bluuebunny/crossref_metadata_2025 huggingface dataset:
The Last Chance
Authors: Blain B.C.R.
Published: April 2005

Considers the debate about training schemes as it affects the
construction industry. Examines the future, benefits and disadvantages
of both Employment Training, and National Vocational Qualifications
within the NCVQ framework. Surmises that a drastic new approach is
called for, the industry favouring a return to traditional craft
apprenticeships.
Productivity for Profit
Authors: Callaghan Bill
Published: April 2005

Examines the recent turnaround in UK productivity compared to other
leading industrial nations and whether the improvement is sustainable,
with reference to trade unions. Considers the policies required to
further improve productivity, the distribution of the benefits among
shareholders and workers, and wider community concerns such as the
environment. Concludes that there has been no UK “economic
miracle” in the 1980s, and that the signs for continued growth are
not encouraging.
Structural similarity to bridge sequence space: Finding new families on the bridges
Authors: Shah Parantu K. , Aloy Patrick , Bork Peer , Russell Robert B.
Published: April 2005

Structures for protein domains have increased rapidly in recent years owing to advances in structural biology and structural genomics projects. New structures are often similar to those solved previously, and such similarities can give insights into function by linking poorly understood families to those that are better characterized. They also allow the possibility of combing information to find still more proteins adopting a similar structure and sometimes a similar function, and to reprioritize families in structural genomics pipelines. We explore this possibility here by preparing merged profiles for pairs of structurally similar, but not necessarily sequence‐similar, domains within the SMART and Pfam database by way of the Structural Classification of Proteins (SCOP). We show that such profiles are often able to successfully identify further members of the same superfamily and thus can be used to increase the sensitivity of database searching methods like HMMer and PSI‐BLAST. We perform detailed benchmarks using the SMART and Pfam databases with four complete genomes frequently used as annotation benchmarks. We quantify the associated increase in structural information in Swissprot and discuss examples illustrating the applicability of this approach to understand functional and evolutionary relationships between protein families.
Sensitivity of the folding/unfolding transition state ensemble of chymotrypsin inhibitor 2 to changes in temperature and solvent
Authors: Day Ryan , Daggett Valerie
Published: April 2005

To better characterize the transition state for folding/unfolding and its sensitivity to environmental changes, we have run multiple molecular dynamics simulations of chymotrypsin inhibitor 2 (CI2) under varying solvent conditions and temperature. The transition state structures agree well with experiment, and are similar under all of the conditions investigated here. Increasing the temperature leads to some movement in the position of the transition state along several reaction coordinates, as measured by changes in properties of the transition state structures. These structural changes are in the direction of a more native‐like transition state as denaturation conditions become more severe, as expected for a Hammond effect. These structural changes are not, however, reflected in the global structure as measured by the total number of contacts or the average S‐values. These results suggest that the small changes in average Φ‐values with temperature seen by experiment may be due to an increase in the sensitivity of the transition state to mutation rather than a change in the average structure of the transition state. A simple analysis of the rates of unfolding indicates that the free energy barrier to unfolding decreases with increasing temperature, but even in our very high temperature simulations there is a small free energy barrier.
Why emotion work matters: sex, gender, and the division of household labor
Authors: Erickson Rebecca J.
Published: April 2005

Attempting to explain why biological sex remains the primary predictor of household labor allocation, gender theorists have suggested that husbands and wives perform family work in ways that facilitate culturally appropriate constructions of gender. To date, however, researchers have yet to consider the theoretical and empirical significance of emotion work in their studies of the gendered division of household labor. Using survey data from 335 employed, married parents, I examine the relative influence of economic resources, time constraints, gender ideology, sex, and gender on the performance of housework, child care, and emotion work. Results indicate that gender construction, not sex, predicts the performance of emotion work and that this performance reflects a key difference in men's and women's gendered constructions of self.
Women's family power and gender preference in Minya, Egypt
Authors: Yount Kathryn M.
Published: April 2005

Structural and ideational theories are adapted to explore the influence of women's resources and ideational exposures on their family power and gender preferences in Minya, Egypt. Data from a household survey of 2,226 married women aged 15–54 years show that residence with marital kin decreases women's family power. Women in endogamous marriages have greater family power than women in nonendogamous marriages but still tend to prefer sons. Educated women report weaker son preference and greater influence in decisions but still tend to prefer sons. The positive association of women's education, paid work, and urban residence with a variable measuring girl or equal preference and family power suggests that selected resources and ideational exposures may improve girls’ well‐being in Minya.
Predictors of parenting among African American single mothers: Personal and contextual factors
Authors: Kotchick Beth A. , Dorsey Shannon , Heller Laurie
Published: April 2005

Guided by family stress theory, relations among neighborhood stress, maternal psychological functioning, and parenting were examined among 123 low‐income, urban‐dwelling, African American single mothers. Using a longitudinal design, structural equation modeling was employed to test the hypothesis that neighborhood stress results in poorer parenting over time through its detrimental effect on maternal psychological functioning. Social support from family and friends was examined as a potential moderator of the association between neighborhood stress and parenting behavior. Results indicated that higher levels of neighborhood stress were related to greater psychological distress among mothers, which in turn, was significantly related to less engagement in positive parenting practices approximately 15 months later. A moderating effect emerged for social support, however, such that the proposed model provided a better fit for mothers reporting low levels of perceived social support than for mothers reporting high levels. Implications of the findings for prevention and intervention are discussed.
Parents’ awareness of lesbian, gay, and bisexual youths’ sexual orientation
Authors: D’Augelli Anthony R. , Grossman Arnold H. , Starks Michael T.
Published: April 2005

