WATER QUALITY: Briefing paper on "Influences of water temperature on aquatic biota" June 23, 1978 QUALITY OF WATER BRANCH TECHNICAL MEMORANDUM NO. 78.11 Subject: WATER QUALITY: Briefing paper on "Influences of water temperature on aquatic biota" by R. J. Hoffman (WRD, Sacramento, Calif.) and R. C. Averett (WRD, Lakewood, Col.). Attached is the latest in the series of briefing papers on water quality entitled, "Influences of water temperature on aquatic biota" by Ray Hoffman and Bob Averett. Please circulate this briefinG paper as widely as possible in all district and project offices. As of this date, the following briefing papers have been distributed by the Quality of Water Branch: QW TECH MEMO NO. 75.03 -- August 14, 1974 -- "Why biology in water quality studies?" by P. E. Greeson QW TECH MEMO N0. 75.04 -- September 24, 1974 -- "Stream biology" by K. V. Slack QW TECH MEMO NO. 75.08 -- November 1, 1974 -- "Species diversity and its measurement" by R. C. Averett QW TECH MEMO NO. 75.18 -- March 27. 1975 -- "Algal growth potential" by W. T. Shoaf QW TECH MEMO NO. 75.23 -- June 12, 1975 -- "Estimation of microbial biomass by measurement of adonosine triphosphate (ATP)" by W. T. Shoaf QW TECH MEMO NO. 76.05 -- October 23, 1975 -- "Why study organic substances in water?" by R. J. Pickering, "Taste and odor in water" by R. A. Baker, and "Classification and fractionation of organic solutes in natural waters" by J. A. Leenbeer QW TECH MEMO. NO 78.04 -- March 14, 1978 -- "Drift organisms in streams" by K. V. Slack QW TECH MEMO NO. 78.07 -- May 14, 1978 -- "Phytoplankton" by G. A. McCoy QW TECH MEMO NO. 78.10 -- June 22, 1978 -- "Phytoplankton" by G. A. McCoy R. J. Pickering Attachment Chief, Quality of Water Branch WRD Distribution: A, B, S, FO-L, PO Influences of Water Temperature on Aquatic Biota By R. J. Hoffman and R. C. Averett The amount of heat in water is a familiar and somewhat exacting requirement for most of us. We are instantly aware of a water temperature that is too high or too low for bathing, swimming, or drinking. Because we obtain our water for everyday use from controlled systems, we can quickly adjust the water temperature at the tap for the desired use of the water. In nature, however, our options for adjusting or altering water temperature are extremely limited. Once the temperature of a stream or lake rises or drops to a particular level, any change to another temperature is a slow process. Aquatic organisms must either adapt to the temperature of the environment, seek an area having a more compatible temperature, or die. With the exception of aquatic birds and mammals, all aquatic organisms are "cold-blooded," meaning that their body temperature varies directly with the water temperature. A rise in water temperature is followed by a rise in body temperature. The scientific adjective to describe this physiological temperature- environment process is "poikilothermic." The opposite of poikilothermic is "homothermic." All birds and mammals (including man) are homothermic animals. Regardless of the air or water temperature, birds and mammals can maintain a nearly constant body temperature throughout a rather wide environmental range. They adjust for air temperature changes by shivering if it is too cold and by perspiring if it is too warm. When the temperature range is extreme, and the body can no longer adjust, death occurs. The body temperature of an aquatic poikilothermic simply varies with the temperature of the water. But, as with homothermic animals, there are definite upper and lower temperature limits beyond which the organism dies. While we often consider water temperature only as a simple descriptive factor, it is an extremely important environmental factor for aquatic life. This briefing paper discusses some of the influences of water temperature on aquatic life. Most of our research on the influence of temperature on poikilothermic animals has been with fish, and much of the discussion that follows will use fish as examples. But, the processes involved are similar for all poikilothermic animals, and as we shall see, plants exhibit some of the same physiological responses to temperature as do animals. Water Temperature as a Controlling Factor A controlling factor is an environmental condition that acts upon the metabolism of the organism, but does not result in death. A controlling factor may cause sufficient discomfort, or shift the energy and material resources of an organism towards a wasteful direction. One metabolic process common to all organisms, and continuous throughout life, is respiration. In the respiratory process, organisms remove oxygen from the environment and use it to oxidize foodstuffs for energy and material. The respiration rate (oxygen uptake per unit time) of aquatic poikilotherms increases, with increasing water temperature, until such time as the lethal temperature for the organism is reached. The result is an interesting paradox; an organism needs more oxygen for respiration at higher temperatures, but the solubility of dissolved oxygen in the water is reduced as the water temperature increases, resulting in less oxygen available for the increased respiratory need. In his study of the metabolic rate of sockeye salmon, Brett (1965) found that the standard metabolism (respiration or dissolved oxygen uptake of a resting poikilotherm) was 45 milligrams of oxygen per kilogram of salmon per hour (mg 02/Kg salmon/hr) at 5' C and 80 mg 02/Kg salmon/hr at 15 C. This is almost a two-fold increase in oxygen consumption for a 10 C increase in water temperature, and corresponds well with the Q-l0 law of biochemistry which states that for each 10 C increase in temperature, the reaction rate (here, oxygen consumption per unit time) will double to triple. In a similar experiment, juvenile coho salmon increased their oxygen consumption from 0.15 mg 02/Kg salmon/hr at 8 C to 0.35 mg 02/Kg salmon/hr at 17 C, a