Effects of prehatching salinity and initial larval biomass on survival and duration of development in the zoea
1 of the estuarine crab, Chasmagnathus granulata.
Initial laboratory work on blue crabs indicated that zoea
larvae have a kinetic response to increasing hydrostatic pressure (harokinesis) regardless of developmental stage (Table 3).
Almost similar in shape to the previous stage; the anterior spine (5.81 mm) and the posteriors (3.53 mm) differing in spinulation equal than in Zoea
The effect of salinity on respiratory metabolism, survival and moulting in the first zoea
of Macrobrachium amazonicum (Heller) (Crustacea, Palaemonidae).
The first zoea
of three Pachygrapsus species and of Cataleptodiusfloridanus (Gibbes) from Bermuda and Mediterranean (Crustacea: Decapoda: Brachyura).
Similar relative digestibilities among the raw materials were observed among all larval stages (Z1-C), but they could be much better utilized at Mp and C stages than zoea
stages (Figure 4).
After hatching, the female crab was removed from the incubation tank, using a scoop net, and the aeration was turned off in order to settle down any debris to the bottom of the incubation tank, while the energetic zoea
remained active at the surface.
The survival rates at each of the five larval stages such as zoea
1 (Z1), zoea
2 (Z2), zoea
3 (Z3), zoea
4 (Z4) and megalopa (M) (identified as per Shinkarenko ) were calculated by daily random sampling (mortality due to any reason other than temperature or salinity variation is assumed to be the same in all the replicates of the values tested under each parameter).
The stage-1 zoea
(hatching stage) will not undergo its initial molt to the stage-2 (first feeding) zoea
until it reaches saline waters (Dugan et al., 1975; Jalihal et al., 1993; Bauer and Delahoussaye, 2008).
The eggs hatch into larvae called zoea
that spend about a month in the ocean as tiny swimming plankton.
of the dominant local blue crab (Callinectes bellicosus) are most abundant in the BMLC during August, when the vast numerical majority (89%) have been observed (Sanchez-Ortiz and Gomez-Gutierrez 1992).
These were taken using a Van Veen grab (30 and 3.5 L of capacity) from R/V Mytilus and its auxiliary boat Zoea
. Samples of the top surface centimetre were collected with a polyethylene spatula of 200 mL and stored in plastic flasks, which were stored in refrigerator at 4[degrees]C.