Bg. Stevens et J. Kittaka, POSTLARVAL SETTLING BEHAVIOR, SUBSTRATE PREFERENCE, AND TIME TO METAMORPHOSIS FOR RED KING CRAB PARALITHODES CAMTSCHATICUS, Marine ecology. Progress series, 167, 1998, pp. 197-206
Swimming behavior was observed and substrate preference determined for
glaucothoe stage postlarvae of the red king crab Paralithodes camtsch
aticus in the laboratory. One hundred 1 d old glaucothoe were placed i
nto each of 3 replicate 10 l aquaria, each containing a choice of 3 su
bstrates: sand. gravel, or synthetic fiber mesh. Glaucothoe began sett
ling on the first day, and <10% remained swimming after Day 6. Glaucot
hoe showed a significant preference for the structurally complex mesh
substrate. Occupancy of mesh increased from 49% on Day 2 to 75% by met
amorphosis to the first crab (C1) instar, with a mean of 62 +/- 11%. G
laucothoe rejected sand, and only 1% were observed on it. Settlement w
as also tested in aquaria with only sand, gravel or mesh substrates. G
laucothoe in gravel- or mesh-only aquaria settled rapidly, whereas 40%
of glaucothoe in the sand-only aquarium continued swimming until meta
morphosis to C1 instar. In addition, mean time-to-metamorphosis in the
sand-only aquarium (17.6 d) was significantly greater than in other e
xperimental aquaria (16.8 d). Glaucothoe in the sand-only aquarium exh
ibited marked diurnal swimming behavior; 66% were swimming at 14:00 h
(vs a maximum of 12% in other aquaria), but only 5% (vs 1%) were swimm
ing at 02:00 h. Daytime swimming probably allows glaucothoe to avoid n
octurnal predators while searching for preferred substrates, i.e. thos
e which are structurally complex, can be easily grasped, and provide a
high degree of interstitial space.