rate increase factor of about 2.1 per 10 C increase in water temperature (Averett and Brockson, 1970). There are numerous examples with poikilothermic organisms where the respiration rate as a function of temperature follows the Q-l0 law. Although respiration can be measured indirectly by oxygen uptake, it is most importantly an energy and material utilization process. Thus, when the respiration rate increases, the amount of energy and material that the organism needs for its life processes also increases. The ratio between respiration rate and the energy and material requirement is not necessarily 1:1, but both increase and decrease together. The respiratory rate also varies with season change as well as with the weight of the animals. Small animals (including the young of large animals) have much higher respiration rates per unit weight than larger animals. The relations between standard metabolism, water temperature, season, and weight of coho salmon are shown in figure 1. In this study, calories, a unit of energy measurement (one calorie is the amount of heat energy needed to raise the temperature of 1 gram of water 1 C) was used in place of oxygen uptake. Note that at 5' C, the smallest fish (diamond-shaped symbol) had twice the standard metabolism of the larger fish (triangle-shaped symbol). Brett (1965) determined the relation between temperature and maximum swimming ability of sockeye salmon. The energy used by the fish was measured in calories (fig. 2). The bottom curve in figure 2 is the standard metabolic rate, and the top curve is the active metabolic rate, or the caloric uptake of the fish when swimming at maximum speed. Brett termed the difference between the top and bottom curves as the "scope of activity" at a given temperature. The optimum temperature for maximum swimming activity for the sockeye salmon was 15 C. The scope of activity concept has obvious practical and physiological implications in designing fish passage systems over dams, and in determining the well-being or aquatic organisms as a function of water temperature, as well as the production of fish for food. Thus far, water temperature as a controlling factor of aquatic life has been related to standard metabolism and activity. But, if an organism is to survive, it must do more than carry out standard and active metabolism; it must also capture and digest food, rid itself of undigested food and other wastes, and grow. A simplified formula for these processes can be written as: Qc = Qs + Qd + Qa + Qw + Qg where: Q refers to material and energy intake and c = total food consumed a = activity s = standard metabolism w = waste material (feces and urine) d = digestion and movement g = growth of food throughout the body It is interesting as well as important to note that the Qg term (growth) cannot take place, that is the organism cannot grow, until all of the other energy and materials terms (Qs, Qd, Qa, and Qw) are satisfied. It also is important to note that each term in the above formula is temperature dependent. When this is realized, it is not difficult to understand why temperature is the master controlling factor of life in the aquatic environment. Water temperature also can influence the reproductive success of aquatic organisms. Bolke and Waddell (1975) reported that after the completion of Flaming Gorge Dam on the Green River, Utah- Wyoming, the annual water temperature range and the season of high and low temperatures in the river downstream from the dam were greatly altered. Prior to closing the dam, the average annual water temperature in the Green River downstream from the reservoir ranged from just above O to 19.5 C as compared to 3.5 to 10 C since closure of the dam. Moreover, before closing the dam, the low water-temperature period was December to February, and the high-water temperature period was July. Since closure of the dam, the low-water temperature period has shifted to March and the high-water temperature period is November. These changes in the water temperature regime of the river downstream from the dam resulted in a marked decrease in the reproductive success of trout. A multiple release device has since been installed in the reservoir so that water having a temperature corresponding to that of the river before dam construction can be released. While the above discussion has been concerned with animals, McCombie (1960) illustrated the effect of temperature on the growth of the green alga, Chlamvdomonas reinhardi (fig. 3). He varied the water temperature but kept light and nutrients the same. McCombie noted that regardless of the light intensity, the upper lethal temperature for this alga was 35 deg. C. The optimum temperature for growth at all three light intensities and nutrient concentrations was between 25 and 30 C. Bacteria are the master decomposers (oxidizers) of organic matter in nature. They rapidly convert organic waste and other materials to carbon dioxide, water, and more bacteria cells. Like other poikilothermic organisms, their respiration rate and hence oxidation rate of organic matter increases with rising water temperatures. Thus, the oxygen demand of warmer waters is almost always higher than that of colder waters. For example, in winter, organic material entering a stream may be transported a considerable distance before it is completely oxidized by bacteria. In summer, bacteria may oxidize the same amount of organic matter close to its point of entrance to the stream. Water Temperature as a Lethal Factor The temperature range within which aquatic poikilotherms can live is often relatively narrow. This range, however, varies with the acclimation temperature; that is, the temperature to which the animal has become accustomed over a period of time. For example, Brett (1956) found that if chum salmon were acclimated at 5 C, their lower lethal temperature (the lowest temperature causing death) was 0.2 C, or just above freezing. The