bluuebunny/crossref_metadata_2025 huggingface dataset:
Lateral migration of fishes in Amazon floodplains
Authors: Fernandes C. C.
Published: July 2006

Abstract— Migrations of fish in the outlet channel of Lago do Rei, a floodplain lake on Careiro Island in the Amazon River, were examined using three capture methods. Of the 85 species found in the Parana do Rei (channel), 20 migrated between the lake and river. Migrations from the lake to the river occurred in two pulses. In August‐September, as the river water level began to recede, some fish migrated to the river with the current. As the river water level rose in December‐January, additional fish migrated towards the main river against the current. Fish returned to the lake by March or April after they had spawned. The migratory patterns of six species, family Curimatidae and Prochilodontidae: Potamorhina latior, Psectrogaster amazonica, P. rutiloides, Curimata kneri, Prochilodus nigricans and Semaprochilodus taeniurus are described in detail. Lateral migrations of fish in this ecosystem appear to be closely linked to breeding and to physical habitat changes related to river water level.
Eel larvae (Anguilla anguilla L.) caught by R.V. “Heincke” at the European continent slope in autumn 1991
Authors: Antunes C. , Tesch F.‐W.
Published: July 2006

Thirty one catches by Isaac Kidd Midwater Trawl were obtained between Oc‐tober 23 and 27, 1991 in the Bay of Biscay and on the west coast of the Iberian Peninsula. The total catch amounted to 95 eel larvae. North of 43°N, 2.8 larvae per hour of towing were captured, south of 43°N (west coast of the Iberian Peninsula) 3.25 larvae per hour of towing. The abundance of eel larvae, north and south, was similar to that in the years following the strong decrease in 1980. Younger eel larvae (stages 1‐11) were dominant (82%) on the west coast of the Iberian Peninsula. In the Bay of Biscay, older stages of eel larvae were more frequent (stages III‐IV, 53.6%). Northern larvae exhibited longer lengths in all development stages than southern larvae.
Distribution of and reproductive isolation among color morphs of a rock‐dwelling Lake Victoria cichlid (Haplochromis nyererei)
Authors: Seehausen O.
Published: July 2006

Abstract— The geographical and macro‐ and microhabitat distribution of and mate recognition among color morphs of a complex of Lake Victoria cichlids were studied. The distribution of most morphs was mutually exclusive, but two morphs overlapped extensively and differed only in microhabitat requirements. Coloration differences between them were inherited, and wild fishes were homozygous in this respect. Positive morph‐assortative female mate choice was demonstrated. Over the largest part of their common geographical range, intermediate phenotypes are absent and the two morphs are to be considered two biological species. However, in populations at one end of the range, intermediate phenotypes with continuously varying male coloration make up the majority of the individuals. It is suggested that the status of color morphs as phenotypes of one species or as separate biological species is a function of environmental conditions that vary considerably between the localities. The data support the hypothesis that polymorphisms can be a step preceding speciation in cichlid fish.
Growth and feeding responses of a hatchery population of brown trout (Salmo trutta L.) at low temperatures
Authors: Koskela J. , Pirhonen J. , Jobling M.
Published: July 2006

Abstract— Feed intake, specific growth rate and changes in body composition were studied in age 1+ (140‐190 g) brown trout (Salmo trutta L.) reared at three temperatures (2, 4 and 6°C) under continuous light conditions. Feed in take increased from 35.7 kJ‐kg−1.day−1 at 2°C to 95.7 kJ‐kg−1‐day−1 at 6°C, and the growth rate increased from 0.19%‐day−1 to 0.42%‐day−1 over the same temperature range. The estimated lower temperature limits for feeding and growth were slightly above 0°C. For all groups of fish, the majority (about 75%) of the weight gain comprised water and protein, but lipid deposition tended to increase with increasing temperature. The deposition of lipid accounted for about 50% of the body energy gain at all temperatures.
Composition and spatial organization of fish assemblages in the lower Guadiana basin, southern Iberia
Authors: Godiaho F. N. , Ferreira M. T. , Cortes R. V.
Published: July 2006

Abstract— A survey of fish assemblages (composition and spatial organization) was made in the lower Guadiana basin (southern Iberia) during the summer of 1994. A total of 6937 specimens belonging to 18 species were collected in 44 channel units and 30 sites (i. c. a series of channel units), comprising all the freshwater species previously recorded in the area except the exotic Esox lucius and the endemic endangered cyprinid Anaecypris hispanica. The endemic cyprinids Chondrostoma lemmingii and Barbus sclateri were rarely encountered, whereas the exotic Lepomis gibbosus was the predominant species found. The lower Guadiana fish community changed in space from assemblages characterized by the high relative abundances of Leuciscus pyrenaicus, smaller size‐classes of Barbus spp. and Tropidophoxinellus alburnoides (all Iberian endemisms), to assemblages characterized by the high relative abundances of L. gibbosus, Micropterus salmoides, Cichlasoma facetum (all exotic species) and the larger size‐classes of Barbus comiza and Barbus microcephalus. The former assemblages used smaller (i. e., narrow and shallow) sites and channel units, usually in tributaries and closer to headwaters, with smaller L. pyrenaicus being dominant in sites located in the tributaries discharging to the brackish Guadiana. This group was also related to channel units rich in emergent macropthytes. The latter assemblages were related to the largest sites and channel units, typically found in the main river or in tributary sites far from the source. Besides these two groups, some species were associated to noticeable environmental conditions; Blennius fluviatilis to channel units with current velocity and heterogeneous substrate, typically found in the main river, and Cobitis paludica to channel units with heterogeneous substrate.
Diet overlap in a piscivore community
Authors: Hodgson J. R. , He X. , Schindler D. E. , Kitchell J. F.
Published: July 2006

