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Sampling Days (sampling + day)
Selected AbstractsEffect of wave exposure dynamics on gut content mass and growth of young-of-the-year fishes in the littoral zone of lakesJOURNAL OF FISH BIOLOGY, Issue 7 2010S. Stoll Total length, body mass and gut content mass of young-of-the-year (YOY) perch Perca fluviatilis, dace Leuciscus leuciscus and bleak Alburnus alburnus were recorded over the summer of 2006 at three littoral sites at Upper Lake Constance. In P. fluviatilis and L. leuciscus, gut content mass correlated positively with wave-induced energy flux (EF) of the respective site and sampling day, while no correlation of gut content mass with EF was found in A. alburnus. It was assumed that benthivorous P. fluviatilis and L. leuciscus profited from suspended or uncovered benthic food items generated by wave action at sites and periods with high EF. Alburnus alburnus, in contrast, feeding mainly on zooplankton in upper parts of the water column, could not profit from increased EF. In P. fluviatilis, increased gut content mass during periods of high EF resulted in higher growth rates. For L. leuciscus, no real growth rates in local fish populations could be determined, as individuals were less sedentary, and when increased growth occurred at sites during the periods of high EF, migration of fish levelled out the resulting size differences within few days. The results of this study show that dynamic habitat variables affect site profitability in the littoral zone of lakes, especially in benthivorous fishes. Therefore, dynamic habitat variables should be considered in addition to fixed habitat properties in analyses of habitat choice of fishes in the littoral zone of lakes. [source] Dietary Na does not reduce dietary Cu uptake by juvenile rainbow troutJOURNAL OF FISH BIOLOGY, Issue 2 2005V. A. Kjoss Rainbow trout Oncorhynchus mykiss fry in moderately hard water were exposed to control or high levels of dietary Cu (c. 6 and 580 ug Cu g food,1) at one of three levels of Na (1·5, 3·0 or 4·5%) in the diet, i.e. six experimental groups. Fish were fed a 4% body mass ration daily for 28 days and 10 individuals from each group were sampled every 7 days. Concentrations of Cu and Na were measured in the gills, liver, gut and remaining carcass of sampled fish. Growth was not affected and no consistent differences were found in mass, total lengths (LT) or indices of body condition among any of the groups on any sampling day. Copper concentration was significantly higher in tissues of Cu-exposed groups, although within treatment types (control Cu v. high Cu diet), it did not differ consistently among groups that received different levels of dietary Na. Tissue Na concentration did not differ among any of the groups and did not show any marked changes over time. In Cu-exposed groups, the proportion of total body Cu burden contained in the liver approximately doubled over time, from c. 30% on day 7 to c. 60% on day 28. In unexposed fish, the liver maintained c. 25% of the total Cu burden throughout the experiment. In contrast, the proportion of the total body Cu burden contained in the gut decreased somewhat over time in Cu-exposed fish, from c. 40% on day 7 to c. 30% on day 28, and remained fairly stable at c. 25,30% in control groups, i.e. approximately equal to liver values. In all groups, the carcass contained by far the largest portion of the total Na content (>80%). Measurements made 36 h post-feeding indicated that all six groups had much higher Na efflux relative to influx, suggesting that the fish were eliminating excess Na taken up from the diet, and differences in Na influx rates were small. Na efflux rate was significantly higher in the high Cu and high Na group than in the high Cu and low Na group. The results indicate that at the concentrations used in this experiment, dietary Na has little effect on dietary Cu uptake by juvenile rainbow trout, and dietary Cu has little effect on Na homeostasis. [source] Relative Abundance and Species Composition of Gram-Negative, Aerobic Bacteria Associated with the Gut of Juvenile White Shrimp Litopenaeus vannamei Reared in Oligotrophic Well Water and Eutrophic Pond WaterJOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 2 2000Shaun M. Moss Gut bacteria may contribute significantly to the growth and survival of cultured shrimp, although little is known about factors that affect bacterial community structure in shrimp guts. The objective of this study was to determine the abundance and species composition of gut bacteria in juvenile white shrimp Litopenaeus vannamei reared in two different environments. Eight 120-L tanks were stocked at a density of 8 shrimphank. Two treatments were tested for 10 d and consisted of tanks receiving flow-through water from one of two sources: 1) well water pumped from a sea-water aquifer (Well treatment), and 2) pond water pumped from an intensive shrimp pond (Pond treatment). Shrimp mid- and hindguts were excised on