Abstract
MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 238:125-138 (2002) - doi:10.3354/meps238125 Growth and development of Calanus helgolandicus reared in the laboratory Catherine Rey-Rassat1,*, Xabier Irigoien2,**, Roger Harris2, Robert Head2, François Carlotti3 1Université Pierre et Marie Curie (Paris VI), Station Zoologique, ESA 7076, CNRS/INSU, BP 28, 06230 Villefranche-sur-mer, France 2Plymouth Marine Laboratory, Prospect Place, Plymouth PL1 3DH, United Kingdom 3Laboratoire d¹Océanographie Biologique, CNRS, Université Bordeaux 1, UMR 5805, 2 rue du Professeur Jolyet, 33120 Arcachon, France *E-mail: catherinerey@aol.com or rey@obs-vlfr.fr **Present address: AZTI, Herrera Kaia portualdea z/g, 20110 Pasaia (Gipuzkoa), Spain ABSTRACT: Two Calanus helgolandicus cohorts were reared under laboratory conditions (150 l tanks) at 15°C with the dinoflagellate Prorocentrum micans as food, at high (278 µgC l-1, Cohort H) and low concentrations (77.5 µgC l-1, Cohort L), respectively. The study focused on the copepodite stages and for each stage, development time, total and structural growth rates, ingestion rate and gross growth efficiency were estimated. The growth rate of each stage was estimated using 2 methods, the classical one (Method I) and a new method (Method II), which considers the initial weight of the 2 successive stages rather than their mean weights. The initial weight corresponds to that estimated at the day (tini) when 50% of the individuals in the cohort entered the stage. Using the new method, the increase in lipid deposition through copepodite stages (increase of the C:N ratio from 4.3 up to 4.7 and 6.9 in Cohorts L and H, respectively) and the effect of food concentration on the growth rate from early CI to CV are clearly shown in the values of the growth rates (the CV growth rate in terms of carbon was 0.063 d-1 in Cohort L and 0.115 d-1 in Cohort H). Both of these features are not apparent for the key stage CV when using the classical method (0.041 d-1 in Cohort L and 0.035 d-1 in Cohort H). Female weight increase after moulting, by up to ~60% in Cohort L and ~40% in Cohort H, is also demonstrated by the new method. Using Method II on field data is however limited to some specific cases in which the cohort development is synchronous; this might be particularly the case for some large copepods. Food supply influences the development time of stages CIV and CV, and differences are also found in the development time of each stage indicating a non-isochronal development. Food concentration also influences the gross growth efficiency (GGE) of all copepodite stages, with significantly higher GGE at the low food concentration. GGE varies with stage, mostly at low food concentration (for GGE in terms of carbon: 0.135 to 0.502 in Cohort L and 0.147 to 0.308 in Cohort H). Finally, we propose an index that can be used to indicate the position of an individual within its stage. KEY WORDS: Calanus helgolandicus · Copepodite · Growth rate · Development · Ingestion · Efficiency · Food concentration · Method Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 238. Online publication date: August 08, 2002 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2002 Inter-Research.
Highlights
In marine ecosystems, copepods are a key component of the zooplankton community and an importantPasaia (Gipuzkoa), SpainMar Ecol Prog Ser 238: 125–138, 2002 e.g. temperature, food concentration, food quality, is often investigated (Peterson et al 1991, Hopcroft et al 1998b, Richardson & Verheye 1998, 1999, Calbet et al 2000)
Each copepodite stage of Cohort H would invest the same amount of food ingested in relation to their respective weight, for their growth. This is not the case in Cohort L, where the gross growth efficiency (GGE) is higher for copepodites CI to CIII, and there are important differences between stages. These results indicate that at low food concentrations early copepodites can somehow adjust their metabolism to reduce the consequences of food limitation, whereas this ability seems to be reduced in Stages CIV and CV
This study provides detailed information on physiological parameters of 2 cohorts reared at different food levels, enabling us to test the impact of food concentration on these parameters: (1) Development times were not synchronous and were affected by the food concentration for Stages CIV and CV but not for the younger stages
Summary
Copepods are a key component of the zooplankton community and an importantPasaia (Gipuzkoa), SpainMar Ecol Prog Ser 238: 125–138, 2002 e.g. temperature, food concentration, food quality, is often investigated (Peterson et al 1991, Hopcroft et al 1998b, Richardson & Verheye 1998, 1999, Calbet et al 2000). Several mathematical models coupling growth and development have pointed out the contribution of growth within stage to population production (Carlotti & Sciandra 1989, Carlotti & Nival 1992a, Miller & Tande 1993). These models showed that the growth curve built from averaged weights within stage did not represent the optimal growth curve due to laggards (Carlotti & Sciandra 1989, their Fig. 4, Carlotti & Nival 1992a, their Fig. 8). The estimation of growth greatly depends on the weight used for the calculation, on the sampling strategy to obtain these values
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