The effect of somatic and gonadal size on the rate of oxygen consumption in the subantarctic echinoid Abatus cordatus (Echinodermata) from kerguelen

Camp. Biochem.

Physiol.

Vol. 9OA,No.

3, pp. 429434,

1988

0300-9629/88

Printed in Great Britain

$3.00 + 0.00

PcrganlonPressplc

THE EFFECT OF SOMATIC AND GONADAL SIZE ON THE RATE OF OXYGEN CONSUMPTION IN THE SUBANTARCTIC ECHINOID ABA TUS CORDATUS (ECHINODERMATA) FROM KERGUELEN PIERRE MAGNIEZ and JEAN-PIERRE F&AL* U.A. C.N.R.S. 699, Biologie des Invert&b&s Marins, M.N.H.N., 55 rue Buffon, F-75005 Paris, France (Received 9 November 1987)

Abstract-l. The rate of oxygen consumption of this burrowing spatangoid was measured for individuals ranging in size from 3-month old 25mm long juveniles to 39-mm long adults. 2. The decrease in the rate of oxygen consumption/dry weight with increasing body size is greater among mature adults than among juveniles because the increase in aerobic tissue (primarily the test) with body size is less than the increase in anaerobic tissues (mainly the gonads). 3. The rate of oxygen consumption/ash-free dry weight decreased more slowly with increasing body size because of the increase in the level of inorganic material. 4. Replacement of the common fresh weight or dry weight specific oxygen consumption by a more synthetic value calculated from ash-free dry weight specific oxygen consumption measurements, to annulate the body-size effect, is proposed for interspecific comparison over a wide range of body size, taking into account parameters such as temperature.

INTRODUCTION

In their review of echinoderm respiration, Lawrence and Lane (1982) compiled data for 123 echinoderm species including 36 echinoids. However, the relation between body size, or weight ( W) and respiratory rate V02 as indicated by values of b (1/O* = a Wb) is known for only nine species. Weight-specific VO, (30,) has been obtained for only a few Ophiuroidea and Holothurioidea (Lawrence and Lane, 1982; Shick, 1983). While data on oxygen uptake in echinoids dates back to the beginning of the century (Montuori, 1913) a discrepancy is apparent between the abundance of references to the body-size effect on oxygen uptake to account for comparison difficulties and the scant interest it has received so far, as a subject of investigation. Echoing these comments on echinoderms, Bayne et al. (1973) stressed that in respirometry measurements in mussels: “much of the variation of the literature is probably due to measurement of respiration rate over a too small range of animal sizes”. Guille and Lasserre (1979) stated that their data on oxygen consumption by Abatus cordutus needed allometric studies relating oxygen uptake to body size or weight, as generally done in respiratory physiology to be complete. The echinoid (Spatangoida, Schizasteridae) Abutus cordurus (Verrill, 1876) is a brooding species endemic to the Kerguelen

archipelago

(49”5O’S, 70’E) whose

embryological development is direct, without any remnant of larval stage or structure (Schatt, 1985a,b). A. cordatus is characterized by an annual reproductive cycle including an average brooding period of *Author to whom reprint requests should be sent. 429

8.5 months in the female marsupia followed by a recruitment period of a few weeks during which the 3-month old 2.5mm long juveniles, just released from the female marsupia, can easily be collected (Magniez, 1980a,b, 1983). The aim of this study is to take advantage of these biological particularities to encompass the widest size variation throughout the life of the echinoid from 3-month old juvenile to the largest available adult to investigate the relationship between size and oxygen consumption, along with its methodological implications. MATERIALS AND METHODS Collection and sampling

Individuals were collected from an intertidal sand flat of the “Halage des Swains”, a well sheltered bay of Kerguelen archipelago. During the recruitment period (December to January) 3-month old juveniles were found on the surface of the substratum. The adults were burrowed a few centimetres below the surface. Echinoids were kept in polyethylene tanks with sediment of the collecting site in running sea-water for 2 weeks prior to use. Potential sources of variation in respiratory activity were avoided by making all measurements within a period of 13 days to avoid extraneous (temperature) and intraneous (physiological state) variations. In addition, only males were used among adults. Measuring the VO, of females would have required removal of eggs and juveniles from the marsupia-a process that would have provoked considerable stress (Magniez, 1980a; Schatt, 1985a,b). Experimental measurements

Oxygen consumption rates were determined in closed respirometers with Clark-type oxygen electrodes: an oxygen detector (Orbisphere Laboratory, Geneva) with a built-in temperature probe and stirring device. The respirometer consisted of a base of Plexiglas mounted with a dome-