days 1, 3, 6, and 10 for enumeration of gram-negative, aerobic bacteria by quantifying colony-forming units (CFU) using standard microbiological plating techniques. Identification of bacterial isolates was made using the Biologaź GN Microplate system. Bacterial numbers were significantly greater (P > 0.05) in Well shrimp than in Pond shrimp on days 1 and 3. Following day 3, a decrease in bacterial numbers occurred in the Well shrimp, and no significant differences between treatments were observed on days 6 or 10. Guts from Well shrimp were dominated by Vibrio and Aero-monas, and these two genera accounted for 80,851 of the bacteria on each sampling day. Guts from Pond shrimp exhibited a greater bacterial diversity and were dominated by Vibrio, Aeromonas, and Pseudomonas. Flavobacterium were identified in the guts of Pond shrimp on days 3 and 10, but were not identified in any of the Well shrimp. A greater understanding of gut bacteria-shrimp interactions could lead to increased production and profitability for shrimp farmers through the development of more cost-effective feeds and novel disease control strategies. [source] Phytoplankton communities and antecedent conditions: high resolution sampling in Esthwaite WaterFRESHWATER BIOLOGY, Issue 10 2006G. MADGWICK Summary 1. The succession of a phytoplankton community was investigated through an intensive period of sampling and related to physical, chemical and biological conditions sampled at an equal, or higher, temporal resolution. 2. Phytoplankton samples were taken on a weekly basis from June to September 2004 and analysed for diversity, species composition, and contribution of different functional groups to total biomass. Physical and chemical data were collected on the sampling days, and physical environmental factors were also logged continuously throughout the period by automatic measuring stations. This continuous logging allowed community structure to be compared with physical data averaged over periods from a day to a week before each sampling date. 3. The Schmidt stability of the lake, a measure of the strength of stratification calculated from thermal data, showed a negative correlation with phytoplankton species diversity. This is consistent with the hypothesis that mixing was preventing exclusion by species that would otherwise dominate in stratified conditions. 4. At a functional level, stress tolerant (S-type) species dominated during the stratified summer conditions, with small, colonising species (C types) and ruderal, disturbance tolerant species (R types) contributing little to the overall biomass. Of the stress tolerant species, the faster growing (SC) phytoplankters were significantly favoured by more stable, stratified conditions and higher solar radiation. Increased abundance of this group resulted in decreased species diversity. Correlations were generally strongest when using the 6- to 7-day averaged physical data, stressing the importance of continuous measurements of these drivers in phytoplankton studies. [source] Salmonella on pig carcasses: positive pigs and cross contamination in the slaughterhouseJOURNAL OF APPLIED MICROBIOLOGY, Issue 5 2003N. Botteldoorn Abstract Aims: The purpose of this study was to investigate the prevalence of Salmonella in pigs at the moment of slaughter and in the slaughterhouse environment. Methods and Results: In total, five different commercial slaughterhouses were sampled during eight slaughterhouse visits. Carcass swabs, colon content and mesenteric lymph nodes were taken to reflect the animal status and from the slaughterhouse environmental samples were taken. Salmonella was isolated from 37% of the carcass samples as a mean value. High variations were noticed between different slaughterhouses (between 0 and 70%) and sampling days in the same abattoir (between 3 and 52%). A correlation was found between the carcass contamination and the status of the delivered animals (P = 0·01675). Cross contamination was estimated to account for 29% of the positive carcasses. The slaughterhouse environment was highly contaminated; before starting the slaughtering activities 25% of the samples were positive on average. The most prevalent serotypes isolated at the slaughterhouse environment and from the colon content were S. Typhimurium, S. Livingstone and S. Derby. On carcasses S. Typhimurium was predominately isolated (71%). The biggest variability of serotypes was found in the mesenteric lymph nodes. Serologically 56·3% of the pigs were found positive for Salmonella using a cut-off level of the optical density percentage higher than 10 (O.D.