The effect of compact formulations on the environmental profile of Northern European granular laundry detergents Part II: Life Cycle assessment

The environmental profile of laundry detergents at three time points (1988, 1992, and 1998) were compared on the basis of two distinct, complementary approaches: Environmental Risk Assessment (ERA) and Life-Cycle Assessment (LCA). The results are presented in this paper and its accompanying paper in this issue (Part I: Product Environmental Risk Assessment). Life-Cycle Inventory (LCI) data from The Netherlands and Sweden were used for this retrospective analysis. The chosen time period studied (1988 - 1998) spans significant, multiple formulation and process change in laundry detergents, including the introduction of compact, then super-compact, granular detergents. Cradle-to-Gate LCAs based on 1 kg of finished product (from raw material supply to packaged finished product leaving the suppliers site) revealed no significant differences between the products themselves, as manufactured between 1988, 1992 and 1998. Cradle-to-Grave LCAs based on 1000 wash cycles (from raw material supply to disposal of used product) indicated that the consumption of raw materials and energy, as well as environmental emissions (air, water and solid waste), decreased after the introduction of compact detergents in 1988. The LCAs revealed that a number of category indicator values decreased (for acidification, aquatic toxicity greenhouse effects, eutrophication, toxicity, ozone depletion and smog). Furthermore, the results of the LCAs support the conclusion that the differences between The Netherlands and Sweden are due to (1) differences in electrical generation between the countries, (2) differences in energy consumption during consumer use, (3) differences in detergent dosage per wash and (4) differences in the wastewater treatment infrastructure.     

高产条件下不同小麦品种耗水特性和水分利用效率的差异

设置不灌水(W0)、底墒水+拔节水(W1)、底墒水+拔节水+开花水(W2)3个灌水处理,采用6个冬小麦(Triticum aestivum.L.)品种,研究了不同品种耗水特性和水分利用效率的差异.结果表明:(1)依据籽粒产量和水分利用效率2个因子,采用聚类分析的方法,将供试品种分为高水分利用效率组(Ⅰ组)、中水分利用效率组(Ⅱ组)和低水分利用效率组(Ⅲ组).同一灌水条件下的籽粒产量,Ⅰ组显著高于Ⅱ组和Ⅲ组;Ⅱ组和Ⅲ组在W0条件下无显著差异,在W1和W2条件下Ⅱ组显著高于Ⅲ组.(2)从Ⅰ组、Ⅱ组、Ⅲ组中分别取1个品种,泰山23、潍麦8号、山农12进一步分析表明,在W0 和W1条件下,泰山23和潍麦8号的阶段耗水量和耗水模系数为开花至成熟>播种至拔节>拔节至开花,山农12为播种至拔节>开花至成熟>拔节至开花.W2条件下,3个品种的阶段耗水量和耗水模系数为开花至成熟>播种至拔节>拔节至开花;播种至拔节和拔节至开花的耗水模系数为泰山23>山农12>潍麦8号,此阶段的耗水量和耗水强度为泰山23品种最高;开花至成熟的耗水模系数为潍麦8号>山农12 >泰山23,此阶段的耗水量和耗水强度为泰山23品种最低.(3) 在W0 和W1条件下,总耗水量和灌水量、降水量及土壤耗水量占总耗水量的百分率为泰山23品种居中;W2条件下,灌水量和降水量占总耗水量的百分率为泰山23>潍麦8号>山农12,土壤耗水量及其占总耗水量的百分率反之,但泰山23的总耗水量最低.(4) 同一灌水条件下,泰山23品种100～200cm土层的土壤耗水量高于潍麦8号,表明该品种能充分利用深层土壤水;山农12品种在W0和W2条件下,100～200 cm土层的土壤耗水量高于泰山23和潍麦8号,但其籽粒产量和水分利用效率显著低于上述两品种.     

