bluuebunny/crossref_metadata_2025 huggingface dataset:
Cryopreservation of the sperm of the Japanese bitterling
Authors: Ohta H. , Kawamura K. , Unuma T. , Takegoshi Y.
Published: April 2005

Sperm of the Japanese bitterling Tanakia limbata that had been cryopreserved with 5 or 10% methanol plus 95 or 90% foetal bovine serum (FBS) showed higher percentage and longer duration of motility than those that had been cryopreserved with 90% FBS and 10% DMSO, glycerol, N,N‐dimethylacetamide or N, N‐dimethylformamide. Foetal bovine serum, used as extender, had some cryoprotective effects when spermatozoa were cooled either with 10% methanol or without methanol. Spermatozoa, cooled to −40° C and then immersed in liquid nitrogen, had greater post‐thaw motility than those cooled to −20, −60, or −80° C. The post‐thaw percentage of motile spermatozoa increased significantly (P < 0·001) with decreases in the freezing rate from 60 to 5°C min−1. These results indicate that 10% methanol plus 90% foetal bovine serum is a suitable diluent for cryopreservation of bitterling spermatozoa and that samples should be cooled to ‐40°C at a low freezing rate for effective storage.
Selective staining and disintegration of intestinal eosinophilic granule cells in Atlantic salmon after intraperitoneal injection of the zinc chelator dithizone
Authors: Paulsen S. M. , Sveinbjørnsson B. , Robertsen B.
Published: April 2005

Following intraperitoneal injection of the zinc ion chelator dithizone into Atlantic salmon Salmo salar, staining and morphological changes in intestinal eosinophiic granule cells (EGC) were observed in both cryo‐preserved and chemical‐preserved tissue sections. In cryo sections rapid and selective vital staining of EGC was observed within 5 min of dithizone injection. Intensely stained red granules appeared as a result of the formation of a complex between dithizone and zinc ions. Stained EGC appeared on both sides of the stratum compactum as well as in the lamina propria. Stained EGC started to disintegrate 5 min after the injection of dithizone, and little of the zinc‐dithizone complex was observed 15 h later. The disappearance of the stain coincided with an intense degranulation and disintegration of EGC. Fifteen hours after dithizone treatment regenerating cells were observed in Masson's trichrome stained sections. Four to five days after injection, a fully regenerated continuous EGC layer was observed. Simultaneously with the disintegration of EGC an increase in plasma lysozyme activity occurred. EGC resembles mammalian Paneth cells in their possession of lysozymecontaining granules and their staining by, and response to, dithizone. EGC may represent a central component of zinc metabolism in Atlantic salmon.
Morphological and histological changes in the swim bladder during maturation of the Japanese eel
Authors: Yamada Y. , Zhang H. , Okamura A. , Tanaka S. , Horie N. , Mikawa N. , Utoh T. , Oka H. P.
Published: April 2005

Silver eels Anguilla japonica (IG 1·5–3·5) had more developed rete mirabile, gas gland and submucosa than yellow eels (IG 0·4–1·5) and the development of swim bladder components increased with sexual maturity only in the early maturation process (IG 3·5). These observations indicate that the Japanese eel develops its swim bladder in either the river or shallow sea water and leaves for the open sea after the swim bladder has become adapted to a deeper‐sea environment.
Histology and mucin histochemistry of the gastrointestinal tract of the mud loach, in relation to respiration
Authors: Park J. Y. , Kim I. S.
Published: April 2005

The gastrointestinal tract of the mud loach Misgurnus mizolepis was divided into an oesophagus, stomach, intestine and rectum which consisted of a mucosa (epithelial layer), lamina propria‐submucosa, muscularis and serosa. The intestine and rectum have shorter mucosal folds and a thinner wall than those of the oesophagus and the stomach. Extensive vascular capillary networks were present near the luminal surface of the intestine and the rectum. The diffusion distance between the vascular capillaries and the viscus lumen in the intestinal and rectal mucosal epithelium was 0·7 μm (±0·11). The intestine and rectum of Misgurnus mizolepis probably have a respiratory function to address the deficient oxygen supply within their environment. The epithelial mucous cells contained acidic or a mixture of acidic and neutral mucins, the former being the most common.
Oviposition site selection and embryo mortality in perch
Authors: Smith C. , Douglas A. , Jurajda P.
Published: April 2005

