Home About us Contact
|
Home About us Contact | ||
|
|
||
Bass
Kinds of Bass Terms modified by Bass Selected AbstractsWork, change and competition: managing for BASS, by D. Preece, G. Steven and,V.INTERNATIONAL JOURNAL OF TOURISM RESEARCH, Issue 2 2001Steven. No abstract is available for this article. [source] An Intraday Examination of the Components of the Bid,Ask SpreadFINANCIAL REVIEW, Issue 4 2002Thomas H. McInish Using transactions data for a sample of NYSE stocks, we decompose the bid,ask spread (BAS) into order,processing (OP) and asymmetric information (AI) components using the techniques of George, Kaul, and Nimalendran (1991) and Madhavan, Richardson, and Roomans (1997). McInish and Wood (1992) demonstrate that the intraday behavior of BASs can be explained by variables measuring activity, competition, risk, and information. We investigate whether these variables explain the behavior of the OP and AI components of the spread over the trading day. We conclude that, on balance, the variables that determine the aggregate BAS also determine its intraday components. [source] JFK and the U.S.-Israeli RelationshipDIPLOMATIC HISTORY, Issue 2 2005Zach Levey Book reviewed: Warren Bass. Support Any Friend: Kennedy's Middle East and the Making of the U.S.-Israel Alliance. New York: Oxford University Press, 2003. 336 pp. Notes, bibliography, index. $30.00 (hardcover). [source] Ontogenetic Changes in the Response of Largemouth Bass (Micropterus salmoides, Centrarchidae, Perciformes) to Heterospecific Alarm PheromonesETHOLOGY, Issue 5 2001Grant E. Brown Juvenile largemouth bass (Micropterus salmoides) undergo an ontogenetic niche shift from invertebrate feeding members of the cyprinid prey guild to piscivory during their first year of growth. We conducted laboratory and field trials to determine whether juvenile bass show a similar ontogenetic shift in their response to the alarm pheromone of finescale dace (Phoxinus neogaeus, Cyprinidae). When exposed to dace skin extract (with alarm pheromone), juvenile bass exhibited a significant positive relationship between standard length and horizontal and vertical area use and time spent moving. Small bass (< 50 mm standard length) tended to reduce area use and time spent moving (indicative of an anti-predator response), while larger bass (> 50 mm standard length) increased area use and time spent moving (indicating a foraging response). Bass exhibited no change in behaviour when exposed to swordtail (Xiphophorus helleri) skin extract, which lacks Ostariophysan alarm pheromone. During field trials, small (30,45 mm standard length) and medium (46,60 mm standard length) bass actively avoided areas labelled with dace alarm pheromone and exhibited a significant increase in dashing behaviour. Large bass (61,80 mm standard length) were attracted to such areas and exhibited a significant increase in approach behaviour. These data suggest that largemouth bass undergo an ontogenetic shift in response to heterospecific chemical alarm signals. [source] Geoarchaeological study of the Phoenician cemetery of Tyre-Al Bass (Lebanon) and geomorphological evolution of a tomboloGEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL, Issue 3 2008Pilar Carmona The geoarchaeological record of the Phoenician necropolis of Al Bass (Lebanon) provides information concerning the geomorphological evolution of a late Holocene tombolo. Physical and chemical analysis of sediments indicates that the cemetery (9th century B.C.) was located near a littoral lagoon, between the dunes of a cuspate spit pointing toward the island of Tyre. From the sea apex of this spit, the moles mentioned in historical chronicles were constructed. Once mainland and island were connected, at the northern coast (where the port of Sidon was located), a sediment trap was formed, which quickly filled with silt. Afterwards, an extensive field of sand dunes buried all the archaeological remains from Phoenician to Roman times. © 2008 Wiley Periodicals, Inc. [source] Effects of High Pressure on Texture and Microstructure of Sea Bass (Dicentrarchus labrax L.) FilletsJOURNAL OF FOOD SCIENCE, Issue 8 2005Romuald Chéret ABSTRACT High pressure is an innovative non-thermal food-preservation technology. We studied the effect of high-pressure treatment up to 500 MPa for 5 min on physical characteristics of sea bass fillets after 0, 7, and 14 d of refrigerated storage. Color results exhibited an increase of lightness and a slight change of hue, which might be imperceptible in cooked fish. High-pressure treatment induced a decrease of exudation and water-holding capacity. Pressure treatment above 300 MPa provoked higher fish hardness after storage than in untreated sample, proving the ability of high pressure to improve textural quality of chilled, stored fish fillet. These assessments were corroborated with microstructure observations. We showed that high-pressure treatment at 500 MPa allowed, after 7 d of storage, a total aerobic count equivalent to that of untreated fresh fish fillet to be obtained. Thus, high pressure might be considered to be a technology able to improve safety and textural quality of fresh fish fillets. [source] Contrasting Burns and Bass: Does the transactional-transformational paradigm live up to Burns' philosophy of transforming leadership?JOURNAL OF LEADERSHIP STUDIES, Issue 3 2007Dmitry Khanin Both proponents and critics view the transactional-transformational paradigm (Bass, 1997, 1998) as the brainchild of Burns' (1978) philosophy of transforming leadership. However, Burns (2003) has criticized the paradigm's narrow managerialist orientation and the claim that it is uniformly