This article was downloaded by: [University of Illinois at Urbana-Champaign]On: 16 May 2013, At: 12:34Publisher: Taylor & FrancisInforma Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House,37-41 Mortimer Street, London W1T 3JH, UK

OpheliaPublication details, including instructions for authors and subscription information:http://www.tandfonline.com/loi/smar19

Pumping and oxygen cunsumption rates of Mytilusedulis L. of different sizesOla Vahl a ba Marine Biological Laboratory, DK-3000, Helsingør, Denmarkb Institute of Biology and Geology, Tromsø University, N-9001, Tromsø, NorwayPublished online: 20 Feb 2012.

To cite this article: Ola Vahl (1973): Pumping and oxygen cunsumption rates of Mytilus edulis L. of different sizes, Ophelia,12:1-2, 45-52

To link to this article: http://dx.doi.org/10.1080/00785326.1973.10430118

PLEASE SCROLL DOWN FOR ARTICLE

Full terms and conditions of use: http://www.tandfonline.com/page/terms-and-conditions

This article may be used for research, teaching, and private study purposes. Any substantial or systematicreproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form toanyone is expressly forbidden.

The publisher does not give any warranty express or implied or make any representation that the contentswill be complete or accurate or up to date. The accuracy of any instructions, formulae, and drug doses shouldbe independently verified with primary sources. The publisher shall not be liable for any loss, actions, claims,proceedings, demand, or costs or damages whatsoever or howsoever caused arising directly or indirectly inconnection with or arising out of the use of this material.

OPHELIA, 12: 45-52 (December 1973)

PUMPING AND OXYGEN CUNSUMPTION RATES

OF MYTILUS ED ULIS L. OF DIFFERENT SIZES

OLA VAHL

Marine Biological Laboratory, DK-3000 Hclsingar, Denmark.Present address: Institute of Biology and Geology, Tromsa University, N-9001 Tromsa, Norway

ABSTRACT

Pumping rate (P), oxygen uptake (R), gill area (A), and absorption efficiency (Ab) in Mytilusedulis have been studied. The parameters are expressed as functions of the dry weight of softparts (W) by a power function Y = aw> where Y is the dependent variable. It is found thaP = 3.90 ·Wo·601/hr, R = 0.37 ·WO. 75 ml 02/hr, A = 34.34 ·WO.65 em", Ab = 78.16 ·W-O.02 %,and P/R = 10.47·W-O.16 1 water pumped/nil 02 consumed. The gill area increases significantlyfaster with size than the pumping rate. The PjR ratio shows that the energy available for growthand reproduction decreases with increasing size as the absorption does not change significantlywith size. The effect of seasonal changes in P and R on the P/R ratio is discussed.

INTRODUCTION

As pointed out by Jorgensen (1952), great interest is attached to the relationshipbetween the rates of water transport and oxygen consumption in suspensionfeeding animals. The rate of water transport gives a measure of the animal'senergy input if the energy content of the water is known, whereas the oxygenuptake is a measure of the metabolic rate. Therefore, the ratio 1 water pumped/ml O2 consumed (Jergensen, 1952) gives an idea of the concentration of foodthat must be present in the inhalent water to meet the bivalve's requirements.Any surplus is available for growth and reproduction. Little is known, however,of the relation between this ratio and body size (see Jorgensen, 1960; p. 113-114).

The oxygen consumption, as a function of size in the suspension feeding bi­valve Mytilus edulis, has been studied by Kruger (1960). The pumping rate hasbeen measured by several authors by a variety of techniques (for references,see Ali, 1970). Nothing appears, however, to have been done on the size depen­dence of pumping rate.

Dow

nloa

ded

by [

Uni

vers

ity o

f Il

linoi

s at

Urb

ana-

Cha

mpa

ign]

at 1

2:34

16

May

201

3

46 OLA VAHL

MATERIAL AND METHODS

Specimens of Mytilus edulis were collected on 25. iv. 72 from a breakwater closeto Marine Biological Laboratory, Helsingar, in water of a salinity of 15.51'00and at l2.2°C. The mussels were taken to the laboratory and transferred to aclosed system of about 200 1 water (Fig. 1) which was placed in a constant tem­perature room at 10.±0.5°C. During the acclimation period (30 days) andexperiments the salinity was 21-231'00 and the oxygen saturation varied between98 and 100 %. Approximately t of the water was replaced every day. Duringthe acclimation period the mussels were fed twice a day. They were given a mix­ture of the flagellates Isochrysis galbana and Monochrysis lutheri in a ratio ofabout 1: 1 by number. Particles in the water were counted by a Coulter CounterModel B. The daily variation in the concentration of 4.8-7.3 fL particles wasusually from 1000 to 2500 particles/nil. In the pumping experiments the musselswere offered flagellate concentrations ranging from about 2000 to 6000 cells/ml.