黄土塬区不同土地利用方式土壤水分消耗与补给变化特征

对黄土塬区不同土地利用方式下2012年3—10月7龄果园(挂果初期)、17龄果园(盛果期)、小麦地、玉米地土壤水文状况进行分析,结果显示,0—600 cm试验土层7龄果园土壤贮水量最高,其次为玉米地、小麦地,17龄果园最低,且不同土地利用方式下贮水量随着降水量的变化而上下波动,但其变化滞后于降水。不同土地利用方式均表现为随土壤深度增加土壤含水量变异程度减弱的特征,且其土壤剖面的水分含量变化存在季节变异。农田和7龄果园中不存在土壤干燥化现象,而17龄果园土壤剖面存在较厚的干燥化土层,其分布深度为320—600 cm。不同的土地利用方式的土壤水分的消耗和补充深度有较大差异,17龄果园消耗深度为500 cm,补充深度为200 cm;7龄果园、玉米地和小麦地消耗深度分别为200、300 cm和300 cm,且补充深度均超过了测定的土壤深度,大于600 cm。     

水分亏缺冬小麦近等基因系冠气温差与群体总耗水量的关系

研究品种之间群体耗水特性的差异及其关键影响因素,为品种耗水特性评价与低耗水品种鉴选方法提供依据。选用水分亏缺条件下产量差异不显著,但耗水量差异极显著的冬小麦品种晋麦47和京411及其15个近等基因系为实验材料。利用防雨池和防雨棚开展实验,模拟水分亏缺条件。监测全生育期土壤水分含量,计算总耗水量,收获后测定籽粒产量,计算水分利用效率(WUE)。同时,分别在拔节-孕穗期、抽穗-开花期和灌浆期3个不同生育期监测冠层-大气温度差值(CTD)、叶片蒸腾速率和气孔导度。结果表明,3个不同生育期,15个近等基因系及其亲本之间,CTD均达到显著差异。CTD的方差分析表明,基因型和年份均对不同生育期的CTD有显著影响,但是二者之间仅在抽穗-开花期存在互作(P=0.0002)。15个近等基因系及其亲本之间耗水量存在显著差异,产量没有显著差异。源于耗水量的差异,部分品种/系之间WUE达显著差异。3个不同生育期,15个近等基因系及其亲本之间,CTD与总耗水量均呈极显著负相关关系。抽穗-开花期最高,2012—2013年度和2016—2017年度分别达到0.7042和0.6095。叶片蒸腾速率和气孔导度与群体总耗水量之间相关性很弱,3个生育期均未达到显著水平。对该组近等基因系材料,影响群体总耗水量的关键因素不是叶片蒸腾生理特性,而是群体冠层生长特性。表明构建合理的群体冠层结构不仅是获得高产的途经,而且是调控群体总耗水量,提高品种水分利用效率的重要途径。     

Relationship between ectoenzymatic activity and availability of organic substrates (Ross Sea, Antarctica): an experimental approach

Organic matter consumption and decomposition were studied in four experimental systems, having collected different organic substrates in the Ross Sea in December 1994. For the experimental approach selected, processes normally acting on a mixed pool of substances could be separated and the main features of each phenomenon could be focused on. Through the strict relationship between each experimental system and natural conditions shown by organic matter assessment, ectoenzymatic activity trends and their relation with Antarctic water substrates could be described. Through ice melting the water column becomes rich in large pools of substrates, as well as enzyme-producing micro-organisms, capable of quick development. The quantitative predominance of leucine-aminopeptidase throughout the year is well known, but its relative importance seems to decrease when, owing to production events, the environment is enriched with autotrophic- and heterotrophic-derived substances, leading to glycolytic enzymes expression. Thus, ectoenzymatic activity is supposed to be one of the factors responsible for organic matter variations, showing quantitative and qualitative changes depending on substrate availability. Received: 26 September 1997 / Accepted: 17 May 1998     

基于供需平衡的北京地区水生态服务功能评价

水生态系统的服务功能受到人类活动的严重胁迫和剧烈影响,对水生态服务功能的人类占用和胁迫效应进行研究具有重要意义.本文采用水当量方法,计算了1998-2007年北京地区人类活动对水生态服务功能的占用当量,并结合水资源供给量评价了人类活动对水生态系统的胁迫效应.结果表明：1）北京地区近10年人类活动的水当量超过其供给量的5～17倍;2）不同生态服务功能类型的水当量排序为：水环境净化>水资源供应>水生境维持>水安全调蓄;3）在时间序列上,水当量超过供给量的倍数呈先升后降的趋势,1999年的占用量超过其供给量的倍数最大.该研究揭示了北京地区人类活动对水生态系统服务的占用量远超过其可供给量,造成该地区水资源的过度占用,进而占用和影响其他地区的水生态服务功能.     