applicable to any culture and organization. In this article, I first summarize and articulate Burns' (1978, 2003) and Bass' (1985, 1998) approaches toward leadership, then compare them by using a new four-dimensional framework. Extending previous research (Yukl, 2006), the framework represents a useful tool for detecting the commonalities and differences between leadership theories with respect to the core dimensions, categories, and aspects of leadership. My inspection indicates that Burns' and Bass' conceptions stem from disparate contexts and differ in their applicability. Thus, Burns' (1978) ideas stem from political movements ideally characterized by mutual quest for shared meaning and active collaboration between leaders and followers. Conversely, Bass' (1985) approach springs from military training in which leaders transfer existing knowledge to followers and stimulate their activity by using a variety of tools from inspirational motivation to individualized consideration. This study has important practical implications as it delineates the boundary conditions of the transactional-transformational paradigm and warns against its uncritical adoption in incongruent leadership contexts. [source] Evaluation of Reduced Fish Meal Diets for Second Year Growout of the Largemouth Bass, Micropterus salmoidesJOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 6 2009Nathan J. Cochran Development of efficient cost-effective diets is a critical component in the refinement of production technologies for the largemouth bass, Micropterus salmoides (LMB). One of the first steps in reducing feed costs can be to decrease the amount of fish meal in the diet. The objective of this study was to evaluate reduced levels of fish meal, and a least-cost formulation diet, for second year growout of LMB under practical pond conditions. Twelve 0.04-ha ponds were stocked with juvenile LMB (210.1±3.3 g) at a stocking density of 8650 fish/ha (350 fish/pond). Each pond was randomly assigned one of the four dietary treatments with three replicate ponds per treatment. The three experimental diets contained varying levels of fish meal. Diets FM-45, FM-24, and FM-8 contained 45, 23.5, and 8% fish meal, respectively. In diets FM-24 and FM-8, fish meal was replaced by varying levels of poultry by-product meal, soybean meal, and blood meal. The fourth diet was a commercial salmonid diet widely used as a LMB growout feed (Nelson and Sons, Inc., SilvercupTM, Steelhead, Murray, UT, USA). This diet served as a commercial control (CC) and contained 46% crude protein. The experimental diets were formulated to be isonitrogenous and isocaloric with the CC diet and were fed once daily to apparent satiation for 180 d. At harvest, there were no significant differences between treatments (P > 0.05) in terms of survival, which averaged 95% overall. Mean weights of fish fed the three experimental diets FM-45, FM-24 and FM-8 were not significantly different (P > 0.05) and averaged 518, 546, and 529 g, respectively, but were all significantly greater (P, 0.05) than those fed the CC (488 g). Feed conversion ratio (FCR) of fish fed the FM-45 and FM-8 diets (1.43 and 1.46, respectively) was significantly greater (P, 0.05) than those fed the FM-24 diet (1.34). The FCR of fish fed the CC diet (1.39) was not significantly different (P > 0.05) from fish fed other diets. Feed cost per unit of weight gain ($US/kg) was significantly lower (P, 0.05) in fish fed the FM-24 and FM-8 diets ($0.73 and $0.72/kg, respectively) than in fish fed other diets. Feed cost per unit gain of fish fed the FM-45 diet ($0.83/kg) was significantly lower (P, 0.05) than those fed the CC diet ($1.04/kg). There were no significant differences (P > 0.05) in dress-out percentages or proximate composition among fish fed the four diets. This study indicates that fish meal levels in feeds used for the second year growout of LMB can be reduced to,8% of the formulation without reducing survival or growth and without negatively impacting body composition. [source] Replacement of Fish Meal with Poultry By-product Meal as a Protein Source in Pond-raised Sunshine Bass, Morone chrysops , × M. saxatlis ,, DietsJOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 5 2008Harvey J. Pine Replacement of fish meal (FM) as a protein source with alternative sources of protein in aquaculture diets has been widely explored in aquaculture. The goal of replacement of FM in production diets is to maintain growth, lower production costs, and increase sustainability. Evaluation of the replacement of FM with poultry by-product meal (PBM) in phase II sunshine bass diets, Morone chrysops × M. saxatilis, was conducted in ponds over 246 d. Four diets were formulated to be isonitrogenous (37%) and isocaloric (4 kcal/g) with different levels of FM replacement with PBM (0, 33, 67, and 100%, Diets 1,4, respectively). Twelve ponds were stocked with 400 phase II sunshine bass (mean weight 5.6 g) and randomly assigned one of the four diets. Fish were fed below satiation based on predicted growth and feed conversion, initially once daily (1700 h) and then twice daily (0700 and 1700 h) as water temperatures and feeding activity increased. Diets were evaluated based on production and performance indicators, body composition, and economic analysis. Production results revealed no significant differences in mean final individual fish weight (511 ± 21 g), net production (4257 ± 247 kg/ha), and survival (85 ± 2%). No significant differences occurred between the performance indicators: mean feed conversion ratio (2.47 ± 0.11), specific growth rate (1.84 ± 0.02), and protein conversion efficiency (23 ± 1.3%). Body composition was statistically similar for mean percent fillet weight (49 ± 0.6%) and percent intraperitoneal fat (9.8 ± 1.0%); however, the hepatosomatic index was significantly different between Diets 3 (3.7 ± 0.1%) and 4 (3.2 ± 0.1%). Mean proximate analysis of whole fish (dry weight basis) was not significantly different among treatments yielding the following: percent protein (46 ± 0.4%), lipid (47 ± 1.3%), and ash (8 ± 0.7%). Mean fillet composition (dry weight basis) also revealed no significant differences: percent protein (72 ± 0.8%), percent lipid (30 ± 1.6%), and percent ash (5 ± 0.2%). Proximate analysis was also performed on the diets and revealed a significantly lower protein content in Diet 3 (34.3 ± 0.5%) compared to the other diets (37.1 ± 0.4%). Amino acid analysis of the diets indicated a possible deficiency in methionine in Diets 3 and 4. Based on production, performance, and body composition, the results indicate that complete replacement of FM with PBM in sunshine bass diets is feasible; however, economic analysis suggests that the replacement of FM with PBM may result in reduced revenue over feed costs. [source] Influence of Vitamin E Source and Dietary Supplementation Level on Production Performance of Sunshine Bass, Morone chrysops , × Morone saxatilis ,, Fillet Tocopherol Content, and Immunocompetency during Stress and Bacterial ChallengeJOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 4 2008Jesse T. Trushenski We evaluated the effects of dietary vitamin E concentration and source on production performance and immunocompetency of sunshine bass, Morone chrysops × Morone saxatilis, following stress and disease challenge. Four diets were formulated to contain requisite levels (1×) or five times (5×) the vitamin E requirement of sunshine bass as met by synthetic vitamin E (SYNE) or natural source vitamin E (NSVE). Each diet was fed to juvenile sunshine bass for 8 wk prior to experimental challenges. Replicate tanks within each dietary treatment were challenged with stressor exposure (chasing with dip net), incidental Flavobacterium columnare exposure, or both; control groups were not challenged. Pathogen and/or stressor exposure largely resulted in significant reductions in immunological performance. Although significant independent dietary effects were not observed among immunological parameters, suppression of complement and macrophage respiratory burst activities was numerically lower within the 5× NSVE treatment. Production performance was largely unaffected by dietary vitamin E source or level. Fillet ,-tocopherol concentration was significantly higher among fish fed the 5× diets (40.7/41.6 vs. 12.2/14.5 ,g/g dry tissue for 1× diets); however, the dietary concentration required to achieve these levels was lower for NSVE. Although super-requirement levels of either source of vitamin E were apparently beneficial, NSVE was effective at ,50% lower supplementation levels. [source] Effect of Stocking Weight and Stocking Density on Production of Hybrid Striped Bass (Sunshine) in Earthen Ponds in the Second Phase of a 2-Phase SystemJOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 1 2004Louis R. D'Abramo Sunshine bass from Phase I or pond production were graded into two weight classes, 3 and 5 g, and stocked into experimental earthen ponds at a density of either 8,649/ha or 11,120/ ha in a 2 × 2 factorial design. After stocking, the fish were fed a commercially manufactured feed (43.0-45.5% crude protein) twice daily to satiation for 17 mo. At harvest, mean survival ranged from 67.4 to 84.8% but was highest for the fish stocked at 5g. Average production Tor ponds stocked at 8,649/ha and 11,120/ha, regardless of stocking weight, was 4,506 kg/ha and 5350 kg/ha, respectively. Production and percentages of assigned weight classes were not significantly different among treatments as a result of wide variation among replicates. Using size-dependent market prices assigned to the different harvest size groups, an economic analysis revealed gross receipts, variable costs, and total costs for the 11,120/ha 5-g treatment. Net returns were not significantly different among the four treatments due to large variation among replicates per treatment. These results confirm that the traditional phase II of pond production can be eliminated in favor of a direct stocking of phase I fish into a single production phase and economically competes very well with traditional three-phase growout management. The potential reduction in turnover time of production units achieved through the direct stock practice is an efficiency trait that should translate into significantly higher returns and a greater profit over the long term. Further reduction of stocking density combined with a stocking weight greater than 5 g should translate into greater proportion of larger, higher valued fish at harvest and a growout period of 18-20 mo, rather than the 24-30 mo traditionally needed for the combined phase II and phase III of production. [source] Comparison of the Stress Response to Seining between Hybrid Sunshine Morone chrysops x M. saxatilis and Palmetto M. saxatilis x M. chrysops BassJOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 1 2004Kenneth B. Davis [source] Examining the Nature and Significance of Leadership in Government OrganizationsPUBLIC ADMINISTRATION REVIEW, Issue 2 2008Tracey Trottier Though the mainstream organizational literature has advanced in the last 20 years with the integration of transformational and distributed leadership theories, as well as genuine attempts at comprehensive models, the public sector literature has lagged, especially