Six identical troughs were used for measuring pumping rates. Five of themcontained mussels and the sixth was used as control. It has been shown thatthe flow rate influences the pumping rate (Walne, 1972). Therefore, for com­parative purposes, a standard flow rate must be chosen. 150 ml/min was usedin this study. This gives enough flow to prevent recirculation when large ani­mals are used. However, as the pumping rate is calculated as flow in 1 per hourX (1 - particles in mussel trough/particles in control), the difference betweenthe particle counts in the mussel trough and control will be insignificant whenonly one small animal is used. Therefore, for smaller mussels, several individuals,carefully matched for size, had to be used simultaneously. Particles of 4.8-7.3 fL

were counted as these sizes are 100 % retained by the Mytilus gill (Vahl, 1972a).To measure the oxygen consumption the mussels from each trough were placedin a glass stoppered bottle. The bottles (including a control) were immersedin the system (Fig. 1). An attempt was made to regulate the experimental timeso as to give a decrease in oxygen tension of 20 %, but actually the decreasevaried between 12 and 36 %.

The gill area of Mytilus of different sizes was measured on animals collected4. vii. 72. The gills were dissected out and their outline traced on paper using acamera lucida. The gill area was estimated from the weight of the paper enclosedby the drawings.

The absorption efficiency of food in Mytilus was measured by Connover's(1966) method which does not require a quantitative recovery of faeces. Theabsorption was measured on mussels feeding on the natural suspension in thehabitat. Mussels and a water sample from the habitat were collected simulta­neously. The animals were sorted into size classes and the different sizes wereplaced in separate aquaria within an hour of collection. The suspended parti­culate matter in the water sample was analyzed for the ash and ash-free dry

Dow

nloa

ded

by [

Uni

vers

ity o

f Il

linoi

s at

Urb

ana-

Cha

mpa

ign]

at 1

2:34

16

May

201

3

OXYGEN CONSUMPTION OF MYTIL US 47

respiration chamber(glass stoppered bottle)

LJ

tray

constant level tank

flagellate culture inflowvia tap and flowmeter

)"1

\..~::HIa1j

baffles

tap

. .

flowmeter

tray

pump

":11:: .

FIG. 1. Experimental setup.

Dow

nloa

ded

by [

Uni

vers

ity o

f Il

linoi

s at

Urb

ana-

Cha

mpa

ign]

at 1

2:34

16

May

201

3

48 OLA VAHL

weight according to the method given by Strickland & Parsons (1968). Thefaeces were collected the following day and treated in the same way as the sus­pended matter.

After the experiments the mussels were analyzed for dry weight of soft tissue.The soft parts were transferred to pre-weighed crucibles and dried to constantweight at 105°C.

The ratio particles in mussel trough/particles in control was transformed toradians and treated according to Sokal & Rohlf (1969). The statistical tests wereperformed on a Diehl "Algotronic" computer.

Thanks are due to Miss H. H. Hansen for doing most of the counting andto Dr. G. M011er Christensen for supplying the phytoplankton cultures, and toDr. W. Nicolaisen for making the programs for the "Algotronic",

RESULTS

The various parameters, pumping rate (P), oxygen uptake (R), gill area (A),and absorption efficiency (Ab) can be expressed as a function of the dry weightof soft parts (W) by a power function:

Y = a'Wb

where Y is the dependent parameter. It was found that the pumping rate (= P)could be expressed as P = 3.90·WD.7D l/hr (Fig. 2). The equation for oxygen up­take (= R) had a larger exponent: R = 0.37 WD.75 ml 02/hr (Fig. 3), resultingin a negative exponent for the P/R ratio (= F): F = 10.47·W-D.lol water pumped/ml O2 consumed (Fig. 4). This exponent is significantly different from 0 at the1 % level, indicating that the amount of water pumped for each ml of O2con­sumed decreased with increasing size of the bivalve.