Chromosomal loci that influence oral nicotine consumption in C57BL/6J x C3H/HeJ F2 intercross mice

Several studies have demonstrated that there are genetic influences on free-choice oral nicotine consumption in mice. In order to establish the genetic architecture that underlies individual differences in free-choice nicotine consumption, quantitative trait loci (QTL) mapping was used to identify chromosomal regions that influence free-choice nicotine consumption in male and female F(2) mice derived from a cross between C57BL/6J and C3H/HeJ mice. These two mouse strains were chosen not only because they differ significantly for oral nicotine consumption, but also because they are at or near phenotypic extremes for all measures of nicotine sensitivity that have been reported. A four-bottle choice paradigm was used to assess nicotine consumption over an 8-day period. The four bottles contained water or water supplemented with 25, 50 or 100 microg/ml of nicotine base. Using micrograms of nicotine consumed per milliliter of total fluid consumed per day as the nicotine consumption phenotype, four significant QTL were identified. The QTL with the largest LOD score was located on distal chromosome 1 (peak LOD score = 15.7). Other chromosomes with significant QTL include central chromosome 4 (peak LOD score = 4.1), proximal chromosome 7 (peak LOD score = 6.1) and distal chromosome 15 (peak LOD score = 4.8). These four QTL appear to be responsible for up to 62% of the phenotypic variance in oral nicotine consumption.     

Systemic injections of gastro-intestinal peptides alter behavior in rats

Twenty-four male albino rats were given daily intraperitoneal injections of vasoactive intestinal polypeptide (VIP), motilin, human gastrin I (1–17) or the diluent control vehicle at a dose of 100 μg/kg for four consecutive days and food intake, water intake, body weight, and running wheel activity were determined every 24 hours. Animals injected with motilin or human gastrin I (1–17) exhibited decreased food intake relative to those injected with VIP or diluent, which did not differ from each other, although food intake increased reliably over days. The mean water consumption followed the same pattern as that of food intake. As expected from the above results, VIP produced weight gains as compared with rats injected with motilin or gastrin but not reliably more than after diluent. A reliable effect of trials for weight gain was the greatest on day three. Running wheel activity was not affected by injections of human gastrin I (1–17), motilin, or diluent but was reliably decreased by VIP. No significant differences existed across days. Although the results indicate that GI peptides may affect behavior when injected systemically and that like other peptides they have multiple effects, caution is urged in the interpretation of behavioral results at this time.     

Moderate alcohol consumption increases cholesterol efflux mediated by ABCA1

Moderate alcohol consumption increases HDL cholesterol, which is involved in reverse cholesterol transport (RCT). The aim of this study was to investigate the effect of moderate alcohol consumption on cholesterol efflux, using J774 mouse macrophages and Fu5AH cells, and on other parameters in the RCT pathway. Twenty-three healthy men (45-65 years) participated in a randomized, partially diet-controlled, crossover trial. They consumed four glasses of whisky (40 g of alcohol) or water daily for 17 days. After 17 days of whisky consumption, serum capacity to induce ABCA1-dependent cholesterol efflux from J774 mouse macrophages was increased by 17.5% (P = 0.027) compared with water consumption. Plasma capacity to induce cholesterol efflux from Fu5AH cells increased by 4.6% (P = 0.002). Prebeta-HDL, apolipoprotein A-I (apoA-I), and lipoprotein A-I:A-II also increased by 31.6, 6.2, and 5.7% (P < 0.05), respectively, after whisky consumption compared with water consumption. Changes of cAMP-stimulated cholesterol efflux correlated (r = 0.65, P < 0.05) with changes of apoA-I but not with changes of prebeta-HDL (r = 0.30, P = 0.18). Cholesterol efflux capacities from serum of lean men were higher than those from overweight men. In conclusion, this study shows that moderate alcohol consumption increases the capacity of serum to induce cholesterol efflux from J774 mouse macrophages, which may be mediated by ABCA1.     

Systemic injections of gastro-intestinal peptides alter behavior in rats

Twenty-four male albino rats were given daily intraperitoneal injections of vasoactive intestinal polypeptide (VIP), motilin, human gastrin I (1–17) or the diluent control vehicle at a dose of 100 μg/kg for four consecutive days and food intake, water intake, body weight, and running wheel activity were determined every 24 hours. Animals injected with motilin or human gastrin I (1–17) exhibited decreased food intake relative to those injected with VIP or diluent, which did not differ from each other, although food intake increased reliably over days. The mean water consumption followed the same pattern as that of food intake. As expected from the above results, VIP produced weight gains as compared with rats injected with motilin or gastrin but not reliably more than after diluent. A reliable effect of trials for weight gain was the greatest on day three. Running wheel activity was not affected by injections of human gastrin I (1–17), motilin, or diluent but was reliably decreased by VIP. No significant differences existed across days. Although the results indicate that GI peptides may affect behavior when injected systemically and that like other peptides they have multiple effects, caution is urged in the interpretation of behavioral results at this time.     