Egg strands of perch Perca fluviatilis around the margins of a lake were associated significantly with submerged vegetation. The proportion of dead embryos was significantly higher in egg strands deposited directly on the lake bottom than those on submerged vegetation.
Elimination of foreign material by epidermal malpighian cells during wound healing in fish skin
Authors: ÅSbakk K.
Published: April 2005

Cultured epidermal malpighian cells and experimental wounds of Atlantic salmon Salmo salar were challenged with a variety of particulate materials. Latex beads and the bacteria Carnobacterium piscicola, Pseudomonas fluorescens and Aeromonas salmonicida salmonicida were engulfed by cultured cells, whereas Staphylococcus intermedius were not. The cells engulfed bacteria that proliferated in culture medium devoid of antibiotics and melanin granules and other cellular debris. Cells at wound margins engulfed latex beads and C. piscicola, P. fluorescens and A. s. salmonicida, but not S. intermedius. Malpighian cells thus appear to be both phagocytic and discriminatory. The results support the hypothesis that malpighian cells remove foreign material from fish skin by sloughing after becoming laden with engulfed material.
Baseline assessment of reef fish assemblages of Parcel Manuel Luiz Marine State Park, Maranhão, north‐east Brazil
Authors: Rocha L.A. , Rosa I. L.
Published: April 2005

A rich and apparently undisturbed fish community (132 species from 52 families) is found in the Parcel Manuel Luiz Marine State Park, Brazil. Comparisons with data obtained in other sites in Brazil and the Caribbean, using the same visual census technique, demonstrate high variation in community structure. The absence of some species found along the Brazilian coast suggests an ecological barrier between the study area and the remaining coastline.
Swimming performance and blood chemistry in Atlantic salmon spawners exposed to acid river water with elevated aluminium concentrations
Authors: Ytrestøyl T. , Finstad B. , McKinley R. S.
Published: April 2005

Exposure of sexually mature pre‐spawning Atlantic salmon Salmo salar to Fossbekk water (pH 5·2) for 7 days led to a significant reduction in critical swimming speed (U‐crit) in females but not in males. Exposure to Fossbekk water +A1 (as AlCl3) for 24 h led to a significant reduction in U‐crit in both males and females. In contrast to fish exposed for 7 days to Fossbekk water, fish exposed to Fossbekk+A1 had accumulated much more aluminium and mucus on their gills. Losses of plasma ions were similar in both groups exposed to acid water. Blood glucose was twice as high in fish exposed to Fossbekk water for 7 days compared with fish exposed to Fossbekk+A1 for 24 h. Plasma cortisol was still elevated compared with controls after exposure to Fossbekk water for 7 days. Possible mechanisms for the observed decrease in U‐crit at the different exposures are discussed.
A model to predict the presence of longfin eels in some New Zealand streams, with particular reference to riparian vegetation and elevation
Authors: Broad T. L. , Townsend C. R. , Arbuckle C. J. , Jellyman D. J.
Published: April 2005

Two logistic regression models were developed from a database of 27 biotic and physicochemical variables for 99 sites in the Taieri River, New Zealand, to predict the probability of occurrence of longfin eels. Average depth was associated positively with eels while woody debris and oxygen concentration were negatively associated. At a macro‐scale probability of eel occurrence declined with increasing elevation and, for a given elevation, was higher in tussock and pasture catchments and lower in pine and native forest settings. Using a separate fish database for the Taieri River this macro‐scale model predicted eel presence 95·4% in agreement with observation. A map was generated from the model showing areas of predicted high, moderate and low probabilities of eel occurrence. The model also estimated the minimum total number of eels present in the Taieri River catchment (excluding lakes, and streams below 100 m and above 1000 m) as 20 865 (95% CL: 10 560‐36 350).
Genetic and demographic variation among colour morphs of cabrilla sea bass
Authors: Medioni E. , Finiger R. Lecomte , Louveiro N. , Planes S.
Published: April 2005

The Mediterranean cabrilla sea bass Serranus cabrilla exhibits two colour morphs (red and yellow) that appear to be depth segregated, with yellow individuals found below 20 m and red ones found above 20 m. Morphology and otolith analyses show that yellow fish are larger and older. There were similar allelic frequencies between colour morphs, but significant differences in the genotypic frequencies with an increase of excess of heterozygotes in yellow specimens. It is proposed that the yellow fish are older and develop from younger red fish that have migrated to deeper water.
Effects of environmental hypercapnia on pulmonary ventilation of the South American lungfish
Authors: Sanchez A. P. , Glass M. L.
Published: April 2005