This study used a sample of 293 lesbian, gay, and bisexual youth to examine factors that differentiated youth whose parents knew of their sexual orientation from youth whose parents did not know. Earlier awareness and disclosure of same‐gender attractions, greater childhood gender atypicality, and less internalized homophobia were characteristic of youth whose parents were aware of youths’ sexual orientation. Youth with aware parents reported more past verbal victimization on the basis of sexual orientation from parents, yet more current family support and less fear of future parental victimization on the basis of their sexual orientation.
Seasonal changes in erythrocyte osmotic fragility and haematocrit in American plaice infected with Haemohormidium terranovae
Authors: Siddall M. E. , Measures L. N. , Desser S. S.
Published: April 2005

American plaice held in captivity for a period of 8 months over winter exhibited increasing erythrocyte osmotic fragility and decreasing haematocrit values until December. In December, osmotic fragility parameters and haematocrit were strongly correlated, suggesting anaemia due to disruption of circulating erythrocytes. Intensity of infection with Haemohormidium terranovae increased through the winter months until March but was not correlated either with osmotic fragility or haematocrit. These results are explained in terms of compensatory haemopoetic changes occurring in plaice. Mortality was apparently unrelated to any of the parameters investigated.
Colour pattern and inhibition of aggression in the cichlid fish Astronotus ocellatus
Authors: Beeching S. C.
Published: April 2005

Oscars Astronotus ocellatus defeated in combat often undergo a colour pattern change in which the normal olive‐green to brown body coloration darkens to near black, interrupted with irregular white barring. Dummy oscars were used in two complementary tests which showed that the dark‐and‐banded colour pattern inhibits aggression in conspecifics under two different experimental designs and with two different subject groups.
Effect of fixation protocols on muscle preservation and in situ diffusion distances
Authors: Egginton S. , Cordiner S.
Published: April 2005

In order to examine the effects of various methods for tissue preparation on ultrastructural analyses, and hence standardize reported values, six commonly used fixatives were examined for their quantitative effect on muscle fibre size and capillary dimensions. Both the composition and osmolarity of fixatives affected structural indices significantly, producing a range of values of similar magnitude to that presented in reports of structural adaptations. When comparing data from different studies, therefore, it is essential to establish that dissimilar values reflect different tissue composition, rather than methodologies. The method of choice for quantitative analysis of intracellular diffusion pathways uses a combined aldehyde fixative with a metabolic poison, and an isotonic buffer as vehicle.
Scale and squamation character polarity and phyletic assessment in the family Cichlidae
Authors: Lippitsch E.
Published: April 2005

Scale and squamation characters have proved to be useful in investigating phyletic relationships in the family Cichlidae. To provide a sound basis for a cladistic analysis the plesiomorphic states have to be determined. This has been done for the family as a whole as well as for some phyletic lineages. Based on those characters the phylogeny within the family has been investigated.
Ambicoloration in two flounders, Paralichthys patagonicus and Xystreuris rasile
Authors: Astarloa J. M. Diaz de
Published: April 2005

Two cases fo ambicoloration were reported in two flounders of Paralichthyidae in the Western South Atlantic. One of the specimens showed almost complete ambicoloration while the other one was partially pigmented.
New evidence of hexaploidy in‘ large’ African Barbus with some considerations on the origin of hexaploidy
Authors: Guégan J. F. , Rab P. , Machordom A. , Doadrio I.
Published: April 2005

Three species of‘ large’ African Barbus from the Republic of Guinea (West Africa), were characterized by the chromosome numbers (2N) of 148 (B. bynni occidentalis and B. wurtzi) and 150 (B. petitjeani Daget, 1962). All these species have a karyotype which corresponds to the evolutionary hexaploid level. The karyotype of B. petitjeani is composed of chromosomes clearly grouped into morphologically homomorphic sextets which may document the origin of hexaploidy via an autopolyploidic event. Present findings extend the known distribution of evolutionary hexaploidy in‘ large‘ African Barbus to West Africa and show evidence of the pan‐African distribution of this phenomenon.
Development of the digestive tract in larval summer flounder
Authors: BISBAL G. A. , Bengtson D. A.
Published: April 2005

Histological changes of the digestive system and its associated glands, and structures of the jaw were studied in summer flounder Paralichthys dentatus from hatching (day 0) until day 44. Specimens for this study were hatched from artificially spawned broodstock and maintained in the laboratory (20 ± 1° C). During the first 3 days after hatching, the formation of the oral jaw apparatus, lengthening of the digestive tube, yolk resorption, and mucosae differentiation are the most conspicuous elements of development. The larval digestive system is morphologically ready to process external food at the time of mouth opening (3–4 days after hatching). Epithelial cells of the anteromedian and the posterior intestine show evidence of lipid and protein absorption, respectively, after first feeding. The most noticeable events occurring during the next month of independent life are an increase in mucosal folding, cellular differentiation in the luminal epithelia, gut segmentation and looping, and liver growth. Gastric glands and pyloric caeca appear by day 31 and complete the morphological digestive features characteristic of the juvenile stage.
A method for long‐term measurement of respiration in intertidal fishes during simulated intertidal conditions
Authors: Steeger H.‐U. , Bridges C. R.
Published: April 2005