Mode of consumption plays a role in alleviating hunger and thirst

While studying the effect of structure on satiety, effects of mode of consumption, additional water to drink, and thirst have been neglected. The objective was to assess effects of structure, mode of consumption of food, and additional drinking of water on fullness and thirst. In study 1, 20 subjects (BMI 22.5 ± 0.5 kg/m(2); age 21.4 ± 3 years) underwent consumption conditions; SEW: solids to eat + 750 ml water to drink; LEW: liquefied soup to eat including 500 ml water + 250 ml water separately to drink; LDW: the same as LEW but served as drinks; SE, LE, and LD: the same as previous but without water to drink. In study 2, a subset of subjects underwent consumption conditions: solid carbohydrate, solid protein, solid fat: the same as SEW, but for each macronutrient separately; liquefied carbohydrate, liquefied protein, liquefied fat: the same as LEW, but for each macronutrient separately. Appetite, insulin concentration, glucose concentration, and ghrelin concentration were measured. Eating, independent of structure, suppressed desire to eat more than drinking (P < 0.01). Drinking water separately vs. water consumption in the food suppressed thirst more (P < 0.001). Regarding protein, satiety was higher in the solid vs. liquefied condition, while blood parameters were not significantly different. Only after drinking a meal most subjects (80%) wanted to consume more of the same meal, in order to alleviate hunger (63%) or quench thirst (37%). We conclude that mode of consumption plays a role in alleviating hunger and thirst. Subjects required further consumption after drinking the meal, motivated by hunger or thirst, showing that drinking a meal causes confusion that may imply a risk of overconsumption.     

A computerized apparatus designed to automatically dispense, measure, and record alcohol consumption by individual members of a rhesus macaque social group: trait-like drinking across social- and single-cage conditions

BACKGROUND: The present study tested the validity of an automated ethanol dispensing apparatus that is capable of identifying individual monkeys and precisely measuring their levels of ethanol consumption while living in a social group, and assessed individual subjects' level of consumption when alone and in social groups. METHODS: In Experiment 1, 21 rhesus macaques (Macaca mulatta) were given access for 1-h each day to the dispensing apparatus, which contained an aspartame-sweetened 8.4% (v/v) ethanol solution. Measurements of blood ethanol concentrations were taken for each subject and compared with the level of consumption recorded by the apparatus for those subjects. To examine the possibility that competition among the animals limited their access to the dispensing unit, in Experiment 2, 10 of the subjects used in Experiment 1 were singly housed to allow them to drink without interference from other monkeys. A correlation was then performed to assess the interindividual relationship between the amount of ethanol consumed in these two housing conditions. RESULTS: In Experiment 1, the volume of solution measured and recorded by the apparatus correlated positively with the true volume dispensed. Furthermore, the volume of solution reported by the computer to have been consumed by an individual subject correlated positively with blood ethanol concentrations. In Experiment 2, the volume of ethanol consumed by individual subjects in single cages correlated positively with their consumption in the social group. CONCLUSIONS: The apparatus accurately identified and measured individual patterns of ethanol consumption among socially housed animals. Additionally, individual differences in ethanol consumption remained stable across settings, as shown by the strong positive correlation between drinking in a social setting versus drinking alone. This finding may thus reflect an individual's constitutional proclivity to consume alcohol.     

Individual differences in peripheral blood immunological and hormonal measures in adult male rhesus macaques (Macaca mulatta): Evidence for temporal and situational consistency

A growing body of research has indicated that consistent individual differences exist in physiological systems with which the immune system interacts. Few data have been reported that demonstrate stable individual differences in immunological measures, however. In the present study, enumerative measures of immune system activity were examined in 36 adult male rhesus macaques over a 13 month period under baseline conditions as well as under conditions of pharmacological and physical challenge. Blood samples were assayed for plasma concentrations of ACTH and cortisol, as well as neutrophil, total lymphocyte, CD4+ and CD8+ lymphocyte numbers, and the CD4/CD8 ratio. Analyses revealed that individual differences in the CD4/CD8 ratio and, to a lesser extent, plasma ACTH and cortisol concentrations, and neutrophil and CD4+ lymphocyte numbers were consistent across situations and times, despite changes in mean values during the various blood sampling sessions. The results suggest that the CD4/CD8 ratio might be considered trait-like and a useful immunological measure of biobehavioral organization. Am. J. Primatol. 44:29–41, 1998. © 1998 Wiley-Liss, Inc.     

