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Abstract

Temperature had a significant and positive effect on the foraging and growth of juvenile common carp Cyprinus carpio (90-105 mm) between 16 and 28 degrees C. Metrics measured were feeding rate (items s(-1)), functional response (feeding rate as a function of food density), specific growth rate and incremental fork lengths. Experiments that were conducted at 16, 20, 24 and 28 degrees C and used two food types revealed a strong thermal influence on foraging, with the highest feeding rates achieved at 24 degrees C. Functional responses also revealed optimal feeding rates in relation to food density occurred at temperatures > 20 degrees C. Specific growth rate and incremental fork lengths were depressed at 16 and 28 degrees C when compared to those achieved at 20 and 24 degrees C. These outputs suggest an increase in foraging and growth of C. carpio according to a thermal gradient that were maximal between 24 and 28 degrees C. (C) 2011 Elsevier Ltd. All rights reserved.

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... Cyprinus carpio was expected to show a type II functional response (Oyugi et al. 2012). The maximum feeding rate in this functional response was the asymptotic constant, a; the feeding rate at 50% of the doi: 10.1111/j.1600-0633.2012.00551.x ...
... asymptote was the half-saturation constant, b. These were integral components of the three-parameter Oyugi et al. 2012), where F = feeding rate and D = food density. ...
... To determine a and b, the paired fish were used in foraging trials where the food source was sinking fishmeal pellets (2 mm diameter; Oyugi et al. 2012) at release densities of between 12 and 160 items. During each trial, fish responses were filmed for 5 min after all the food items were released. ...
... Despite the negative isolated effects of warming and nitrate, some species seem to thrive in warm nutrient-rich waters. For instance, common carp (Cyprinus carpio), a widely distributed fish species with great ecological and economic importance, tends to live in warmer rivers (Korwin-Kossakowski, 2008;Oyugi et al., 2012). Moreover, their natural habitats are characterized by turbid, nitrate-rich (thus frequently hypoxic) waters (Huser et al., 2016), partly due to the their tendency to perform bioturbation (Bajer and Sorensen, 2015). ...
... It is hypothesized that sub-and supra-optimal temperatures reduce the MMR due to the limited biochemical mechanisms that sets the aerobic capacity of cells and tissues of the circulatory and ventilatory systems (Pörtner, 2017). Given this, elevation of MMR in 26 • C-acclimated fish seems logical as C. carpio has been documented to prefer living in warmer rivers with temperature reaching 28 • C (Oyugi et al., 2012), and the species can tolerate temperature approaching 35 • C (Eaton and Scheller, 1996). Hence, it is likely that 18 • C is suboptimal for AS relative to 26 • C, and that 26 • C is not high enough to reduce the AS of C. carpio. ...
Article
Climate warming is a threat of imminent concern that may exacerbate the impact of nitrate pollution on fish fitness. These stressors can individually affect the aerobic capacity and stress tolerance of fish. In combination, they may interact in unexpected ways where exposure to one stressor may heighten or reduce the resilience to another stressor and their interactive effects may not be uniform across species. Here, we examined how nitrate pollution under a warming scenario affects the aerobic scope (AS), and the hypoxia and heat stress susceptibility of a generally tolerant fish species, common carp Cyprinus carpio. We used a 3 × 2 factorial design, where fish were exposed to one of three ecologically relevant levels of nitrate (0, 50, or 200 mg NO 3-L − 1) and one of two temperatures (18 • C or 26 • C) for 5 weeks. Warm acclimation increased the AS by 11% due to the maintained standard metabolic rate and increased maximum metabolic rate at higher temperature, and the AS improvement seemed greater at higher nitrate concentration. Warm-acclimated fish exposed to 200 mg NO 3-L − 1 were less susceptible to acute hypoxia, and fish acclimated at higher temperature exhibited improved heat tolerance (critical thermal maxima, CTMax) by 5 • C. This cross-tolerance can be attributed to the hematological results including maintained haemoglobin and increased haematocrit levels that may have compensated for the initial surge in methaemoglobin at higher nitrate exposure.
... A nemzetközi szakirodalomban a különböző hőmérsékleti kezeléseknek a juvenilis pontyok (Cyprinus carpio) (Oyugi et al. 2012) és ezüstkárászok (Carassius gibelio) (Kestemont 1995) növekedésére és táplálékfelvételére gyakorolt hatására vonatkozóan is találni adatokat. A pontyok esetében 24 °C-ig folyamatosan nőtt mind a táplálékfelvétel, mind a növekedés sebessége, 28 °C-nál azonban már csökkenést mutatott. ...
... Ezzel szemben télen, mikor a külső környezeti hőmérséklet alacsonyabb, a víz hőmérséklete sem haladja meg a 30 fokot. A szakirodalmi adatok szerint a ponty számára a 24 °C körülire tehető a hőmérsékleti optimum (Oyugi et al. 2012). Terepi méréseink alapján a téli vízhőmérséklet e körül az érték körül alakul, ami magyarázatként szolgál arra, hogy miért pont tél végére, tavaszra lesz jobb a pontyegyedek kondíciója. ...
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In this study we examined the population dynamics of fish in the thermal water provided boating lake of Hajdúszoboszló. Our investigation was made four times in the spring and autumn in 2017 and 2018. Our study sample consisted of 314 carp (Cyprinus carpio) and 402 Prussian carp (Carassius gibelio) individuals collected by electrofishing. We measured the standard length (SL) and the weight (W) of the fish in the field. We identified the relations between the length and the weight, and the conditions of the individuals. Covariance analysis (ANCOVA), Kruskal‐Wallis test and Mann‐Whitney test were used for statistical evaluation of data. The water temperature of the lake is continuously and considerably high (annual average is 21,7 °C, in summer more than 30°C) and this factor had different effects on the fish condition. Based on our results, significant differences were observed between the b values of length‐weight relationships (carp: 2.803–3.0796; Prussian carp: 3.0045–3.2840) and mean condition factor (carp: 2.37–2.48; Prussian carp: 2.83–2.86) of fish living in thermal lake and those of fish living in natural water bodies in temperate zones. This phenomenon may be the result of the lack of significant annual alternations of water temperature in the thermal lake. On the other hand, there was no significant differences between seasonal conditions of fish in the thermal lake, may be due to lack of winter dormancy of fish. Based on the results it can be established that the permanently relatively high temperature increased the condition of generalist Prussian carp more than that of carp. As a result of global climate change gradual warming of water bodies can be expected. Since the ecological tolerance and physiology of fishes are different, therefore investigation of their adaptative capability in changed environment should be a priority.
... The WaterT at the Ghrib Reservoir varies between 10 to 25°C. The experiences of Oyugi et al. (2012) show that between 24 and 28°C, there is an increase in the search for food and the growth of C. carpio. Therefore, the temperature is an essential factor that rules many processes for fishes; the species are in a thermic range, where the physiological processes worked in an optimal manner (Oyugi et al., 2012). ...
... The experiences of Oyugi et al. (2012) show that between 24 and 28°C, there is an increase in the search for food and the growth of C. carpio. Therefore, the temperature is an essential factor that rules many processes for fishes; the species are in a thermic range, where the physiological processes worked in an optimal manner (Oyugi et al., 2012). Cyprinus carpio has the capacity to grow more rapidly in regions where the temperatures are higher and longer growth seasons (Englund et al., 2011). ...
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This study was conducted with a sample of 733 Cyprinus carpio collected between May 2013 and February 2016 from the ecosystem lake in the Ghrib dam which is eutrophic. Cyprinus carpio in this dam is characterized by a single fractional spawning that begins in the spring and ends in the late summer. The distributions of the viscerosomatic and gonadosomatic indices decrease between the spring and summer seasons. These periods correspond to the spawning period and the biological break of this species. They progressively increase between autumn and winter when the biological activity of the species returns. The hepatosomatic index progressively decreases between the spring and the summer when the hepatic reserves are used for reproduction. The repletion index shows that the trophic activity of C. carpio is intense in the spring. The condition factor varies between 1.1 and 1.35. The evolution of the biological indices of both sexes is well stressed in well-defined periods according to the seasons. The values are weak for males and high for females. The redundancy analysis allows the characterization of the influence of the physico-chemical parameters of the dam water, especially the role of the nutritious elements, in the biological seasonal cycle of C. carpio.
... Ембріональний період онтогенезу риб різних видів може фізіологічно протікати у певних межах температурного оптимуму. Вплив температури, наближеної до показників нижньої та верхньої межі для певного виду, при інкубації ікри може призвести до критичних змін в ембріональному періоді (аномальні процеси у личинок та їх летальності) (Metz et al., 2003;Oyugi et al., 2012;Martseniuk et al., 2017). ...
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Abiotic factors of the water environment are essential for the life of hydrobionts. They are determined by two main criteria – the intensity of the impact factor and the tolerance of each species. The work aims to substantiate the adaptive capabilities of this summer's koi carp (Cyprinus carpio koi) under the influence of low and high temperatures, to compare the coefficients and breathing rhythms of the research objects. Experimental research was carried out in the conditions of the aquarium-basin complex of the Department of Ichthyology and Zoology of the Bila Tserkva National Agrarian University. Two aquariums with a volume of 800 dm3 were used for the experiment. Individuals of approximately the same size and weight (25–30 g) were divided into two groups. The first group of fish was kept at a temperature of 11–14 °C for 30 days, and the second group was kept at a temperature of 24–29 °C for 30 days. During the experiment, there were 20 specimens in each aquarium. This summer koi carp (Cyprinus carpio koi). Feeding was carried out with Alltech Coppens Pre Grower feed – 15EF, 2.0 mm. Composition of ingredients (%) per 1 g of feed: raw protein – 50; fats – 15; fiber – 0.80; ash – 8.6; phosphorus – 1.21. In experimental conditions, changes in consumption of koi carp (Cyprinus carpio koi) O2, the release of CO2 and NH3 (per 1 g of live weight in 1 hour) at temperatures of 11–14 °С and 24–29 °С were studied. The consumption of O2 and the release of NH3 in these summers of koi carp at low and high temperatures were compared. The change in respiration (RR) and ammonia (N/O) coefficients in “warm” and “cold” fish with increasing temperature was analyzed. The breathing rhythm and oxygen per breath at different environmental temperatures were determined. Based on the obtained data, the adaptive reactions of this year's koi carp to the influence of reduced and increased temperature indicators of the aquatic environment were determined.
... The specific growth rates recorded for carp were at the low end of the range recorded in other studies cited (Table 8), most of which occurred in warmer temperatures. The growth rates of carp are positively correlated with temperature [77], and the optimum temperature range for the growth of carp is 24-28 • C [78]. Lower temperatures, such as those during most of our study, can result in reduced feeding and growth rates [79]. ...
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Aquaponics has the potential to contribute to food security in urban Nepal, where agricultural land near cities is rapidly being converted for other uses. This system’s use is expanding in Nepal, but the relatively high cost of commercial fish food is a hindrance. As a result, some aquaponics operators are resorting to alternative, less expensive fish foods. Since the primary input of nutrients to the plants grown in aquaponics comes from the fish food, an evaluation of the impact of fish foods on plant and fish growth is needed to help operators evaluate the costs and benefits of commercial compared to alternative fish diets. This study evaluated the growth of lettuce and common carp, the most common species of plant and fish used in aquaponics in Nepal, with three fish diets (commercial fish food, commercial chicken food, and a homemade diet with mustard oil cake and rice bran) at a commercial aquaponics farm with nine identical systems allowing for three replicates of the three fish food treatments. There were no significant differences in the measurements of lettuce growth (stem length, root length, and stem mass) and few differences in nutrient concentrations in leaf tissue. The specific growth rate of the carp fingerlings was lowest for the fish in the systems fed with the homemade diet (0.21) compared to those fed commercial fish food or commercial chicken food (0.31 and 0.28, respectively). These findings suggest that aquaponics operators who have been buying the more expensive commercial fish food with fish meal as its protein source can save 60–95% of the related costs by using commercial chicken food or the homemade diet defined in this study. This could potentially encourage the expansion of aquaponics systems in Nepal.