in utilizing large-scale empirical studies. This study takes advantage of a very large government data set to test the utility of one of the best known theories, the "full range" leadership theory of Bernard Bass. It addresses three important research questions: How inclusive is Bass's operational definition of leadership? How much of an impact do Bass's leadership competencies have on follower satisfaction? Finally, how important is transformational leadership compared to transactional leadership in government settings? The results indicate that Bass's broad definition of leadership comes quite close to capturing what federal employees perceive to be effective leadership. The relationship between good leadership in an organization and follower satisfaction is also presented as an important outcome in the federal government. Finally, both transactional and transformational leadership are perceived as important in the federal government, although transformational leadership is considered slightly more important even after shifting one important factor, individualized consideration, back to the transactional model. [source] Leading Lives that Matter: What We Should do and Who We Should be , Edited by Mark R. Schwehn and Dorothy C. BassRELIGIOUS STUDIES REVIEW, Issue 3 2008Aaron Klink No abstract is available for this article. [source] Muscle Cellularity at Cranial and Caudal Levels of the Trunk Musculature of Commercial Size Sea Bass, Dicentrarchus labrax (Linnaeus, 1758)ANATOMIA, HISTOLOGIA, EMBRYOLOGIA, Issue 5 2005I. Abdel Summary In eight specimens of Atlantic sea bass of commercial size (,350 g) muscle cellularity was studied at two selected sampling levels of the trunk axial musculature: caudal (anal opening) and cranial (fourth radius of the dorsal fin). The following parameters were quantified at both sampling levels: white muscle cross-sectional area, white muscle fibre diameter (900,1200 fibres), muscle fibre number and muscle fibre density. Results showed a higher total cross-sectional area at cranial than at caudal level (P < 0.05), what is related with their different gross morphology. However, the white muscle fibre size distribution, as well as the muscle fibre number and density did not show significant differences between them. This study contributes to typify muscle fibre sampling in sea bass of commercial size what is of great interest for morphometric studies where white muscle cellularity is commonly correlated with textural or organoleptic parameters. [source] Determination of physical behaviour of feed pellets in Mediterranean waterAQUACULTURE RESEARCH, Issue 2 2006Paolo Vassallo Abstract Settled uneaten feed causes the most intense impact under sea cages, and settling velocity of the feed pellets represents a key parameter for waste dispersion models. Even if some data about physical properties of feed pellets have been published in the framework of salmonid rearing, there is a complete lack of information related to the Mediterranean Sea, as regards typical values of temperature, salinity and feed composition for Gilthead Sea Bream (Sparus aurata L.) and Sea Bass (Dicentrarchus labrax L.). In this study we try to fill this lack, determining dimensions, water adsorption properties, floating times and settling velocities of a typical growing sequence of pellets for the species mentioned above, under defined laboratory conditions reproducing Mediterranean Sea water. The settling velocity increases with pellet size from 0.087, for the smallest pellet (3 mm), to 0.144 m s,1, for the 5 mm pellet. The biggest extruded pellet (6 mm) falls slower (0.088 m s,1). The floating time before pellet's fall is found to be a critical parameter in determining settling velocity. The latter depends on pellet's size, water temperature and salinity. The examined pellets reach a 42% of weight increase after 10 min of immersion, while no appreciable dimension change is observed. Our results are in part different from previous ones and could play a role in evaluating and modelling Mediterranean aquaculture environmental impact. [source] Ethical Values of Transactional and Transformational LeadersCANADIAN JOURNAL OF ADMINISTRATIVE SCIENCES, Issue 4 2001Rabindra N. Kanungo Ethical leadership literature (Bass & Steidlmeier, 1999; Kanungo & Mendonca, 1996) suggests that authentic transformational leadership must be based on some moral foundation. Such literature is not as clear, however, on whether transactional leadership can have moral foundation as well. The paper argues that transformational and transactional leadership behaviours are judged to be ethical based on two different sets of values, motives, and assumptions. These values, motives, and assumptions are grounded in two types of ethical perspective for understanding the behaviour of the two types of leaders. Transformational leaders have an organic worldview and moral altruistic motives grounded in a deontological perspective. Transactional leaders, on the other hand, have an atomistic worldview and mutual altruistic motives grounded in a teleological perspective. Résumé La littérature sur le leadership éthique (Bass & Steidlmeier, 1999; Kanungo & Mendonca, 1996) suggère que le leadership transformationnel authentique doit être basé sur des fondements moraux quelconques. Par con-tre, la littérature ne précise pas si le leadership trans-actionnel doit aussi avoir des fondements moraux. Cette étude démontre que les comportements de leadership transformationnels ainsi que transactionnels sont jugés comme étant basés sur deux différents groupes de valeurs, motifs et suppositions en ce qui attrait à l'éthique. Ces valeurs, motifs