086