... The results of the research agreed with the findings of Al-Taee (2010) The accumulation of heavy elements in the water lentil plant depends on the contents of the growth medium. Temperature has a significant and positive effect on the nutrition and growth of common carp fish Cyprinus carpio male Oyugi et al. (2012) When rearing carp fish at different temperatures (16, 20, 24 and 28) the temperature of 24 °C achieved good growth Compared to other degrees, the best temperature for searching for food and eating feed was 24-28 °C for carp fish. Desai and Singh (2009) indicated that feeding carp fish at 28°C was better than 32°C, which gave the best growth and increase in feeding efficiency. ...
... Since ectotherm metabolic rates increase with temperature (Angilletta Jr & Angilletta, 2009;Brown et al., 2004), ectotherms require more energy to sustain these higher metabolic rates of growth and respiration under climate change. While feeding rates tend to increase to meet metabolic needs (Briceño et al., 2020;Nowicki et al., 2012;Oyugi et al., 2012), the response may be insufficient, if for instance there is insufficient food availability, or the organism lacks the aerobic scope to increase feeding rate (Pörtner & Knust, 2007). If energy uptake requirements cannot be met, growth rates decrease (Donelson et al., 2010(Donelson et al., , 2011Munday et al., 2008), resulting in a decrease of growth conversion efficiency (GCE) (Barneche et al., 2019), defined here as: ...
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Ocean warming is already causing widespread changes to coral reef ecosystems worldwide. Warming is having direct and indirect impacts on food webs, but their interaction is unclear. Warming directly affects fishes and invertebrates by increasing their metabolic rate, resulting in changes to demographic processes such as growth rates. Indirect effects involve a loss of reef habitat quality as coral bleaching reduces the availability of refuges. We used a size‐structured dynamic energy budget model of fishes and invertebrates, coupled to a spatially explicit model of coral and algae, to explore potential changes to ecosystem function with warming. Modeled changes in biomass for +3°C of warming were found to be controlled predominantly by the direct effects of warming on growth rates, rather than by indirect effects via the changed coral habitat. Crucially for fisheries, the biomass of predators decreased by at least 50% with +3°C of warming, and productivity of predators decreased by at least 60%.
... Viable common carp lacustrine populations in Europe were mostly absent in areas with continental climate, while they were more frequent in areas with marine influence near the Baltic Sea, the Mediterranean Sea, the North Sea and the Atlantic Ocean. Common carp populations thrive in dry and warm climates (Oyugi et al. 2012;Vilizzi 2012;Marr et al. 2013). Even though our results confirmed this pattern, they also indicated that areas with suboptimal climatic conditions can also allow the establishment of viable populations. ...
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Climate is a major driver of species distribution and biological invasions worldwide. In this study, we combined the catches of a widespread and invasive species, the common carp (Cyprinus carpio), with climate data to assess the importance of climate variables on the ability of the species to maintain self-sustaining populations in European lakes. Data were collected on common carp populations in 378 lakes in six European countries over a 16-year period (551 sampling campaigns). All catches followed the same standardized sampling procedure (European CEN gillnets). Climate data consisted of daily averages of air temperature and precipitation. Population self-sustainability was determined by the relative catches of different size classes and the presence of juveniles. The climate data were used to train a classification tree model to characterize the effects of climate on common carp population viability. Results indicated that climate is an important predictor of common carp population viability, which is particularly enhanced under dry conditions and elevated temperatures during spring and summer months. Areas of high population viability strongly Supplementary Information The online version contains supplementary material available at https://doi.().,-volV) (01234567 89().,-volV) overlapped with the invasive range of the species. According to Intergovernmental Panel on Climate Change (IPCC) climate projections, some areas where common carp currently have a low probability of maintaining viable populations will shift toward climatic conditions that enhance their viability and invasion potential.
... In 2018, farmed production of this species totaled 4,189,500 metric tons, accounting for 7.7% of world finfish aquaculture output (Food and Organization, 2020). One previous study revealed that the foraging performance and growth rates of juvenile C. carpio were strongly regulated by temperature and produced the highest foraging rates and fastest growth in the C. carpio between 20 • C and 24 • C (Oyugi et al., 2012). C. carpio growth is fastest in areas where water temperatures remain about 20 • C throughout the year (Oyugi et al., 2011), and above 35 • C is not conducive to the growth performance of C. carpio (Eaton and Scheller, 1996). ...
Article
The present study aimed to evaluate the effects of using different feeding strategies on the growth performance, feed efficiency, antioxidant capacity, digestive enzyme activities, and serum biochemical parameters of common carp, Cyprinus carpio for 40 days under high-temperature stress. A total of 120 fish (average initial weight 25.30 ± 1.27 g) were distributed in 12 tanks maintained in a circulating aquarium system (a water flow rate of 1 L/min). Fish were divided into four treatments: feeding every day with two meals, feeding one-day intervals with two meals, feeding two-day intervals with two meals, and feeding four-day intervals with two meals (named as T0, T1, T2, and T3, respectively). The results show that the weight gain (WG) and specific growth rate (SGR) of the T2 group were significantly higher than the other groups, while the feed conversion rate (FCR) of the T2 group was lower than in the other groups (P < 0.05); Serum glucose (GLU) content of fish in the T2 group was significantly higher than the other groups; The liver total superoxide dismutase (T-SOD) activity of fish in the T0 group had a significantly lower value than in the T2 group (P < 0.05); The liver malondialdehyde (MDA) content of fish in the T0 group had a significantly lower value than those others (P < 0.05); the gut trypsin and lipase (LPS) activity of fish in the T2 group showed the highest value, while the gut amylase (AMS) activity of fish in the T0 group showed the lowest value compared to the others; the IBR index showed the lowest value in the T2 group. It can be concluded that the T2 group of fish showed the best growth performance and gut digestive enzyme activities, with reduced negative impacts during high-temperature stress. This intermittent feeding strategy improved the antioxidant status of fish. Therefore, feeding every third day is recommended as an improved feeding regime for C. carpio during periods of elevated water temperature. The results of this study further extend our understanding of how feeding strategies in C. carpio culture can be implemented rationally during summer under high temperatures, which will provide valuable information for improving aquaculture management.
... However, at 24 • C, the BR population demonstrated no further increase in either mass or length suggesting an upper thermal limit for growth in this population (e.g. Koskela et al., 1997;Oyugi et al., 2012). In contrast, the WR population had increased in size with each temperature. ...
Article
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Temperature is one of the most important abiotic factors regulating development and biological processes in ectotherms. By 2050, climate change may result in temperature increases of 2.1–3.4◦C in Manitoba, Canada. Lake sturgeon, Acipenser fulvescens, from both northern and southern populations in Manitoba were acclimated to 16, 20 and 24◦C for 30 days, after which critical thermal maximum (CTmax) trials were conducted to investigate their thermal plasticity. We also examined the effects of temperature on morphological and physiological indices. Acclimation temperature significantly influenced the CTmax, body mass, hepatosomatic index, metabolic rate and the mRNA expression of transcripts involved in the cellular response to heat shock and hypoxia (HSP70, HSP90a, HSP90b, HIF-1α) in the gill of lake sturgeon. Population significantly affected the above phenotypes, as well as the mRNA expression of Na+/K+ ATPase-α1 and the hepatic glutathione peroxidase enzyme activity. The southern population had an average CTmax thatwas 0.71 and 0.45◦C higher than the northern population at 20 and 24◦C, respectively. Immediately following CTmax trials, mRNA expression of HSP90a and HIF-1α was positively correlatedwith individualCTmax of lake sturgeon across acclimation treatments and populations (r=0.7, r=0.62, respectively; P<0.0001). Lake sturgeon acclimated to 20 and 24◦C had decreased hepatosomatic indices (93 and 244% reduction, respectively; P<0.0001) and metabolic suppression (27.7 and 42.1% reduction, respectively; P<0.05) when compared to sturgeon acclimated to 16◦C, regardless of population. Glutathione peroxidase activity and mRNA expression Na+/K+ ATPase-α1 were elevated in the northern relative to the southern population. Acclimation to 24◦C also induced mortality in both populations when compared to sturgeon acclimated to 16 and 20◦C. Thus, increased temperatures have wide-ranging population-specific physiological consequences for lake sturgeon across biological levels of organization.
... The pH values remained relatively constant (ranged from 7.2 to 7.4), and did not change in any of the systems during the study period.Cahill et al. (2010) suggested that a lack of change in pH between systems may be attributed to the systems being maintained under good aeration. Water temperature in the fish tanks was around the average of 24°C, which is within the optimum temperature of common carp foraging and growth (24 and 28 °C) reported byOyugi, et al. (2012).The overall means of NH 4 -N, NO₂-N and NO 3 -N concentrations in fish tanks did not differ significantly (P>0.05) between the electromagnetic field system and the control system (Table 2). The results of the present study are comparable with the findings of various authors (Krzemieniewski et al., 2004; Hassan et al., 2018a; Hassan et al., 2019) who found no changes in ammonium concentrations between the magnetic field system and the control system. ...
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An integrated recirculating aquaculture system (IRAS) is considered as an alternative solution for efficient utilization of available resources, nutrient recycling and maintaining ecological balance. The effects of using magnetized water on the growth performance of common carp (Cyprinus carpio L.) and water quality parameters were investigated in an IRAS. Six independent IRASs were designed; each system consisted of three tanks: a fish rearing tank, a waste-collection tank and a biological filter tank. An additional crop of macrophyte (Lemna minor) was used as a medium in the biological filter tanks in order to qualify as an IRAS. Two treatments with three replicates were set up in a randomized design. The experimental treatment was supplied with the magnetic field device, while there was no device in the control treatment. The fish growth, feeding efficiency and water quality parameters were measured in all systems. The results revealed that the use of magnetized water in the IRASs increased the specific growth rate of common carp and the growth rate of plants; while, decreased the feed conversion ratio. However, the magnetized water had no effects on the concentrations of ammonium nitrogen, nitrite nitrogen and nitrate nitrogen. The study suggested that the use of magnetized water in the IRASs could be beneficial as a cost-effective technique to increase the profitability of the system.
... The ecological spectrum of carp is broad. Best growth is obtained when water temperature ranges between 23 and 30 • C (Sapkale et al., 2011;Oyugi et al., 2012). ...
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As a consequence of global warming, increase of water temperature is likely to alter physiological functions of fish. Hence, we examined the effects of high temperature on blood glucose, hematological parameters (hemoglobin, Hb; red blood cell, RBC; and white blood cell, WBC), and nuclear and cellular structure of blood cells of common carp (Cyprinus carpio) after exposure to three temperature regimes (27, 31 and 35°C) for 14 days. Fish were sacrificed on 3, 7 and 14 days of exposure. The blood glucose level increased significantly in the fish exposed to 35°C compared to 27°C and 31°C. The Hb and RBC contents decreased but WBC increased significantly in the blood of fish exposed to 35°C compared to 27°C and 31°C at 7 and 14 days of exposure. Consequently, the frequencies of erythroblasts (Ebs), erythrocytic nuclear abnormalities (ENA) and erythrocytic cellular abnormalities (ECA) were found to be increased in the blood of fish exposed to 35°C compared to 27°C and 31°C. There was a significant increase in neutrophils and decrease in lymphocytes in the highest temperature (35°C). With increasing temperature, dissolved oxygen decreased but free CO2 increased significantly during the study period. The present study demonstrated that common carp are better adapted to 27°C and 31°C environmental temperatures, while the higher temperature 35°C is likely stressful to this fish species.
... It is therefore of great importance for the carp farmer to be able to determine the fat content during the year in order to adjust the diet. Especially in the warm summer months, the fat content can be influenced by feeding (Yamamoto et al., 2003;Okos et al., 2006;Oyugi et al., 2012). Furthermore, it is of great interest to the carp farmer to determine the fat content of the fish during harvesting in order to achieve the best price for high quality fish with fat contents below 10%. ...
