MEPS 216:151-165 (2001)  -  doi:10.3354/meps216151

Influence of algal diet on growth and ingestion of Calanus helgolandicus nauplii

C. Rey1,*, R. Harris2, X. Irigoien2, R. Head2, F. Carlotti3

1Université P. et M. Curie (Paris VI), Station Zoologique, ESA 7076, CNRS/INSU, BP 28, 06230 Villefranche-sur-mer, France
2Plymouth Marine Laboratory, Prospect Place, West Hoe, Plymouth PL1 3DH, United Kingdom
3Laboratoire d'Océanographie Biologique, C.N.R.S./Université Bordeaux 1, UMR 5805, 2 rue du Professeur Jolyet, 33120 Arcachon, France

ABSTRACT: Nauplii of Calanus helgolandicus were raised from eggs, laid within a 12 h period, to Copepodite Stage I (CI) on 5 different species of algae at high concentrations at 15°C. The diets used were Isochrysis galbana (5 µm spherical diameter), Rhodomonas baltica (7 µm), the coccolithophorid Pleurochrysis carterae (12 µm), the diatom Thalassiosira weissflogii (14 µm) and the dinoflagellate Prorocentrum micans (30 µm). Each day a sample was taken and preserved for later cohort analysis. Growth was estimated from CHN samples collected almost daily, from which naupliar stages were also distinguished. Ingestion was measured for each naupliar feeding stage. The fastest development was obtained with I. galbana and P. micans. We found the highest value of carbon and nitrogen content of Naupliar Stages NV to CI for individuals reared on the smallest algae, I. galbana and R. baltica. However, ingestion rate in terms of carbon or nitrogen was lowest with these same (smallest) algae. Therefore, the gross growth efficiency was highest for the smallest algae. These results suggest the following: Firstly, that factors influencing development time and weight in stage are different; weight in stage is negatively related to algal size, whereas development time is independent of it. The quality of the algal biochemical components could be the factor influencing development. Secondly, that small algae are fully assimilated in the gut whereas larger cells, i.e. those with indigestible components around the cell (theca, frustule, calcium layer) are only partly assimilated.

KEY WORDS: Calanus helgolandicus · Nauplii · Growth · Development · Ingestion · Efficiency · Food quality

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