Abstract— We examined prey selection of largemouth bass (Micropterus salmoides), smallmouth bass (M. dolomieu), and yellow perch (Percaftavescens) by comparing diet overlap in a small, unexploited lake in Michigan, USA from 1988 to 1990. Niche hypervolume principles were applied to diet data as a means of assessing diet space for each species and the community as a whole. Largemouth bass occupied the largest proportion of community diet space (70.2%), followed by smallmouth bass (44.2%), and yellow perch (21.7%). The majority of community diet space (58.8%) was occupied by a single species, and 41.2% was shared by ≥ 2 species. Diet overlap was assessed by measuring the amount of diet space of one species occupied by the other species. Our analyses demonstrated that diet partitioning in a three species piscivore community is reflected in different use of the prey resource by co‐occurring species. Niche overlap of largemouth bass with smallmouth bass and yellow perch is strongly asymmetric, largely due to the ability of largemouth bass to effectively consume prey of terrestrial origin.
Microdistribution and fluctuations in niche overlap in a rocky shore cichlid community in Lake Victoria
Authors: Seehausen O. , Bouton N.
Published: July 2006

Abstract— The microdistribution of ten numerically dominant species in a fish community at a rocky island in Lake Victoria was studied using invasive sampling. All were haplochromine cichlids. The community was characterized by high fish densities and by a dominance of Aufwuchs feeders. Species were non‐randomly distributed, showing significant associations with water depth and other topographic parameters. Species occupied unique positions in a network of recurrent species groups. Niche partitioning through differential microdistribution was even more subtle than that reported for Lake Malawi's rock‐dwelling cichlids. Species‐specific microdistribution fitted qualitative predictions from ideal free distribution models with asymmetrical interference competition for food. No evidence was found for interspecific contest competition for space. Temporal niche shifts have been observed between periods of high and low water levels. Owing to a combination of reduced habitat availability with niche expansion in most species, niche overlap was larger during the lowwater period.
Behavioral interactions between coho (Oncorhynchus kisutch) and chinook salmon (Oncorhynchus shawytscha) and prey fish species
Authors: Savitz J. , Bardygula‐Nonn L.
Published: July 2006

Abstract— The predator‐prey behavioral interactions between two salmon species, coho salmon (Oncorhynchus kisutch) and chinook salmon (Oncorhynchus tshawytscha), and their prey species were examined under laboratory conditions. These behaviors were studied to determine the bases for prey selection by salmon in Lake Michigan and ultimately facilitate predictions on shifts or changes in salmon diets. Chinook and coho salmon captured all prey items in the open water portion of the aquarium, and they had similar attack behaviors. Average attack swimming speeds varied from 2.6 to 3.6 m/s, and average escape swimming speeds varied from 2.6 to 2.9 m/s. There were no significant differences in attack swimming speeds and escape swimming speeds. There was a significant difference in median reactive distances between the prey captured and those that escaped. There was no reactive distance (0.00 m) for 96% and 98% of the successfully captured prey by chinook and coho salmon, respectively. Only 4% and 10% of the unsuccessful attacks by chinook and coho salmon, respectively, had no reactive distance (0.00 m). Salmon would repeatedly attack a school and capture individuals separated from the school. Alewives, bloaters and fathead minnows were easy prey because they remained in the open water portion of the aquarium and stayed in schools until only a few individuals remained. The schooling behavior of spottail shiners and emerald shiners was an effective anti‐predation tactic against salmon attacks. After some experience with yellow perch, salmon were reluctant to attack them and would often break off attacks on them. When coho salmon were presented with different proportions of bloaters and yellow perch, they significantly attacked and captured bloaters in preference to yellow perch.
Resource partitioning among rock‐dwelling haplochromines (Pisces: Cichlidae) from Lake Victoria
Authors: Bouton N. , Seehausen O. , van Alphen J. J. M.
Published: July 2006

Abstract— Resource partitioning was studied on four assemblages of haplochromine cichlids at rocky islands in the southern part of Lake Victoria. The emphasis was put on diet segregation, while data on microhabitat segregation were mainly used to determine potential competitors for food. Diet and microhabitat segregation were demonstrated in all four assemblages. In one of the assemblages we observed little partitioning of resources among two filamentous algae feeders. The role of competition for food is discussed on the basis of fluctuations in diet overlap in relation to seasonal changes in food supply. Diet overlap proved to be highest in periods of food abundance. This is in concordance with the hypothesis that competition decreases in case of food abundance. Furthermore, we compared fish densities between assemblages, because competition would regulate density. We found that diets were most diverse in the assemblage with lowest fish density, while interspecific differences in diet were smallest. Food seems not to be limiting in this particular assemblage, and factors other than competition for food are probably more important in regulating density here.
Bioenergetic relations in submerged aquatic vegetation: an experimental test of prey use by juvenile bluegills
Authors: Richardson W. B. , Zigler S. J. , Dewey M. R.
Published: July 2006