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Carps are the third largest species in aquaculture worldwide and belong to the fish family ‘cyprinids’, which make up the largest part of aquaculture production. The production of lean carp is one of the main goals in the carp farming business. Carps are usually traded alive; in order to ensure product quality and achieve a high consumer acceptance, it is important to estimate the fat content of the living fish. Therefore, during this study, a total of 250 living carps were examined using a mobile ultrasound device. Additionally, a microwave technology based Fish Fatmeter (Distell, Fauldhouse, Scotland, UK) was used to determine the fat content of the living fish. Further measurements included weight, lengths, height and circumferences. The ultrasound measurements were performed on non-sedated fish using narrow water-filled containers. Two sagittal images per fish were taken to measure the backfat thickness at defined locations. Subsequently, the fish were taken out of the water in order to determine the fat content using the Fish Fatmeter. Weight and linear measurements were taken. After the in vivo measurements, about 10 fish per pond, in total 51 fish, were slaughtered and the fillets were analysed chemically. Linear regression models were developed. The Fish Fatmeter turned out to be an accurate method to determine the fat content of the fillet in mirror carps (R2 = 0.95). Regarding the ultrasound measurement of the backfat thickness, moderate correlations between ultrasound and Fish Fatmeter were achieved (R2 = 0.33–0.45). Pearson's correlation for linear measurement and the Fish Fatmeter showed negative prediction. In order to evaluate the relative backfat thickness, the ultrasound measurement was divided by linear measurements. The best correlation was found using the ultrasound measurement point where the backfat thickness reached a constant thickness divided by the circumference around the thinnest part of the tail fin (R2 = 0.74). In the next step, the carps were divided into groups of ten fish per pond. The mean Fish Fatmeter measurement and ultrasound measurement divided by circumference was calculated and correlated achieving an R2 of 0.92. Based on these findings, it seems plausible to estimate the fat content using a small sample of ten fish with an ultrasound device and a measuring tape.
... In our conditions, the growth of fish and feed efficiency decreased mainly during the last 39 d of trial due to a reduction in water temperature (< 20˚C) and feeding rate. In conventional Fish density and vegetables growth in a low-tech AP system aquaculture systems, according to Oyugi et al. [33], European Carp juveniles reached the highest growth rate at 20˚C to 24˚C, whereas Somerville et al. [11] reported that the optimal temperature of water for European Carp is between 25˚C and 30˚C. ...
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Aquaponics (AP) is a semi-closed system of food production that combines aquaculture and hydroponics and represents a new agricultural system integrating producers and consumers. The aim of this study was to test the effect of stocking densities (APL, 2.5 kg m⁻³; APH, 4.6 kg m⁻³) on water quality, growth performance of the European Carp (Cyprinus carpio L.), and yield of leafy vegetables (catalogna, lettuce, and Swiss Chard) in a low-technology AP pilot system compared to a hydroponic cultivation. The AP daily consumption of water due to evapotranspiration was not different among treatments with an average value of 8.2 L d⁻¹, equal to 1.37% of the total water content of the system. Dissolved oxygen was significantly (p < 0.05) different among treatments with the lowest median value recorded with the highest stocking density of fish (5.6 mg L⁻¹) and the highest median value in the hydroponic control (8.7 mg L⁻¹). Marketable yield of the vegetables was significantly different among treatments with the highest production in the hydroponic control for catalogna (1.2 kg m⁻²) and in the APL treatment for Swiss Chard (5.3 kg m⁻²). The yield of lettuce did not differ significantly between hydroponic control and APL system (4.0 kg m⁻² on average). The lowest production of vegetables was obtained in the APH system. The final weight (515 g vs. 413 g for APL and APH, respectively), specific growth rate (0.79% d⁻¹ vs. 0.68% d⁻¹), and feed conversion (1.55 vs. 1.86) of European Carp decreased when stocking density increased, whereas total yield of biomass was higher in the APH system (4.45 kg m⁻³ vs. 6.88 kg m⁻³). A low mortality (3% on average) was observed in both AP treatments. Overall, the results showed that a low initial stocking density at 2.5 kg m⁻³ improved the production of European Carp and of leafy vegetables by maintaining a better water quality in the tested AP system.
... (Kamiński, Kamler, Wolnicki, Sikorska, & Wałowski, 2010). Oyugi, Cucherousset, Baker, and Britton (2012) We found no external signs of the influence of water temperature on the biological quality and welfare of fish. However, in the present study, crucian carp juveniles reared at 28 and 31°C showed a significantly lower leucocyte count than the fish at 22 and 25°C. ...
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The performance of larvae and juveniles of the crucian carp, Carassius carassius, held at temperatures of 22, 25, 28 and 31°C was evaluated in terms of growth, survival and, only in juveniles, haematological indices. The best growth in both larvae and juveniles was recorded at 28°C (relative growth rate (RGR) of 27.52% and 3.50%/day, respectively). The highest final survival rates were found at temperatures of 25–28°C, exceeding 99% in larvae and equal to 100% in juveniles. Haematopoietic activity and leucocyte count were significantly disturbed at temperatures of 28 and 31°C. These temperatures were stressing to the juveniles, as shown by the lymphopaenia and neutrophilia found in their peripheral blood and haematopoietic kidney. Thus, the optimum temperature for growth of larval and juvenile crucian carp is close to 28°C. However, stress indicators found at this temperature in juvenile fish strongly suggest that the most favourable temperature range for long‐term rearing is below 28°C and near to 25°C.
... Dragonfly larvae feeding rates on mosquito prey increased on average by 42% between 24 and 32 °C (Fig. 1a). Positive associations between feeding rate and temperature have also been observed in other omnivorous insects (e.g., Vucic-Pestic et al. 2011), herbivorous insects (e.g., Birkemoe et al. 2016), and in fish (e.g., Oyugi et al. 2012). This suggests that increasing temperatures could put greater pressure on prey (Dell et al. 2014)-potentially leading to stronger top-down effects and influencing energy and nutrient cycling through food webs (Kratina et al. 2012). ...
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Warming due to climate change is expected to alter species interactions. These interactions are shaped by components of individual behavior, particularly foraging behaviors. However, few studies consider species’ behavioral responses to warming to predict how species interactions will be affected by warming. We chose two complementary approaches to examine how climate warming may affect the behavior and interactions of aquatic intraguild predators. First, we measured behavioral responses to warming in six larval dragonfly species, expecting that feeding rate and activity would increase with temperature. Secondly, we conducted intraguild predation (IGP) trials with three species to understand how temperature affects IGP, and if species’ behavioral responses to warming are indicative of the outcome of IGP interactions. Warming increased feeding rates by 42% on average across species but had no effect on activity rate. The magnitude of change in feeding rate was positively correlated with the maximum temperatures species experience across their ranges. Lastly, warming increased rates of IGP twofold, however, species’ behavioral responses alone were not predictive of their susceptibility to become IG prey of other larvae at warmer temperatures. Our results provide evidence that IGP interactions may be greatly affected by future increases in temperature; however, activity responses to warming alone are weak predictors of the outcomes of these interactions. Future studies should consider other species’ traits when forecasting the effects of climate change on species interactions.
... There was an improvement in water quality when exposed to the magnetic field with considerable change in the pH, total dissolved solids, total hardness, conductivity, salinity, dissolved oxygen, evaporating temperature, minerals, organic matter and total count of bacteria (Khudiar and Ali, 2012;Al-Mufarrej et al., 2005). Increasing the permeability of the cells, allowing the expansion of the gastrointestinal tract and increase feed utilization, which lead to increasing water permeability to improve absorption of nutrients and minerals in the body (Oyngi et al., 2012). In addition, magnetic water improves blood picture and increase the concentration of ions in the blood and therefore at the speed of chemical reactions and feed metabolism and increase the minerals, vitamins and immunity of animals (Lam, 2001;Saeed and Al-Shidede, 2013). ...
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A total number of 120 28 week-old laying hens of Gimmizah strain were distributed among four treatment groups in a completely randomized design with three replicates per treatment and ten hens per replicate. The first group kept as a control group received non-magnetized tap water and the other groups received tap water exposed to different intensity of magnetic strengths 2000, 3000 and 4000 gauss respectively. Laying hens were housed in 12 floor pens (2 m × 1.2 m × 2 m) furnished with wheat straw. Laying hens on-3000 and 4000 gauss magnetized water consumed significantly more feeds and all groups on the magnetized water had significantly better feed conversion ratio (FCR) than the control group. Egg weight and egg mass were significantly increased in groups supplemented with different strengths of magnetized water compared with the control group and albumen (%) and albumen dry matter (%) were significantly higher of groups offered 2000 and 3000 gauss tap water. Yolk (%) was significantly higher of group on 3000 gauss tap water compared to the control group. Shell thickness was significantly increased in group received 4000 gauss tap water compared with control group. Blood serum glucose and globulin were significantly increased in groups supplemented with 2000 and 3000 gauss water compared with the control group and group supplemented with 4000 gauss water. However, all groups supplemented with different strength of magnetic water had significantly decreased albumin/ globulin ratio. Serum phosphorus level, and blood pH increased. Triiodothyronine increased significantly in groups received magnetized water compared to control and the 2000 gauss group showed the highest response. Red blood cell count (RBCs) and haemoglobin (Hgb) were significantly increased in groups supplemented with 2000 and 3000 gauss water compared with control group. It could be concluded that productive performance, physiological response and egg shell quality of Gimmizah chicken were improved due to offering magnetized water with 2000 gauss was adequate to provide the beneficial effects.
... In the present study, the experiments were performed at 20°C, which is below the physiologically optimal temperature for common carp of about 24°C, when common carp had the best growth performance and feed conversion. Growth performance was slightly lower at 20°C and clearly depressed at 16 or 28°C (Oyugi, Cucherousset, Baker, & Britton, 2012). This indicates that 20°C, which reflect a usual temperature in European carp aquaculture ponds, is within the physiologically preferred temperature range of carp. ...
Article
The effect of dietary β-glucan on the bacterial community in the gut of common carp (Cyprinus carpio) was examined after oral application of Aeromonas hydrophila. Carp received either feed supplemented with 1% MacroGard®, a β-1,3/1,6-glucan, or a β-glucan-free diet. Fourteen days after feeding, half of the carp from each group were intubated with 10⁹ colony-forming units (CFU) of a pathogenic strain of A. hydrophila. Gut samples were taken 12 hr to 7 days after application and analysed using microbiological and molecular biological techniques (NGS, RT-PCR-DGGE). The reaction of the mucosa and the microbiota to an A. hydrophila intubation differed in carp fed with β-glucan compared to carp from the control group. In β-glucan fed carp, the total bacterial amount was lower but the number of bacterial species was higher. Bacterial composition was different for carp from both treatment groups. The number of mucin filled goblet cells was reduced in carp fed the β-glucan diet. Mucus was obviously released from the goblet cells and was probably washed out of the gut together with high numbers of bacteria. This might be protective against pathogenic bacteria and, therefore, feeding with β-glucan may provide protection against infections of the gut in carp.
... These man-made lakes are used extensively as aquaculture sites whereby, for example, juvenile mullets are released regularly to promote fisheries. Due to the significant reproduction and growth rates of carp in these hot latitudes (Oyugi et al. 2012;Weber and Brown 2013), this species currently provides the highest yields, representing 36% of the freshwater landings in terms of biomass. ...
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The aim of the present study was to understand how seasonal fish distributions affect acoustically derived fish biomass estimates in a shallow reservoir in a semi-arid country (Tunisia). To that end, sampling events were performed during four seasons (spring (June), summer (September), autumn (December) and winter (March)) that included day and night surveys. A Simrad EK60 echosounder, equipped with two 120-kHz split-beam transducers for simultaneous 5 horizontal and vertical beaming, was used to sample the entire water column. Surveys during spring and summer and daytime hours of winter were deemed unusable owing to high methane flux from the sediment, and during the day survey of autumn, fish were close to the reservoir bottom leading to low detectability. It follows that acoustic surveys should be conducted only at night during the cold season (December–March) for shallow reservoirs having carp Cyprinus carpio (L.) as the dominant species. Further, night-time biomass estimates during the cold season declined significantly (P , 0.001) 10 from autumn to winter. Based on our autumn night-time survey, overall fish biomass in the Bir-Mcherga Reservoir was high (mean (AE s.d.) 185 AE 98 tons (Mg)), but annual fishery exploitation is low (19.3–24.1 Mg) because the fish biomass is likely dominated by invasive carp not targeted by fishers. The results suggest that controlling carp would help improve the fishery.
... These man-made lakes are used extensively as aquaculture sites whereby, for example, juvenile mullets are released regularly to promote fisheries. Due to the significant reproduction and growth rates of carp in these hot latitudes (Oyugi et al. 2012;Weber and Brown 2013), this species currently provides the highest yields, representing 36% of the freshwater landings in terms of biomass. ...