430

PIERRE MAGNIEZ and JEAN-PIERRE &AL

shaped lid fitted with ground-glass vents adjusted to the external diameter of the oxygen probe. Two models of glass lids were used, allowing for capacities of 87 and 324ml. Plastic and aluminium caps of various sizes were used to accommodate the echinoid and the surrounding sediment, while keeping sand volumes proportionate to the body size to minimize measurement errors. Perfect gas insulation was provided by greasing the base of the lid and the inside of the vent with Voltalef grease 90 (Ugine Kuhlmann). The oxygen electrode was coupled to a Ponselle recorder to produce a continuous print-out of the temperature in the respirometer and the oxygen depletion curve. Guille and Lasserre (1979) noted that A. eora’atus monitored in non-ecological conditions, without sediment, increased their YO, by approximately 30%, and when placed on the sediment, adults and subadults went through an acclimation period during which burrowing took place and VO, was higher than once settled in the sediment. Consequently, in the present study, to reduce stress and come closer to ecological conditions, only two groups of younger 3-month old juveniles were placed on the sediment, while all other indi~duals were gently burrowed in it. The container with the echinoid and the sediment was then placed in the respirometer and filtered air-saturated water was added. A running water system ensured control of the temperature at 9.0 & 0.5”C. After 30min the electrode was inserted and monitoring began. Experiments were continued for 45-90 min periods. The echinoid was then gently removed from the sediment, freshly filtered sea-water added and the oxidative activity of the sediment was monitored for an equivalent length of time. VO, measurements were obtained with the formula: YO, pl/hr = (overall VO, - sediment VO,) yl/ml/hr x water volume ml where overall YO, = (sediment + echinoid) I/O, and water volume = vessel capacity - (cap + sand volumes). Within the range of these experiments, from 10.3 to 6 ppm Or, the depletion curves obtained from oxidative activity of the sediment and echinoids are linear with individuals of all sizes. Oxygen consumption of seven adult males and five juveniles of both sexes were monitored individually while 12 3-month old juveniles were monitored in 2 groups of 8 and 4 individuals. Sizes of 3-month old juveniles were measured with a binocular microscope and micrometer, while sizes of other individuals were measured with precision calipers. Fresh weight (FW) of whole body (after being allowed to drain for 5min on paper towelhng), dry weight (DW) of body-wall, gonads and emptied gut after 24 hr at iOS”C, ash weight (giving ash-free dry weight: AFDW) after 48 hr at 500°C (Paine, 1971) were determined to the nearest 0.1 mg. Analysis of results

Shick (1983) pointed out the lack of data available for comparing oxygen uptakes in Echinodermata because results are us~lly expressed in terms of FW or DW and the levels of inorganic components may vary widely both interand intra-specifically. To overcome this difficulty, results of this study are expressed in two ways: in terms of DW to establish a common basis with most existing studies, and in terms of AFDW. To compare individuals differing in size and weight, the allometric model VO, = aW* is used, where VO, is the rate of oxygen consumption per unit time, W the body FW or DW, a is the level of metabolism per time and b, the regression coefficient which defines the rate of change of metabolism with body weight. The regression is carried out on the data after a double logarithmic transformation: log VOr = log a + b lag W.

However, the regression coefficients resulting from regression analysis cannot be validly used because VOZ and body weight variables are not normally distributed, even after logarithmic transformation. This non-normal distribution of the variables is directly linked to the sampling method taking both oldest (largest) and youngest individuals into account: indi~duals of intermediate sizes between the 3-month old juveniles and the estimated i5-month old juveniles are not available, producing a gap in the data distribution, This pattern will appear any time a population with an annual reproductive cycle and a limited recruiting period is studied over its complete size range. Such data can be treated with non-parametric tests, as r~ommend~ by Sokal and Rohlf (1981). This also precludes compa~ng regression lines with such methods as the analysis of covariance (ANCOVA) that is frequently applied to variables which do not have a normal distribution and which are often derived variables, such as weight-specific VO, (li0,). According to Sokal and Rohlf (1981), derived variables are usually non-normally distributed. As the regression coefftcient cannot be retied upon, linear regression is used here, not as a statistical test, but as a graphic aid to summarize the results, facilitate comparisons with other studies and to illustrate the comments on the Kendall correlation coefficient r. This efficient non-parametric test requires only ordinal measurements from the two variables, a realistic assessment in respirometry experiments.

