OXYGEN CONSUMPTION ASSOCIATED WITH FEEDING HABITATS OF Munida subrugosa (CRUSTACEA, DECAPODA) IN THE BEAGLE CHANNEL

M. C. ROMERO; F. A. VANELLA; F. TAPELLA; G. A. LOVRICH

Berichte zur Polar- und Meeresforschung / Reports on Polar and Marine Research. Extended Abstract of the IBMANT / ANDEEP International Symposium & Workshop

Alfred-Wegener-Institut

Lugar: Bremerhaven; Año: 2005 vol. 507 p. 178 - 179

1618-3193

 Munida subrugosa constitute up to 50% of hte benthic community biomass and the 85% of the density of anomuran and brachiuran crabs south to the Beagle Channel. This specie represents an interesting study case because has two different and simultaneous feeding habits: predator, hunting preys with the chelaes, and deposi feeder, catching particulate organic matter and ........from benthos. In the majority of the studies in decapods metabolism the oxygen consumption of the animals increase with both temperature and animal size. However, there is only little information available about oxygen consumption of decapods related with their feeding habits. The aims of the present work was determined the basal metabolism of M. subrugosa kept at 8ºC, and the oxygen consumption whereas they were assimilated food, with each one of its feeding habits. The animals were caught in the Beagle Channel with an epibenthic trawl at <40 m depth. A subsample of 20 females and 20 males was selected ramdonly and transported to the laboratory. The carapace length mean was 21.6 ± 1.1 and 23 ± 1.9 mm, for females and males, respectively. The experiment was designed in four times. In each time, each one of 10 animals was placed into a respiration chamber of 490 ml of capacity. These ten chamber were sumerged in a bath of 40 l of aerated seawater at 8 ± 1ºC. The photoperiod of the chambers was 12h–12h (ligth–dark). The oxygen consumption was measure with an oximeter of polarographic electrodes (Clarke type). Two kind of food was selected, isopods (CRU) and pulverized food for fish (ABP), as predator and deposit feeder feeding habits, respectively. The basal metabolism of an animal represents the minimal energy consumption needed to maintain the animal, without consider muscle activity, and process as feeding or food digestion. The basal metabolism of M. subrugosa was obtained 25.8 ± 5.0 h after animal manipulation. The basal metabolism for females and males was similar (t-Student, t= 0.65, n= 20, p= 0.26), and was 14.4 ± 3.8 and 15.4 ± 5.9 µlO2·h-1·g-1, respectively. The oxygen consumption for females and males of M. subrugosa under stress condition after manipulation, was similar (t-Student, t= -1.03, n= 20, p= 0.16), and was 35.8 ± 10.8 and 32.0 ± 11.2 µlO2·h-1·g-1, respectively. The oxygen consumption significativaly increased (t-Student, t= -12.9, n= 40, p< 0.001), when M. subrugosa assimilated food. The maximum value of oxygen consumption were similar for both kind of food (ANOVA, F= 1.55, p= 0.22) but different between sexes (ANOVA, F= 5.1, p= 0.03). Females consumed less oxygen per unit of time to assimilate both food than males (Table 1). Nevertheless, there was no statistical interaction in the maximum oxygen consumption between food and sexes (ANOVA, F= 1.92, p= 0.18). The total oxygen consumed by M. subrugosa to assimilate both kinds of food was similar (ANOVA, F= 3.97, p= 0.054), but females and males consumed more oxygen to assimilate CRU than ABP (Table 1). Differences in the total oxygen consumed appeared between sexes (ANOVA, F= 23.91, p< 0.0001). Females consumed less oxygen to assimilate both food than males (Table 1). Nevertheless, there was no statistical interaction in the total oxygen consumed between food and sexes (ANOVA, F= 0.45, p= 0.51). Munida subrugosa from Beagle Channel presents a basal metabolism of 14.9 ± 4.9 µl∙h-1·g-1. The oxygen consumption increases significativaly under stress conditions, by handly or feeding. The increment in the oxygen consumption and the total of oxygen consumption to assimilate food as predator or deposit feeder is similar, but females consumed less oxygen than males. Therefore, the energetic cost inverted by females to feed is minor. It would be an advantage because the more energy economy in food assimilation the more energy inversion assignment in reproduction.