Abstract— We experimentally tested the hypotheses that bluegills in vegetated habitats grow more rapidly than in nonvegetated habitats because (1) vegetated habitats contain a greater caloric density and (2) are less susceptible to energetic depletion. The 10‐week experiment was conducted in enclosures containing factorial combinations of the presence or absence of Vallisneria americana and juvenile bluegills Lepomis macrochirus. After 6 weeks, Vallisneria‐only treatments contained a mean of 1048 cal/m2 in the benthos, whereas treatments with both Vallisneria and bluegills contained 610 cal/m2. Hyalella azteca, a preferred prey of bluegill, were nearly depleted in nonvegetated enclosures, whereas Hyalella densities in enclosures with Vallisneria were much less effected by fish. Bluegill growth was significantly greater with Vallisneria than without but declining water temperatures after week 6 resulted in slower growth despite abundant prey. Ultimately, growth of bluegill resulted from an interaction between availability and ingestion of prey, and water temperature.
Feeding of Atlantic salmon,Salmo salarL., parr in the subarctic River Teno and three tributaries in northernmost Finland
Authors: Erkinaro H. , Erkinaro J.
Published: July 2006

Abstract—Available food and feeding of Atlantic salmon parr were studied in different parts of a subarctic river in northernmost Finland, the River Teno: in the large main stem, in a major tributary influenced by lakes, and in two minor tributaries. The highest density of benthic organisms was found in an outlet of a lake, but drifting organisms were the most abundant in the small tributaries. Migrant parr that move to the small tributaries from the main stem have better food resources in their new habitat. Plecoptera nymphs were the most important prey for salmon parr early in the spring. Later in the summer dipterans were usually the dominant prey group. In September the importance of Plecoptera was emphasized in the small tributaries and the lake outlet, and that of Trichoptera in other sites. Drifting prey was used more by large than by small parr. The utilization of drifting food appeared to be related to the water temperature rather than to the availability of the drift.
The reliability of whitefish (Coregonus lavaretus (L.)) age determination ‐ differences between methods and between readers
Authors: Raitaniemi J. , Bergstrand E. , Flöystad L. , Hokki R. , Kleiven E. , Rask M. , Reizenstein M. , Saksgård R. , Ångström C.
Published: July 2006

Abstract— Age determinations of whitefish (Coregonus lavaretus (L.)) were compared in two different tests. In the first test, the readers determined the age of each individual from one calcified structure (scale, otolith, or opercular bone) at a time. The samples from three populations, 50 specimens in each, were mixed so that the readers did not know which population each calcified structure was from. A sample of known‐age whitefish was used in the second age determination test, where information such as time of catch, length, weight, and sex was available to the readers. In each of the 50 envelopes the reader got scale impressions and two otoliths, one of which had been burned and ground. In the first test, the precision of the readers was low both between readers and between different structures. In the samples of slow‐growing populations, the determinations made from the otoliths showed older ages than the determinations from the scales. In the second age determination test the results were better; 73‐90% (average 82%) of the determinations were correct. The use of two calcified structures and the knowledge of the material were considered to improve the accuracy. Age determination bias may occur that affects the age distribution: even though 80% of the fish were aged correctly, an exceptionally strong or weak year class could remain unidentified. The estimation of growth rate seemed less sensitive to incorrect age determination than age distribution.
Movements of the yellowfin shiner, Notropis lutipinnis
Authors: Goforth R. R. , Foltz J. W.
Published: July 2006

Abstract— Yellowfin shiner, Notropis lutipinnis, movements were observed in two streams located near Clemson, South Carolina (USA). Subcutaneous paint tags were used to associate fish with the pools in which they were initially captured, tagged and released. Few mortalities related to marking techniques were observed in both captive and field‐tagged fish. Tag longevity varied among paint colors used and anatomical locations marked. Movements were inferred from recaptured fish collected over a 12‐month period. Recaptures within release pools were proportionally greater than movements outside release pools, although the sampling technique used likely overestimated recaptures within release pools. Recaptures outside release pools were more frequent in late spring and early summer, coinciding with the N. lutipinnis spawning season. The linear home range estimate for this species was 42.9 ± 79.0 m, although this represents a minimum estimate because complex movements by individual fish could not be detected.
Early life history and recruitment of black crappie (Pomoxis nigromaculatus) in two South Dakota waters
Authors: Pope K. L. , Willis D. W.
Published: July 2006

Abstract— We compared the early life history of black crappie (Pomoxis nigromaculatus) in Richmond (an impoundment) and Brant (a natural lake) lakes during 1994‐1996. We expected variable recruitment (i. e., missing year classes) in the natural lake and more consistent recruitment in the impoundment. Larval black crappie abundance was always higher in Richmond Lake than Brant Lake. Peak abundance of larval black crappie was highest during 1994 in both waters. However, peak larval abundance did not correspond with fall trap‐net catch per unit effort (CPUE) of age‐0 black crappie, which was highest during 1995. Thus, recruitment of black crappie was not simply a function of the number of larvae hatched. Similar trends in catches of age‐0 black crappie with the ichthyoplankton trawl and trap nets for both water bodies during 1994‐1996 suggest that broad environmental factors similarly affected reproduction and recruitment in Richmond and Brant lakes.
Long‐term patterns of microhabitat use by fish in a southern Appalachian stream from 1983 to 1992: effects of hydrologic period, season and fish length
Authors: Grossman G. D. , Ratajczak R. E.
Published: July 2006