RESULTS Oxygen consumption rates in Abatus cordatus increase with body weight (Tables 1 and 2). This increase in oxygen consumption is not proportional: from the average smallest juvenile (no.1) to the largest adult (no. 14) body FW, DW and AFDW increase 3384-, 2430- and 614-fold, respectively, while oxygen uptake increases only 123 times. As a consequence, oxygen consumption per unit wt for FW, DW and AFDW respectively are 21-, 20- and S-fold less in the largest adult than in the smallest average juvenile. As the values for body FW and DW are almost the same, only the latter is given here, its correlation values being slightly better. Plotted on a log-log scale, oxygen consumption rate and weight-specific oxygen consumption rate as functions of body DW and AFDW are linear (Fig. 1).

Oxygen c~ns~rn~ti#n per individual V02 increases markedly with body weight in juveniles and adults of both DW and AFDW groups (Fig. 1A and B). The slopes of the regression lines of adult populations are, respectively, 30 and 16% less than in

Table

1.Weights

(mg) width and height (mm) of f2 3-month-old juveniles monitored in two groups

NO.

wet wt

Dry wt

Length

Width

Height

I

6.1 8.1 6.3 7.0

1.9 2.5 2.6 2.6

2.25 2.55 2.40 2.48

2.25 2.25 2.10 2.18

1.50 1.I3 I .73 1.65

2

6.7 10.0 9.1 9.8 10.7 11.2 12.0 12.5

2.0 2.4 3.3 3.5 3.8 3.8 3.9 4.7

2.10 2.85 2.85 2.70 2.85 2.85 2.85 3.00

1.95 2.40 2.55 2.25 2.55 2.70 2.40 2.40

1.65

1.65 I .65

1.80 1.95 1.80 I .95

1.80

431

O2 consumption in Abutus Table 2. Weights (g), sizes (mm) and oxygen consumption (~O~:~i/hr) of 12 3-month old juveniles monitored in two groups (average data) and 12 older juveniles and adult males monitored individually No.

Wet wt

Dry wt

Ash-free dry wt

Length

Width

Height

1

0.0069 0.0103

0.0024 0.0034

0.0014 0.0017

0.242 0.276

0.220 0.240

0.165 0.178

0.0300 0.0585 0.0784 0.1046 0.1578

1.10 I .25

1.40 1.55 1.80

1.00 i.15 1.30 1.40 1.70

0.70 0.85 0.90 1.oo 1.10

17.4 34.6 35. I 45.6 51.4

0.2115 0.2798 0.3158 0.3974 0.3208 0.6231 0.8593

2.05 2.30 2.35 2.50 2.80 3.50 3.90

1.85 2.15 2.15 2.35 2.65 3.2.5 3.75

1.35 1.40 1.50 1.60 1.85 I .95 2.45

56.1 70.8 118.2 125.6 122.7 111.2 182.2

3-month juveniles

2

IS-month juveniles or older

3 4 S

0.46 0.75

6

1.oo 1.40

I

2.16

0.1098 0.2263 0.2176 0.3943 0.6591

8 9 10 I1 12 13 14

3.14 4.47 4.80 5.90 8.88 14.41 23.35

0.8313 1.3300 1.4400 1.8300 2.5690 4.4607 5.8324

Adult males

the case of the juveniles. ability is greater. Weight -specific

In adults, individual

vari-

oxygen consumption

In juveniles and adult males, there is a marked decrease in r’02 as body DW increases. The decrease

(r1.h

V02

-1

I .48

1.78

accelerates in adults with a steeper regression line (Fig. iC). In contrast, the decrease in 6’0, as a function of body AFDW is four times less (Fig. 1D). The decrease accelerates in the adult group, Individual variability in weight-specific oxygen consumption is greater among adults (Fig. IC and D).

V02

250-

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10050-

6

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5

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,,.f 500 1000

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Fig. 1. (A) Oxygen consumption rate (VO,) as a function of body DW (W) for juveniles (m) (log V02 = 0.663 log W - 0.088) and adult males (0) (log VOz= 0.462 log W + 0.488). (B) V02 as a fimction of body AFDW (W) for juveniles (m) (log V02 = 0.780 log W 4 0.075) and adult males (0) (log VO, = 0.655 log W -I-0.329). (C) Weight-s@flc oxygen consumption rate (30,) as a function of body DW (W) for juveniles (m) (log VO, = -0.337 log W+2.912) and adult males (0) (log PO,= -0.539log W + 3.490). (D) VO, as a function of body AFDW (W) for juveniles (m) (log PO* = -0.220 log W + 3.075) and adult males (0) (log PO* = -0.345 log W + 3.329).

