Physiological Ecology Essay Example for Free

Physiological Ecology Essay ABSTRACT   Ã‚   Mytilus edulis or the common mussels, very commonly found around the British Isles coast, with large commercial beds in the Wash, Morecambe Bay, Conway bay the estuaries of south- west England, north Wales west Scotland; belongs to the phylum Mollusca e.g. snails, slugs, mussels cockles clams class Pelecypoda e.g. clams, cockles, mussels, oysters scallops. The Mytilus is an extremely widely studies specie, mainly because of its widespread distribution, abundance, ecological commercial importance. It is also used as a bio – indicator. The objective of the study conducted was to find out the effects of respiration, water pumping activity environmental stresses on the mussel’s growth. The environmental stress includes prolonged air exposure, low salinity its action combined with elevated temperature. The main focus was regarding the age growth of the Mytilus. The mussels were challenged to a number of tests to determine their behaviour to record their response to different environments.   The tests prove that Mytilus species that live in an uncontaminated area grow faster than ones that live in polluted areas. This can be deduced effectively by the research conducted along with the experiments. INTRODUCTION   Ã‚   Mytilus are usually present on the rocky shores of open coasts attached to the rock surfaces in crevices, on rocks piers in sheltered harbours estuaries, often occurring as dense masses in cooler waters of the world; usually extending from the Arctic to the Mediterranean in the North east Atlantic. Two important factors that play an important part in the growth life of Mytilus are: TEMPERATURE: it is a vital factor responsible for the growth limitation of mussels. Extreme low temperature causes damage in Mytilus but is minimised due to nucleating agents in the haemo- lymph. The Mytilus is prone to perilous freezing conditions sporadically in even moderate temperatures; large adults can endure lab conditions of -16 degree C. easily for 24 hours are capable of surviving even if the tissue temperature falls below -10 degree C. In Sweden, mussels actively ingested seston at -10 degree C., suggesting that they can utilise spring phytoplankton blooms in boreal waters even at low temperatures. M.edulis can tolerate high temperature desiccation as well, for example the British M.edulis has an upper sustained thermal tolerance limit of about 29 degree C. (Mytilus edulis) SALINITY: in contrast with other biogenic reef species, M.edulis can bear a wide range of salinity. But it is noted that it stops the feeding process when exposed to low salinities. The M. edulis adapts well to low salinities as low as 4-5 %. Exposure to 16% salinity for a month resulted in reduced shell growth as much as 26% to 32%, while in 22% exposure caused a minute drop in growth rate. When exposed to 13% the growth rate recovered from zero to more than 80% in 32% in a month. MATERIALS AND METHODS Materials: Incubation tubes, incubator, cotton, knob, benzoic acid, All samples were divided into four groups. Two groups of prestine A and prestine B were compared with polluted A and polluted B. Pristine A Pristine B Polluted A Polluted B Curves were drawn to compare Pristine A with Polluted A and Pristine B with Polluted B. With change of temperature change in mass was observed. Mytilus were cultured in flat trays measuring 20-40 cm. Two trays had pristine while remaining two were for polluted growth. Affect of temperature change was observed in all the four trays with consequently change in mass. Mytilus was put over the trays to be cultured. Tests conducted in five different labs are being analyzed to prove that the Mytilus favor a pristine environment as compared to a polluted one. LAB #1    This particular lab deals with the energy content in a food substrate or in animal tissue which is considered as the most important component for growth of any organism. The method used to determine the energy content of biological materials is the micro- bomb calorimetry method; by using susceptible microelectrodes to assess the heat produced by igniting a pellet of dry tissue within a stainless steel bomb. The calibration is obtained through a chemical having fixed energy content; the temperature change can be transformed into energy content for the tissue. In order to deal with a small sample, a micro- bomb calorimeter is used, filled with oxygen a small wire, that works like a light bulb filament is used to ignite the tissue    Using the oxygen supplied by potassium dichromate; a strong oxidizing reagent, contained with concentrated sulfuric acid, the tissue is burnt chemically. The orange Cr is