The gill area (= A) is expressed by the equation A = 34.34·WD.65cm2 andabsorption efficiency by Ab = 78.16 ·W-D.D2 %. The exponent 0,02 in the equa­tion for absorption is not significantly different from 0 (0.25 >P >0.20) indicatingno difference between large and small Mytilus edulis in this respect. The hypo­thesis that the exponents in the equations for pumping rate and gill area areidentical i. e. the slope of the two regression lines is the same was tested by aprocedure given by Ostle (1969). It appears that there is little support for thishypothesis (0.05 > P >0.025).

Dow

nloa

ded

by [

Uni

vers

ity o

f Il

linoi

s at

Urb

ana-

Cha

mpa

ign]

at 1

2:34

16

May

201

3

OXYGEN CONSUMPTION OF MYTILUS 49

10.0

1.0....::Jos:<,"0Qla.E::Ja.

p. 3.90WO.60 I/hr

0.1

10.01.00.010.01' ! ! I !!! !! ! I!! ! I I I! I!! I ! ! ! I!

0.001 0.1

g dry weight of soft tissue

FIG. 2. Pumping activity of various sizes of Mytilus edulis. 95 % confidence interval of the meanis indicated.

1.0

0.1

....s:<,

evoE

0.01

R<O.37W O. 75 ml O:!/hr

10.00.001 I I I!!!! ! I! I!! !!!! ! I I!!! I

0.001 0.01 0.11.0

g dry weight of.soft tissue

Fro. 3. Oxygen uptake of various sizes of Mytilus edulis. 95 % confidence interval of the meanis indicated.

4

Dow

nloa

ded

by [

Uni

vers

ity o

f Il

linoi

s at

Urb

ana-

Cha

mpa

ign]

at 1

2:34

16

May

201

3

F =10.47W-O.16

..

OLA VAHL

0.01 0.1 1.0 10.0

g dry weight of soft tissue

FIG. 4. Relative efficiency of pumping activity in Mytilus edulis.

50

100

"'DQ)

E:::Jenc00

0'" 10

E<,"'DQ)c.E:::JC.

-

10.001

DISCUSSION

The mussels had been kept for 30 days before the experiments were started.This means that they were acclimated with reference to temperature (Widdows& Bayne, 1971). In the equation for the pumping rate the exponent is 0.60 whichis similar to that found in the cockle, Cardium edule, which had an exponentof 0.58 under the same experimental conditions. In Mytilius, however, the pump­ing rate was nearly double that of Cardium (see YaW, 1973). However, the ratesand size dependence of oxygen consumption were nearly the same in the twospecies, viz. R = O.37·WO.77 in the cockle and R = 0.37·WO. 75ml 02/hr in themussel. This results in a similar size dependence for the P/R ratio in the twospecies, but as the pumping rate in Mytilus is higher, the amount of water pumpedper ml oxygen consumed is higher. This probably means that Mytilus has ahigher energy profit per calorie spent. This is amplified when the retention ef­ficiencies of the two bivalves are compared because Mytilus retains smallerparticles than Cardium (YaW, 1972a, 1973). The profit in Mytilus seems to beless than in Chlamys opercu/aris which had a very high P/R ratio. On the otherhand C. opercularis had the lowest retention efficiency yet measured (YaW, 1972b).Unfortunately, the relative profits of the various bivalves cannot be ascertainedbefore the calorific content of the various particle fractions in the inhalent waterhave been studied.

The negative exponent in the equation for the P/R ratio (--0.16) (Fig. 4) isdue to the fact that the metabolism increases faster than the pumping rate, theexponent being 0.75 and 0.60 respectively. This difference might be associatedwith a limitation in the pumping mechanism in the larger mussels. The pumping

Dow

nloa

ded

by [

Uni

vers

ity o

f Il

linoi

s at

Urb

ana-

Cha

mpa

ign]

