Geographic distribution, seasonal life cycle, biomass and production of a planktonic copepod <i>Calarms sinicus</i> in the Inland Sea of Japan and its neighboring Pacific Ocean

The 'Moult Rate' (MR) method has been used widely to derive stage-specific growth rates in juvenile copepods. It is the most common field-based method. Unfortunately, the equation underlying the method is wrong and, consequently, large errors in juvenile growth rate estimates are widespread. The equation derives growth from the mean weight of 2 consecutive stages (i and i + 1) and the duration of stage i. The weight change and the period to which this change is attributed are, therefore, offset. We explore this potential source of error in the MR method critically. Errors arise as a result of 2 primary factors: (1) unequal durations of successive stages and (2) unequal rates of growth of successive stages. The method of deriving the mean weight (arithmetic or geometric) also has an impact and is examined. Using a steady-state assumption, a range of scenarios and the errors that arise are examined. The literature is then reviewed and the size of errors resulting from MR method application in both field and laboratory situations is estimated. Our results suggest that the MR method can lead to large errors in growth estimation in any stage, but some stages are particularly prone. Errors for the C5 stage are often large because the following stage (the adult) does not moult, and has a different rate of body weight increase. For the same reason, errors are also great where the following stage is not actively moulting (e.g. when diapausing). In these circumstances, published work has commonly greatly underestimated growth. For example, MR growth ranges from 11 to 47% of the value derived correctly for this stage, g i_corr (calculated assuming the non-moulting stage does not grow). In late stages that are followed by actively moulting stages, the MR method has commonly given values in excess of 150% of g i_corr , but underestimation also occurs, with values < 90% of g i_corr. We propose new methods and equations that overcome these problems. These equations are written with and without within-stage mortality included. The equations are relatively insensitive to mortality rates within the range found in the field, but only provided that the stage duration is not determined from moult rate. Stage duration estimates obtained from measuring moulting rates of field-collected animals are very sensitive to mortality rates of the animals prior to capture, and field mortality rates are often high enough to produce dramatic over-estimation of stage duration. KEY WORDS: Copepod · Moult Rate · Growth · Error · Stage duration · Mortality Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 296: [263][264][265][266][267][268][269][270][271][272][273][274][275][276][277][278][279] 2005 ondary production (the product of specific growth and biomass). This is why, over the last 3 decades, much effort has been expended in measuring near-natural rates of growth and development in copepods.Historically, the most common method for examining 'growth' in copepods has been through the mea...

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“…Burkill & Kendall 1982, Uye et al 1983, Kimoto et al 1986, Huang et al (1993, Kang & Kang 1998). Instead of the exponential form described in Eq.…”

Section: Resale or Republication Not Permitted Without Written Consenmentioning

confidence: 99%

Errors in juvenile copepod growth rate estimates are widespread: problems with the Moult Rate method

Hirst¹,

Peterson²,

Rothery³

2005

Mar. Ecol. Prog. Ser.

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“…Analysis of the monthly proportions of the various copepodite stages revealed that all stages occurred continuously, indicating that reproduction of the species takes place throughout the year. No diapausing CVs were found in the study area (Huang et al, 1993a). Effects of temperature, salinity, and depth on population size From zooplankton surveys conducted in different seasons and areas of the Inland Sea of Japan for two decades, a total of 374 data points on carbon biomass of Calanus sinicus has been accumulated.…”

Section: Geographical and Seasonal Distribution Across The Continentamentioning

confidence: 99%

“…Although some biological attributes (e.g. feeding, fecundity, development time, growth, diel vertical migration, spatio-temporal distribution, seasonal life cycle) of C. sinicus have been demonstrated in previous field and laboratory investigations (Uye, 1988(Uye, , 1994Uye et al, 1990aUye et al, , b, 1999Huang et al, 1992Huang et al, , 1993aUye and Yamamoto, 1995;Uye and Murase, 1997;Uye and Shimazu, 1997), little has been said about the maintenance mechanism of C. sinicus populations in shelf waters.…”

Section: Introductionmentioning

confidence: 99%

Why does Calanus sinicus prosper in the shelf ecosystem of the Northwest Pacific Ocean?

Uye

2000

ICES Journal of Marine Science

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“…), and Fleminger (1985) found the proportion of C. pacificus californicus quadritheks to vary from 11 to 7 % . C. sinicus (Huang et al 1993) have a continuous reproduction cycle and do not go into diapause, whereas a proportion of C. pacificus californicus does rest at these latitudes. However, in C. finmarchicus from the Greenland Sea, with a supposed annual generation (McLelland 1967, Hirche 1991, a proportion of 38% quadritheks was found in March, similar to observations in North Norwegian fjords.…”

Section: Distribution Of Quadrithek Femalesmentioning

confidence: 99%

Sex change and female dimorphism in Calanus finmarchicus

Svensen¹,

Tande²

1999

Mar. Ecol. Prog. Ser.

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ABSTRACT. Adult females were examined from November until spring in northern Norway (30" N) to determine the fraction with the quadrithek and the fraction with the trithek setal pattern on the antennule. The quadrithek (Q) pattern is a male characteristic in which odd numbered, proximal segments carry 2 aesthetascs and 2 setae; the trithek (T) pattern has 1 aesthetics on all antennular segments. The frequency of quadrithek females (%Q = 100 X [Q/T]) varied with season. It peaked at 38% in February, declining to 25 % in March. Higher proportions appeared early, consistently between years, i.e. higher proportions were found among the first females emerging from the stock of resting copepodids. In light of the hypothesis of Fleminger (1985; Mar Biol 88:273-294) that females w t h the quadrithek pattern result from sex switching by genetic males, we tested whether %Q in newly moulted females could be altered by separate exposure of the maturing CVs to adult males or females. The experiments were run with specimens from Gratsund during the last 3 wk prior to moulting of CVs in the field. Of females not exposed to adults as CVs, 35% had quadrithek patterns, while those exposed to adult males or females produced 33 and 37% quadritheks respectively. In these experiments, presence of adult Calanus finmarchicus (Gunnerus) did not influence the proportion of females with male characteristics. No evidence for sex specific pheromones was found and therefore the stimulus for sex change was not revealed. A possible influence of the environment on C. finmarchicus sex determination (ESD) is suggested and discussed.

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Geographic distribution, seasonal life cycle, biomass and production of a planktonic copepod Calarms sinicus in the Inland Sea of Japan and its neighboring Pacific Ocean

Cited by 48 publications

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Errors in juvenile copepod growth rate estimates are widespread: problems with the Moult Rate method

Errors in juvenile copepod growth rate estimates are widespread: problems with the Moult Rate method

Why does Calanus sinicus prosper in the shelf ecosystem of the Northwest Pacific Ocean?

Sex change and female dimorphism in Calanus finmarchicus

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