reduced to green Cr, while burning; this change can be quantified using a spectrophotometer. LAB #5:    By determining the effects of geometric constraints biological processes, the allometric isometric relationships of organism are studied. The lab deals with the examination of gill area, shell volume foot weight scale with the size of mussels; observing how the size of the mussel effects the different biological processes. The allometric scaling is explained by equations of the form Y= Ax B; the A as a constant, B an exponent, X is mass Y is a biological process. Allometric relationships are represented as curves on linear axes, but when plotted on log/log axes they become straight. The scaling exponent of the function is determined by the slope of the line. LAB #6:    This lab’s research aims to calculate the following at ambient temperature using a meticulous mode: The respiration rate of one mussel from polluted area The respiration rate of one mussel from a pristine area control respiration    The materials employed in this test are a fiber optic oxygen electrode indicating vestiges on the quenching of light emissions from a Ruthenium compound due to oxygen presence, so as to calculate the flux of oxygen in due course.   To measure the respiration rates, the mussels will be enclosed in individual restrained Respirometers, filled with seawater connected to an oxygen electrode located with a slow flow of water from a peristaltic pump, in a separate chamber. Set up the oxygen system to record data every minute for an hour. Place a cleaned mussel, attach the lid submerge the chamber. Place the electrode in the holder attach hoses to pump chamber, so that the water is flowing past them, turning on the pump to slow. The data logging will go on for an hour start a mark for a downward slop in the recorded readings. Measure the volume of chambers the water level in hoses length of the mussel to estimate the tissue weight Mussel volume to ascertain the exact volume of water in the chamber.   LAB # 7:   Ã‚   The labs main concern was to calculate the protein content in mussel tissues, by using the Lowry chemical assay, which comprises of combining a dye reagent with soluble protein to produce coloration that is directly proportional to the amount of protein present. Protein is often used in physiological ecology as it plays a functional structural role by normalizing the data, through its direct association with functional components within the cells. Often in this experiment, the Bradford assay has been used since it is an alternate method for protein determination. Dilute copper tartar- ate solution is added to the protein that forms a complex. To develop the coloration, the Folin reagent is added to the protein – copper complex, within 15 minutes it results in a blue color. This has a peak absorbance at 750nm can be quantified at this wavelength using a spectrophotometer. A calibration must be done with a known construction of known concentration of protein a calibrated line constructed.   Ã‚   The reagents in the assay when reacted with a series of known protein solution (0.2- 1.5 mg/ml) dissolved in a sodium oxide buffer to remove buffer effects in the calibration. Prepare a series of clean 2ml snap cap tubes. The likely concentration series will be made by diluting the stock Bovine Serum Albumin from concentrations stock: –x x/10 x/2 x/4 3x/4   Ã‚  Ã‚  Ã‚  Ã‚   Into the 1.7 ml soap cal tubes, transfer 25ul of the standards then add 125ul of reagent A. swirl warily. In each tube add 1.0 ml of reagent B vortex carefully. Leave for 15 minutes then measure the absorbance against 750nm distilled water. Plot the protein content along the X axis the absorption along the Y axis to obtain the calibration line. The calculation of the calibrated line can be done to estimate the protein content X from an unknown absorption Y; in the form Y= A – BX LAB # 9:   Ã‚  Ã‚   This lab research is to study the functional attributes of living enzymes, employing a quantitative approach to their measurement. By using a simple spectrophotometric assay to quantify the enzyme citrate synthase in two populations of Mytilus, any possible consequences of this variation will be identified by its functional value. The enzyme Citrate Synthase limits the rate mediating the transfer of pyruvate into the TCA cycle as citric acid. The process determines: Quantification of CS activity Quantification of the protein content to allow the CS content to be normalized. The extraction of the living tissue in a way that the enzymes remain operative is the base, on which the reaction is dependant on. The DTNB is reduced by the CoASH which is a stiochiometric by product of the reaction. The