Article
The aim of the present study was to understand how seasonal fish distributions affect acoustically derived fish biomass estimates in a shallow reservoir in a semi-arid country (Tunisia). To that end, sampling events were performed during four seasons (spring (June), summer (September), autumn (December) and winter (March)) that included day and night surveys. A Simrad EK60 echosounder, equipped with two 120-kHz split-beam transducers for simultaneous 5 horizontal and vertical beaming, was used to sample the entire water column. Surveys during spring and summer and daytime hours of winter were deemed unusable owing to high methane flux from the sediment, and during the day survey of autumn, fish were close to the reservoir bottom leading to low detectability. It follows that acoustic surveys should be conducted only at night during the cold season (December–March) for shallow reservoirs having carp Cyprinus carpio (L.) as the dominant species. Further, night-time biomass estimates during the cold season declined significantly (P , 0.001) 10 from autumn to winter. Based on our autumn night-time survey, overall fish biomass in the Bir-Mcherga Reservoir was high (mean (AE s.d.) 185 AE 98 tons (Mg)), but annual fishery exploitation is low (19.3–24.1 Mg) because the fish biomass is likely dominated by invasive carp not targeted by fishers. The results suggest that controlling carp would help improve the fishery.
... The faster daily growth rates of the fish that spawned later in the year were likely to have been associated with the higher water temperatures experienced in the river in July and August, given the importance of temperature for fish physiology and metabolism, and also its influence on the availability of food resources (Takasuka et al., 2007;Oyugi et al., 2012). Kestemont (1995) reported that the growth rates of juvenile C. auratus increase as the temperature increases up to 28°C. ...
Article
The consequences of fractional spawning on the early-life growth rates of invasive goldfish (Carassius auratus) from the Qinghai-Tibet Plateau were studied using the otolith microstructure of samples collected in June 2011. The effect of the estimated hatching date on the subsequent growth of individual fish was determined by back-calculating their number of growth days, daily growth rates and the onset of their second growth season. The number of growth days in the first growth season ranged from 93 to 186 days. Following hatching, daily growth rates increased rapidly to a maximum of 0.55 mm days−1 before declining to 0.09 mm days−1. The effect of the duration of the first growth season on individuals was significant (P < 0.01), with later spawned fish having faster growth rates. These later spawned fish were, however, still significantly smaller in body length at the end of the first growth season (37 ± 4 mm in late hatched fish vs 55 ± 9 mm in early hatched fish). However, the smaller, later hatched fish started growing earlier in their second growth season than all other fish (P < 0.01) and subsequently achieved larger growth increments (P < 0.01), suggesting that the larger, early-hatched fish were investing more resources in gonadal growth than somatic growth in their second growth year. Thus, this invasive population revealed considerable plasticity in their early-life growth rates that were associated with the hatching date, potentially having substantial effects on their development in their second year of life.
... In the present study, fish spent long periods without food when temperature was maintained at 22 • C. Fasting in low temperatures was also demonstrated in other fish species (Sun et al., 2006;Oyugi et al., 2012;Wu et al., 2015). In L. alexandri, the large amount of visceral fat could be an energy resovoir on which animals draw during periods of fasting. ...
... Each fish species has an optimum water temperature range in which the fish can grow fast. The experimental evidence suggests that water temperature is an important factor which has influence on aquaculture practices (Desai and Singh 2009), and it has also a profound impact on feeding rate, functional response and growth rate (Oyugi et al. 2012). Feeding rate, water temperature and fish size are three important factors synergistically affecting the growth of fish (Gardeur et al. 2007). ...
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Two feeding trials were conducted to determine the effects of feeding rates in juvenile Korean rockfish, (Sebastes schlegeli) reared at 17 and 20 °C water temperature. Fish averaging 5.5 ± 0.2 g (mean ± SD) at 17 °C and 5.5 ± 0.3 g (mean ± SD) at 20 °C water temperature were randomly distributed into 18 indoor tanks. At each water temperature, triplicate tanks were randomly assigned to one of six different feeding rates: 2.8, 3.8, 4.1, 4.4, 4.7 % and satiation (4.99 % BW day−1) at 17 °C and 2.8, 3.8, 4.1, 4.4, 4.7 % and satiation (5.0 % BW day−1) at 20 °C. After 4 weeks of feeding trial, weight gain (WG) and specific growth rate of fish fed groups at satiation and 4.7 % (BW day−1) were significantly higher than those of fish fed groups at 2.8, 3.8 and 4.4 % (BW day−1) in both 17 and 20 °C temperature. Feed efficiency and protein efficiency ratio of fish fed group at 2.8 % (BW day−1) was significantly lower than those of fish fed groups at 3.8, 4.1, 4.4 and 4.7 % (BW day−1) in both experiments. Hematocrit was significantly higher in fish fed group at 4.4 % (BW day−1) at 17 °C, and there was no significant difference in hemoglobin content amongst all fish fed groups at 20 °C. Glutamic oxaloacetic transaminase and glutamic pyruvic transaminase of the fish fed group at 2.8 % (BW day−1) were significantly higher than those of all other fish fed groups in both experiments. Broken line regression analysis of WG indicated that the optimum feeding rate of juvenile Korean rockfish was 4.48 % (BW day−1) at 17 °C and 4.83 % (BW day−1) at 20 °C. Therefore, these results indicated that the optimum feeding rate could be >4.1 % but 4.4 % but
... the food must be reduced (Türker and Yildirim, 2011). The experimental evidence suggests that water temperature is an important factor that influences aquacultural practices (Desai and Singh, 2009), as it has a profound impact on feeding rate, functional responses, and growth rate (Oyugi et al., 2012). The optimum water temperature increases the metabolic rate and the feeding demand of the fish, while low temperatures cause sluggishness by slowing down the rate of digestion (Park et al., 2012). ...
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Seven feeding trials were conducted to determine the effects of feeding rate and frequency in the Korean rockfish Sebastes schlegeli at seven different water temperatures. Two feeding-rate experiments for 5-g Korean rockfish at 17°C and 20°C; three feeding rate experiments for 16-g Korean rockfish at 16°C and 24°C; and finally, two feeding frequency experiments for 93- and 100-g at 15°C and 20°C were conducted. Twenty fish averaging 5.5 ± 0.2 g (mean ± SD) were randomly distributed into 18 indoor tanks containing 40-L seawater from a semi-recirculation system. Fish were fed a commercial diet for 4 weeks at water temperatures of 17°C and 20°C. Two feeding trials were conducted to determine the optimum feeding frequency in growing Korean rockfish reared at temperatures of 15°C and 19°C. Broken line regression analysis of weight gain (WG) indicated that the optimum feeding rates of 5-g growing Korean rockfish were 4.48% (BW/day; BW, body weight) at 17°C and 4.83% (BW/day) at 20°C. Broken line regression analysis of WG showed optimum feeding rates of 16-g juvenile Korean rockfish of 3.41% (BW/day) at 16°C, 3.75% (BW/day) at 20°C, and 3.34% (BW/day) at 24°C. The biological performance, results, along with morphological indices and serological characteristics, suggest that a feeding frequency of 1 meal/day was optimal to improve WG in growing Korean rockfish grown from 93 to 133 g at a water temperature of 15°C, and 100 to 132 g at 19°C.
... E-mail: rbritton@bournemouth.ac.uk the experiment (Table 1). As water temperatures have significant and positive effects on the growth and foraging rates of these fishes (e.g., Oyugi et al. 2012), then the experiment was performed at water temperatures of 18 and 22°C to identify whether these temperatures influenced the outcome of the trials. They were completed in aquaria of 45 l volume, arranged in columns of three shelves (one aquarium per shelf) on re-circulating systems. ...
... This would enable the prediction of foraging outcomes in relation to environmental and biological changes, in situations where direct observation was not possible. The degree to which these influencing factors can be investigated depends upon how they may be replicated under laboratory conditions, although both water turbidity (Vollset & Bailey 2011) and temperature ( Oyugi et al. 2012a,b) effects should be feasible in the current system. ...
Article
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The functional response is the relationship between the feeding rate of an animal and its food density. It is reliant on two basic parameters; the volume searched for prey per unit time (searching rate) and the time taken to consume each prey item (handling time). As fish functional responses can be difficult to determine directly, it may be more feasible to measure their underlying behavioural parameters in controlled conditions and use these to predict the functional response. Here, we tested how accurately a Type II functional response model predicted the observed functional response of roach Rutilus rutilus, a visually foraging fish, and compared it with Type I functional response. Foraging experiments were performed by exposing fish in tank aquaria to a range of food densities, with their response captured using a two‐camera videography system. This system was validated and was able to accurately measure fish behaviour in the aquaria, and enabled estimates of fish reaction distance, swimming speed (from which searching rate was calculated) and handling time to be measured. The parameterised Type II functional response model accurately predicted the observed functional response and was superior to the Type I model. These outputs suggest it will be possible to accurately measure behavioural parameters in other animal species and use these to predict the functional response in situations where it cannot be observed directly.
... Unfortunately, there are no previous studies demonstrating how water temperature may affect black pacu growth over an extended time, as it exists for other fishes (Ayala, 1999;Kubitza, 2000;Arizcun et al., 2002;Piedras et al., 2004). Oyugi et al. (2012) revealed a strong thermal influence on foraging and growth in juvenile common carp Cyprinus carpio (90-105 mm) between 16 and 28 °C. They showed optimal feeding rates occurred at temperatures >20 °C with SGR being depressed at 16 and 28 °C when compared to those achieved at 20 and 24 °C. ...
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Los organismos ectotérmicos viven normalmente dentro de un rango específico de variación térmica, tanto que la vida fuera de ese rango puede ser difícil o letal. El cultivo de la gamitana Colossoma macropomum en el Perú, se haexpandido hacia áreas con distintas condiciones climáticas. En acuicultura, recientemente se han evaluado nuevos insumos y dietas balanceadas para este pez, pero existe poca información referente al efecto de las variablesmedioambientales sobre el crecimiento, alimentación y utilización de los alimentos en esta especie. Este vacío de información, limita nuestra habilidad para optimizar la ingestión y utilización apropiada de los alimentos en C.macropomum y dificulta la planificación ante escenarios futuros de cambios de temperatura. El objetivo del presente estudio fue evaluar y comparar el crecimiento, la utilización de alimentos y la sobrevivencia de alevinos degamitana criadas en tres temperaturas: 27.5, 30 y 32.5 ºC. Noventa alevinos (peso promedio de 1.38 ± 0.03 g) fueron distribuidos en grupos de 10 ejemplares y colocados dentro de nueve tanques de fibra de vidrio de 30 L devolumen. Los peces fueron sometidos a un periodo de aclimatación de 7 días previo al inicio del periodo experimental que tuvo una duración de 21 días. Los peces criados a 30 °C tuvieron niveles de peso final, ganancia de peso, tasa específica de crecimiento, tasa de conversión alimenticia y tasa de eficiencia proteica significativamente mejores que los peces de los tratamientos térmicos 27.5 y 32.5 ºC (P<0.05). No se reportaron diferencias significativas en lo referente a la ingesta de alimento, ingesta de proteínas y factor de condición. Elestudio sugiere que un incremento de temperatura puede afectar la habilidad de la gamitana de utilizar adecuadamente sus alimentos y que el cultivo de este pez a temperaturas mayores a 30 ºC puede ser limitante para la especie.
... Oyugi et al. (2012) studied the Effects of temperature on the foraging and growthrate of juvenile common carp, Cyprinus carpio. The experiments revealed that the foraging performance and growth rates of juvenile C. carpio were strongly regulated by temperature. ...
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A review of the literature published in 2012 on topics relating to thermal effects. This review is divided into the following sections: regulatory aspects, pollution prevention, metal treatment methods, cyanide treatment, sludge treatment, pollution prevention, and waste minimization.
Article
The objective of this study was to elucidate the effect of temperature on food intake and time for digestion in larvae of Lophiosilurus alexandri. An experiment was performed with four constant temperatures (23°C, 26°C, 29°C, and 32°C), four ages (8, 13, 18, and 23 days post-hatching (DPH)) and eight sampling times (5, 15, 30, 45, 60, 120, 180, and 300 minutes after feeding). The effect of temperature was more evident at 18 and 23 DPH. Due to the increase in age and temperature, there was a decrease in the time to reach the highest rate of digested nauplii. In addition, the larvae were estimated to ingest up to 0.30 ± 0.10 MJ/larva at 32°C in the first meal of the day. Temperatures of 29°C and 32°C provided the most satisfactory results for intake, digestion rate, and intake as percentage of live weight in one meal.