Abstract— We quantified microhabitat use by members of a southern Appalachian stream fish assemblage over a ten‐year period that included both floods and droughts. Our study site (37 m in length) encompassed riffle, run and pool habitats. Previous research indicated that species belonged to either benthic or water‐column microhabitat guilds. Most species exhibited non‐random microhabitat use in all seasons, and benthic and water column species generally were over‐represented in the deeper portions of the site. In addition, water column species generally were over‐represented in microhabitats with lower average velocities. The majority of seasonal shifts in microhabitat use were passive (i. e. correlated with changes in microhabitat availability), whereas, most shifts associated with hydrological periods appeared to be active responses to changing environmental conditions. Most species exhibited length‐related shifts in microhabitat use, which were strongly affected by hydrologic period for four of ten species. Microhabitat use patterns of assemblage members appeared to be a consequence of species‐specific responses to changing environmental conditions. The highly flexible patterns of microhabitat use exhibited by these species necessitate that decisions regarding their management be based on data covering a range of environmental conditions.
Brook trout spawning areas in lakes
Authors: Ridgway M. S. , Blanchfield P. J.
Published: July 2006

Abstract—Nine lakes containing self‐sustaining populations of brook trout (Salvelinus fontinalis) were surveyed to provide quantitative information on the abundance and distribution of redd sites. We measured rates of groundwater flow at redds in four of these lakes, and in one of these lakes we also compared the frequency of site use over four years from spawning observations. The number of redd sites in each lake ranged from 1 to 53 (mean=30) with most found relatively close to shore (∼ 1 m deep). Spawning areas per lake (16.9–829.4 m2) were not related to lake size and were often not continuous areas of littoral zone habitat. Rates of groundwater flow in lakes, averaged across redd sites in each lake, ranged from 20.0 to 107.9 ml. m.−2min−1.The intensive survey of redd site use in one lake demonstrated that only 11% of sites (10 of 92) were used in all four years of observation. The mean rates of groundwater flow at sites used in all four years were significantly greater than at sites used intermittently. Data from this and other studies point to the conservation of subcatchments associated with groundwater discharge areas used by spawning brook trout as a means of maintaining self‐sustaining populations.
Abundance, depth distribution, diet composition and growth of perch (Perca fluviatilis) and burbot (Lota lota) larvae and juveniles in the pelagic zone of Lake Constance
Authors: Wang N. , Appenzeller A.
Published: July 2006

Abstract— Surveys of larval and juvenile fish in the pelagic zone were made in Lake Constance between April and July 1994 with a plankton net. Perch (Perca fluviatilis) and burbot (Lota lota) were caught persistently, while other species were found only occasionally. Perch and burbot coexisted in the pelagic zone; both species were found first in mid‐May, reached peak density in June, and disappeared from the pelagic zone in late July. However, the abundance of perch was much higher than that of burbot. Perch were distributed mainly near the surface, whereas burbot were more abundant at the deeper strata of 5 and 10 m, exhibiting habitat segregation. Perch fed mainly on copepods and positively selected them during their first month of life, and afterwards, they consumed principally on Daphnia, while burbot fed mainly on copepods and positively selected them throughout the study period. Perch grew significantly faster than burbot, and the mean lengths of perch were about 3 times greater than that of burbot in July. The results demonstrate that perch and burbot were the main species of pelagic larvae in Lake Constance between May and July, and that the two species differed somewhat in depth distribution, diet composition and growth.
Trophic polymorphism among Arctic charr Salvelinus alpinus L., from Loch Ericht, Scotland
Authors: Fraser D. , Adams C. E. , Huntingford F. A.
Published: July 2006

Abstract— This article examines the morphology and ecology of Arctic charr Salvelinus alpinus in Loch Ericht, Scotland, Gill netting revealed that two forms of charr existed within the loch, a pale form and a colored form. Multivariate analysis of nine size‐corrected morphometric measurements of the head region revealed that pale and colored charr differed significantly in the size and shape of the head characteristics and that both groups were easily discriminated on the basis of these characteristics. Stomach contents showed that the colored form fed predominantly on zooplankton and the pale form mainly consumed benthic macro‐invertebrates, with larger pale individuals consuming other fish. On the basis of diet and morphology, the terms planktivorous and piscivorous were adopted for the two forms respectively. Length at age also distinguished the two groups, with piscivorous charr being smaller than colored charr up to age 8+ then surpassing the maximum length attained by planktivorous charr at ages of 9+ and above. The results are discussed in relation to other instances of sympatric morphs of Arctic charr.
An experimental test of the genetic component of the ontogenetic habitat shift in Arctic charr (Salvelinus alpinus)
Authors: Langeland A. , L'Abée‐Lund J. H.
Published: July 2006

Abstract— Fry of the Arctic charr, Salvelinus alpinus, were experimentally stocked into a small fish‐free lake to test the hypothesis that the size‐dependent habitat shift from the epibenthic to the pelagic habitat is genetically determined. The charr originated from a nearby lake inhabiting predatory brown trout Salmo trutta. The cohort of stocked charr was investigated for three years. The Arctic charr started to exploit the pelagic habitat in their first summer at a size of 7–9 cm in contrast to about 15 cm in the donor lake. In the next two summers, the pelagic fraction of the cohort increased. The main fraction lived in epibenthic areas, utilizing the same prey as pelagic charr. Water temperature moderated the habitat use of juveniles such that they avoided warm (>16°C) waters and resided in cool, deep areas. The result was consistent with the hypothesis of a tradeoff between feeding benefit and the predation risk producing spatial segregation of Arctic charr and demonstrated that the fish can facultatively respond to predation risk and adjust the size at which they migrate to the pelagic zone to feed on zooplankton.
Hypoxic wetland tributaries as faunal refugia from an introduced predator
Authors: Rosenberger A. E. , Chapman L. J.
Published: July 2006

