Length-weight relationship of fishes from Anambra ... - Zoo-unn.org

Animal Research International (2004) 1(1): 16 - 22 16EFFECTS OF TEMPERATURE AND pH ON THE OXYGEN CONSUMPTIONRATE OF Sudanonautes (Convexonautes aubryi) floweri(DE MAN) (CRUSTACEA: DECAPODA)INYANG, Nicholas Mathias and NWANKWO, Enyinnaya LewechiDepartment of Zoology, University of Nigeria, Nsukka. Enugu State, Nigeria.Corresponding author: INYANG, Nicholas Mathias, Department of Zoology, University of Nigeria,Nsukka. Enugu State, Nigeria.ABSTRACTThe oxygen consumption rate of a freshwater sub-terrestrial crab, Sudanonautes floweriin relation to different temperatures and pH was investigated. The average temperatureand pH o f the crab’s peaty stream habitat were 29.50 C and 7.5 respectively. The lethaltemperatures at pH 7.0 recorded for the species were 14.5 0 C and 34.5 0 C respectively. Theoxygen consumption rate (Q) within the temperature range of 21 0 C – 31 0 C increasedwith temperature but decreased in the zones of temperature stress (≤ 16 0 C and ≥ 31 0 C).There was no significant difference (P>0.05) between weight specific oxygenconsumption (QW -1 ) of the male and female crabs. The oxygen consumption rate waspositively correlated with the body weight of the crabs (r = 1.0); but was inverselyrelated to the unit weight of the crab per hour (r = -0.95). The average oxygenconsumption of the animal at 30 0 C and pH 7.0 was 53.1 µg O 2 g -1 h -1 .Key words: Temperature, pH, Oxygen consumption, Sudanonautes floweriINTRODUCTIONFactors affecting the metabolic rate ofinvertebrates can be either endogenous (bodysize, respiratory surfaces, activity, nutritionalstatus and state of reproductive cycle (Newell etal., 1979) or exogenous (temperature, salinity,hydrogen ion concentration (pH), photoperiodand oxygen concentration among others).These factors affect the life pattern andactivities of animals in a particular ecosystem.Temperature is a measure of “hotness” and“coldness” in an animal’s body. It is usually afunction of the rate of molecular agitation whichis controlled to a large extent by the rate ofphysico-chemical reactions in the body of theanimal (Hardy, 1979). Since crabs arepoikilotherms, it is expected that temperaturewill grossly affect their metabolic rates. Thoughmetabolic rate of an animal tends to increasewith increasing temperature, Aldrich (1975)noted that because of the complex interactionsof environmental, demographic andphysiological factors it may not be surprising tonotice individual variability of oxygenconsumption rates in some crustaceans. Lagleret al. (1977) stated that there is similarity ofeffects of oxygen carrying capacity of the bloodby carbon (IV) oxide (CO 2 ) tension and pH.Thus, respiratory rate is generally expected toincrease with increasing hydrogen ionconcentration.Bell et al. (1970) defines metabolism asthe total chemical changes occurring in the cellor in the body. Metabolic rate in an animal canbe quantified from the rate of foodconsumption, energy released as heat or theamount of oxygen consumed in its oxidationprocesses to obtain energy. Of these threemethods, the third is more widely used becauseit is easy and technically accurate. Thus,metabolic rate conventionally means orrepresents the rate of oxygen consumption.Information on the metabolic rates ofanimals is of basic importance in defining theenergy budget of animals. Such information isuseful for the establishment of aquaculturefacilities and for the evaluation of theaquaculture perspectives of the species involved(Buesa, 1979).The relationship between oxygenconsumption (Q) and the unit body weightoxygen requirement (QW -1 ) is a welldocumented phenomenon in the animalkingdom and is most evident in animalsweighing from one gram (1 g) to 1000 grams (1kg). Though metabolism in poikilothermsgenerally varies with the environmentaltemperature, it is also influenced by size (Bell etal., 1970). So for strict quantitative purposes