Seasonal variations in length, dry weight, carbon and nitrogen of Calanus helgolandicus from the Celtic Sea

Bottrell, HH; Robins, DB

doi:10.3354/meps014259

Cited by 32 publications

(21 citation statements)

References 20 publications

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“…Our low concentration appears to be close to the limiting food concentrations encountered in the field since our estimates of length and weight correspond to the lower range of the values reported by Bottrell & Robins (1984) on field animals sampled in summer (temperature ~15°C) in the Celtic Sea. Some of the CIV, CV and adults of C. helgolandicus collected off Plymouth at a similar temperature were even smaller and lighter than those from our Cohort L (unpubl.…”

Section: Effects Of the Food Level On The Cohortmentioning

confidence: 66%

Growth and development of Calanus helgolandicus reared in the laboratory

Rey-Rassat¹,

Irigoien²,

Harris³

et al. 2002

Mar. Ecol. Prog. Ser.

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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 µg C l -1 , Cohort H) and low concentrations (77.5 µg C 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 (t ini ) 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. 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.

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Section: Effects Of the Food Level On The Cohortmentioning

confidence: 66%

Growth and development of Calanus helgolandicus reared in the laboratory

Rey-Rassat¹,

Irigoien²,

Harris³

et al. 2002

Mar. Ecol. Prog. Ser.

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“…However, seasonal studies have shown that large weight changes in a species through the year may only be reflected by very small prosome length changes (Bottrell & Robins 1984). Furthermore, relatively large changes in the body weights of individual copepods may accompany only small changes in body length , McKinnon 1996, and statistically significant changes in body carbon, nitrogen and dry weight may not accompany significant changes in prosome length (Thompson et al 1994).…”

Section: Recommendations For New Protocolsmentioning

confidence: 99%

Does egg production represent adult female copepod growth? A call to account for body weight changes

Hirst¹,

McKinnon²

2001

Mar. Ecol. Prog. Ser.

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An almost universal assumption in determining growth in copepods is that, over short periods, an individual adult female's net growth is equal to the amount of material expelled as eggs. This assumption relies upon adult body mass being in steady-state between the start and end of the same period. We explore different situations where this assumption is violated. Initially, concepts of how adult body weight and egg output are coupled over time are addressed. Using a refined concept of growth, we show that using typical 24 h incubation methods to measure egg output in sac spawners or broadcasters that produce clutches of eggs with a periodicity of >1 d may give correct mean population growth rates, but erroneous individual rates (including maximum and minimum individual growth, and measurements of individual variability such as coefficient of variation). Measurements derived from laboratory and field studies are then used to explore errors associated with the steady-state assumption. Decoupling of egg production from assimilation, and non-steady-state body weight in large lipid-storing higher-latitude species are relatively well documented, yet growth estimates allowing for such changes have almost never been made. Errors are not limited only to such species, however, and changing adult body weights can occur in small temperate and tropical species too. Body weight can increase or decrease whether or not eggs are exuded over the same period. The errors that can arise if we assume that the output of eggs by females equals their net growth rate are large and variable; in our compilation they range from -208% (i.e. egg output being 9.7% of body carbon weight per day, but adult carbon weight simultaneously declining by 13.7% d -1 ) to + 71% (i.e. egg output being 1.5% of body carbon weight per day, and adult carbon weight simultaneously increasing by 4.3% d -1). Using measurement of the natural variability in adult body weights, we determined that in order to be able to discriminate significant changes in body weight of 1 and 10% respectively, >1000 and <100 replicates are necessary, if applying typical sacrificial weighing methods. If we are to make accurate estimates of growth in adult copepods, then changes in body weight are of fundamental importance. We make initial recommendations for tackling these problems and reducing errors in the future KEY WORDS: Copepod · Egg production · Body weight · Net growthResale or republication not permitted without written consent of the publisher

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“…However, CIII, CIV, and CV are 3 1, 54, and 64% heavier than predicted by this line, as might be expected for these increasingly lipid-rich stages. Bottrell and Robins (1984) found in C. helgolandicus from the Celtic Sea that dry weight and cephalothorax length showed little or no correlation with food concentration, ingestion rate, population numbers, biomass, or temperature. They did, however, conclude that dry weights of C. paciJicus females (from Vidal 1980a,b), for food concentrations and temperatures in the Celtic Sea, gave predictions that were reasonably good for May through September, but poor for January through March.…”

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confidence: 90%