Abstract– The introduction of Nile perch (Lates niloticus) into the Lake Victoria basin of East Africa has coincided with the decline or disappearance of hundreds of indigenous species. To mitigate additional biodiversity loss, we must learn what limits the spread of Nile perch and what habitats serve as refugia for prey species. Heavily vegetated wetlands may protect fishes from Nile perch predation by providing both structural and low‐oxygen refugia for prey species tolerant of hypoxia. To examine the potential of wetlands as refugia we quantified the composition, persistence, and stability of fish assemblages in a wetland tributary of Lake Nabugabo, a satellite lake of Lake Victoria in which Nile perch have been introduced. Nile perch were extremely rare in the wetland, and nine of the 18 species that have disappeared from the open waters of the satellite lake were captured in the tributary in this study. Dissolved oxygen was chronically low in the river and may be important in shaping fish community characteristics. Faunal attenuation occurred as the dry season progressed and oxygen levels dropped; however, the most common species remained through seasonal changes. The chronically low oxygen conditions in the werland tributary may permit persistence of only hypoxia‐tolerant species. However, wetland conditions seem to limit exploitation by Nile perch providing critical refugia for a subset of the basin fauna.
Persistence of Florida largemouth bass alleles in a northern Arkansas population of largemouth bass, Micropterus salmoides Lacèpéde
Authors: Johnson R. L. , Fulton T.
Published: July 2006

Abstract– Lake Ashbaugh, located in northeast Arkansas, was constructed in 1981, and initially stocked with Florida largemouth bass followed by supplemental stockings of northern largemouth bass. Allele frequencies of three discriminant allozyme loci (sAAT‐B, sIDH‐B, sMDH‐B) between Florida and northern largemouth bass were determined for 414 largemouth bass collected between 1994 and 1996. Fx bass dominated our sample, with 62.3% possessing Florida largemouth bass alleles. A high incidence of Hardy‐Weinberg disequilibrium was observed, indicative of genetic change within the population. No significant differences were identified for frequency of age classes, relative weight, and length at age between the northern, F1 and Fx phenotypes. Despite being located north of what is generally considered suitable for stocking Florida largemouth bass, it was demonstrated that temperature is not selective at present against bass possessing Florida largemouth bass alleles. However, caution should prevail when introducing non‐native stock into native gene complexes, as introduced genes persist through many generations.
An experimental comparison of cannibalistic response in different Arctic charr (Salvelinus alpinus(L.)) stocks
Authors: Amundsen P.‐A. , Svenning M.‐A. , Slikavuoplo S. I.
Published: July 2006

Abstract–The cannibalistic response of four domesticated Arctic charr stocks were compared experimentally using a radiographic technique. Charr from Arctic Spitsbergen (80°N) consistently exhibited a much higher frequency of cannibalistic response than fish from three charr strains from mainland Norway (70°N). The results indicate that the extent of cannibalistic feeding in Arctic charr is population specific and support the hypothesis that charr from Arctic populations have stronger cannibalistic tendencies than do fish from more temperate regions.
The effect of meal size on the rate of gastric evacuation of burbot, Lota lota (L.)
Authors: Pääkkönen J. ‐P. J. , Myyrä R. , Marjomäki T. J.
Published: July 2006

Abstract– The effect of meal size on the gastric evacuation rate of burbot Lota lota (L.), was determined at a constant temperature of 1.5°C. Burbot were fed vendace Coregonus albula (L.), in varying amounts from 1.0% to 12.6% of burbot weight. Although gastric evacuation rate decreased exponentially with increasing meal size, the absolute amount of food evacuated per day (g. day−1 increased when meal size increased. The estimated maximum daily gastric evacuation rates were 0.8, 1.3 and 1.6 g/day with meal sizes 1%, 5% and 10% of burbot weight (200 g). No difference in gastric evacuation rate was observed between meals of the same size (8 g) but which consisted of either one or three vendace.
Larger eggs in resident brown trout living in sympatry with anadromous brown trout
Authors: Olofsson H. , Mosegaard H.
Published: July 2006

Abstract– Freshwater resident brown trout (Salmo trutta L.) in the stream Jorlandaan (southwestern Sweden) had larger eggs (range of actual mean egg wet weights, 65.9–108.5 mg) than both sympatric migratory trout (76.8–84.2 mg) and trout from five other Swedish streams with allopatric resident (23.7–80.1 mg) or migratory populations (44.5–121.9 mg), after accounting for differences in body size. In Jörlandaån, some resident females even had a larger absolute mean egg weight than any of the migratory females found in the stream. Resident trout had low absolute fecundity, and our data suggest that resident females in Jörlandån produce large eggs at the expense of their fecundity. The extremely large relative egg size in resident Jörlandaån females suggests that the production of large offspring enhances fitness, possibly through increased fry survival.
Habitat use by age‐0 yellow perch in two South Dakota glacial lakes
Authors: Fisher S. J. , Pyle C. R. , Willis D. W.
Published: July 2006