at 1

2:34

16

May

201

3

OXYGEN CONSUMPTION OF MYTILUS 51

"unit" in a bivalve gill may be considered as the space between a pair of filamentsand the various kinds of cilia attached to the filaments. It is well known that anincrease in gill area with increasing size of the bivalve results only from an in­crease in length of the filaments and addition of more filaments, whereas thedistances between cilia, their length, and the distance between the filaments remainthe same. Therefore, a doubling of the gill area should double the amount ofwater pumped if no other factors interact. Other factors, however, do seem tointeract as there is a significant difference in the slopes of the regression linesof pumping rate and gill area against weight. This means that the gill area in­creases faster with the size of the mussel than does the pumping rate. This limi­tation in the pumping mechanism does not account for the whole differencein the slopes of the regression lines of pumping and respiration rates. Whateverthe reason for this lack of coordination between these two rates, it means thatthe energy available for growth and reproduction decreases with increasing size.It is likely that the P/R ratio will vary throughout the year as it has been shownthat the rate of oxygen consumption in Mytilus varies throughout the year(Kruger, 1960; Widdows & Bayne, 1971). The size dependence of this ratealso changes during the year as the exponent in the equation for oxygenuptake varies between 0.70 and 0.93 (Kruger, 1960). The pumping rate, however,seems to be constant (see Widdows & Bayne, 1971), which means that the ex­ponent in the equation for the P/R ratio will vary between ca. -0.10 and -0.40.To what extent this decrease in energy available for growth and reproductionwill influence somatic and gonadal growth in mussels of different sizes is deter­mined by processes other than the levels of metabolism and pumping. The ef­ficiency of absorption of food may be of importance. The absorption efficiencyin Mytilus is dependent on food concentration. At low level it is about 90 %and approaches zero at very high concentrations (Thompson & Bayne, 1972).The efficiency seems to be independent of size as the exponent in the equationAb = 78.16·W-o•o2 % is not significantly different from zero. An independenceof size in this respect is also found in Modiolus modiolus but not in Arctica islan­dica (Winter, 1969). This means that the decrease in available energy for largermussels is not compensated by more efficient utilization of the food.

REFERENCES

Au, R. M. 1970. The influence of suspension density and temperature on filtration rate ofHiatella arctica. Mar. BioI. Berlin, 6: 291-303.

CONOVER, R. J. 1966. Assimilation of organic matter by zooplankton. LimnoI. Oceanogr., 11:338-345.

J0RGENSEN, C. B. 1952. On the relation between water transport and food requirements in somemarine filter feeding invertebrates. BioI. Bull. mar. bioI. Lab., Woods Hole, 139: 248-264.

- 1960. Efficiency of particle retention and rate of water transport in undisturbed Iamellibranchs.J. Cons. perm. into Explor. Mer, 26: 94-116.

4"

Dow

nloa

ded

by [

Uni

vers

ity o

f Il

linoi

s at

Urb

ana-

Cha

mpa

ign]

at 1

2:34

16

May

201

3

52 OLA VAHL

KRUGER, F. 1960. Zur Frage der Grossenabhangigkeit des Sauerstoffverbrauchs von Mytilusedulis L. Helgolander wiss, Meeresunters., 7: 125-148.

OSTLE, B. 1963. Statistics in Research, 2. Ed. The Iowa State University Press. 585 pp.SaKAL, R. R. & F. J. ROHLF. 1969. Biometry - The principles and practise of statistics in bio­

logical research. W. H. Freeman and Company, San Francisco. 776 pp.STRICKLAND, J.D.G. & T.R.PARSONS. 1968. A practical handbook of sea water analysis. Fish.

Res. Bd Can. Bull. 167. Ottawa. 311 pp.THOMPSON, R.J. & B.L.BAYNE. 1972. Active metabolism associated with feeding in the mussel

Mytilus edulis L. J. expo mar. BioI. Eco!., 9: 111-124.VAHL, O. 1972 a. Efficiency of particle retention in Mytilus edulis L. Ophelia, 10: 17-25.

1972 b. Particle retention and relation between water transport and oxygen uptake in Chlamysopercularis (L.) (Bivalvia). Ibid., 10: 67-74.1973. Porosity of the gill oxygen consumption and pumping rate in Cardium edule (L.).Ibid., 10: 109-118.

WALNE, P. R. 1972. The influence of current speed, body size and water temperature on thefiltration of five species of bivalves. J. mar. bioI. Ass. U. K., 52: 345-374.

WIDDOWS, J. & B. L. BAYNE. 1971. Temperature acclimation of Mytilus edulis with referenceto its energy budget. Ibid., 61: 827-843.

WINTER, J. E. 1969. tiber den Einfluss der Nahrungskonzentration und anderer Faktoren aufFiltrierleistung und Nahrungsausnutzung der Muscheln Arctica islandica and Modiolusmodiolus. Mar. Bio!. Berlin, 4: 87-135.

Dow

nloa

ded

by [

Uni

vers

ity o

f Il

linoi

s at

Urb

ana-

Cha

mpa

ign]

at 1

2:34

16

May

201

3