Chapter
Over the last century, water temperatures in Lake Tanganyika have risen due to climate change, which increased thermal stratification and reduced the magnitude of nutrient availability. A rise in temperature increases the C:N:P ratio resulting in a poor algal diet. In addition, lake littoral habitat is experiencing increased sediment load due to deforestation of the watershed caused by anthropogenic activities. Sediments cover benthic algae and reduce its nutritional value, consequently affecting the foraging behavior, distribution, and growth performance of algivorous fish. Algae and algivorous fish are an important link in the lake food chain; therefore, if the rise in temperature will continue as predicted, then this may have a cascading effect for the rest of the community in the food chain including human being. This, in turn, may contribute to food insecurity at local and regional levels. To counteract this adaptation and mitigation measures such as environmental monitoring systems and creating new opportunities should be considered.
Article
Fishes are subject to numerous stressors, including climate change, fishing and impacts by alien species. One of the challenges in understanding species and community responses to these stressors is identifying how they modify predator–prey interactions, a key process shaping aquatic food webs. Here, we aim to synthesize how species traits, such as size, activity level and alien status, and environmental factors, such as water temperature, shape the functional response: the change in predator consumption rate in relation to changes in prey density. We compiled over 300 fish functional responses and examined sources of variation in two key parameters dictating its shape: handling times and space clearance rates. We found that compared to cold waters, warmer waters were characterized by decreased handling times and increased space clearance rates for smaller predators, but had an opposite effect for bigger predators, suggesting that, across species, altered predation rates may underlie the decrease in size at higher temperatures (the temperature‐size rule). We also found that the negative effect of increased temperature on the functional response of larger predators is more pronounced in active species. Finally, we found that known alien species do not exhibit different functional response parameters when examined on their native prey, suggesting that alien species are not primed for invasion via their high functional response. Together, these asymmetric changes imply that, across species, warmer waters may alter predator–prey relationships differentially according to predator size, prey size and activity levels.
Article
The common carp (Cyprinus carpio L.) is one of the most important freshwater fish species. As C. carpio culture has escalated, bacterial and parasitic infections have become a real threat to the industry. Antibacterial and antiparasitic treatments are provided for infection control in C. carpio. However, adequate vaccines have not yet been developed. Trichlorfon (TCF), an organophosphate, is an antiparasitic agent used in aquaculture to treat external parasites. However, there are few pharmacokinetic (PK) studies on its use in fish. This study investigated the residue elimination and temperature‐dependent PK characteristics of TCF in C. carpio at 15°C and 25°C after 30 mg/L TCF bath immersion for 30 min. TCF residue concentrations in plasma and muscle tissues were determined using liquid chromatography‐tandem mass spectrometry and further analyzed using a noncompartmental model. Temperature significantly affected specific PK parameters. Increasing the temperature from 15°C to 25°C shortened the elimination half‐life from 36.07 to 22.72 h. The time to reach the maximum plasma TCF residue concentration (Cmax) (Tmax) remained the same (0.5 h), but Cmax increased from 67.72 to 70.76 µg/L. The area under the plasma concentration–time curve decreased from 1,057.31 to 962.14 h∙µg/L. The muscle TCF Cmax was 446.99 µg/L with a corresponding Tmax of 0.5 h at 25°C, and 267.53 µg/L, with a corresponding Tmax of 1.0 h at 15°C. The temperature‐sensitive PK parameters, such as increased in Cmax and decreased elimination and distribution rates, significantly affected the plasma TCF residue concentration and its overall exposure to increasing temperature. Temperature affected the therapeutic outcomes of TCF treatment in C. carpio and likely other freshwater fish. Therefore, proper dosing regimens should take temperature into consideration.
Article
Seed stunting of rohu, Labeo rohita (Ham.) carried out for 6 months in 24 large (50 m2) concrete tanks using 20 and 40 fry m−2 rearing densities under open and shade (50% light incidence) conditions. A significant influence of tank shading observed on all the water quality parameters, unlike the density effect only on the dissolved oxygen content in water. Highly significant stunting effects of both higher density and shading observed on juvenile growth and survival after 2‐, 4‐ and 6‐month stunting. Doubling the density caused 22.9 and 27.8% weight suppression after 6‐month stunting under open and shaded conditions respectively. Similarly, shading caused 31.7 and 36.1% suppressed body weight after 6 months in the low‐ and high‐density groups respectively. However, the best stunting effect observed through a compounded effect of high density and shading as 50.7–57.0% growth suppression recorded within 2–6 months stunting. The study revealed both higher rearing density (two times) and tank shading (50% light incidence) to be effective tools for rohu juvenile stunting, while a combination of these factors yielded greater stunting effect. Such protocol can be used for production of stunted carp juveniles to ensure their round‐the‐year availability for stocking grow‐out ponds.
Article
• The mosquitofish (Gambusia affinis: Poeciliidae) is one of the world's most widespread invaders, but our ability to predict the consequences for native species in the tropics is limited by a paucity of research and a lack of knowledge of how environmental factors influence mosquitofish impacts. • We undertook a field experiment using cages to manipulate mosquitofish densities in a Hong Kong wetland during the warm wet season and the cool dry season. We measured fish effects on invertebrates and periphyton, and tested whether the results were affected by vegetation type (sedge vs. water lily). • Mosquitofish reduced abundance and richness of invertebrates, and altered assemblage composition, but had no effect on periphyton biomass. Effects on invertebrate abundance were consistent between seasons, but mosquitofish reduced invertebrate richness only during the wet season, when effects on assemblage composition were more obvious. Vegetation type had no influence on the experimental results. • This study adds to the few tropical, or Asian, field studies of the ecological impacts of mosquitofish, and is, as far as we are aware, the only such study measuring their seasonal variability. While we detected some cage effects during our field experiment, they were insufficient to obscure the strong influence of mosquitofish on invertebrate abundance and composition.
Chapter
Over the last century, water temperatures in Lake Tanganyika have risen due to climate change, which increased thermal stratification and reduced the magnitude of nutrient availability. A rise in temperature increases the C:N:P ratio resulting in a poor algal diet. In addition, lake littoral habitat is experiencing increased sediment load due to deforestation of the watershed caused by anthropogenic activities. Sediments cover benthic algae and reduce its nutritional value, consequently affecting the foraging behavior, distribution, and growth performance of algivorous fish. Algae and algivorous fish are an important link in the lake food chain; therefore, if the rise in temperature will continue as predicted, then this may have a cascading effect for the rest of the community in the food chain including human being. This, in turn, may contribute to food insecurity at local and regional levels. To counteract this adaptation and mitigation measures such as environmental monitoring systems and creating new opportunities should be considered.
Article
The study was conducted to analyze the water quality of Shahpur Dam, Pakistan, health of native fish Cyprinus carpio, and health risks associated to humans as consumers. Metal (Pb, Cu, Cr, Fe, Ni) concentrations in water and its bioaccumulation in fish tissues (liver, gills, muscles, kidneys, and brain) were determined by using an atomic absorption spectrophotometer. Pb was abundantly found in water (8.15 mg L−1) and fish organs compared with other metals, beyond the permissible referred guidelines. Metal pollution index (MPI) was found high in fish liver followed by gill, muscle, kidney, and brain. Toxicity potential of water pollution was determined in the form of oxidative stress by analyzing catalase (CAT), glutathione S-transferase (GST), and reduced glutathione (GSH) activities in liver and gill of Cyprinus carpio, using UV spectrophotometer. The CAT activity was found higher with inhibition of 41.1% and 2.1% in liver and gill of exposed fish. Inhibition of GST in liver and gill was recorded as 29.4% and 28.1%, respectively, whereas that of the GSH was observed 12.8% and 13.9%, respectively, showing significant oxidative stress in exposed fish of the dam compared with farm fish. Consequently, people consuming the contaminated fish are prone to health impacts, which was estimated by target hazard quotient (THQ), hazard index (HI), and cancer risk (CR). No metal was found to pose potential noncarcinogenic health risk individually or collectively at present but people consuming contaminated fish regularly were expected to be at target cancer risk in 70 years or more of their lifetime.
Article
Common Carp Cyprinus carpio is a nonnative species that often has deleterious effects on aquatic systems. As such, there is interest in suppressing nonnative Common Carp populations in areas where humans have introduced them. The objectives of this study were to 1) provide insight on efficient techniques for capturing Common Carp, 2) describe their population demographics and dynamics, 3) evaluate whether temperature and water elevation were related to growth and recruitment, and 4) develop an age-structured population model for evaluating different management scenarios of Common Carp removal in Lake Spokane, Washington. Catch rates of Common Carp varied among sampling gears with slightly higher catch rates in monofilament (mean ± SD; 15.5 ± 9.8 fish/net night) vs. multifilament (12.7 ± 7.3 fish/net night) gill nets. Catch rates of Common Carp with nighttime electrofishing (0.3 ± 0.4 fish/min) were higher than daytime electrofishing (0.1 ± 0.2 fish/min). Common Carp in Lake Spokane exhibited variable recruitment, rapid growth, large-length structure, high longevity (i.e., age 18 y), and low total annual mortality (17.0%). Air temperature was positively associated with annual growth increments ( R ² ≤ 0.25). Neither air temperature nor water elevation was highly correlated ( R ² ≤ 0.20) to recruitment of Common Carp. A Beverton–Holt yield-per-recruit model suggested that yield declined with increasing exploitation. Recruitment overfishing would occur at exploitation rates of 20–40% for all targeted minimum length categories (i.e., 150, 300, 450 mm) except 600 mm. Results from this study provide important information on the ecology of Common Carp that can be used to guide management efforts (e.g., suppression) in western systems.
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Functional responses - the relationships between consumer foraging rate and resource (prey) density - provide key insights into consumer-resource interactions and predation mechanics while also being a major contributor to population dynamics and food web structure. We present a global database of standardized functional response parameters extracted from the published literature. We refit the functional responses with a Type II model using standardized methods and report the fitted parameters along with data on experimental conditions, consumer and resource taxonomy and type, as well as the habitat and dimensionality of the foraging interaction. The consumer and resource species covered here are taxonomically diverse, from protozoans filtering algae to wasps parasitizing moth larvae to wolves hunting moose. The FoRAGE database (doi:10.5063/F17H1GTQ) is a living data set that will be updated periodically as new functional responses are published.
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The effect of juvenile Nile tilapia (Oreochromis niloticus, in unit I) and Common carp (Cyprinus carpio, in unit II) on plant growth (cucumber - Cucumis sativus, tomato - Solanum lycopersicum and lettuce - Lactuca sativa in co-cultivation) was investigated in two identical gravel substrate ebb-and-flood coupled aquaponic units (I, II) with 3.81 m³ total water volume and without addition of fertiliser for 70 days. The daily extruded floating feed input of 1.2% (200 g) of initial fish biomass (16.7 kg) per unit equalled 12.0 g feed per kg fish or 52.5 g m− 3. Growth of O. niloticus (unit I) was better (p < 0.05) in final weight (57.4 g ± 27.9), final biomass (27,683.3 g ± 160.7), specific growth rate (0.70% d− 1 ± 0.01) and feed conversion ratio (1.31 ± 0.02) in comparison to C. carpio (unit II, 42.7 g ± 22.2, 21,866.7 g ± 568.6, 0.39% d− 1 ± 0.02, 2.69 ± 0.20). Tomato gross biomass was two times higher in combination with O. niloticus and tomato fruit weight was slightly higher. Plant growth in cucumber showed higher total fresh biomass in the C. carpio unit. Lettuce yield was near zero as a result of inter-specific competition. The Aquaponic Growth Factor (AGF), describing the growth performance of fish and plant combinations, was highest in tomato (1.12) combined with O. niloticus compared with C. carpio (0.53). However, the AGF of cucumber was slightly higher in combination with C. carpio (0.14) compared with O. niloticus (0.12). This study demonstrates best plant growth for the combination of O. niloticus with tomato and C. carpio with cucumber. The unit stocked with C. carpio had higher levels of oxygen (6.3 mg L− 1 ± 0.8) and oxygen saturation (78.6% ± 8.4) in contrast to O. niloticus (5.8 mg L− 1 ± 0.8, 73.2% ± 8.9). The long steady state of dissolved oxygen inside both units allowed a higher daily feed input of 0.3% of fish initial biomass during spring and summer seasons, 25% above the optimal feed input estimated for the same units during winter time (0.9% = 150 g). C. carpio extended the equilibrium phase during plant production before a significant oxygen drop occurred, beneficial for coupled aquaponics. Different growth performance of fish and plant combinations suggest multiple fish species use or polyponics (polyculture + aquaponics) in coupled aquaponics to increase plant yield.
