Influence of limited food supply on growth and elemental composition (C, N, H) of Carcinus maenas (Decapoda) larvae, reared in the laboratory

Abstract

Zoea 1 larvae of Carcinus maenas L. (Decapoda, Brachyura, Portunidae) were reared in the laboratory through ecdysis at 18OC. Dry weight (DW) and elemental contents of carbon (C), nitrogen (N), and hydrogen (H) were analyzed in newly hatched Zoea 1, after different inihal feeding periods, and in newly moulted Zoea 2. If food was continuously available, Zoea 1 larvae revealed considerable growth through the moult cycle, and biomass slightly declined shortly before ecdysis. Changing biomass and energy show best fits to quadratic equations with time. Gain at times of maximum biomass has been defined as maximum growth (MG; Dawirs et al. 1986). which was attained with 60 % DW, 71 % C, 52 % N, 89 % H, and 73 % energy. Zoea 1 larvae lost considerable amounts of biomass and energy whenever food supply was interrupted. Biomass of newly moulted Zoea 2 is llnearly correlated with feeding periods in Zoea 1, showing hgher values the longer initial feeding lasted. The point-of-reserve-saturation (PRS) was reached at the transition of intermoult to premoult, when about 80 % of MG was attained. If food supply ceased after this point, newly moulted Zoea 2 exhibited, at the most, 33 % DW. 40 % C. 31 % N. and 41 % J ind-l less than their continuously fed siblings. Growing Zoea 1 gained C at higher rates than N. During periods of subsequent starvation C decreased at higher rates than N. Lipid is assumed to be the main source of energy, which controls the maintenance of the moult cycle and further development through periods of occasional starvation.