432

PIERRE MAGNIEZ and JEAN-PIERRE FERAL Table 3. Values of Kendall coefficient (7) and associated values of level of significance (a) (in %), as a measure of correlation between YO, and body wt for juveniles, adult males and whole population sample (adults + juveniles) I’O, f(body

Correlation

between

Weight-specific YO, f(body wt)

wt)

Juveniles

Adult males

Whole samole

Juveniles

Adult males

Whole samnle

Wet wt

7 1

1.00 0.02

0.62 3.5

0.91 0.003

-0.90 0.14

-0.52 6.8

-0.85 0.003

Dry wt

T a

1.oo 0.02

0.62 3.5

0.91 0.003

- 1.00 0.02

-0.52 6.8

-0.87 0.003

Ash-free dry wt

T E

1.00 0.02

0.71 1.5

0.93 0.003

-0.90 0.14

-0.24 28. I

-0.76

VOZ and body weight

Table 3 sums up the results of the Kendall 7 coefficient of correlation between oxygen consumption and FW, DW and AFDW. As results from FW and DW data are almost identical, the latter being occasionally more significant, only DW and AFDW are commented upon. Whole sample data, significant in all cases at the tl = 5% level, are given as a reference to appreciate the relative weight of the juveniles and adult males population data. VO, f(body weight). The positive correlation z coefficient between VO, and body weight varies from 0.62 to 1 (Table 3). All results are highly significant, the significance levels varying from 3.5 to 0.003%. Juveniles have the strongest correlation coefficients. ri0, f(body weight). PO, and body weight are inversely correlated, values of 7 varying from -0.24 to - 1 (Table 3). For adult males, results are not significant at the tl = 5% level whereas the significance levels vary from 0.14 to 0.003% for other groups. Correlation coefficients for the relation between 30, and body weight are strongest among juveniles. VOZ and VO, are inversely related. Correlation coefficients and significance levels are generally better for VOZ calculated with AFDW, whereas the highest correlation coefficients and significance levels for VO, are obtained with DW.

DISCUSSION

Although echinoids, like other echinoderms, are aerobic organisms, they exhibit both aerobic and anaerobic metabolic pathways. Respiratory activity accounts for the main part of metabolic activity of echinoderm tissues, the proportion of energy production achieved by anaerobic metabolism being considered to be minimal. But this implies that respiration rate is not a complete indication of the total metabolic activity of echinoderm tissues (Ellington, 1982; Lawrence and Lane, 1982; Shick, 1983). Variation of VO, with somatic and gonadal size

The inverse correlation

between body weight and

VOZ is not constant over the entire range of body size of Abatus cordatus. The correlation is strongest in

juveniles that invest most energetic surplus in growth once the energetic need for maintenance is met.

0.011

In contrast, the correlation, although still significant, is much less among adult males whose energetic surplus is used for both overall and gonadal growth. This points to the possibility of individual variation in adult males in the use of nutrients for overall and gonadal growth resulting in a weaker correlation between body weight and V02. On the other hand, adult male organ indices (% AFDW) during reproductive cycle (Magniez, 1983) show yearly averages of organ indices for body-wall, gut and testis of 81, 11.2 and 7.8%, respectively, while their corresponding standard deviations (SD) represent 3.1, 15.2 and 30.4% of the organ indices. The highest variability is found in testis indices which are twice as variable as corresponding gut indices which means that testis weight is not strongly related to total weight. As the average gonad index is far less dependent on total weight than body-wall and gut indices, it must be concluded that mean annual gonadal weight is partially independent of general growth. One can assume this to be the origin of the differences between the very strong correlation coefficients of juvenile samples and the moderate corresponding values of adult male samples (Table 3). The fact that energy surplus available for nongonadal growth in juveniles is also needed for cyclic gonadal growth in sexually active males, thus reducing the amount available for general growth, is expressed by the slope decrease between the regression lines of juveniles and adult male populations (Fig. 1A and B). The decrease in correlation between body wt and V02 from juveniles to sexually active males can be attributed to individual variations among males in the proportions of nutrients devoted to non-gonadal and gonadal growths. No data exist for the oxygen uptake of adult female A. cordatus but data on adult female organ indices (% AFDW) during reproductive cycle (Magniez 1983) show an even stronger variability of mean gonadal index-with an average SD of 33.5% of the mean ovarian index-than among males. This, combined with the fact that standard female (1 g AFDW) spawn energy output (228 cal) is higher than the male one (200cal; Magniez, 1983) suggests that conclusions concerning the male population can probably be applied to females. Concerning the individual variations of energy amounts devoted to general and gonadal growth, the female population can reasonably be expected to show at least as much individual variability as the male population.