Abstract– We determined the habitat use of age‐0 yellow perch (Perca flavescens) in two South Dakota (USA) lakes. Larval perch abundance was based on trawl catches and related to environmental variables on two late spring dates. Juvenile perch abundance was based on late July shoreline seine and bottom trawl catches. Day and night juvenile abundance relations to environmental variables were examined. Larval abundance appeared to be related to biological environmental variables, and no significant (P≥0.05) correlations with physical habitat variables were found. Juvenile yellow perch abundance was related to physical variables, particularly substrate, water temperature and water depth. The only biological variable that could be related to juvenile abundance was chironomid abundance. Finally, juvenile perch abundance was positively associated with abundance of other juvenile fishes and minnows, but these associations varied by lake, time of day and habitat type. Understanding age 0 perch habitat use will allow fishery biologists to better assess sampling designs and recruitment processes.
First‐year overwinter mortality in Eurasian perch (Perca fluviatilis L.) Results from a field study and a simulation experiment
Authors: Radke R. J. , Eckmann R.
Published: July 2006

Abstract– The importance of overwinter mortality of 0+ perch (Perca fluviatilis L.) in central European lakes was estimated using a stochastic simulation model. The probability of overwinter mortality of a perch cohort was calculated by using a model developed for yellow perch (P. flavescens Mitchill). Winter duration from a long‐term data set and the length of perch at the end of the first year from five lakes were used as input data. After 1000 simulation runs, the total extinction of a cohort in the lakes studied was never predicted. Mortality rates of more than 0.5 were only predicted in two of the five lakes, and rates of more than 0.3 in these two lakes were predicted in approximately 10% of all cases. For two consecutive winters differing in duration, the length‐frequency distributions of 0+ perch in the autumn and following spring were compared by a graphical method. No significant size‐dependent mortality of smaller individuals could be detected in any of the populations studied. Simulated spring length‐frequencies were derived from observed autumn length distributions by the same model that was used for the stochastic simulation. These simulated and the empirical spring length‐frequency distributions were not identical. The differences between the two distributions were attributed to growth, which occurred between the sampling dates. The results from the simulation and the analysis of the empirical data suggest that high overwinter mortality caused by starvation is rare in central European lakes.
Longitudinal variation in fish species composition in the Angabanga river, Papua New Guinea with observations on the trophic status of certain fish species
Authors: Hyslop E. J.
Published: July 2006

Abstract– Longitudinal variation in fish species composition at various sites on the Angabanga river showed an increase in diversity from source to mouth and that only a few fish species occur at all sites. The fish assemblage of floodplain pool areas contained fewer species than the main channel and was dominated by two exotic species Oreochrornis mossambicus (Peters 1852) and Trichoguster pectoralis (Regan 1910). Most native fish species utilize invertebrates as a food source. The absence of indigenous detritus/substrate feeders in the Angabanga community may account in part for the success of the two introduced species on the floodplain.
Genetic basis of phenotypic differences between transplanted stocks of brown trout
Authors: Palm S. , Ryman N.
Published: July 2006

Abstract– We present results from an experiment testing for the existence of genetically based phenotypic differences among populations of brown trout (Salmo trutta L.) born and raised under entirely natural environmental conditions. Genetically tagged individuals from two stocks (A and B) were introduced into a drainage system in Sweden previously void of brown trout, and the first generation (F1) progeny were sampled from two lakes during nine consecutive years. Phenotypic differences among groups of progeny (A, B, and the AB hybrid) are expected to reflect genetically determined dissimilarities between the introduced stocks. Phenotypic differences among progeny groups were observed for age at maturity and for migratory and reproductive behavior, and these characters are apparently determined by genetic factors to an extent that permit their detection even in the presence of confounding and naturally occurring sources of variation such as lake, age, cohort and year of sampling. There was also significant variation among offspring groups with respect to body size (length), but only a small proportion of the total variation in size could be attributed to stock differences. These genetically based stock characteristics may represent local adaptations, and the fishery management implications of these findings are discussed.
Distribution and population genetic structure of river‐ and sea‐type sockeye salmon in western North America
Authors: Gustafson R. G. , Winans G. A.
Published: July 2006

Abstract– In contrast to the well‐known "lake‐type" sockeye salmon, two additional anadromous life‐history types have been recognized within the species: ‘river‐type’ sockeye salmon whose juveniles spend 1 or 2 years in off‐channel river habitats prior to migrating to sea, and “sea‐type” sockeye salmon that initially rear in similar river habitats yet migrate to sea as underyearlings. Persistent populations of river‐/sea‐type sockeye salmon occur in small numbers throughout the species’range in North America but are usually associated with glacier‐fed rivers. We found published and unpublished records showing that riverine‐spawning sockeye salmon occur in 11 rivers in western Washington, USA, that don't have access to juvenile lake‐rearing habitat. Evidence of persistent spawning was strongest for the Nooksack and Skagit rivers in northern Puget Sound. We analyzed allozyme frequency differentiation in 26 laketype and 12 river‐/sea‐type populations of sockeye salmon in North America, ranging from northern Puget Sound, Washington (including 3 in the Nooksack and Skagit rivers) to northern Southeast Alaska. Across this 2000 km range, river‐/sea‐type sockeye salmon showed very little genetic differentiation between populations, much less than that displayed by the highly divergent lake‐type sockeye salmon. Genetic similarity among river‐/sea‐type sockeye salmon in this study is likely a result of common ancestry and a high level of historical gene flow among river‐/sea‐type sockeye salmon populations.
Genetic characterization of Portuguese brown trout (Salmo trutta L.) and comparison with other European populations
Authors: Antunes A. , Alexandrino P. , Ferrand N.
Published: July 2006