Aquatic and aerial respiration of the amphibious fishes Lipophrys pholis and Periophthalmus barbarus were examined using a newly designed flow‐through respirometer system. The system allowed long‐term measurements of oxygen consumption and carbon dioxide release during periods of aquatic and aerial respiration. The Mo 2 of L. pholis, measured at 15° C, was 2·1 μmol O2 g–1 h–1 during aquatic and 1·99 μmol O2 g–1 h–1 during aerial exposure. The corresponding values of the Mco2 were 1.67 and 1.59 μmol O2 g–1 h–1 respectively, giving an aquatic respiratory exchange ratio (RER) of 0·80 and an aerial RER of 0·79. The Mo2 of P. barbarus, measured at 28°C, was 4·05 μmol O2 g–1 h–1 during aquatic and 3·44 μmol O2 g–1 h–1 during aerial exposure. The corresponding values of the Mco2 were 3·29 μmol CO2 g–1 h–1 and 2·63 μmol CO2 g–1 h–1 respectively, giving an aquatic RER of 0·81 and an aerial RER of 0·77. While exposed to air for at least 10 h, both species showed no decrease in metabolic rate or carbon dioxide release. The RER of these fishes equalled their respiratory quotient. After re‐immersion an increased oxygen consumption, due to the payment of an oxygen debt, could not be detected.
Is the ragged‐tooth shark cosmopolitan? First record from the western North Atlantic
Authors: Bonfil R.
Published: April 2005

This paper describes the first reported occurrence of Odontaspis ferox, in the western Atlantic (Yucatan shelf, Mexico). The geographical distribution of O. ferox is summarized and the likely cosmopolitan distribution of the species is discussed.
Competition between mullet fry
Authors: Gisbert E. , Cardona L. , Castello F.
Published: April 2005

The fry of Liza ramada, L. aurata, L. saliens, Chelon labrosus and Mugil cephalus in a lagoon in NE Spain fed mainly on zooplanktonic crustacea, such as cyclopoids, calanoids and cladocerans, but adult chironomids were also important. A high trophic and temporal overlap was found between the fry of several of these species. Trophic overlap was asymmetrical for almost all the species pairs and niche breadth expanded for the less competitive species when they were alone in the estuary. In contrast, niche breadth did not expand for the most competitive species (L. ramada) when it was alone. These results suggest that competition was occurring among these species, but experimental evidence is needed to prove its existence.
Gill anomalies of perch and roach from four lakes differing in water quality
Authors: Haaparanta A. , Valtonen E. T. , Hoffmann R. W.
Published: April 2005

This study examined gill anomalies of two common freshwater fish species, roach Rutilus rutilus and perch Perca fluviatilis, collected over five seasons in 1989–1990 from four lakes in central Finland. The lakes differed both in water quality and in fish parasite species composition. Particular attention was paid to the differences in chloride cell proliferation. Gill anomalies were generally more common and abundant in roach than in perch. Chloride cell proliferation was the most frequent histological change in roach but was that least often found in perch. Most of the changes were systemic and light in severity. In perch an unidentified lesion of noncellular eosinophilic inclusions in an enlarged epithelium was also recorded. There was a marked pattern in the severity of histological changes in perch when comparing those from the natural Lake Peurunka to those from three ‘altered’ lakes. Gills of perch from Lake Peurunka possessed more alterations in all the recorded parameters. In roach, a significant differences were detected in chloride cell and epithelial proliferation: these were greater in Lake Peurunka and ‘polluted’ Lake Vatia. In perch, all histological changes were significantly more frequent at the end of autumn 1989 when compared to other seasons. In roach, increased frequencies of all gill changes were noted in winter and spring samples. Tissue reactions to parasites were either only localized or absent. The systemic gill alterations in freshwater fish may reflect the soft nature and low winter temperature of Finnish fresh waters, in which chemical imbalances, such as acid peaks, may induce more dramatic changes in fish tissues than in harder waters.
Population dynamics of Oreochromis shiranus in two small water bodies in Malaêi
Authors: Mattson N. S. , Kaunda E. K. W. H.
Published: April 2005

Growth curves of Oreochromis shiranus in two small reservoirs, Chisombezi (2·2 ha) and Mbvoniha (3·6 ha), were constructed by fitting a seasonally oscillating von Bertalanffy growth function to tag‐recapture data. Annual average numbers were calculated for each length class from gillnet cpue data corrected for selectivity. The lengths at first maturity were estimated from samples, and annual brood numbers were deduced from the linear relation between female length and brood number. Annual instantaneous mortality rates were estimated by linearized length‐converted catch curves for lengths >90 mm, and for lengths between 10 and 90 mm by inference from the theoretical annual brood numbers. Estimated mean biomass was 84 and 106 kg ha −1, while production was 417 and 872 kg ha −1 year −1 in Chisombezi and Mbvoniha, respectively. Thus, the production‐biomass ratios were high at 5.0 in Chisombezi and 8.2 in Mbvoniha.
Ontogenetic development and composition of the mucous cells and the occurrence of saccular cells in the epidermis of Atlantic halibut
Authors: Ottesen O. H. , Olafsen J. A.
Published: April 2005