433

0, consumption in Abotus This variability in the distribution of nutrients between the non-gonadal and gonadal growths within the same population of A. cordatus points to the difficulty in interpreting the data on oxygen uptake and nutrition in adult echinoids and the un~rtainties of compa~son between species. Investigating methods should be modified accordingly. Whenever the energetic metabolism of adult population is studied, juveniles should be studied systenzatically as a control group even if it is accepted that the reproductive condition has no effect on respiratory rates in echinoids (Lawrence and Lane, 1982). Weight -speezjk V02 PO2 is more strongly related to DW than to AFDW (Table 3), as indicated by the reduced slopes of Fig. 1D compared to Fig. 1C. This does not mean DW measurements are more valuable than AFDW but merely illustrates the increase in ash content as the echinoid gets older. Analysis of the data of Table 2 gives a proportion of ash material of 47, 74 and 84% DW for 3-month old juveniles, older juveniles and adults, respectively. The higher variation range of the VO, per unit DW results in a stronger correlation This pattern can be expected in all species where the amount of metabolically inert tissue increases with age and size as Webster and Giese (1975) found for Strongylocentrotuspurpuratus, a conclusion that Lawrence and Lane (1982) extended to all echinoderms. The Kendall coefficient for PO, for FW, DW and AFDW is equal for DW juveniles but is systematically weaker for juveniles and adult males than the same correlation coefficient on VO,. It is the same if the whole sample (juveniles + adults) is considered. AFDW PO2 is none-the-less the most useful expression of results for inter- and intra-specific comparisons. Comparisons of respiratory rates not based on organic (ahs-free) material or nitrogen is difficult because of the variable level of inorganic material present (Lawrence and Lane, 1982). Its lower correlation coefficient is explained by its effectiveness in reducing the variation of VO, due to the mass effect of living tissues, revealing more individual variability (Table 3; Fig. 1D). If the correlation is weakest, it is still negative and signi~cant at the a = 5% level in juveniles and whole sample, meaning that the “bulk” effect of body mass is still present after transformation. If it were not, the slope of the regression line would be null and the value of t would be near zero. Inler -specific co~par~on

The lack of a standard method to express results independently of body size effects has deprived researchers of a common basis for wide inter-specific comparisons such as the effect of the mode of life and latitude, and thus temperature, on oxygen consumption. in some comparative studies taking into account a few species represented by population samples with size ranges that are somewhat equivalent, the effect of body size on PO, is not neutralized but equally present in the resulting figures. This allows for comparisons as in a study on respiration in tropical echinoids by Lewis (1968) who demonstrated

differences between oxygen consumption rates of burrowing irregular urchins and regular epifaunal species. As can be seen in Fig. 3 of the paper of Guille and Lasserre (1979), when plotting the results of the present study, the spectrum is very wide compared to available data on 22 other polar, temperate and tropical urchins. From 32 measurements concerning these species, three out of four fall into the limits range of the present study (FW PO, = 214.5 to 7.7 ~1 OZ/g/hr). Such a range of variability obtained through a limited number of measurements in a short period of time in a single population, underlines the need for standard statistical method to characterize VO, for juvenile and adult populations while eliminating the body-size effect. The common use of VO,, either measured in FW or DW, is too simplistic, allowing comparisons between adults of one species with adults of another IO-fold bigger or, within a common size range between juveniles of one species and adults of another. Using such data led to negative conclusions concerning the relationship between latitude and the respiratory rate of echinoderms on the one hand and between epifaunal species and burrowing ones on the other: after studying FW PO, in nine species of temperate and tropical echinoids Webster (1975) estimates there is no such relation while Lawrence and Lane (1982) conclude from their review (of 123 echinoderm species) that the necessary adaptions have occurred, allowing for the appropriate rate of utilization of nutrients over the entire range of temperature at which ~hinode~s are found (ca -2 to 35°C). The relation between temperature and oxygen consumption has been demonstrated, using multivariate analysis (Feral and Magniez, in press). Although this method may be considered as very efficient, it does not resolve the problem of inter-specific comparisons because, for a given temperature, it is not possible to distinguish clearly the species from each other. The projected points representing the individuals of different sizes of one species can be mixed with those of another species. A mode of expression of the results, independent of size, is needed. Replacement of the common FW or DW 30, by a more synthetic value calculated from AFDW 1’4 measurements to annulate completely the body-size effect, along with the distinction between juvenile and adult samples of the population, could renew the interest in comparative studies in echinoderms both inter- and intra-specifically, and bring more positive results. Acknowledgements-This work was supported by the Mission de Recherche des Terms Australes et Antarctiques Franqises (programme “Benthos”; A. Guille, Scientific Director). We thank M. Van Beveren for technical assistance. We are indebted to Prof. J. M. Lawrence for stimulating discussions and for improving the English of the text.

