Nutritional vulnerability of early zoea larvae of the crab Maja brachydactyla (Brachyura, Majidae)

Abstract

We investigated the nutritional vulnerability of Zoeae I of the spider crab Maja brachydactyla in experimental treatments with differential periods of starvation. As response variables, the moulting and survival rates, the point-of-reserve-saturation (PRS), the point-of-noreturn (PNR), dry mass, elemental composition (carbon, hydrogen, nitrogen; CHN), hepatopancreas lipid vacuoles and activities of digestive enzymes were measured. Average median time spans when 50% of the larvae reached PNR or PRS (PNR 50 and PRS 50 ) values were 2.8 and 1.9 d, respectively. In PNR treatments, complete mortality occurred only after extended initial starvation periods of ≥5 d, and in PRS treatments, Zoeae I were capable of completing the moulting cycle after a short initial feeding period (1 d). In continuously starved control larvae, the moulting cycle was arrested at the onset of apolysis. Concomitantly, considerable amounts of biomass were lost and the C:N ratio decreased, indicating lipid degradation during starvation. This effect was also microscopically visible as a decline of lipid vacuoles in the hepatopancreas. Feeding after previous starvation periods of < 7 d resulted in a re-establishment of the lipid vacuoles, indicating successful capture and ingestion of food, but this did not necessarily allow for completing the moulting cycle. In fed Zoea I larvae, digestive enzyme activities increased during the moulting cycle, while a significant decrease of enzyme activities occurred under starvation conditions. In newly moulted Zoeae II, biomass values and enzyme activities were linearly correlated with the duration of the feeding periods in Zoeae I. This study shows that biomass, elemental composition, the occurrence of lipid vacuoles in the hepatopancreas and activities of digestive enzymes are suitable indicators of the nutritional condition of early zoeal stages of M. brachydactyla.

Body size reduction under starvation, and the point of no return, in ephyrae of the moon jellyfish Aurelia aurita

“…Error bars = SD. D: initial starvation duration; DR: duration needed to reach advanced ephyra stage after feeding began the PNR 50 is, in general, much smaller in other taxa: 16% loss for Maja brachydactyla (Guerao et al 2012), 25 to 34% loss for Carcinus maenas (Dawirs 1987) and 21% loss for Hyas araneus (Anger & Da wirs 1982). However, the loss is exceptionally high (44 to 51%) for Euphausia superba (Ross & Quetin 1989).…”

Resistance to starvation of first-stage juveniles of the Caribbean spiny lobster

“…The D 0 threshold has been confirmed in early life stages of decapod crustaceans from different families, e.g., Crangonidae (Paschke et al, 2004), Diogenidae (Harms, 1992), Majidae (Figueiredo et al, 2008; Guerao et al, 2012), and Portunidae (Harms et al, 1990). In our study, results of both PRS experiments, with high mortality rates in individuals subjected to treatments F3, F6 and F9, and shorter intermolt periods and higher mortality rates than in PNR experiments, as well as the similarity in PRS 50 values between seasons (unlike in PNR 50 values), suggest that feeding in P. argus JIs is more important near the PRS (or D 0 threshold) than immediately after molting to the first-stage juvenile.…”

The complete life cycle in captivity of the spider crab,Maja brachydactyla,Herbst 1788

“…Biochemical composition of cultured zoeas was very similar to wild caught zoeas (Iglesias et al., ; Rotland, Guergo, Sastre & Anger, ). The relationship between the food and lipid reserves in zoeas was demonstrated showing that food limitation affected the lipid reserves stored in the digestive gland (Guerao, Simeó, Anger, Urzúa & Rotllant, ). The biochemical composition of cultured zoeas differed considerably from that of Artemia nauplii used to feed them.…”