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The functional response describes the relationship between feeding rate and prey density, and is important ecologically as it describes how foraging behaviour may change in response to food availability. The effects of habitat complexity and food item size were experimentally tested on the foraging parameters and functional responses of the freshwater fish roach Rutilus rutilus. Habitat complexity was varied through the manipulation of substrate and turbidity, and food item size was varied by using fishmeal pellets in two sizes. As water turbidity and substrate complexity increased, the reaction distance and consumption rate (per number) significantly decreased. Increased food item size significantly decreased consumption rates (per number) but had no influence on any other foraging parameter. Analysis of the interactions between substrate complexity, turbidity and food item size revealed food item size had the greatest influence on consumption rate (per number). Turbidity had the least effect on all the foraging parameters tested. Across all experiments, the functional responses were best described by the Type II response, a relatively consistent finding for R. rutilus. These outputs reveal that fish foraging behaviours and functional responses are highly context dependent, varying with environmental parameters and the availability of food resources of different sizes.
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Index of published papers on thermology or temperature measurement Volume 4: 2011 to 2013
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Published papers on thermology or temperature measurement, between 2011 and 2012,
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The impact of anthropogenic climate change on terrestrial organisms is often predicted to increase with latitude, in parallel with the rate of warming. Yet the biological impact of rising temperatures also depends on the physiological sensitivity of organisms to temperature change. We integrate empirical fitness curves describing the thermal tolerance of terrestrial insects from around the world with the projected geographic distribution of climate change for the next century to estimate the direct impact of warming on insect fitness across latitude. The results show that warming in the tropics, although relatively small in magnitude, is likely to have the most deleterious consequences because tropical insects are relatively sensitive to temperature change and are currently living very close to their optimal temperature. In contrast, species at higher latitudes have broader thermal tolerance and are living in climates that are currently cooler than their physiological optima, so that warming may even enhance their fitness. Available thermal tolerance data for several vertebrate taxa exhibit similar patterns, suggesting that these results are general for terrestrial ectotherms. Our analyses imply that, in the absence of ameliorating factors such as migration and adaptation, the greatest extinction risks from global warming may be in the tropics, where biological diversity is also greatest. • biodiversity • fitness • global warming • physiology • tropical
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Utilizing optimal foraging theory and laboratory estimates of foraging costs, the choice of foods and use of habitats by fish in the field are predicted. Predictions are tested with bluegill sunfish Lepomis macrochirus foraging in open water, sediments, and vegetation in a pond. The optimal diet and profitability (net energy return) for each habitat through time were then determined. Predictions of optimal habitat use, ie when the fish should switch habitats to maximize feeding rates, showed striking correspondence to the actual habitat use of the fish.-from Authors
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A foraging model was developed to predict the optimal diet breadth and maximum energetic intake of a given-sized fish foraging in each of three aquatic habitats: the open water, vegetation, and bare sediments. Model parameters of prey encounter rates and prey handling times were quantified as functions of fish size, prey density, and prey size through a series of laboratory feeding experiments using the bluegill sunfish (Lepomis macrochirus). Results of these experiments show both searching ability and prey handling efficiency to increase with increasing fish size. Predictions of prey size selection and optimal habitat use based upon maximizing energetic gain were then examined in a small Michigan lake for three size classes of bluegills. Bluegills > 100 mm standard length were highly size selective in their feeding and their diets closely matched predictions of an optimal diet model. From two estimates of relative prey visibilities I show that these fish selected larger prey items than would be predicted if prey were consumed "as encountered." Habitat use of large bluegills was also shown to maximize foraging return as fish switched from utilizing vegetation-living prey to utilizing open-water zooplankton as relative foraging profitabilities in the two habitats changed across the summer. Bluegills
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This work proposes modifications to the existing system for identifying the steps of embryonic and larval development in fish. The term “compensatory phase of development” is proposed for the phase from hatching to the first intake of food. Both the new designations of these steps and the new name of this phase do not require a declaration of whether the hatched individual is considered to be an embryo or a larva, something that has been, to date, a matter of dispute. Unification will allow for the wider use of the new nomenclature, and make easier the comparison of results. This work examines the influence of the thermal history during the embryonic period (temperatures of 20, 24, 28, and 32°C) on later development, growth, and survival of common carp, Cyprinus carpio L., and grass carp, Ctenopharyngodon idella (Val.) larvae, at a constant temperature of 23°C. It was confirmed that the optimal temperature ranges for the embryonic development of common carp and grass carp are higher than those currently applied widely in practice of 18-22°C and 21-26°C, respectively. Based on the evaluation of the development, growth, and survival of the larvae, it was determined that the optimal temperature for embryonic development is 26-28°C for the common carp and 32°C for the grass carp. It was confirmed that even a short-term increase in temperature from 20°C to 24°C during the compensatory phase has a positive influence on subsequent common carp larvae growth.
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The effects of climate warming on the thermal habitat of 57 species of fish of the U.S. were estimated using results for a doubling of atmospheric carbon dioxide that were predicted by the Canadian Climate Center general circulation model. Baseline water temperature conditions were calculated from data collected at 1,700 U.S. Geological Survey stream monitoring stations across the U.S. Water temperatures after predicted climate change were obtained by multiplying air temperature changes by 0.9, a factor based on several field studies, and adding them to baseline water temperatures at stations in corresponding grid cells. Results indicated that habitat for cold and cool water fish would be reduced by ~50%, and that this effect would be distributed throughout the existing range of these species. Habitat losses were greater among species with smaller initial distributions and in geographic regions with the greatest warming (e.g. the central Midwest). Results for warm water fish habitat were less certain because of the poor state of knowledge regarding their high and low temperature tolerances; however, the habitat of many species of this thermal guild likely will also be substantially reduced by climate warming, whereas the habitat of other species will be increased.
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Feeding rate experiments were conducted for pink salmon Oncorhynchus gorbuscha fry [mean fork length (LF) 39 mm], juveniles (103–104 mm LF) and juvenile chum salmon Oncorhynchus keta (106–107 mm LF). Fishes were presented with small copepod (Tisbi sp.) or larger mysid shrimp (Mysidopsis bahia) prey at varying densities ranging from 1 to 235 prey l−1 in feeding rate experiments conducted at water temperatures ranging from 10·5 to 12·0° C under high light levels and low turbidity conditions. Juvenile pink and chum salmon demonstrated a type II functional response to mysid and copepod prey. Mysid prey was readily selected by both species whereas the smaller bodied copepod prey was not. When offered copepods, pink salmon fry fed at a higher maximum consumption rate (2·5 copepods min−1) than larger juvenile pink salmon (0·4 copepods min−1), whereas larger juvenile chum salmon exhibited the highest feeding rate (3·8 copepods min−1). When feeding on mysids, the maximum feeding rate for larger juvenile pink (12·3 mysids min−1) and chum (11·5 mysids min−1) salmon were similar in magnitude, and higher than feeding rates on copepods. Functional response models parameterized for specific sizes of juvenile salmon and zooplankton prey provide an important tool for linking feeding rates to ambient foraging conditions in marine environments, and can enable mechanistic predictions for how feeding and growth should respond to spatial-temporal variability in biological and physical conditions during early marine life stages.
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To evaluate the potential invasiveness of pumpkinseed Lepomis gibbosus introduced to northwestern European inland waters, growth and reproduction traits were examined in ten populations along a trajectory spanning northwestern Europe (Norway, England, Holland, Belgium and France) and evaluated in light of published dataset from Europe. In the 848 pumpkinseed captured, maximum age was 3–4 years, with a sex ratio near unity in all but one population. Significant variations with increasing latitude were observed in adult growth (age 2–3 increment in total length, TL) and mean age at maturity (A M), with non-significant variations observed in juvenile growth (TL at age 2), sex ratio and gonado-somatic index. As observed elsewhere in Europe, mean A M decreased significantly with increasing TL at age 2. Using this relationship, which has been proposed elsewhere as a potential predictive model of pumpkinseed invasiveness, eight of the ten populations could be provisionally categorized as ‘non-invasive’ (five populations), ‘transitional’ (one population) and ‘potentially invasive’ (two populations), with two populations not categorized due to insufficient data. Based on the available knowledge on each population, the relationship between juvenile growth and age at maturity appeared to predict reasonably the status of pumpkinseed in northwestern Europe and its applicability to other species should be tested.
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The eastern mosquitofish (Gambusia holbrooki) is among the most invasive fish worldwide and yet, while very abundant in most Mediterranean countries, it is unable to tolerate the colder winters of northern and central Europe. Understanding the effects of latitude on its life history traits is essential to predict the potential for its invasion of central Europe in current scenarios of climate change. We studied the variation of life-history traits and parasite load in the eastern mosquitofish along a latitudinal gradient from southern France to southern Spain, sampling mosquitofish populations in eight Mediterranean river mouths ranging 5° in latitude. Southern mosquitofish populations displayed higher catch rates, allocated more energy to reproduction (gonadosomatic index and gonadal weight after accounting for fish size) and had a lower condition (total weight and eviscerated weight after accounting for fish size) than in northern populations. Despite variability among populations, size-at-maturity (L50) significantly varied with latitude and northern individuals matured at smaller size (lower L50). Parasite prevalence ranged from 0.0 to 26.7% but parasite richness was very low; all the parasites identified were larvae of pleurocercoid cestodes belonging to the order Pseudophyllidea. The abundance of mosquitofish parasites decreased with latitude and the presence and number of parasites infecting the mosquitofish had a significant negative effect on fish condition. The significant effects of latitude on the catch rates, life history and parasites of mosquitofish highlight the importance of latitudinal studies of invasive species to understand the interactive mechanisms of climate change and biological invasions.
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The effect of temperature on the functional response of female adults of the two-spot ladybird, Adalia bipunctata L. (Coleoptera: Coccinellidae) was examined in petri dish arenas containing sweet pepper leaves infested with different densities of the green peach aphid, Myzus persicae (Sulzer) (Hemiptera: Aphididae). The predator showed a type II functional response at three tested temperatures ranging from 19°C to 27°C. The theoretical maximum number of prey captured by the predator increased with temperature. Based on the random predator equation, the estimated attack rates ranged from 0.13h−1 at 19°C to 0.35h−1 at 27°C on a leaf area of 20–25cm2. There was no significant difference between the attack rates of the predator at 23°C and 27°C. Handling time significantly decreased as temperature increased from 19°C (0.39h) to 27°C (0.24h). This study shows that A. bipunctata displays high predation rates on M. persicae for a wide range of temperatures, indicating its potential for augmentative releases against this aphid pest. The limitations of the predictions generated by functional response experiments are discussed. Keywords Adalia bipunctata - Myzus persicae -Coccinellidae-Aphididae-Functional response-Predation-Augmentative biological control
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As field determinations take much effort, it would be useful to be able to predict easily the coefficients describing the functional response of free-living predators, the function relating food intake rate to the abundance of food organisms in the environment. As a means easily to parameterise an individual-based model of shorebird Charadriiformes populations, we attempted this for shorebirds eating macro-invertebrates. Intake rate is measured as the ash-free dry mass (AFDM) per second of active foraging; i.e. excluding time spent on digestive pauses and other activities, such as preening. The present and previous studies show that the general shape of the functional response in shorebirds eating approximately the same size of prey across the full range of prey density is a decelerating rise to a plateau, thus approximating the Holling type II ('disc equation') formulation. But field studies confirmed that the asymptote was not set by handling time, as assumed by the disc equation, because only about half the foraging time was spent in successfully or unsuccessfully attacking and handling prey, the rest being devoted to searching. A review of 30 functional responses showed that intake rate in free-living shorebirds varied independently of prey density over a wide range, with the asymptote being reached at very low prey densities (
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The Arrhenius equation has emerged as the favoured model for describing the temperature dependence of consumption in predator-prey models. To examine the relevance of this equation, we undertook a meta-analysis of published relationships between functional response parameters and temperature. We show that, when plotted in lin-log space, temperature dependence of both attack rate and maximal ingestion rate exhibits a hump-shaped relationship and not a linear one as predicted by the Arrhenius equation. The relationship remains significantly downward concave even when data from temperatures above the peak of the hump are discarded. Temperature dependence is stronger for attack rate than for maximal ingestion rate, but the thermal optima are not different. We conclude that the use of the Arrhenius equation to describe consumption in predator-prey models requires the assumption that temperatures above thermal optima are unimportant for population and community dynamics, an assumption that is untenable given the available data.