Water-use efficiency in rice (Oryza sativa L.) in relation to resistance to salinity

Abstract The effects of sodium chloride on water-use efficiency of a number of varieties of rice have been investigated. Sensitivity to salinity in rice arises in large part from excessive rates of sodium ion transport to the shoot consequent upon high rates of transpirational water loss. Varietal differences in water-use efficiency were found: these were greater when measured for whole shoots over a period of one week, than when made as instantaneous measurements on individual leaves. Salinity had rather little effect on water use efficiency but overall resistance of seedlings to salt was, in general, greater the greater the water-use efficiency. The reasons for the differences between varieties are discussed in terms of differences in growth pattern: among the seven varieties investigated, water-use efficiency and salt-resistance were lower in dwarfed as opposed to non-dwarfed varieties.     

Quantification of Goods Purchases and Waste Generation at the Level of Individual Households

Quantifying differences in resource use and waste generation between individual households and exploring the reasons for the variations observed implies the need for disaggregated data on household activities and related physical flows. The collection of disaggregated data for water use, gas use, electricity use, and mobility has been reported in the literature and is normally achieved through sensors and computational algorithms. This study focuses on collecting disaggregated data for goods consumption and related waste generation at the level of individual households. To this end, two data collection approaches were devised and evaluated: (1) triangulating shopping receipt analysis and waste component analysis and (2) tracking goods consumption and waste generation using a smartphone. A case study on two households demonstrated that it is possible to collect quantitative data on goods consumption and related waste generation on a per unit basis for individual households. The study suggested that the type of data collected can be relevant in a number of different research contexts: eco‐feedback; user‐centered research; living‐lab research; and life cycle impacts of household consumption. The approaches presented in this study are most applicable in the context of user‐centered or living‐lab research. For the other contexts, alternative data sources (e.g., retailers and producers) may be better suited to data collection on larger samples, though at a lesser level of detail, compared with the two data collection approaches devised and evaluated in this study.     

Interannual variations in the lipids of the Antarctic pteropods Clione limacina and Clio pyramidata

Antarctic pteropods, Clione limacina (Order Gymnosomata) and Clio pyramidata (order Thecosomata), were collected near Elephant Island, South Shetland Islands, during 1997 and 1998. Total lipid was high in C. limacina (29--36 mg g(-1) wet mass) and included 46% of diacy1glyceryl ether (DAGE, as % of total lipid) for both 1997 and 1998. DAGE was not detected in C. pyramidata, which had mainly polar lipid and triacy1glycerol. 1-O-Alkyl glyceryl ethers (GE) derived from the DAGE consisted primarily of 15:0 and 16:0, with lower 17:0 and a17:0. The principal sterols of both pteropods included trans-dehydrocholesterol, brassicasterol, 24-methylenecholesterol, cholesterol and desmosterol. Levels of 24-methylenecholesterol and desmosterol were lower in both pteropods in 1997 compared to 1998. C. limacina had high levels of the odd-chain fatty acids 17:1(n--8)c and 15:0 in contrast to C. pyramidata. The previously proposed source of elevated odd-chain fatty acids in C. limacina is via propionate derived from phytoplankton DMPT; another possible source may be from thraustochytrids, which are common marine microheterotrophs. C. pyramidata had twice as much PUFA as C. limacina, largely due to higher 20:5(n--3). The PUFA 18:5(n--3) and very long chain fatty acids (C(24), C(26) and C(28) VLC-PUFA) were only detected in 1998 pteropods. In comparison, 1996 samples of C. limacina contained lower DAGE levels, which also may reflect differences in diet and oceanographic conditions. Interannual variations in specific lipid biomarkers are discussed with respect to possible different phytoplankton food sources available in the AMLR survey area.     