Abstract– Allozyme and other protein loci were examined to study the genetic structure of Portuguese brown trout (Salmo trutta) populations. A total of 247 individuals from three tributaries of the Lima hydrological basin and a hatchery, all located in northern Portugal, were analyzed. Four of 22 protein coding loci were found to be polymorphic: CK‐A1*, GPI‐A2*, MPI‐2* and TF*. A new allelc at the latter locus was found in Atlantic populations. The data obtained for Portuguese brown trout were compared with published data for 14 European populations and three hatchery stocks. Six polymorphic loci (CK‐A1*, GPI‐A2*, GPI‐B2*, LDH‐C*, ME* and MPI‐2*) were used in a cluster analysis. This showed the similarity of Portuguese natural populations and northern Iberian populations and that Portuguese hatchery fish have an autochthonous origin, distinct from that of other Atlantic hatchery stocks.
Resource partitioning between Siberian sculpin (Cottus poecilopusHeckel) and Atlantic salmon parr (Salmo salarL.) in a sub‐Arctic river, northern Norway
Authors: Gabler H. ‐M. , Amundsen P. ‐A.
Published: July 2006

Abstract–Food resource partitioning between Siberian sculpin (Cottus poecilopus) and Atlantic salmon parr (Salmo salar) was investigated throughout a summer season in the subarctic River Reisa, northern Norway. The two species had almost identical diets, feeding primarily on benthic invertebrates and selecting the same prey species. There was no strong segregation in the diel feeding rhythms of the two species, although the salmon parr consumed a large proportion of their food at night during August and September. The results suggest that the two species compete for food, and that interspecific competition for limited food resources may explain the low production of Atlantic salmon in this river. The observation of a high degree of dietary overlap between the sculpin and the salmon parr contrasts with expectation of interactive segregation. Further, the findings conflict with general niche and competition theories, being inconsistent with the competitive exclusion principle.
Diel and seasonal movements by adult Sacramento pikeminnow (Ptychocheilus grandis) in the Eel River, northwestern California
Authors: Harvey B. C. , Nakamoto R. J.
Published: July 2006

Abstract– In late summer and fall, radio‐tagged adult Sacramento pikeminnow (Ptychocheilus grandis) at three sites in the Eel River of northwestern California moved more at night than during the day. Fish moved up to 535 m at night and returned to their original positions the following morning. Adult Sacramento pikeminnow at all sites occupied only pools during the day, but at one site moved through high gradient riffles and occupied fast water habitats at night. Adult Sacramento pikeminnow at the upstream limit of their range in one Eel River tributary moved downstream up to 23 km during the winter and tended to return to their original position the following spring, where they remained through the summer. Fish radio tagged at downstream sites exhibited more variable behavior, moving 2‐92 km over >393 days. Our observations suggest that the most appropriate scale of consideration for attempts to manage this species or estimate population size includes entire river drainages.
Stereotactic Device for Gamma Knife Radiosurgery in Experimental Animals: Technical Note
Authors: Im Yong-Seok , Nam Do-Hyun , Kim Jong-Soo , Ju Sang-Gyu , Lim Do-Hoon , Lee Jung-Il
Published: July 2006

Objective: Radiosurgery has become a well-established treatment modality for many intracranial lesions and the information obtained from animal experiments is crucial in devising new strategies with improved efficacy and less risk. We constructed a stereotactic device for rats which can be used for both usual laboratory work and radiosurgery using a Gamma Knife. Materials and Methods: The stereotactic device was made by modifying the basic design of the ordinary stereotactic frames used for usual laboratory work. It was developed for both Gamma Knife model B and C. An auxiliary tool was also devised which facilitates the placement of the target point at the radiation isocenter. Results: The reliability of the device was verified by checking the radiation profile and absorbed dose. The results of the experimental irradiation in normal and tumor-cell-inoculated rats demonstrated the usefulness of the device. Conclusions: The modified animal stereotactic frame described herein can be used for both the production of experimental animal models and for performing radiosurgery with a common apparatus.
Molecular Diagnosis of Fatal Nocardia farcinica Pneumonia in an HIV-Negative Patient
Authors: Bocchino Marialuisa , Paglia Maria Grazia , Marruchella Almerico , Contini Silvia , Festa Anna , Saltini Cesare
Published: July 2006