An increase in the number of mucous cells of the epidermis, as well as qualitative changes of the mucus composition from predominantly neutral to a mixture of neutral and sulphated glycoproteins occurred during the development from a pelagic larva to a bottom‐dwelling flatfish. Numerous saccular cells were observed in the epidermis of the yolk‐sac larvae that disappeared simultaneously as the mucous cells increased in number in the epidermis of the metamorphosed halibut. These findings may help to understand the protective role of the mucus layer of Atlantic halibut during development as compared to other fish species in aquaculture.
Feeding, Ichthyophonus sp. infection, distribution and growth history of Norwegian spring‐spawning herring in summer
Authors: Holst J. C. , Salvanes A. G. V. , Johansen T.
Published: April 2005

After its collapse in the late 1960s, 1991 was the first year of systematic herring investigations after the Norwegian Sea stock returned to the traditional summer‐feeding areas. Of 11 prey groups three dominated the diet; Calanus finmarchicus, Parathemisto spp. and Sebastes spp. There was a high prevalence of Ichthyophonus sp. at stations in the central and western parts of the Norwegian Sea where the cpue was low. This suggests that infected individuals were unable to return from the feeding to the wintering area of the Norwegian fjords. Highest cpue were recorded between 68–73° N and 5–15° E. Age groups 2, 3 and 8 were most frequently caught and age group 8 (the 1983 year class) dominated the samples. Herring occurred in dense concentrations where C. finmarchicus dominated diet. 0‐group fish dominated diet at stations along the coast from 66–73° N and out to c. 300 km off the coast. Mature herring overlapped in distribution with 0‐group fish and Sebastes spp. contributed largely to herring diet in this area. The first rich year‐class after the collapse, the 1983 year class, had a faster growth than rich year classes from past herring periods, but slower than poor ones.
Discrimination of native and introduced brown trout in the River Doubs (Rhône drainage) by number and shape of parr marks
Authors: Mezzera M. , Largiadèr C. R. , Scholl A.
Published: April 2005

Significant differences in the number and shape of parr marks were found between native, introduced hatchery and hybrid brown trout parr in the River Doubs. Similar differences in number of parr marks were observed in selective cross‐breedings.
Cold stress‐induced changes in the aerobic heterotrophic gastrointestinal tract bacterial flora of red hybrid tilapia
Authors: LeaMaster B. R. , Walsh W. A. , Brock J. A. , Fujioka R. S.
Published: April 2005

Fifteen juvenile red hybrid tilapia Oreochromis mossambicus×O. macrochir averaging 50 g body weight were cold‐stressed by immersion in 18° C sea water; control fish (n= 15) were kept at the acclimation temperature of 26° C. Three fish from each group were killed 0, 24, 48 and 72 h after the start of the experiment. Gastrointestinal tracts were removed and dissected into the stomach, anterior gut and posterior gut regions. Aerobic heterotrophic bacteria were identified and enumerated relative to temperature, exposure time and gastrointestinal tract region. Gram negative genera included Alcaligenes, Flavobacterium, Photobacterium, Pseudomonas and Vibrio; the latter three were predominant. Mean bacterial numbers and taxonomic composition of the microflora varied significantly (P<0·05) in response to the three test variables. There were greater mean total bacterial numbers at 18 than at 26° C, due primarily to proliferation of Vibrio spp. Mean bacterial numbers after 24 h were greater than those at both the earlier and later sampling periods. Mean bacterial numbers in the stomach were less than those in the anterior and posterior gut, which were not significantly different. The relative abundance of Vibrio spp. was negatively correlated with that of Flavobacterium, which may have reflected competition between pathogenic and nonpathogenic species. Such stress‐induced changes in the bacterial microflora may contribute to the onset of disease because several species of Vibrio are known primary or opportunistic fish pathogens.
An experimental study on the natural removal of dead trout fry in a Lake District stream
Authors: Elliott J. M.
Published: April 2005

The chief objective was to discover why few moribund or deadSalmo truttafry were observed on the stream bed when mortality within the stream was known to be high (c. 13 000 dead fry year−1for whole stream). Newly dead fry were placed in 20 boxes embedded in the stream bed (20 fry of known total weight per box) and arranged in pairs with one box open and one closed. One pair was removed every 2 days, the fish remains being weighed and the invertebrates in the open box being identified and counted. The experiments were performed from late April to early May in 1967, 1968, 1969 and the results were similar in each year. Both wet and dry weights of fry decreased exponentially but the rate of decrease was much higher in the open boxes; detectable fish remains were about 55% of initial weights after 20 days (end of experiment) in closed boxes but zero after 16 days in open boxes. Invertebrate scavengers were responsible for the higher loss rates in the open boxes and showed a definite succession with caddis larvae and carnivorous stonefly larvae dominant at first, but then being replaced by detritivorous stonefly larvae and freshwater shrimps. These experiments show clearly why dead fry disappear rapidly from the stream bed.
Parasites of wrasse (Labridae) in inshore waters of west Scotland stocked as cleaner fish of sea lice (Caligidae) on farmed Atlantic salmon
Authors: Treasurer J. W.
Published: April 2005