% , 10). While on individual pig level the correlation between the bacteriological and serological data was poor, because of recent Salmonella infections, a better correlation was found at the herd level on the moment of slaughtering. Conclusion: A high degree of carcass contamination is noticed after slaughtering. This contamination resulted from the delivery of Salmonella -positive pigs and cross-contamination from the slaughterhouse environment. Significance and Impact of the Study: In pigs, Salmonella carriage is high, but it is obvious that slaughterhouse hygiene is a determinative factor for managing carcass contamination. [source] Inhalation efficacy of RFI-641 in an African green monkey model of RSV infectionJOURNAL OF MEDICAL PRIMATOLOGY, Issue 2 2003W.J. Weiss Abstract: Human respiratory syncytial virus (RSV) is a major cause of acute upper and lower respiratory tract infections. RFI-641 is a novel RSV fusion inhibitor with potent in vitro activity. In vivo efficacy of RFI was determined in an African green monkey model of RSV infection involving prophylactic and therapeutic administration by inhalation exposure. Inhalation was with an RFI-641 nebulizer reservoir concentration of 15 mg/ml for 15 minutes (short exposure) or 2 hours (long exposure). Efficacy and RFI-641 exposure was determined by collection of throat swabs, nasal washes and bronchial alveolar lavage (BAL) on selected days. The short-exposure group (15 minutes) exhibited no effect on the nasal, throat or BAL samples. The throat and nasal samples for the long-exposure group failed to show a consistent reduction in viral titers. RFI-641 2 hours exposure-treated monkeys showed a statistically significantly log reduction for BAL samples of 0.73,1.34 PFU/ml (P -value 0.003) over all the sampling days. Analysis indicates that the long-exposure group titer was lower than the control titer on day 7 and when averaged across days. The results of this study demonstrate the ability of RFI-641 to reduce the viral load of RSV after inhalation exposure in the primate model of respiratory infection. [source] Sperm whale depredation of sablefish longline gear in the northeast Pacific OceanMARINE MAMMAL SCIENCE, Issue 1 2008Michael F. Sigler Abstract Interactions between marine mammals and fisheries include competition for prey (catch), marine mammal entanglement in fishing gear, and catch removal off fishing gear (depredation). We estimated the magnitude of sperm whale depredation on a major North Pacific longline fishery (sablefish) using data collected during annual longline surveys. Sperm whale depredation occurs while the longline gear is off-bottom during retrieval. Sperm whales were observed on 16% of longline survey sampling days, mostly (95% of sightings) over the continental slope. Sightings were most common in the central and eastern Gulf of Alaska (98% of sightings), occasional in the western Gulf of Alaska and Aleutian Islands, and absent in the Bering Sea. Longline survey catches were commonly preyed upon when sperm whales were present (65% of sightings), as evidenced by damaged fish. Neither sperm whale presence (P= 0.71) nor depredation rate (P= 0.78) increased significantly from 1998 to 2004. Longline survey catch rates were about 2% less at locations where depredation was observed, but the effect was not significant (P= 0.34). Estimated sperm whale depredation was <1% of the annual sablefish longline fishery catch off Alaska during 1998 to 2004. [source] Toward quantifying the usage costs of human immunity: Altered metabolic rates and hormone levels during acute immune activation in menAMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 4 2010Michael P. Muehlenbein There is a paucity of data on the energetic demands of human immune functions, despite the fact that both clinical medicine and evolutionary biology would benefit from further clarification of these costs. To better understand the energetic requirements of mounting a mild immune response, as well as some of the major hormonal changes underlying these metabolic changes, we examined changes in resting metabolic rate (RMR) and hormones during and after respiratory tract infection in young adult men. An epidemiologic passive detection design was used to recruit 25 nonfebrile subjects naturally infected with respiratory tract pathogens. Symptomology, percent body fat, RMR, salivary testosterone and cortisol, and other information were collected at a minimum of three time points during and after convalescence. Comparisons of the differences in RMR, testosterone, and cortisol between sampling days within individual cases were made using paired t -tests. Participants experienced 8% higher RMR during illness, and a subset of these men experienced a mean increase greater than 14%. The participants also experienced 10% lower testosterone levels during illness, and a subset of these participants experienced a mean decrease of 30%, although cortisol levels did not change significantly. These results document elevated RMR following natural pathogen exposure in adult humans, demonstrating that even mild immune reactions can elicit significant increases in energy expenditure. Understanding the costs of immunity and the immunomodulatory actions of hormones are central to understanding the role of immunity in human life history evolution. Am. J. Hum. Biol. 2010. © 2010 Wiley-Liss, Inc. [source] | |||||||||||||