Nocardiosis is a rare and potentially life-threatening infection caused by several species of the Nocardia genus. Most cases occur in immunocompromised patients, and a delay in establishing the diagnosis is common due to the non-specific clinical presentations and the difficulty in cultivating Nocardia. Although the majority of pulmonary nocardiosis cases are caused by Nocardia asteroides, cases of human infection due to N. farcinica are increasingly diagnosed due to recent developments in taxonomy and diagnostic methods. N. farcinica is a separate species from N. asteroides and appears to be more virulent and resistant to antibiotics. Herein, we describe the case of a 65-year-old HIV-negative immunocompromised patient with a fulminant bilateral pulmonary nocardiosis while on empirical treatment with trimethoprim/sulfamethoxazole and imipenem. Post-mortem diagnosis of N. farcinica infection was performed by means of DNA amplification and sequencing of the 65-kDa bacterial heat shock protein.
Evaluation of the Spatial Diffusion of Methylene Blue Injected in vivo by Bronchoscopy into Non-Small Cell Lung Carcinoma
Authors: Vignaud Jean-Michel , Ménard Olivier , Weinbreck Nicolas , Siat Joëlle , Borrelly Jacques , Marie Béatrice , Martinet Nadine , Martinet Yves
Published: July 2006

Background: Due to smoking prevalence and the poor efficiency of current therapy, lung cancer is the leading cause of cancer death in developed countries, and its worldwide incidence is steadily increasing. Gene therapy by direct intratumoral injection of different types of gene constructs through a fiberscope has been suggested and evaluated in a few patients. Objective: It was the aim of this study to observe the actual volume of diffusion within a lung tumor using a color marker. Methods: Using bronchoscopy, just after anesthesia, methylene blue was injected into patient tumors. These patients subsequently underwent surgery for treatment of a non-small cell lung cancer. Results: We observed a diffusion of methylene blue in resected lung tumors with a mean infiltrated versus noninfiltrated tumor volume ratio of 29 ± 15%. Interestingly, some large tumor areas were not stained. At the cellular level, a preferential diffusion of the dye was observed in the tumor stroma compartment versus the tumor cellular compartment, where basal cells were more frequently and strongly labeled than the other tumor cells. Conclusions: Since a cancer is cured when most, if not all, cancer cells are killed, the preliminary evaluation of the spatial diffusion of any injected gene construct should be carried out as a first step in any cancer type.
Training Depletes Muscle Glutathione in Patients with Chronic Obstructive Pulmonary Disease and Low Body Mass Index
Authors: Rabinovich Roberto A. , Ardite Esther , Mayer Ana Maria , Polo Maite Figueras , Vilaró Jordi , Argilés Josep M. , Roca Josep
Published: July 2006

Background: A physiological increase in muscle glutathione after training is not seen in patients with chronic obstructive pulmonary disease (COPD), indicating abnormal peripheral muscle adaptations to exercise. Objective: We hypothesized that oxidative stress is primarily associated with low body mass index (BMI). Methods: Eleven patients with preserved BMI (BMIN: 28.2 ± 1.2 kg·m–2), 9 patients with low BMI (BMIL: 19.7 ± 0.60 kg·m–2) and 5 age-matched controls (26.5 ± 0.9 kg·m–2) were studied before and after 8 weeks of high-intensity endurance training. Reduced glutathione (GSH) and γ-glutamyl cysteine synthase heavy-subunit chain mRNA expression (γGCS-HS mRNA) were measured in the vastus lateralis. Results: After training, exercise capacity increased (ΔVO2PEAK, 13 ± 5.2%; 10 ± 5.6% and 15 ± 4.3% in BMIL, BMIN and controls, respectively; p < 0.05 each). GSH levels decreased in BMIL (from 5.2 ± 0.7 to 3.7 ± 0.8 nmol/mg protein, ΔGSH –1.5 ± 0.7 nmol/mg protein, p < 0.05); no changes were seen in BMIN (from 5.4 ± 0.7 to 6.7 ± 0.9 nmol/mg protein, ΔGSH 1.3 ± 0.9 nmol/mg protein), whereas GSH markedly increased in controls (from 4.6 ± 1 to 8.7 ± 0.4 nmol/mg protein, ΔGSH 4.1 ± 1 nmol/mg protein, p < 0.01). ΔGSH in BMIL was different from ΔGSH in BMIN and controls (p < 0.05, each). Consistent changes were observed in γGCS-HS mRNA expression. Conclusions: GSH depletion after training in BMIL may suggest that oxidative stress plays a key role in muscle wasting in COPD patients.
Direct Hydrothermal Synthesis of Highly Ordered Sn–SBA-15 Mesoporous Materials
Authors: Shah Pallavi , Ramaswamy Arumugamangalam V , Ramaswamy Veda
Published: July 2006

Well-ordered Sn4+-incorporated mesoporous silica SBA-15 samples have been synthesized from tetraethyl orthosilicate (TEOS) and SnCl4 (Si/Sn = 114–15) using nonionic surfactants under a slightly higher pH medium (optimum H2O to HCl molar ratio) and characterized by XRD (an increase in lattice parameter), TEM (no SnO2 species) and UV–vis spectral (absorption at 211 nm) techniques to show that Sn4+ ions are in tetrahedral coordination in Sn–SBA-15.
Formation of a Stable Sulfenic Acid by Hydrolysis of a Thionitrate and a Sulfenyl Bromide
Authors: Goto Kei , Shimada Keiichi , Furukawa Shunsuke , Miyasaka Shinji , Takahashi Yusuke , Kawashima Takayuki
Published: July 2006

Alkaline hydrolysis of a thionitrate and a sulfenyl bromide bearing a bowl-type steric protection group produced a stable sulfenic acid. This provides a conclusive demonstration of these elementary processes. It was shown that a very efficient steric protection group is necessary to prevent the condensation of the sulfenate anion generated during the hydrolysis.