The prevalence, abundance and intensity of protistan and metazoan parasites were examined in the labrid fishes Ctenolabrus rupestris, Centrolabrus exoletus, Crenilabrus melops, Labrus bergylta and L. mixtus in west Scotland. The 22 parasite species identified do not appear to be a major threat to farmed Atlantic salmon. Few mortalities of wrasse stocked on salmon farms were due to resident parasites or to transfers from salmon.
A case of reversal in Paralichthys orbignyanus a shallow‐water flounder from the south‐western Atlantic
Authors: de Astarloa J. M. Díaz
Published: April 2005

A right‐sided Paralichthys orbignyanus was reported for the first time in the western South Atlantic. Some morphometric peculiarities were noticed in the reversed specimen compared with the normal flatfish of the same species.
Inadvertent hybridization in a carp hatchery as detected by nuclear DNA RFLP
Authors: Padhi B. K. , Mandal R. K.
Published: April 2005

The Indian Major Carps Catla catla, Labeo rohita and Cirrhina mrigala, when spawned together in a ‘spawning pool’, hybridized at an estimated frequency of about 10%. The Fl hybrids of these species lack any improved economic traits but are fertile and can backcross with the parental species causing genetic introgression.
Controlled breeding studies to verify the identity of roach and common bream hybrids from a natural population
Authors: Peitts C. S. , Jordan D. R. , Cowx I. G. , Jones N. V.
Published: April 2005

The occurrence of post‐F1 generation hybrids between common bream and roach in natural populations has still to be qualified. To do this, common bream, roach, F1 and F2 hybrid progeny were produced under controlled conditions. All progeny groups exhibited overlaps in the ranges of their meristic characters. Discriminant analysis of meristic data combined with allozymes allowed identification of post‐Fl hybrids. Enzyme electrophoresis showed Fl progeny to be heterozygous at diagnostic loci. Back‐crossed F2 progeny had a mixture of homozygosity and heterozygosity at diagnostic loci. Meristic and genetic analysis of fish from a natural population indicated that they were all F1 hybrids. Post‐Fl hybridization cannot be ruled out from natural populations because Fl hybrids are known to be fertile. It is suggested that post‐Fl hybrids were not detected either because of their low incidence of occurrence or due to biological phenomenon Such as inferior fitness.
Changes in the levels and distribution of glycogen during regeneration of cutaneous wounds in Heteropneustes fossilis: a histochemical investigation
Authors: Rai A. K. , Mittal A. K.
Published: April 2005

Incisional wounds of the same length and depth were made in the skin of catfish Heteropneustes fossilis, and the response in terms of levels of glycogen in cells during healing was studied histochemically. After injury, glycogen disappeared completely from the cells in the migrating epidermis. This disappearance is correlated with the migration of the epidermal cells toward the wound gap for epithelialization and the increased production of mucous cells at the initial stages of healing. The gradual accumulation of glycogen in the epithelial cells and the basal cells after epithelialization of the wound during the early stages of healing suggests that in these cells gluconeogenesis predominates. The gradual disappearance of glycogen from the epithelial cells 72 h after injury and from the basal cells 36 h after injury indicates the gradual resumption of their metabolic activities. The increased gradients of glycogen in club cells that are undergoing vacuolization and disintegration are discussed. No significant levels of glycogen were observed during the formation of granulation tissue and biosynthesis of the sub‐cutis. The depletion of glycogen in the degenerating muscle bundles is correlated with the synthesis of lactic acid which contributes to local acidity and favours the autolysis of muscles.
Individual variations in habitat use and morphology in brook charr
Authors: Bourke P. , Magnan P. , Rodríguez M. A.
Published: April 2005

The specific objectives of this study were to determine if there is individual specialization in habitat use by lacustrine brook charr Salvelinus fontinalis and if so, if specialization is related to fish morphology. Localizations of 28 brook charr equipped with thermosensitive radiotransmitters were recorded during three summers (1991, 1992, and 1993) in two lakes of the Mastigouche Reserve (Québec, Canada). Fifty per cent of the fish were found mainly in the benthic zone (hereafter benthic individuals), 18% in the pelagic zone (pelagic individuals), and 32% travelled regularly between the two zones (generalist individuals). The observed interindividual differences in habitat preference were related to differences in body morphology and coloration: (i) the pectoral fins of benthic and generalist individuals were significantly longer than those of pelagic ones; and (ii) the coloration of the lower flank of benthic and generalist individuals was silver‐grey while that of pelagic individuals was red. The results of this study suggest that brook charr inhabiting oligotrophic lakes of the Canadian Shield exhibit trophic polymorphisms, where some individuals are specialists better adapted to feeding in the littoral zone whereas others are specialists better adapted to feeding in the pelagic zone. The potential for reproductive isolation between the two morphs is discussed.
Fecundity of the American eel Anguilla rostrata at 45° N in Maine, U.S.A.
Authors: Barbin G. P. , McCleave J. D.
Published: April 2005