DTNB changes color, as is reduced with a peak absorbance of 412um. The procedure relies on the extraction of the CS in a cold buffer. A small portion is diluted with an Acetyl-CoA solution, the reaction begins when the Oxalo- acetate solution is added, as a result the color changes which can be monitored in a spectrophotometer. RESULTS      Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚   Results clearly show that mytilus grow more in pristine as compared to polluted areas. There are several factors that affect mytilus growth in polluted areas. Graph polluted A (obtained from polluted A readings) Lab 6 The threshold salinity levels were recorded for the individual age groups consisting of a variation of behavioural response to salinity fluctuations. Low levels of water salinity below the critical values caused the isolating responses like closing the mantle cavity, withdrawal of siphons closing the shell valves in Mytilus. Another factor noticed was that the age did not influence the sensitivity of mussels to low salinity elevated temperature. However the older mussels exhibited a slightly lower critical salinity value after going through the fluctuations.   Ã‚   The scope for mussel growth except under treatments of no algae high silt; remained positive when carbon assimilation true, the rates of respiration excretion were balanced against energy intake. In estuarine systems, where the seston quality quantity is variable, makes the mussels living there evolve a feeding strategy involving minimal metabolic cost, at the same time maximizes energy assimilation while acquiring food from the environment. DISCUSSION AND CONCLUSIONS      Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚   A number of factors can hinder growth of mytilus in polluted areas. In polluted areas the change in mass of mytilus was much greater with slight variations of temperature. However, contrary to this the change in mass was negligible in pristine area. Several factors can hinder growth of mytilus on polluted surface. Pollutant in water and air can hinder their growth. Pollutants also destroy the food stuff and nutrients, hence, the mytilus species may find difficulty in getting well nourishment. Environmental variations have also deep affect on their growth. The blue mussels can subsist in air for 10 14 days at a varying temperature from 10 -20 degree C. even longer at lower temperatures. Like many other intertidal mollusc, M. edulis uses a complex behavioural physiological bio chemical mechanism to tolerate prolonged periods of air exposure extreme salinity changes or other un- favourable environmental conditions. Mussels that are smaller medium in size are not as predisposed to air exposure unlike large mussels, mainly because of higher absolute values of metabolic rate in the large mussels. In our experimental research, the size did not play a role in survival in air. The factors change from specie to specie, for example in some species of mussels the resistance increases the developmental age of the animal, and once it reaches the maximum level it may be possible that the process reverses.   Ã‚   When blue mussels M. edulis were exposed to high concentrations of copper Antarctic scallop Adamussium colbecki to high concentrations of cadmium, the age factor did not influence the survival; however the capacity to convalesce deteriorates with age.   Ã‚  The physiological traits of food ingestion rate, carbon assimilation efficiency, and respiration excretion rates are integrated by the energy accessible for growth, by supplying a prompt quantitative estimation of the energy status of the mussels. Conducting researched on this fact can provide insight into the growth process the influence of physiological activities. The Geukensia demissa or commonly known as the ribbed mussels can exert a profound influence on ecological processes of salt marshes on the Atlantic coast of North America. These mussel species are quite vulnerable to predators in the sub tidal area, since they have relatively thin shells; however they are very much physiologically adapted to the extreme environment where they are exposed to 70% air of the tidal cycle, this exposure draws the mussels against some severe stress since they are unable to perform feeding, defecation other essential physiological functions due to limitation of time. The mussels favour a pristine environment over REFERENCES â€Å"Mytilus edulis† Environmental Requirements: (n.d.) UK marine special areas of conservation [Accessed 4 December 2007] http://www.ukmarinesac.org.uk/communities/biogenic-reefs/br3_4.htm Tyler-Walters, H., 2007. Mytilus edulis. Common mussel. 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