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We present a handy mechanistic functional response model that realistically incorporates handling (i.e., attacking and eating) and digesting prey. We briefly review current functional response theory and thereby demonstrate that such a model has been lacking so far. In our model, we treat digestion as a background process that does not prevent further foraging activities (i.e., searching and handling). Instead, we let the hunger level determine the probability that the predator searches for new prey. Additionally, our model takes into account time wasted through unsuccessful attacks. Since a main assumption of our model is that the predator''s hunger is in a steady state, we term it the steady-state satiation (SSS) equation. The SSS equation yields a new formula for the asymptotic maximum predation rate (i.e., asymptotic maximum number of prey eaten per unit time, for prey density approaching infinity). According to this formula, maximum predation rate is determined not by the sum of the time spent for handling and digesting prey, but solely by the larger of these two terms. As a consequence, predators can be categorized into two types: handling-limited predators (where maximum predation rate is limited by handling time) and digestion- limited predators (where maximum predation rate is limited by digestion time). We give examples of both predator types. Based on available data, we suggest that most predators are digestion limited. The SSS equation is a conceptual mechanistic model. Two possible applications of this model are that (1) it can be used to calculate the effects of changing predator or prey characteristics (e.g., defenses) on predation rate and (2) optimal foraging models based on the SSS equation are testable alternatives to other approaches. This may improve optimal foraging theory, since one of its major problems has been the lack of alternative models.
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Biological impacts of climate warming are predicted to increase with latitude, paralleling increases in warming. However, the magnitude of impacts depends not only on the degree of warming but also on the number of species at risk, their physiological sensitivity to warming and their options for behavioural and physiological compensation. Lizards are useful for evaluating risks of warming because their thermal biology is well studied. We conducted macrophysiological analyses of diurnal lizards from diverse latitudes plus focal species analyses of Puerto Rican Anolis and Sphaerodactyus. Although tropical lowland lizards live in environments that are warm all year, macrophysiological analyses indicate that some tropical lineages (thermoconformers that live in forests) are active at low body temperature and are intolerant of warm temperatures. Focal species analyses show that some tropical forest lizards were already experiencing stressful body temperatures in summer when studied several decades ago. Simulations suggest that warming will not only further depress their physiological performance in summer, but will also enable warm-adapted, open-habitat competitors and predators to invade forests. Forest lizards are key components of tropical ecosystems, but appear vulnerable to the cascading physiological and ecological effects of climate warming, even though rates of tropical warming may be relatively low.
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Non-native brook trout have become widely established in North European streams. We combined evidence from an artificial-stream experiment and drainage-scale field surveys to examine whether brook trout suppressed the growth of the native brown trout (age 0 to age 2). Our experimental results demonstrated that brown trout were unaffected by the presence of brook trout but that brook trout showed reduced growth in the presence of brown trout. However, the growth reduction only appeared in the experimental setting, indicating that the reduced spatial constraint of the experimental system may have forced the fish to unnaturally intense interactions. Indeed, in the field, no effect of either species on the growth of the putative competitor was detected. These results caution against uncritical acceptance of findings from small-scale experiments because they rarely scale up to more complex field situations. This and earlier work suggest that the establishment of brook trout in North European streams has taken place mainly because of the availability of unoccupied (or underutilized) niche space, rather than as a result of species trait combinations or interspecific competition per se.
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The relationship between the encounter rate of predators with prey and the density of this prey is fundamental to models of predator-prey interactions. The relationship determines, among other variables, the rate at which prey patches are depleted, and hence the impact of predator populations on their prey, and the optimal spatial distribution of foraging effort. Two central assumptions that are made in many models are that encounter rate is directly proportional to prey density and that it is independent of the proportion of prey already removed, other than via the decreased density. We show here, using captive great tits searching for winter moth caterpillars in their natural hiding positions, that neither of these assumptions hold. Encounter rate increased less than directly in proportion to prey density, and it depended not only on the current density of prey, but also on the proportion of prey already removed by previous foragers. Both of these effects are likely to have major consequences for the outcome of predator-prey interactions.
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As field determinations take much effort, it would be useful to be able to predict easily the coefficients describing the functional response of free-living predators, the function relating food intake rate to the abundance of food organisms in the environment. As a means easily to parameterise an individual-based model of shorebird Charadriiformes populations, we attempted this for shorebirds eating macro-invertebrates. Intake rate is measured as the ash-free dry mass (AFDM) per second of active foraging; i.e. excluding time spent on digestive pauses and other activities, such as preening. The present and previous studies show that the general shape of the functional response in shorebirds eating approximately the same size of prey across the full range of prey density is a decelerating rise to a plateau, thus approximating the Holling type II (‘disc equation’) formulation. But field studies confirmed that the asymptote was not set by handling time, as assumed by the disc equation, because only about half the foraging time was spent in successfully or unsuccessfully attacking and handling prey, the rest being devoted to searching.
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The foraging activities of the predators depend on environmental variables, including air temperature. In the present study, the searching behavior and maximum consumption of prey of all developmental stages of Coccinella septempunctata was carried out with respect to the changing values of the air temperature. A strong relationship between two important factors of functional response "instantaneous attack rate" (a') and "prey handling time" (Th) was found with respect to temperature changes. The prey intake ratio per unit time was increased with increasing temperature up to a certain level beyond which it levels off and goes down to the extent of '0'predation. The temperature range for the foraging activities falls between 10°C-40°C However, maximum prédation rates were observed between 20-23°C and 23°C-25°C The lower temperature where the foraging activities were completely ceased was between 10-12°C irrespective of prey densities available. A parabolic (curvilinear) relationship with high scale of co-relation (r2= 0.86 - 0.99 α = 0.01) (Th) was found.
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Functional response experiments with alternative prey demonstrate how an exotic zooplankter co-exists with salmonid fish in Lake Superior. Young lake trout (Salvelinus namaycush) response to Daphnia, a typical prey genus, and to Bythotrephes, a spined invertebrate predator that invaded North America in the mid-1980s, is examined in a variety of laboratory experiments that span various prey densities, frequencies, experience, and consumer size. Bythotrephes’ caudal spine protects the animal from small fish predation. At intermediate densities, the spiny cladoceran also disrupts foraging behavior of young-of-year fish. Lake trout response to Bythotrephes is dependent on the length of the spine and fish size. The degree to which lake trout are able to discriminate between prey and resume their prior attack rate on Daphnia depends on the absolute density of Daphnia and the frequency with which fish encounter Bythotrephes. For both experienced and naïve fish, aversive behavior to Bythotrephes occurs after a certain threshold of encounters. Under conditions of high encounter rates, once aversive behavior is established in YOY fish, foraging efficiency on Daphnia improves because Bythotrephes is recognized and ignored. The density-dependent behavioral and functional responses resemble classical predator reactions to unpalatable prey.
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The Distribution and Abundance of Animals By H. G. Andrewartha and L. C. Birch. Pp. xv + 782. (Chicago: University of Chicago Press; London: Cambridge University Press, 1954.) 112s. 6d. net.
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Young-of-the-year piscivores undergo ontogenetic diet shifts, but mechanisms influencing prey selection and implications for growth are unclear. We examined foraging and growth of 20- to 150-mm walleye (Sander vitreus) fed either zooplankton, benthic invertebrates, or fish over a range of prey densities in the laboratory. The number of each prey type consumed was influenced by walleye size and prey density. Walleye exhibited type II functional responses on each prey type; attack coefficients were constant across zooplankton and fish densities but decreased with benthic invertebrate densities. Handling time estimates were greater for fish than for other prey types but similar for zooplankton and benthos. Foraging efficiencies on zooplankton and benthic invertebrates increased with walleye size but were variable for fish prey. The smallest walleye size class (20 mm) had similar energy return (J·min–1) and growth (g·day–1) on zooplankton, benthic invertebrates, and fish. For larger walleye, both energy return and growth were highest on fish, intermediate on benthic invertebrates, and lowest on zooplankton. Diet shifts of juvenile piscivores and, consequently, growth can be explained by ontogenetic changes in foraging abilities and prey densities.
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In an earlier study (Holling, 1959) the basic and subsidiary components of predation were demonstrated in a predator-prey situation involving the predation of sawfly cocoons by small mammals. One of the basic components, termed the functional response, was a response of the consumption of prey by individual predators to changes of prey density, and it appeared to be at least theoretically important in population regulation: Because of this importance the functional response has been further examined in an attempt to explain its characteristics.
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Radio tagged common carp Cyprinus carpio in a Namibian reservoir, where this species has been introduced, experienced 100% mortality or tag loss ( n = 13) with surgically implanted transmitters and 100% survival ( n = 5) with externally attached transmitters at water temperatures of 24–25° C. It seems that the negative effects of the tagging were greater for surgical implantation than for external attachment. The body shape of common carp make them well suited for external tagging, and this tagging method is recommended for common carp studies at high water temperatures or under other stressful conditions.
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Interactions between adult individuals of the introduced Eastern mosquitofish Gambusia holbrooki and two native fish species to the Iberian Peninsula, the Iberian toothcarp Aphanius iberus and the Valencia toothcarp Valencia hispanica, were studied in mesocosm and laboratory experiments. Eastern mosquitofish always excluded both Valencia and Iberian toothcarp when the ratio introduced-to-native was at unity or favourable to the non-native species. Food availability did not decrease significantly in the mesocosm experimental units. However, specimens of native species had a greater number of empty guts than those of Eastern mosquitofish at the end of the mesocosm experiment. Ethograms were constructed based on qualitative observations in aquaria, with a special emphasis on social behaviours, in particular agonistic (which ultimately were not observed between the species). Satiety (maximum prey number) and voracity (number of prey consumed per unit of time) of the three species were measured in aquaria. The Eastern mosquitofish achieved the highest foraging values (maximum prey = 11, at 11–12 prey min−1), whereas Valencia toothcarp achieved the lowest values (maximum prey = 7, at 5–6 prey min−1). The observed interactions between Eastern mosquitofish and the two native species are discussed.
Article
1. Functional response models that predict the relationship between feeding rate and food density often include only two behavioural parameters, handling time and searching rate. However, vigilance can occupy a large proportion of foraging time and, consequently, may affect the functional response. Previous functional response models of granivorous birds showed no effect of vigilance on predicted feeding rates; these models assumed that all of handling time is compatible with vigilance and, therefore, overestimated the potential time for cost free vigilance to occur.
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Terrestrial invertebrate subsidies are believed to be important energy sources for drift-feeding salmonids. Despite this, size-specific use of and efficiency in procuring this resource have not been studied to any great extent. Therefore, we measured the functional responses of three size classes of wild brown trout Salmo trutta (0+, 1+ and >= 2+) when fed either benthic- (Gammarus sp.) or surface-drifting prey (Musca domestica) in laboratory experiments. To test for size-specific prey preferences, both benthic and surface prey were presented simultaneously by presenting the fish with a constant density of benthic prey and a variable density of surface prey. The results showed that the functional response of 0+ trout differed significantly from the larger size classes, with 0+ fish having the lowest capture rates. Capture rates did not differ significantly between prey types. In experiments when both prey items were presented simultaneously, capture rate differed significantly between size classes, with larger trout having higher capture rates than smaller trout. However, capture rates within each size class did not change with prey density or prey composition. The two-prey experiments also showed that 1+ trout ate significantly more surface-drifting prey than 0+ trout. In contrast, there was no difference between 0+ and >= 2+ trout. Analyses of the vertical position of the fish in the water column corroborated size-specific foraging results: larger trout remained in the upper part of the water column between attacks on surface prey more often than smaller trout, which tended to seek refuge at the bottom between attacks. These size-specific differences in foraging and vertical position suggest that larger trout may be able to use surface-drifting prey to a greater extent than smaller conspecifics.
