Combined effects of photoperiod and feeding frequency on survival and growth of juvenile cuttlefish Sepia officinalis L. in experimental rearing

The combined effects of photoperiod and feeding frequency on survival and growth of juvenile cuttlefish has been studied in experimental rearing. During juvenile cuttlefish growth, survival and growth rate were low when the photoperiod was short (8 h of light and 16 h of dark). Increased frequency of diet did not stimulate the appetite of animals reared in normal or long photoperiod (16 h of light and 8 h of dark). However, by studying the combined effects of photoperiod and feeding frequency, we have demonstrated that an increase in feeding frequency can enhance survival and growth in the group receiving the shortest period of light per day. Temperature is an important factor in the regulation of the incubation period of eggs and of growth after hatching, but it also appears in this investigation that the combined effect of photoperiod and feeding frequency must be considered during growth of juvenile cuttlefish

An examination of the role of the digestive gland of two loliginid squids, with respect to lipid: storage or excretion?

The role of the digestive gland, with respect to non-structural lipid, was examined using proximal analysis, histochemistry and quantitative histological techniques in the tropical loliginid squids Sepioteuthis lessoniana (Lesson) and Photololigo sp. The digestive gland of both species was characterized by large and numerous lipid droplets in the apical portion of the digestive cells and very few in the basal portion. The apical lipid droplets were released into the lumen of the gland and subsequently rapidly removed. Despite the numerous large apical lipid droplets, the lipid concentration in the digestive glands of S. lessoniana and Photololigo sp. was lower than that reported for most squid species. There was no relationship between lipid concentration and stage of digestion, suggesting that lipid is not stored in the gland after a meal. There was also no relationship between lipid concentration and the sex of an individual or stage of reproductive maturity, suggesting that these squids are not storing lipid in the digestive gland for use in fuelling reproductive maturation or providing an energy source for oocytes. I believe this study is the first to combine proximal analysis and quantitative histological techniques to examine the role of the squid digestive gland with respect to non-structural lipids. The results indicate that the digestive gland of these tropical loliginid squids is excreting, not storing, excess dietary lipid

Effect of enriched natural diet on survival and growth of juvenile cuttlefish Sepia officinalis L.

Juvenile cuttlefish hatched in the laboratory were reared for 30 days with different enriched diets, in spring and in summer. The groups fed an enriched natural diet exhibited a high rate of survival even when seawater quality decreased during the summer. The natural diet enriched in polyunsaturated fatty acids (PUFA) induced faster growth in juvenile cuttlefish; the stimulating effect of PUFA on growth was evident during the very early juvenile stage, and the benefit resulted is conserved during further growth. The maximum daily ration was lower in groups fed with the enriched diet than in the control. These data indicate the importance of n−3 PUFA such as docosahexaenoic acid (DHA; 22:6n−3) and eicosapentaenoic acid (EPA; 20:5n−3) in cephalopod juvenile nutrition

Peptidergic control of egg-laying in the cephalopod Sepia officinalis: involvement of FMRFamide and FMRFamide-related peptides.

International audienceThe peptidergic control of egg-laying was investigated in Sepia officinalis by using a myotropic bioassay. Three myotropic high-performance liquid chromatography fractions were obtained from optic lobe extracts. In the first fraction, FMRFamide (FMRFa) and FLRFa were isolated and sequenced. FMRFa-related peptides then were sought by dotting immunobinding of optic lobes extracts. The four immunoreactive fractions detected revealed the occurrence of FMRFa, FLRFa, FIRFa, and ALSGDAFLRFa predicted by the precursor already cloned from the optic lobes of S. officinalis (J Exp Biol 200:1483-9;1997). These peptides clearly appeared to be involved in the regulation of oocyte transport through the oviduct: the tetrapeptides FMRFa and FLRFa stimulated the contractions, whereas FIRFa and ALSGDAFLRFa lowered the tonus, the frequency, and the amplitude of the contractions. The occurrence of FaRPs in the nervous endings of the accessory sex glands suggested that this peptide family is involved in the regulation of secretory processes of the egg capsule. Indeed, FMRFa modulates the contractions of the main nidamental glands in vitro and, thus, should induce mechanical release of the secretion in vivo during ovulation. These results show that the FaRPs could play an important role in the synchronization of ovulation and egg capsule coating

Biochemical indices for instantaneous growth estimation in young cephalopod Sepia officinalisL.

Aspartate transcarbamylase (ATCase) activity was used to estimate instantaneous growth in young cuttlefish (Sepia officinalis) reared under different diet conditions, and compared with estimation obtained by RNA concentration. During the first month of life, the changes in ATCase activity and RNA content of muscle are related to growth. ATCase appears to be a good index of growth during the first stage of intense cell multiplication. ATCase activity is correlated to food intake up to a maximum ration, but decreases when animals are more than 40 days old. The approach of using ATCase activity as a biochemical index for estimating short-term change in growth rates of young cuttlefish in experimental rearing could be extended to young cephalopods collected in the field, and used to predict the effect of biotic factors in recruitment

Growth and proteolytic activity of Octopus vulgaris paralarvae with different food rations during first feeding, using Artemia nauplii and compound diets

18 pages, 4 figures, 3 tablesExperiments were conducted to investigate growth and proteolytic activity of the common octopus Octopus vulgaris, reared with different diets and ration levels during first feeding. Four ration levels were tested, 0.2, 2, 4 and 10 Artemia nauplii ml−1 day−1 and co-feeding techniques were tested using 10 Artemia nauplii ml−1 day−1 plus three different compound millicapsules. Total proteolytic activity, trypsin and chymotrypsin levels were recorded from eggs, hatchlings and during the first month of paralarval rearing. Five days after hatching, paralarval weight and proteolytic activity was dependent on food ration. The low-food treatment did not lead to an increase in hatchling weight, in contrast with the positive increase of the other treatments. After 20 days, best survival was observed in treatments fed 2 and 4 nauplii ml−1 day−1. High nauplii rations of 10 nauplii ml−1 day−1 plus millicapsule diet treatments produced higher growth and higher proteolytic, trypsin and chymotrypsin levels, but poor survival. Total proteolytic activity was correlated with paralarval weight, whereas trypsin and chymotrypsin were maintained at hatchling levels only for the high food and co-feeding treatments, and decreased in the others. The trypsin activity in the high-food treatment showed a sharp increase after 15 days and 880 μg of the mean dry weight (2.5 times hatchling weight). Millicapsules were ingested by the paralarvae after 5 days but did not lead to a significant increase in weight. Enriched Artemia nauplii seem to be useful only as an initial diet until a doubling in hatchling weight is achieved. This period can extend from 11 to 14 days at 20 °C, after which a larger prey and/or suitable microdiet is requiredThis study was funded by the Centre de Referència de Recerca i Desenvolupament en Aqüicultura, Generalitat de Catalunya and by the Planes Nacionales JACUMAR, Secretaría General de Pesca Marítima, SpainPeer reviewe