et suppositions sont fondés sur deux types de perspectives éthiques defaçon à com-prendre le comportement des deux types de leaders. Les leaders transformationnels out une perception orga-nique du monde ainsi que des motifs moraux altruistes basés sur une perspective déontologique. À l'opposé, les leaders transactionnels ont une perception atomiste du monde et des motifs mutuels basés sur une perspective téléologique. [source] Contrasting Burns and Bass: Does the transactional-transformational paradigm live up to Burns' philosophy of transforming leadership?JOURNAL OF LEADERSHIP STUDIES, Issue 3 2007Dmitry Khanin Both proponents and critics view the transactional-transformational paradigm (Bass, 1997, 1998) as the brainchild of Burns' (1978) philosophy of transforming leadership. However, Burns (2003) has criticized the paradigm's narrow managerialist orientation and the claim that it is uniformly applicable to any culture and organization. In this article, I first summarize and articulate Burns' (1978, 2003) and Bass' (1985, 1998) approaches toward leadership, then compare them by using a new four-dimensional framework. Extending previous research (Yukl, 2006), the framework represents a useful tool for detecting the commonalities and differences between leadership theories with respect to the core dimensions, categories, and aspects of leadership. My inspection indicates that Burns' and Bass' conceptions stem from disparate contexts and differ in their applicability. Thus, Burns' (1978) ideas stem from political movements ideally characterized by mutual quest for shared meaning and active collaboration between leaders and followers. Conversely, Bass' (1985) approach springs from military training in which leaders transfer existing knowledge to followers and stimulate their activity by using a variety of tools from inspirational motivation to individualized consideration. This study has important practical implications as it delineates the boundary conditions of the transactional-transformational paradigm and warns against its uncritical adoption in incongruent leadership contexts. [source] Influence of hatch duration and individual daily growth rates on size structure of age-0 smallmouth bass cohorts in two glacial lakesECOLOGY OF FRESHWATER FISH, Issue 3 2008Q. E. Phelps Abstract,,, We assessed hatch dates and daily growth rates of age-0 smallmouth bass from two glacial lakes over a 3-year period. Hatching durations (19,27 days among years) of smallmouth bass occurred from late May until late June. Mean daily growth rate of age-0 smallmouth bass ranged from 0.56 to 1.56 mm·day,1. Correlation analysis indicated that hatch date had little effect on daily growth rates. Hatch date was significant in explaining variation in total length (TL) of age-0 smallmouth bass at time of capture in only three of six cases and hatch date never explained >50% of the variation in bass length. Daily growth rate significantly explained variation in smallmouth bass TL at time of capture in all six models, accounting for 31,86% of the variability in bass length. Our findings suggest that size structure of age-0 cohorts in some populations may be more strongly regulated by variation in individual daily growth rate than by hatch timing. [source] Diet-induced phenotypic plasticity in the skull morphology of hatchery-reared Florida largemouth bass, Micropterus salmoides floridanusECOLOGY OF FRESHWATER FISH, Issue 4 2005A. P. Wintzer Abstract , Hatchery-reared Florida largemouth bass, Micropterus salmoides floridanus, feed on inert pellet food while their wild counterparts capture elusive prey. Differences in levels of prey elusivity often mandate the use of alternate methods of prey capture. This study examines whether elusivity-based variation in prey capture translates to a phenotypic change during skull development, and if this change results in a functional difference in the feeding mechanism. The developmental pattern of the skull was conserved between hatchery and wild bass until 80,99 mm TL. At this point, wild bass quickly developed morphological changes of the jaw apparatus including a more fusiform head and elongated jaw structures. Natural development in hatchery bass, however, was retarded at this size. Post-release, the skulls of hatchery fish converged towards those of wild bass by 135 mm TL. Despite variation in skull development, no theoretical advantage in food capture was found between these two groups. Resumen 1. Los individuos de Micropterus salmoides floridanus criados en cautividad se alimentan de cápsulas inertes de comida mientras que sus congéneres salvajes capturan presas elusivas. A menudo diferencias en los niveles de elusividad de las presas permiten la utilización de métodos alternativos para capturar presas. Este estudio examina si la variación basada en la elusividad de la captura de presas se traduce en un cambio fenotípico durante el desarrollo del cráneo y si este cambio resulta en una diferencia funcional en el mecanismo de alimentación. 2. El patrón de desarrollo del cráneo se mantuvo entre individuos criados en cautividad y en individuos salvajes hasta los 80,99 mm longitud total. En este punto, los individuos salvajes desarrollaron rápidamente cambios en el aparato mandibular incluyendo una cabeza más fusiforme y estructuras mandibulares mas alargadas. Sin embargo, en individuos de cautiverio, el desarrollo natural se retrasó en este tamaño. 