The northern portion of the geographic range of the American eel Anguilla rostrata may contribute a great proportion of the reproductive potential to this panmictic species because of apparent increases in average female size and female percentage with latitude. The regressions of fecundity on body length and on body weight of 63 female eels captured at about 45° N latitude on their spawning migration to the sea were log F= 1·2601 + 2·9642 log L and log F= 4·1646+0·9153 log W, where F is fecundity, L is total length (cm), and W is total weight (g). Length and weight each explained about 90% of the variation in fecundity. Estimates of fecundity from counts of aliquots of eggs ranged from 1·84 million to 19·92 million eggs for eels ranging in length from 45 to 113 cm, nearly the range of sizes of migrating females reported in the literature. Fecundities of the American eel were greater than reported in one study at about 37° N and greater than reported for the European eel, A. anguilla, shortfin eel, A. australis, and longfin eel, A. dieffenbachii. If a geographic cline in fecundity does exist in American eels, it is established anew each generation because the species forms a single panmictic population.
Diel and seasonal patterns of food intake and prey selection byCoregonussp. in re‐oligotrophicated Lake Lucerne, Switzerland
Authors: Mookerji N. , Heller C. , Meng H. J. , Bürgi H. R. , Müller R.
Published: April 2005

Feeding intensity by whitefishCoregonussp., in oligotrophic Lake Lucerne in Switzerland was high during dusk when the bulk of potential prey items were in the depth zone occupied by the fish. Diet composition was fairly uniform throughout the day but changed substantially over the seasons. The fish fed opportunistically; differences between seasons reflected changes in prey availability. During the intensive feeding and growing period (May‐September), fish were found in the upper 20 m of the lake feeding primarily on cladocerans. Large and non‐evasive species,Daphniaspp. andBythotrephes longimanus, were the most numerous and frequent organisms in the diet during the major part of the growing season. Smaller (Bosminaspp.) as well as evasive species (cyclopoid copepods) were consumed in large numbers when larger, non‐evasive species were rare in the lake. The fish showed strong preference for the least abundant crustacean,B. longimanus, while the most abundant crustaceans, calanoid copepods, were rare in the diet. The fish not only selected particular species but, within each species, selected the larger individuals. Diel vertical migration of the prey items in this lake could be, at least in part, attributed to fish predation pressure. The observed selectivity patterns shown by the fish are explained in terms of prey visibility, escape ability, the overlap in distribution of predators and prey in time and space, the profitability of the prey and the present trophic state of the lake.
Relationships between fishes and habitat in rainforest streams in Sabah, Malaysia
Authors: Martin‐Smith K. M.
Published: April 2005

Distinct fish assemblages were found at the mesohabitat scale in 14 streams in eastern Sabah, Malaysia. Sites were designated a priori as pool, run or riffle on the basis of physical habitat structure and properties. Principal components analysis of physical habitat data confirmed the validity of the a priori designation with a major axis of three correlated variables: water velocity, depth and substratum type. Canonical discriminant analysis on fish abundance and biomass data confirmed the existence of a specialized assemblage of fishes from riffle areas of all streams. Overall, pool and run assemblages were highly variable, dependent on stream size, but also variable between streams of the same size. Multiple regression of species richness, diversity, abundance and biomass data on principal components revealed significant but low correlations with measured habitat variables. Riffle habitats showed lower species richness and diversity but high abundance. The fish assemblage in riffles was dominated by balitorid species, specialized for fast‐water conditions. Pool assemblages had the highest species diversity and were dominated by cyprinid species of a number of morphological and ecological guilds. Run assemblages were intermediate in assemblage characteristics between riffle and pool assemblages. Between‐stream variation in assemblage composition was less than within‐stream variation. Of 38 species collected, seven could be designated as riffle specialists, 18 as pool specialists and 13 as ubiquitous, although most of the latter showed size‐specific habitat use with larger size classes found in slower, deeper water.
Is there always an influence of shoal size on predator hunting success?
Authors: Krause J. , Ruxton G. D. , Rubenstein D.
Published: April 2005

Theoretical and empirical studies predict that there should be a decrease in hunting success of predators with increasing prey group size. Most of these studies investigated situations in which predator and prey were in full view of each other before, during and after an attack. In this study, single rock bassAmbloplites rupestriswere given an opportunity to launch surprise attacks at shoals of creek chubSemotilus atromaculatusthat ranged in size from two to 13 fish. There was no significant influence of either shoal size or attack distance on predator success rate and no significant relationship between attack distance and shoal size. Furthermore, it was found that the leading fish of a shoal was attacked significantly more often than fish in other shoal positions, indicating that predation risk was not shared equally among shoal members. Also, leading fish in larger shoals (eight to 13 fish) were not more likely to survive a predator attack than ones in small shoals (two to seven fish).The consequences of these results are discussed in the general context of antipredator benefits of grouping.
An intersexual migratory (silver) longfinned New Zealand eel and its gonadal response to treatment with salmon pituitary homogenate
Authors: Lokman P. M. , Young G.
Published: April 2005