upper lethal temperature (the highest temperature causing death) was 21.8 C. If the salmon were acclimated at 20 C, their lower lethal temperature was 6.5 C, and their upper lethal temperature was 23.7 C. By changing the temperature of acclimation, Brett found that the overall temperature range of the chum salmon was from 0.2 to 25 C. Acclimation to a given temperature is a time response that varies from about 3 to 60 days with aquatic poikilotherms. In nature aquatic organisms are usually able to easily acclimate to high and low temperature extremes because the water temperature in lakes and streams normally changes slowly because of the high heat capacity of water. We would expect, then, that an aquatic organism would have a definite seasonal lethal temperature. This is exactly what Brett (1964) found when he determined the lethal temperatures of the bullhead from Lake Opeongo, Ontario (fig. 4). In August when the lake water was warmest, the upper lethal temperature for the bullhead was near 36 C. In late October immediately before ice formation and in May immediately after ice break-up, the two coldest water periods in the lake, the upper lethal temperature was near 29 C. There is, then, no single upper or lower lethal temperature, but rather a changing lethal temperature associated with the temperature of acclimation. We can relate these two temperature events for the chum salmon and bullhead as shown in figure 5, taken from Brett (1956). Note that the bullhead, a warm- water fish has a much wider range than the salmon, a cold-water fish. Of timely concern is what happens to aquatic poikilotherms if there is a rapid change in the water temperature of their environment. Such events happen with the shutdown of power plants that release cooling water to rivers or lakes, or with release changes from the top or bottom of a reservoir. A study by Doudoroff (1942) provides insight as to the time required for an organism to acclimate to a rapidly rising or lowering water temperature. Doudoroff determined that the marine greenfish acclimated rapidly to rising water temperatures, becoming fully acclimated in 3 to 10 days. In contrast, the green fish acclimated slowly to faling temperatures, becoming fully acclimated only after about 30 days. What this means is that a rapid drop in the water temperature is likely to be more costly, in terms of aquatic life, than is a rapid rise in the water temperature. We know that "chill" or "cold death" in aquatic life is a common and costly event. As a result, this is presently a field of active research. There is a final consideration of the toxic effects of water temperature that frequently is ignored. It is the uptake of lethal amounts of toxic materials by aquatic organisms because of increased respiratory rates resulting from an increased water temperature. For a material to be toxic to an animal, it must enter the bloodstream in a quantity sufficient to stop metabolic processes. With aquatic organisms, oxygen, as well as most toxic materials enter through the gill tissue. Potentially toxic materials in water may be in such low concentrations that during low water temperatures the animal would not accumulate enough toxin in its bloodstream to cause death. But, if the water temperature rises, respiration increases and more oxygen as well as more of the toxic material is passed through the gill tissue and into the bloodstream. Thus, a rising water temperature can be an insidious cause of death even below the upper lethal temperature limit. While we make numerous water temperature measurements in the WRD, we often fail to consider that an alteration in the temperature regime of a river or lake can have a profound influence on the aquatic biota in the system, either by increasing metabolic rates and hence energy and material utilization, or by causing death. Alteration of the temperature regime can have significant economic consequences in areas where commercial or sport fisheries are important. Moreover, water temperature may influence decomposition and the assimilative capacity of water to handle waste material. Such temperature influences are of great significance in the management of rivers, lakes, and estuaries. Selected References Averett, R. C. and Brockson, R. W., 1970, Measuring the influence of water-quality changes on fish: Am. Water Resources Assoc. Symposium on Hydrobiology, Miami Beach, Flor., p. 212-222. Bolke, E. L. and Waddell, K. M., 1975, Chemical quality and temperature of water in Flaming Gorge Reservoir, Wyoming-Utah, and the effect of the reservoir on the Green River: US Geol. Survey Water-Supply Paper, 2039-A, 26 p . Brett, J. R., 1956, Some principles in the thermal requirements of fishes: Quart. Rev. Biology, v. 31, no. 2, p. 75-87. Brett, J. R., 1964, The respiratory metabolism and swimming performance of yound sockeye salmon: Fisheries Research Board Canada Jour., V. 21, no . 5, p . 1183-1226 . Brett, J. R., 1965, The swimming energetics of salmon: Scientific American, Vol. 213, no. 2, p. 80-85. Doudoroff, P., 1942, The resistance and acclimatization of marine fishes to temperature changes. I. Experiments with Girella nigricans (Ayres): Biol. Bull., v. 83, p. 219-244. Fry, F. E. J., 1947, Effects of the environment on animal activity: Toronto Univ. Studies on Biol. Ser. 55, Ontario Fisheries Research Labor. Pub. 68, 434 p . McCombie, A. M., 1960, Action and interactions of temperature, light intensity and nutrient concentrations on the growth of green alga (Chlamydomonas reinhardi) Dangeard: Fisheries Research Board of Canada Jour., v. 17, no. 6, p. 871-894. Stevens, H. H. Jr., Ficke, J. F., and Smoot, G. F., 1975, Water temperature influential factors, field measurement, and data presentation: US Geol. Survey, Techniques of Water-Resources Investigations, Book 1, Chapter Dl, 65 p. Warren, C. E., 1971, Biology and water pollution control: Philadelphia, W. B. Saunders Co., 434 p.