3. Tras una suelta, los cráneos de individuos procedentes de cautiverio convergieron hacia los individuos salvajes en los 135 mm longitud total. A pesar de la variación en el desarrollo del cráneo, no encontramos ninguna ventaja teórica en la captura de alimento entre estos dos grupos. [source] Diet dynamics of the juvenile piscivorous fish community in Spirit Lake, Iowa, USA, 1997,1998ECOLOGY OF FRESHWATER FISH, Issue 4 2001M. E. Pelham Abstract , We assessed temporal dynamics and variation among species and age-classes in the diets of age 0 and age 1 piscivorous fish species in Spirit Lake, Iowa, USA during 1997 and 1998. Species included walleye Stizostedion vitreum, yellow perch Perca flavescens, smallmouth bass Micropterus dolomieui, largemouth bass Micropterus salmoides, black crappie Pomoxis nigromaculatus and white bass Morone chrysops. Thirty taxa were identified in diets, including 12 species of fish. We found dramatic differences in diets among species, among age-classes within species and over time. Walleye, largemouth bass, smallmouth bass and white bass were piscivorous at age 0. Black crappie began piscivory at age 1. Yellow perch also began piscivory at age 1, but fish were a very small fraction of age-1 diets. The primary temporal pattern, seen in several species and age-classes, was an increase in piscivory from spring to fall. This pattern was due to the lack of small, age-0 prey fish in spring. Although some patterns were evident, the taxonomic composition of the diets of all species was highly variable over time, making generalizations difficult. A surprising result was the absence of yellow perch in the diet of age-0 walleye, despite their abundance in Spirit Lake and prominence in diets of age-1 walleye and other age 1-piscivores. Age-0 yellow perch were consistently too large to be eaten by age-0 piscivores, which preyed primarily on invertebrates and smaller fish such as johnny darters Etheostoma nigrum and age 0 bluegill Lepomis macrochirus. This finding suggests that predator-prey interactions and resulting population dynamics may be quite different in Spirit Lake than in other systems dominated by walleye and yellow perch., [source] Development of a bacterial challenge test for gnotobiotic sea bass (Dicentrarchus labrax) larvaeENVIRONMENTAL MICROBIOLOGY, Issue 2 2009K. Dierckens Summary The use of probiotic microorganisms in aquaculture is gaining a lot of interest. Gnotobiotic model systems are required in order to fully understand the effects and modes-of-action of these microorganisms, as the native microbial communities present in non-sterile animals can lead to false conclusions. In this study, a gnotobiotic sea bass larvae (Dicentrarchus labrax) test system was developed. In order to obtain bacteria-free animals, the eggs were disinfected with glutaraldehyde and subsequently incubated in a solution of rifampicin and ampicillin. Axenity was confirmed using culture-dependent and -independent techniques. The gnotobiotic larvae were fed axenic Artemia sp. from 7 days after hatching onwards. In the challenge test, one of the three opportunistic pathogens, Aeromonas hydrophila, Listonella anguillarum serovar O1 and O2a, was added to the model system via the water and encapsulated in Artemia sp. Only serovar O2a led to increased mortality in the sea bass larvae. The presented gnotobiotic model can be used for research on, among others, reciprocal metabolic effects between microorganisms and the host (e.g. as measured by gene expression), immunostimulants, pharmacological research and the histological development of the gastrointestinal tract and growth of larvae. [source] Reproductive health of bass in the Potomac, USA, drainage: Part 1.ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 5 2009Exploring the effects of proximity to wastewater treatment plant discharge Abstract Intersex (specifically, testicular oocytes) has been observed in male smallmouth bass (SMB; Micropterus dolomieu) and other centrarchids in the South Branch of the Potomac River, USA, and forks of the Shenandoah River, USA, during the past five years. This condition often is associated with exposure to estrogenic endocrine-disrupting chemicals in some fish species, but such chemicals and their sources have yet to be identified in the Potomac. In an attempt to better understand the plausible causes of this condition, we investigated the reproductive health of bass sampled up- and downstream of wastewater treatment plant (WWTP) effluent point sources on the Potomac River in Maryland, USA. Smallmouth bass were sampled from the Conococheague Creek and the Monocacy River, and largemouth bass (LMB; Micropterus salmoides) were collected near the Blue Plains WWTP on the mainstem of the Potomac River. Chemical analyses of compounds captured in passive samplers at these locations also were conducted. A high prevalence of intersex (82,100%) was identified in male SMB at all sites regardless of collection area. A lower prevalence of intersex (23%) was identified in male LMB collected at the Blue Plains site. When up- and downstream fish were compared, significant differences were noted only in fish from the Conococheague. Differences included condition factor, gonadosomatic index, plasma vitellogenin concentration, and estrogen to testosterone ratio. In general, chemicals associated with waste-water effluent, storm-water runoff, and agriculture were more prevalent at the downstream sampling sites. An exception was atrazine and its associated metabolites, which were present in greater concentrations at the upstream sites. It appears that proximity to effluent from WWTPs may influence the reproductive health of bass in the Potomac watershed, but inputs from other sources likely contribute to the widespread, high incidence of testicular oocytes. [source] Reproductive health of bass in the Potomac, USA, drainage: Part 2.ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 5 2009Seasonal occurrence of persistent, emerging organic contaminants Abstract The seasonal occurrence of organic contaminants, many of which are potential endocrine disruptors, entering the Potomac River, USA, watershed was investigated using a two-pronged approach during the fall of 2005 and spring of 2006. Passive samplers (semipermeable membrane device and polar organic chemical integrative sampler [POCIS]) were deployed in tandem at sites above and below wastewater treatment plant discharges within the watershed. Analysis of the samplers resulted in detection of 84 of 138 targeted chemicals. The agricultural pesticides atrazine and metolachlor had the greatest seasonal changes in water concentrations, with a 3.1- to 91-fold increase in the spring compared with the level in the previous fall. Coinciding with the elevated concentrations of atrazine in the spring were increasing concentrations of the atrazine degradation products desethylatrazine and desisopropylatrazine in the fall following spring and summer application of the parent compound. Other targeted chemicals (organochlorine pesticides, polycyclic aromatic hydrocarbons, and organic wastewater chemicals) did not indicate seasonal changes in occurrence or concentration; however, the overall concentrations and number of chemicals present were greater at the sites downstream of wastewater treatment plant discharges. Several fragrances and flame retardants were identified in these downstream sites, which are characteristic of wastewater effluent and human activities. The bioluminescent yeast estrogen screen in vitro assay of the POCIS extracts indicated the presence of chemicals that were capable of producing an estrogenic response at all sampling sites. [source] Dietary uptake models used for modeling the bioaccumulation of organic contaminants in fish,,ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 4 2008M. Craig Barber Abstract Numerous models have been developed to predict the bioaccumulation of organic chemicals in fish. Although chemical dietary uptake can be modeled using assimilation efficiencies, bioaccumulation models fall into two distinct groups. The first group implicitly assumes that assimilation efficiencies describe the net chemical exchanges between fish and their food. These models describe chemical elimination as a lumped process that is independent of the fish's egestion rate or as a process that does not require an explicit fecal excretion term. The second group, however, explicitly assumes that assimilation efficiencies describe only actual chemical uptake and formulates chemical fecal and gill excretion as distinct, thermodynamically driven processes. After reviewing the derivations and assumptions of the algorithms that have been used to describe chemical dietary uptake of fish, their application, as implemented in 16 published bioaccumulation models, is analyzed for largemouth bass (Micropterus salmoides), walleye (Sander vitreus = Stizostedion vitreum), and rainbow trout (Oncorhynchus mykiss) that bioaccumulate an unspecified, poorly metabolized, hydrophobic chemical possessing a log KOW of 6.5 (i.e., a chemical similar to a pentachlorobiphenyl). [source] In situ reproduction, abundance, and growth of young-of-year and adult largemouth bass in a population exposed to polychlorinated biphenylsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 7 2004Dudley W. Reiser Abstract We conducted a two-year field study (2000,2001) in the Housatonic River, Massachusetts (USA) to determine if we could detect in situ population-level effects on largemouth bass (Micropterus salmoides) exposed to elevated levels of polychlorinated biphenyls (PCBs). Calculated whole-body PCB concentrations in adult bass in 2002 averaged 121 mg/kg (range = 34,556 mg/kg). Polychlorinated biphenyl concentrations in young-of-year (YOY) composites in 2000 and 2002 averaged 28 mg/kg (range = 21,41 mg/kg) and 19 mg/kg (range = 16,24 mg/kg), respectively. Laboratory studies of fish have reported PCB toxicity at exposure levels below and within the range of those found in the Housatonic River. We evaluated five field-derived metrics: reproductive activity, relative abundance of YOY, YOY growth rates, adult growth, and adult condition to determine whether we could detect effects of PCBs in the largemouth bass population. These computed metrics, when compared with data sets assembled for numerous largemouth bass populations in North America, provided no evidence of population-level impairment. Results of this study suggest that PCB tissue concentrations associated with effects in laboratory studies do not necessarily translate to detectable effects on largemouth bass populations in their natural environment. [source] Contamination of fish in streams of the Mid-Atlantic Region: An approach to regional indicator selection and wildlife assessmentENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 3 2003James M. Lazorchak Abstract The extent of contamination of fish in the Mid-Atlantic Region was evaluated as part of the U.S. Environmental Protection Agency's Monitoring and Assessment Program's regional assessment in 1993 through 1994. Fish assemblages from wadeable streams were dominated by small, short-lived fishes (e.g., minnows, darters, and sculpins) that were more widely distributed and abundant than large fishes typically chosen for tissue contaminant studies (e.g., trout, black bass, sunfish, common carp). Chemical concentrations in whole-fish homogenates exceeded detection limits for mercury, DDT, and polychlorinated biphenyls (PCBs) in 75 to 