Effect of increased atmospheric CO2 on the performance of an aquatic detritivore through changes in water temperature and litter quality

Cold water woodland streams, where terrestrially derived organic matter fuels aquatic food webs, can be affected by increases in atmospheric CO₂ concentrations, as these are predicted to lead to increases in water temperature and decreases in organic matter quality. In fact, elevated CO₂ (580 ppm) decreased the initial phosphorus concentration of birch litter by 30% compared with litter grown under ambient conditions (380 ppm). Here, we first assessed the effect of differences in litter quality on mass loss, microbial colonization and conditioned litter quality after submersion in a mountain stream for 2 weeks. Leaching did not change the relative differences between litter types, while fungal biomass was two fold higher in elevated litter. We then offered this litter (conditioned ambient and elevated) to a stream detritivore that was kept at 10 and 15 °C to assess the individual and interactive effects of increased temperature and decreased litter quality on invertebrate performance. When given a choice, the detritivore preferred elevated litter, but only at 10 °C. When fed litter types singularly, there was no effect of litter quality on consumption rates; however, the effect of temperature depended on individual size and time of collection. Growth rates were higher in individuals fed ambient litter at 10 °C when compared with individuals fed elevated litter at 15 °C. Mortality did not differ between litter types, but was higher at 15 °C than at 10 °C. Increases in temperature led to alterations in the individual body elemental composition and interacted with litter type. The performance of the detritivore was therefore more affected by increases in temperature than by small decreases in litter quality. However, it seems conceivable that in a future global warming scenario the simultaneous increases in water temperature and decreases in litter quality might affect detritivores performance more than predicted from the effects of both factors considered individually.     

Long Term Feeding Patterns Highlight Preference for Sucrose in the Fruit Fly <Emphasis Type="Italic">Anastrepha serpentina</Emphasis> When Given a Choice over Other More Nutritious Food Sources

Insects are known to be able to regulate food ingestion according to its nutrient composition rather than its energetic content. Several studies have found that individuals can feed selectively when given the opportunity, and balance the intake of different nutrients so as to optimize fitness. However, there are cases in which individuals do not strictly adopt this pattern of optimal nutrient balancing. This study examined the periodicity of feeding on different food substrates and also water by adult individuals of Anastrepha serpentina (Wiedemann) (Diptera: Tephritidae) over a 38-day observation period analyzing daily feeding patterns, feeding time, and sequences of feeding events. Two artificial food substrates, one rich in protein (hydrolyzed yeast) and one rich in carbohydrates (sucrose), and one natural diet (open sapodilla fruit) were offered alone or paired (sucrose vs. open fruit or sucrose vs. yeast) to newly emerged individuals during 38 days or until death. Water was also provided in all cases. Our results provide new and interesting insights on long-term individual dietary preferences and feeding periodicity in a tropical fruit fly, including water consumption. In general, flies exhibited different feeding patterns according to the diet, but preferred to feed on sucrose when offered a choice of sucrose and yeast. This preference was evident from the outset of the trial. When sucrose was offered together with an open fruit, the latter was preferred. However, there were conspicuous individual differences in temporal feeding patterns among flies fed the same diet, including variability in the number of consecutive days some individuals did not consume any food or water (up to five days in some cases). Individuals fed with sucrose only exhibited the lowest survival and those fed with sucrose-open fruit the highest. We discuss these feeding choices and their possible causes, including individual differences in the gut microbiota and nutritional reserves of newly emerged flies.     

Effects of food ration on SMR: influence of food consumption on individual variation in metabolic rate in juvenile coho salmon (Onchorhynchus kisutch)

1. Consistency of differences in standard metabolic rate (SMR) between individual juvenile salmonids and the apparently limited ability of individuals to regulate their SMR has led many researchers to conclude that differences in individual SMR are fixed (i.e. genetic). 2. To test for the effects of food ration on individual performance and metabolism, SMR was estimated by measuring oxygen consumption using flow-through respirometry on individually separated young of the year coho salmon (Oncorhynchus kisutch) placed on varying food rations over a period of 44 days. 3. Results demonstrate that the quantity of food consumed directly affects SMR of juvenile coho salmon, independent of specific dynamic action (SDA, an elevation in metabolic rate from the increased energy demands associated with digestion immediately following a meal) and indicates that higher food consumption is a cause of elevated SMR rather than a consequence of it. Juvenile coho salmon therefore demonstrated an ability to regulate their SMR according to food availability and ultimately food consumption. 4. This study indicates that food consumption may play a pivotal role in understanding individual variation in SMR independent of inherent genetic differences. We suggest that studies involving SMR need to be cautious about the effects of intra-individual differences in food consumption in communal tanks or in different microhabitats in the wild as disproportionate food consumption may contribute more to variation in SMR than intrinsic (genetic) factors. 5. In general, our results suggest that evolutionary changes in SMR are likely a response to selection on food consumption and growth, rather than SMR itself.