REFERENCES Bayne B. N., Thompson R. J. and Widdows J. (1973) Some effects of temperature and food on the rate of oxygen consumption by Mytilus edulis L. In Ef/ects of Tem-

434

PIERRE

MAGN~EZand JEAN-PIERREF~CRAL

perature

on Ectothermic Organisms (Edited by Wieser W.), pp. 181-192. Springer-Verlag, Berlin. Ellington W. R. (1982) Intermediary metabolism. In Echinoderm Nutrition (Edited bv Jannoux M. and Lawrence J. M.), pp, 395-415. Balkema, R\tterdam. Feral J.-P. and P. Magniez (1988) Relationship between rates of oxygen ~nsumption and somatic and gonadal size in the subantarctic echinoid Abatus coraktus from Kerguelen. In Proc. 6th Znt. Echinoderm Con& Victoria B.C. (Edited by Burke R. D., Mladenov P. V., Lambert P. and Prasley R. L.). Balkema, Rotterdam. Guille A. et Lasserre P. (1979) Consommation d’oxygbne de l’oursin Abatus cordatus (Verrill) et activite oxydative de son biotope aux iles Kerguelen. M&r. Mus. natn. H&t. nat. Paris, N.S. 43, 21 I-219.

Lawrence J. M. and Lane J. M. (1982) The utilization of nutrients by post-metamorphic echinoderms. In Echinoderm nutrition (Edited by Jangoux M. and Lawrence J. M.), pp. 331-371. Balkema, Rotterdam. Lewis J. B. (1968) Comparative respiration of tropical Echinoids. Camp. Biochem. Physioi. 24, 649-652. Magniez P. (1980a) Le cycle sexuel d’dbatus cordatus (Echinoidea: Spantangoida): modalites d’incubation et evolution histologique et biochimique des gonades. These de doctorat 3e cycle, univ. Paris-6, 82 pp. Magniez P. (1980b) Modalite’ de l’incubation chez Abatus cordatus. oursin endemiaue des Iles Kerguelen. In Echinoderms: Present and Pas;, Proc. Europ-Col. on Echinoderms, Brussels (Edited by Jangoux M.), pp. 399403. Balkema, Rotterdam. Magniez P. (1983) Reproductive cycle of the brooding

echinoid Abatus cordatus (Echinodermata) in Kerguelen (Antarctic Ocean): changes in the organ indices, biochemical composition and caloric contents of the gonads. Mar. Biol. 74, 55-64. Montuori A. (1913) Les processus oxydatifs chez les animaux marins en rapport avec la loi de superflcie. Archs ital. Biol. 59, 213234. Paine R. T. (1971) The measurement and application of the calorie to ecological problems. Ann. Rev. Ecol. Syst. 2, 1455164. Schatt Ph. (198Sa) Developpement et croissance embryonnaire de l’oursin incubant Abatus cordatus (Echinoidea: Spatangoida). These de doctorat de l’universite Paris-6, 151 pp. Schatt Ph. (1985b) L’edification de la face orale au tours du dheloppement direct de Abatus cordatus, oursin incubant subantarctique. In Proc. 5th Znt. Echinoderm Con& Galway (Edited by Keegan B. F. and O’Connor B. D. S.), pp. 339-345. Balkema, Rotterdam. Shick J. M. (1983) Respiratory gas exchange in Echinoderms. ~ch~noderm Studies 1, 61-l 10. Sokal R. R. and Rohlf F. J. (1981)Biomefry, the PrirtcipZes and Practice of Statistics in Biological Research, 859 pp. W. H. Freeman, San Francisco. Webster S. K. (1975)Oxygen consumption in Echinoderms from several geographical locations, with particular reference to the Echinoidea. Biol. BUN.. Woods Hole 148. 157-164. Webster S. K. and Giese A. C. (1975) Oxygen consumption of the purple sea urchin with special reference to the reproductive cycle. Biol. Bull., Woods Hole 148, 165- 180.