INFLUENCE OF SIZE ON OXYGEN CONSUMPTION OF THE BEARDED HORSE BARBATUS (LINNAEUS, 1758) AND THE NOAH’S ARK SHELL NOAE LINNAEUS, 1758

Nenad Antolovic 1*, Nikša Glavic 1, Valter Kozul 1, Jaksa Bolotin 1 and Iris Dupcic Radic 1 1 University of Dubrovnik Institute for Marine and Coastal Research - [email protected]

Abstract Oxygen consumption and ammonia excretion were investigated on Bearded horse mussel and Noah’s ark shell under laboratory conditions in relation to the shell size (< 25 mm; 25 to 50 mm and > 50 mm). Body size of both significantly influenced oxygen consumption and ammonia excretion of the Noah’s ark shell. In both species, respiration decreased with body size while excretion rate increased with body size.

Keywords: Bivalves, Aquaculture, Oxygen, Adriatic Sea

Introduction M. barbatus the respiration rate decreased with body size. For both studied Sustainable management of bivalve molluscs requires an interdisciplinary species increase in AE rate is observed with an increase in the body size, approach involving knowledge of the physiology of farmed as well as candidate consistent with finding that small have a relatively low rate of ammonia species. In this paper, oxygen consumption (OC), ammonia excretion (AE) excretion during spring [5]. In bivalve molluscs, due to a disproportionate related to the size of the Noah’s ark shell and the bearded horse mussel was reliance on protein metabolism for energy production by smaller individuals the investigated. Comparison of physiological responses of these two species due relationship between ammonia excretion rates and body size can be very variable to the size of the individuals was also made. When assessing the suitability of [6]. certain species for culture, it is important to know how physiological responses are influenced by the size of an . Materials and methods References Measurements of oxygen consumption and ammonia excretion were performed 1 - Solorzano, L. (1969). Determination of ammonia in natural waters by the on the shellfish samples of both species collected from Mali Ston Bay phenolhypochlorite method. Limnology and oceanography, 14(5), 799-801. (Southeast Adriatic). Oxygen consumption (OC) and ammonia excretion (AE) 2 - Ivancic, I., & Degobbis, D. (1984). An optimal manual procedure for were measured with respect to the different size categories of shellfish (< 25 ammonia analysis in natural waters by the indophenol blue method. Water mm; 25 to 50 mm and > 50 mm). The measurements were performed in the Research, 18(9), 1143-1147. closed respiratory chamber using Oxyscan graphic probe (UMS Gmbh, 3 - Brown, J.H., Gillooly, J.F., Allen, A.P., Savage, V.M., & West, G.B. (2004). Germany). After the measurement period, 50 ml of the sea water sample was Toward a metabolic theory of ecology. Ecology, 85(7), 1771-1789. taken from the closed chamber, fixated with 2ml of phenol and refrigerated for 4 - Sukhotin, A.A., & Pörtner, H.O. (2001). Age-dependence of metabolism in AE measurement. The concentration of ammonium was determined by the Mytilus edulis (L.) from the White Sea. Journal of experimental marine indolfenol blue method [1] modified by [2]. Stastical analysis was carried out biology and ecology, 257(1), 53-72. using parametric ANOVA and Tukey post-Hoc analysis (p<0,01). To compare 5 - Bayne, B.L., & Scullard, C. (1977). An apparent specific dynamic action in the metabolic rates between species, t-test was used. Mytilus edulis L. Journal of the Marine Biological Association of the United Results and discussion Kingdom, 57(2), 371-378. Mean oxygen consumption of both A. Noae (ANOVA, p=0,000195, F=10,543) 6 - Bayne, B.L., & Newell, R.C. (1983). Physiological energetics of marine and M. Barbatus (ANOVA 0,000006, F=16,63) depended significantly on body molluscs. In A.S.M. Saleuddin & K.M. Wilbur (Eds.), The , Volume 4 size (Figure 1a). In both investigated species, there was a trend of higher Physiology, Part 1 (pp. 407-515). New York, USA, Academic Press., 523 pp. respiration rate in smaller animals. T-test showed statistically significant difference for respiration rate between these two species for groups smaller than 25 mm (t=-2.610; P <0.001). Excretion rate (AE) of A. noae depended strongly (ANOVA, P <0.000676, F=8,899) on body size (Figure 1b) and significant difference was observed for largest animals compared to the other size groups (Tukey, P <0.01). Ammonia excretion of M. barbatus was not influenced by body size. T-test showed a statistically significant difference for AE rate between A. noae and M. barbatus for organisms smaller than 25 mm (t=2.173; P <0.05).

Fig. 1. Oxygen consumption (a) and Ammonia excretion (b) of and related to shell size.

[3] have developed the theory of varying metabolic rates with regard to body size and temperature. The body size is one of the main endogenous factors influencing the energy costs of organisms [4]. In this study, in both A. noae and

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