An intersexual adult New Zealand longfinned eel Anguilla dieffenbachii, displaying testicular tissue within its ovaries, is described. Gonad samples were collected at 0, 21, 42 (by biopsy) and 54 days (autopsy) after the start of an experiment that aimed to induce ovarian maturation by repeated treatment with 5 mg kg−1 salmon pituitary homogenate (SPH). Very small patches of testicular tissue (almost always single seminiferous tubules), not visible macroscopically, were observed on all sampling dates. Treatment with SPH resulted in advanced stages of spermatogenesis in these seminiferous tubules, synchronous with the development of oocytes, which reached the migratory nucleus stage after 53 days. This finding is discussed in relation to current knowledge on sexual development in anguillid eels.
Body shape, diet and ontogenetic diet shifts in young fish of the Sinnamary River, French Guiana, South America
Authors: Mérigoux S. , Ponton D.
Published: April 2005

A total of 1468 young fish representing 66 taxa from the Sinnamary River, French Guiana was classified by complete cluster analysis of mean relative body width and mean relative body height into four groups. These had anguilliform, disciform, flat or intermediate body shapes and belonged chiefly to Gymnotiformes, Perciformes, Siluriformes and Characiformes, respectively. Several of the taxa shifted from one to another body shape during ontogenesis. Seven diet groups were defined by complete cluster analysis. Among these, six groups were represented by carnivorous fish. The three most frequent groups had diets of (1) mainly insect larvae and small crustaceans, (2) insect larvae, and (3) predominantly terrestrial insects. The majority of the fish taxa showed ontogenetic diet shifts. Carnivorous fish usually switched from small‐size prey, such as small crustaceans, to intermediate‐size prey, such as insect larvae and/or to large‐size prey, such as insects and/or fish. However, taxa differed in their capacities to switch from small prey to intermediate and/or to large prey. Taxa of different body shapes had significantly different diets. Disciform fish fed mainly on aquatic insect larvae and terrestrial insects but also, in small amounts, on small curstaceans. Most anguilliform taxa ate insect larvae. Individuals belonging to the depressiform or intermediate morphotype had varied diets ranging from plant debris and substratum to fish.
Muscle fibre growth dynamics in diploid and triploid rainbow trout
Authors: Suresh A. V. , Sheehan R. J.
Published: April 2005

The effect of triploidy on muscle fibre growth was determined by comparing hyperplasia and hypertrophy of white muscle fibres in all‐female, diploid and triploid rainbow trout Oncorhynchus mykiss (100–400 mm total length). Conventional morphometry and protein and DNA concentrations were used to assess muscle fibre hyperplasia and hypertrophy in white muscle samples derived from an anterio‐dorsal location. Muscle fibre distributions were significantly different between triploids and diploids in trout <300 mm. The proportion of fibres <20 μm was higher in diploids than in triploids and the proportion of fibres in the 20–40 μm category was higher in triploids than in diploids. This indicates that the hyperplastic fibres of triploids are larger than those of diploids. Larger hyperplastic fibres in triploids are probably due to the combined effect of increased nuclear size in triploids and the relatively high nucleus: cell ratio observed in small muscle fibres. These larger fibres may be less favourable to cellular metabolic exchange because of their smaller surface area to volume ratios, and perhaps account for reduced viability and growth observed in triploids during early life stages. On the other hand, the lack of difference in the distribution of fibres <20 μm between diploids and triploids at larger body size ranges (301–400 mm) imply that triploid trout may have higher rates of new fibre recruitment and growth capacity at these sizes. There was no difference between diploid and triploid trout in the mean size of muscle fibres; however, the number of fibres per unit area was reduced by 10% in triploids. No differences were observed in protein or DNA concentrations in muscle tissues between the two genetic groups. Since triploid nuclei have 1·5 times more DNA than diploid nuclei, this deviation from the expected muscle DNA concentration (1·3–1·4 times more DNA in triploids when the 10% reduction in fibre density is considered) suggests that the number of nuclei per muscle fibre is reduced. In both diploids and triploids, mean fibre size increased with body length while fibre density decreased. Similarly, protein concentration in the muscle tissue increased and DNA concentration declined with increasing body length. Protein/DNA ratio was strongly and positively correlated with fibre size. These results demonstrate that changes in DNA and protein concentrations can be used to assess hyperplasia and hypertrophy in muscle tissues. However, the morphometric procedure provides better insight into muscle fibre growth as it enables the direct visualization and analysis of muscle fibre distribution patterns.
Early starvation limits survival in amphidromous fishes
Authors: Iguchi K. , Mizuno N.
Published: April 2005

Newly hatched amphidromous larvae drift downstream to the sea. Since there is practically no food available for drifting larvae, an extended downstream migration may enhance the risk of starvation. We hypothesized that early survival of amphidromous fish varies among populations according to the length of the river, due to its effect on larval starvation. The hypothesis was tested with the common Japanese amphidromous goby, Rhinogobius brunneus . Based on morphological characteristics, larvae were categorized as being in an endogenous feeding state (EFS) or irrecoverable starved state (ISS). The frequency of ISS larvae in the population from a long river was nearly twice the frequency in the population from a short stream. More than half of larvae were judged to be dying during downstream migration in the comparatively long river, although this was possibly an underestimation. It is suggested that early starvation limits reproductive success far from the sea.
Movements of adult Atlantic salmon in relation to a hydroelectric dam and fish ladder
Authors: Gowans A. R. D. , Armstrong J. D. , Priede I. G.
Published: April 2005