100% of the stream length assessed using small fishes and 84 to 100% of the stream length assessed using large fishes. Wildlife values (WVs) representing a threshold for toxic effect were developed to allow examination of the spatial extent of potential risk to piscivorous wildlife. For mercury, DDT, dieldrin, and chlordane, estimates of the regional extent of streams where fish contaminant concentrations exceeded the WVs were greater when based on small fishes than on large fishes. However, within the distribution of stream lengths assessed using small and large fishes, the percentage of stream kilometers exceeding the WVs were quite similar. Our data demonstrate that the greater abundance and distribution of small, short-lived fishes provide greater estimates of regional extent of contamination for first- through third-order streams and can be used for regional assessments of potential exposure and effects in wildlife. [source] Ontogenetic Changes in the Response of Largemouth Bass (Micropterus salmoides, Centrarchidae, Perciformes) to Heterospecific Alarm PheromonesETHOLOGY, Issue 5 2001Grant E. Brown Juvenile largemouth bass (Micropterus salmoides) undergo an ontogenetic niche shift from invertebrate feeding members of the cyprinid prey guild to piscivory during their first year of growth. We conducted laboratory and field trials to determine whether juvenile bass show a similar ontogenetic shift in their response to the alarm pheromone of finescale dace (Phoxinus neogaeus, Cyprinidae). When exposed to dace skin extract (with alarm pheromone), juvenile bass exhibited a significant positive relationship between standard length and horizontal and vertical area use and time spent moving. Small bass (< 50 mm standard length) tended to reduce area use and time spent moving (indicative of an anti-predator response), while larger bass (> 50 mm standard length) increased area use and time spent moving (indicating a foraging response). Bass exhibited no change in behaviour when exposed to swordtail (Xiphophorus helleri) skin extract, which lacks Ostariophysan alarm pheromone. During field trials, small (30,45 mm standard length) and medium (46,60 mm standard length) bass actively avoided areas labelled with dace alarm pheromone and exhibited a significant increase in dashing behaviour. Large bass (61,80 mm standard length) were attracted to such areas and exhibited a significant increase in approach behaviour. These data suggest that largemouth bass undergo an ontogenetic shift in response to heterospecific chemical alarm signals. [source] Introduction of a new physiological acoustic electromyogram transmitterFISHERIES MANAGEMENT & ECOLOGY, Issue 5-6 2008G. LEMBO Abstract, Electromyogram (EMG) radio transmitters have proven to be a useful tool to monitor activity levels in free swimming fish. Unfortunately, the availability of the EMG transmitter in only radio mode limited its use to the freshwater environment. Applications in the marine environment are numerous and include monitoring activity levels in both wild and cultured finfish. This study presents preliminary data from trials examining activity levels in free swimming sea bass, Dicentrarchus labrax, L., using an acoustic EMG transmitter. Three adult sea bass were surgically implanted with the newly created prototype EMG transmitters. Signals from the transmitter were calibrated to swimming speed using a Bla,ka-style chamber. Swimming trials showed a high correlation between EMG signal and swimming velocity (r2 = 0.978) and were described using a sigmoid model. No significant differences (P < 0.05) were found among the four swimming trials conducted on the same fish or among the trials of the three different fish, indicating minimum variation from the prototypes tested. [source] Analysis of the trophy sport fishery for the speckled peacock bass in the Rio Negro River, BrazilFISHERIES MANAGEMENT & ECOLOGY, Issue 2 2008M. H. HOLLEY Abstract, The middle portion of the Rio Negro River in Brazil near the equator supports a popular recreational sport fishery for speckled peacock bass, Cichla temensis (Humboldt). The objective of this study was to determine the effect of fishing mortality on this population. Fish were collected from sport-fishing (n = 72) and commercial (n = 103) catches and otoliths were aged to estimate longevity, growth and natural mortality. Recreational anglers in this region seek to catch, then release, larger speckled peacock bass; and fish larger than 62 cm standard length (SL) (about 4.5 kg) served as a bench mark to assess the potential impact of subsistence and commercial harvest on the abundance of larger fish in the sport fishery. Time of opaque band formation on otoliths generally coincided with the dry season (November to April); these bands appeared to form once per year, but formation was highly variable. Speckled peacock bass grew to 62 cm SL on average in 6.4 years, but some fish obtained this size in 4,5 years. Maximum age was 9 years, but most fish were less than 7 years. Instantaneous annual natural mortality (M) estimated from maximum size, longevity and growth ranged from 0.19 to 0.44. Simulation modelling predicted that exploitation rates of fish >25 cm SL similar to the estimated natural mortality rates would reduce the abundance of fish >62 cm by 67,89% compared with no harvest. Even modest exploitation rates of 5% and 10% would result in approximately 30,50% reduction, respectively, of these larger fish. Abundance of large speckled peacock bass that sustains the sport fishery is susceptible to low rates of exploitation in this remote region of Brazil. [source] | ||||||||||||||||||||||