Article
1In models of size-structured predator–prey systems, the effects are evaluated of gape-size limited predation on prey population growth and density when predators are non-interacting, cannibalistic, interfering, and cannibalistic and interfering.2Predation from non-interacting predators markedly reduces prey density, compared with prey densities in the absence of predation. When density-dependent cannibalism between predators is introduced, predator density and therefore total functional response decrease, resulting in a decrease in predation pressure and higher prey densities.3Size- and density-dependent interference between predators substantially decreases functional responses in the predators, and the prey population is thus allowed to grow more dense. Allowing for cannibalism between interfering predators also decreases predator density, but here the decreased number of predators does not have the releasing effect seen in solely cannibalistic predators. The interference between predators decreases with predator density, and per capita functional responses increase and compensate for the decrease in predator density.4These theoretical results are compared with results from natural systems with pikeperch and northern pike. Both species are cannibalistic, and pike are also kleptoparasitic, mirroring the models. Results from introductions of the different piscivores into natural systems corroborate the outcome of the models, since introduction or increased densities of pikeperch have shown to have severe and long-lasting effects on prey, while pike have only initial, decreasing over time effects on prey stock. Thus, predator behaviour may seriously affect predator impact on prey, and size- and density-dependent interactions between predators may be a major key to the understanding of predator–prey dynamics and community composition in lakes.
Article
1. Temperate regions with fish communities dominated by cold-water species (physiological optima <20 °C) are vulnerable to the effects of warming temperatures caused by climate change, including displacement by non-native cool-water (physiological optima 20–28 °C) and warm-water fishes (physiological optima >28 °C) that are able to establish and invade as the thermal constraints on the expression of their life history traits diminish. 2. England and Wales is a temperate region into which at least 38 freshwater fishes have been introduced, although 14 of these are no longer present. Of the remaining 24 species, some have persisted but failed to establish, some have established populations without becoming invasive and some have become invasive. The aim of the study was to predict the responses of these 24 non-native fishes to the warming temperatures of England and Wales predicted under climate change in 2050. 3. The predictive use of climate-matching models and an air and water temperature regression model suggested that there are six non-native fishes currently persistent but not established in England and Wales whose establishment and subsequent invasion would benefit substantially from the predicted warming temperatures. These included the common carp Cyprinus carpio and European catfish Silurus glanis, fishes that also exert a relatively high propagule pressure through stocking to support angling and whose spatial distribution is currently increasing significantly, including in open systems. 4. The potential ecological impacts of the combined effects of warming temperatures, current spatial distribution and propagule pressure on the establishment and invasion of C. carpio and S. glanis were assessed. The ecological consequences of C. carpio invasion were assessed as potentially severe in England and Wales, with impacts likely to relate to habitat destruction, macrophyte loss and increased water turbidity. However, evidence of ecological impacts of S. glanis elsewhere in their introduced range was less clear and so their potential impacts in England and Wales remain uncertain.
Article
Following the accidental introduction of the carp Cyprinus carpio into Lake Naivasha during 1999, a sustainable population became rapidly established and in early 2004 became the principal species exploited in the commercial fishery. Over 9000 kg of carp were harvested from the lake between October 2005 and 2006, when fish were captured between fork lengths (LF) 200 and 800 mm (>8 kg). Diet of carp <100 mm LF was dominated by zooplankton, >100 mm LF there was a shift to benthic macro-invertebrates, with these carp feeding principally upon food resources previously unexploited by the fish community. Contrary to predictions and despite the increasing carp abundance, there has been macrophyte regeneration in littoral areas since 2004. There have been substantial increases in areal cover, with coverage in 2006 at levels not observed since the late 1980s, and significant increases in species richness. Possible reasons for this, and the significance of this carp introduction, are discussed.
Article
Young Sebastes melanops live as pelagic larvae and juveniles in offshore waters, recruiting to the nearshore environment at an age of approximately six months. In the summer upwelling season, juveniles may be captured in tidepools and shallow coastal waters, where temperatures may be as low as 8C, or in shallow estuarine habitats where temperatures reach 18C. This study was conducted to determine the effects of temperature, ration, and fish size upon growth. Juveniles 35 to 93 mm standard length were acclimated to 7, 12, and 18C and provided four daily rations (nominally 0, 25, 50, and 100% maximum ration); growth and food consumption were monitored over 57 days.Growth in length ranged from –0.023 to 0.314 mm per day, relative growth in weight ranged from –0.689 to 1.495% body weight per day, and gross conversion efficiencies ranged from –13 to 21% among treatments. Under starvation conditions, weight loss increased with increasing temperature. At rations expressed as percent maximum at a given temperature, growth increased with increasing temperature. Maximum relative ration (% body weight per day), however, decreased with decreasing temperature; at equivalent relative rations, growth did not differ significantly among temperatures. Evacuation rates determined at the experimental temperatures suggest that daily ration is limited by digestion rate and that temperature therefore affects energy turnover.Growth was analyzed with multiple regression models with ration, temperature, and initial weight as independent variables. Relative growth increased with increasing initial weight. The model predicts that relative maintenance rations decrease with increasing size. The percentage of full ration represented by maintenance ration is relatively greater for small fish at low temperatures, suggesting a basis for ontogenetic change in thermal optima for growth. The results of this study suggest that thermal environment may have an important effect upon first year growth of juvenile S. melanops.
Article
Freshwater ecosystems are seriously imperiled by the spread of non-native fishes thus establishing profiles of their life-history characteristics is an emerging tool for developing conservation and management strategies. We did a first approach to determine characteristics of successful and failed non-native fishes in a Mediterranean-climate area, the Iberian Peninsula, for three stages of the invasion process: establishment, spread and integration. Using general linear models, we established which characteristics are most important for success at each invasion stage. Prior invasion success was a good predictor for all the stages of the invasion process. Biological variables relevant for more than one invasion stage were maximum adult size and size of native range. Despite these common variables, all models produced a different set of variables important for a successful invasion, demonstrating that successful invaders have a combination of biological traits that may favor success at all invasion stages. However, some differences were found in relation to published studies on fish invasions in other Mediterranean-climate areas, suggesting that characteristics of the recipient ecosystem are as relevant as the characteristics of the invading species.
Article
The allocation of energy to growth and reproduction, in relation to temperature and food availability, was investigated in laboratory experiments with the mosquitofish,Gambusia affinis. At constant temperature of 20, 25 and 30°C and ad libitum feeding, specific growth rates increased with increasing temperature at 1.7, 3.1 and 3.4% dry mass day−1, respectively. Growth rates in a cycling temperature regime (20–30°C,\(\bar x = 25^ \circ C\)) were faster than in a 25°C constant temperature. As temperature increased from 20 to 30°C, mean age at first reproduction decreased from 191 to 56 days and brood size and mass of offspring increased significantly. Interbrood interval was also temperature dependent; estimates at 25 and 30°C for females >1000 mg were 22.6 and 18.6 days, respectively. Interbrood interval could not be calculated at 20°C. Although fitness was highest at 30°C, females at 25°C invested a greater proportion of surplus energy (growth and reproduction) to reproduction (38%) than at 20 (17%) or 30°C (36%) during the 32-week study. Fish at cooler temperatures began reproduction at a smaller size. Where rations were controlled at low, medium, and ad libitum levels, somatic and gonadal growth increased with increasing temperatures and food availability. The proportion of energy invested in reproduction was highest at 25°C for each comparable ration level. Calculated energy budgets indicated that over the 10-week study, 17–22% of the food energy was invested in growth, 0–7% in reproduction, and 75–83% in respiration and excretory losses, depending on feeding and temperature conditions.
Article
Britton JR, Harper DM, Oyugi DO. Is the fast growth of an equatorial Micropterus salmoides population explained by high water temperature? Ecology of Freshwater Fish 2010: 19: 228–238. © 2010 John Wiley & Sons A/S Abstract – Marginal increment analysis of scales collected from the introduced Micropterus salmoides population of Lake Naivasha, Kenya revealed the formation of an annual growth check, validating their use to age individual fish. Subsequent analysis of scales from 372 fish collected between 2002 and 2009 revealed individuals were very fast growing compared with native populations in North America and other introduced populations in Europe, South America, Africa and Asia. This was likely to be as a result of the water temperatures in Lake Naivasha exceeding 20 °C throughout the year. This was corroborated by a meta-analysis of the growth parameters asymptotic length L∞ and growth coefficient K from across their geographical range that revealed variance was explained by differences in mean annual air temperatures. At a break point of approximately 10 °C, there was a shift to reduced L∞ and increased K, suggesting a temperature driven trade-off between growth rate and ultimate length. When adjusted for temperature and weighted for sample size, there were significant differences between the growth parameters of the North American and introduced populations, suggesting that other abiotic and biotic variables were also important determinants of the growth of individuals between the two ranges.
Article
Arrocampo Reservoir is used as a cooling basin for a nuclear power plant located in southern Europe. Its annual mean temperature is about 30 °C with maxims that achieved 41.5 °C near the hot water effluent. Common carp (Cyprinus carpio, Linnaeus 1758) is the dominant pelagic fish species in this reservoir. Hydroacoustic surveys were conducted bimonthly over 9 years to characterize common carp abundance and distribution in the reservoir on an annual and seasonal temporal scale. Mean fish density during the period was 0.029 fish m−3, varying from a maximum of 0.038 in 2003 to a minimum of 0.012 in 1998. There were no significant differences in the mean fish density among years. Each year, fish distribution showed significant seasonal variation. Carp were homogeneously distributed during autumn and spring; in winter carp occupied warmer outfall areas, whereas in summer, fish were distributed in the coldest area of the reservoir (dam area) but avoided the warm outfall area. These seasonal tendencies of carp distribution was repeated every years. Behavioural reaction appears to be particularly important in explain carp distribution in this reservoir.
Article
To clarify the environmental factors regulating the annual reproductive cycle of the female mosquitofish, Gambusia affinis, a viviparous teleost, histological changes of the ovary in natural population, and laboratory experiments were examined. The results, extending over two years, suggested that ovarian recrudescence is initiated by the rise in temperature during spring and that ovarian regression is caused by the shorter daylength during late summer. The first rearing experiments using four photoperiod-temperature groups to investigate the factors triggering the onset of reproduction revealed that females with regressing ovaries began reproduction with the rise of temperature regardless of the photoperiod during spring. The results of the second experiment using three different temperature groups indicated that vitellogenesis occurred at over 14 degrees C and pregnancy at over 18 degrees C. The third experiment with four photoperiod-temperature groups was arranged to investigate the factors in the cessation of reproduction. Sexually active females ceased vitellogenesis of the next clutch of oocytes due to the shorter daylength regardless of temperatures during late summer; however, temperature seemed to influence the rate of embryo development. The critical photoperiod is estimated at about 12.5 hr. In nature, it is supposed that vitellogenesis starts when the temperature rises to about 14 degrees C, and final maturation of oocytes occurs when the temperature reaches about 18 degrees C during spring. Then, vitellogenesis of the next clutch of oocytes ceases when the daylength becomes shorter than 12.5 hr during late summer; the last gestation proceeds at a rate dependent on the temperature, and finally reproduction ends by the last parturition. J. Exp. Zool. 286:204-211, 2000.
R: A Language and Environment for Statistical Computing. R foundation for Statistical Computing, Vienna, Austria. ISBN 3-900051-07-0 Life history traits of non-native fishes in Iberian watersheds across several invasion stages: a first approach
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R Development Core Team, 2009. R: A Language and Environment for Statistical Computing. R foundation for Statistical Computing, Vienna, Austria. ISBN 3-900051-07-0, URL /http://www.R-project.orgS. Ribeiro, F, Elvira, B., Collares-Pereira, M.J., et al., 2008. Life history traits of non-native fishes in Iberian watersheds across several invasion stages: a first approach. Biol. Invasions 10, 89–102.
A field and laboratory investigation of the effect of heated effluents on fish. Fish. Inv., Ser. I, VI. Her Majesty's Stationery Office Vigilance and the functional response of granivorous foragers
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