The movements of adult Atlantic salmon were recorded as they approached, entered and ascended the pool‐and‐orifice fish ladder at Pitlochry Dam, Scotland. Thirty‐nine returning salmon were captured in the River Tummel by rod‐and‐line angling, radio‐tagged and released near where they were caught. The subsequent movements of each fish were then monitored. An electronic fish counter collected additional data on movements of untagged fish past a fixed point in the ladder. Of the 39 fish that were radio‐tagged, 29 individuals were recorded approaching and ascended the ladder. The remaining fish either did not approach the dam (three fish), approached the dam after detailed tracking had ended (two fish), were recaptured by anglers (three fish), or the radio tags failed (two fish). Salmon released earlier in the year delayed longer before first approaching the dam. Delays between first approaching the dam and ascent of the ladder were greater for fish that approached the dam earlier. The majority of salmon visited the ladder entrance more than once (maximum 10 visits) before ascending. Having entered, all but four salmon ascended the fish ladder successfully on their first attempt. The four individuals that failed to do so succeeded on their second attempt. The rate at which salmon ascended the ladder was related directly to temperature. The shortest ascent time of a radio‐tagged salmon was 5·25 h. Movements of eight of 11 tagged fish through the ladder ceased with the onset of darkness but continued on the following morning. No radio‐tagged fish entered the ladder at temperatures below 9) C. Similarly, few untagged fish were recorded ascending the ladder by the electronic fish counter at water temperatures below 8·5) C. Records from the fish counter indicated that 92% of upstream movements were made during daylight.
Effects of environmental factors on survival, growth, and production of American shad larvae
Authors: Leach S. D. , Houde E. D.
Published: April 2005

Episodic increases in temperature of 5°C above 20° C, over 48 h or declines in pH of 1·0 unit from pH 7·0 reduced survival of yolk‐sac and feeding‐stage larvae of American shad Alosa sapidissima . Over 16 days all measures of survival, growth, and production were more favourable at each higher temperature in the 15–25° C range. More favourable responses were also obtained at the higher prey level (500 v . 50 Artemia nauplii l‐1) and at the higher pH (7·5 v . 6·5). Combinations of high temperature and high prey levels, at pH 7·5, led to highest larval production. Little growth or production occurred at 15° C, regardless of pH or prey level. The effect of pH was strong with respect to survival, but weak with respect to growth. In attempts to restore American shad populations by larval stocking, release times and sites can be critical to optimize survival and eventual returns. Releases of larvae potentially will be most effective when made at temperatures >20° C, pH>7·0, and prey levels >50 1‐1. These conditions are most likely to occur in Maryland tributaries of Chesapeake Bay between mid‐May and early June.
Importance of electrode positioning in biotelemetry studies estimating muscle activity in fish
Authors: Beddow T. A. , McKinley R. S.
Published: April 2005

Red and white axial muscle activity of adult Atlantic salmon Salmo salar was examined using conventional electromyography (EMGx) and activity radio‐transmitters (EMGi) at 0·5 and 0.7 body lengths (L) along the body of the fish. Critical swimming trials were conducted and maximum sustainable speeds (Ucrit) were unaffected by the presence of electrodes, being 1·51 ± 21 m s−1 (3.33 ± 0.34 L s−1) (n=44). Regardless of longitudinal position of the electrodes within the musculature, both EMGx s and EMGi s indicated increasing red muscle activity with increasing swimming speed, whereas white muscle fibres were recruited only at speeds > 86±5% Ucrit. Telemetered EMGi signals indicated that muscle activity varied significantly for electrodes implanted at different longitudinal positions along the fish (P < 0·001). These results suggest that electrode placement is an important influence affecting the signals obtained from radio transmitters that estimate activity and location should be standardized within biotelemetry studies to allow accurate and consistent comparisons of activity between individuals and species. Optimal location for electrode placement was determined to be in the red muscle, towards the tail of the fish (0·7 L).
Muscle parvalbumin isoforms of Clarias gariepinus, Heterobranchus longifilis and Chrysichthys auratus: isolation, characterization and expression during development
Authors: Focant B. , Mélot F. , Collin S. , Chikou A. , Vandewalle P. , Huriaux F.
Published: April 2005

The white‐muscle parvalbumin isoforms of Clarias gariepinus, Heterobranchus longifilis and Chrysichthys auratus were purified and their physicochemical parameters determined. The three catfish isoforms are distinct but those of C. gariepinus and H. longifilis are more similar. In the course of development, the successive appearance of larval and adult parvalbumins was observed. Larval isoforms (PA I, PA IIa, PA IIb) displayed a lower isoelectric point (pI) and molecular mass than adult ones (PA IIc, PA IIIa, PA IIIb, PA III, PA IV). The PA IIa isoform appeared as an omnipresent typical larval isoform. PA IIb appeared mostly larval, being insignificant in adult specimens; its physicochemical features were the same in the three catfish species. In Chrysichthys auratus, there were three PA II isoforms, one appearing as an adult isoform (PA IIc). The fact that the two types of parvalbumin isoforms appear at different times should reflect specific physiological needs (mobility, feeding) of different developmental stages.