Aquatic hypercapnia at PCO2 of 55 mmHg significantly increased pulmonary ventilation in the South American lungfish Lepidosiren paradoxa, whereas no significant increases occurred when hypercapnia was applied to the gas phase with or without concomitant aquatic hypercapnia. On return from gas phase hypercapnia to inspiration of air there was a marked transient increase of ventilation. This post‐hypercapnic response is discussed in relation to the possible presence of upper airway or pulmonary CO2 receptors that inhibit pulmonary ventilation during hypercapnia. Post‐hypercapnic hyperpnea has been reported for various groups of reptiles and for anuran amphibians. The occurrence of post‐hypercapnic hyperpnea in Lepidosiren adds new information related to the evolution of respiratory regulation in vertebrates.
Characterizing diversity in salmon from the Pacific Northwest*
Authors: Waples R. S. , Gustafson R. G. , Weitkamp L. A. , Myers J. M. , Jjohnson O. W. , Busby P. J. , Hard J. J. , Bryant G. J. , Waknitz F. W. , Nelly K. , Teel D. , Grant W. S. , Winans G. A. , Phelps S. , Marshall A. , Baker B. M.
Published: April 2005

Information developed during recently completed evaluations of the status of seven species of anadromous Pacific salmonids (Oncorhynchus spp.) in the Pacific Northwest was used to characterize patterns of intraspecific diversity along three major axes: ecology, life history and biochemical genetics. Within the study area, the species’ ranges, and therefore the number of distinct ecological regions inhabited differ considerably, with pink and chum salmon limited to the northern areas and chinook salmon and steelhead distributed over the widest geographic range. The species showed comparable differences in the patterns of life history and genetic diversity, with chinook and sockeye salmon and steelhead having the most major diversity groups and pink, chum and coho salmon having the least. Both life history and genetic diversity showed a strong, positive correlation with the extent of ecological diversity experienced by a species, and the correlation between the number of major genetic and life history groups within a species was even stronger (r=0.96; P<0.05). Departures from these general diversity relationships found in some species (especially sockeye and coho salmon and cutthroat trout) can be explained by different interactions with the freshwater environment and, for cutthroat trout, by the occurrence of substantial intrapopulational diversity in life history traits, a hierarchical level not considered in this study.
Anthropogenic changes in the freshwater fish fauna of Italy, with reference to the central region and Barbus graellsii, a newly established alien species of Iberian origin
Authors: Bianco P. G. , Ketmaier V.
Published: April 2005

In a survey of the west‐central Italian rivers Ombrone, Fiora, Albegna and Bruna, among established exotic species, the Iberian barbel Barbus graellsti was recorded in Italian fresh waters for the first time. Morphological identification was supported by comparison of cytochrome b sequences with those from related barbel species. Other exotics of particular note were Barbus barbus, Pseudorasbora parva and Leuciscus cephalus, together with the Padano‐Venetian Chondrostoma genei and Padogobius bonelli. Native species still present included Leuciscus lucumonis, Telestes muticellus, Rutilus rubilio and Padogobius nigricans, but were now more restricted to upper reaches and smaller watercourses. The deleterious effect of alien species on native forms is discussed with particular reference to probable competition between C. genei and L. lucumonis, and between the two gobies. The checklist of species introduced to the fresh waters of Italy is now updated to 34. For the Italian freshwater fish fauna in general, the conservation status of three native species (Acipenser naccari, Salmo marmoratus and Knipowitschia punctatissima) has been improved but five species are believed to be at risk (Salmo carpio, L. lucumonis, Scardinius scardafa, Gobio benacensis and P. nigricans) and four anadromous species (Petromyzon marinus, Lampetra fluviatilis, Acipenser sturio and Huso huso) no longer breed in Italian fresh waters. The processes of change in the composition of the Italian freshwater fish fauna as a whole may be summarized as successively ‘padanization’, ‘danubization’ and now ‘globalization’.
Status, habitat use, and vulnerability of the European ggrayling in Austrian waters
Authors: Uiblein F. , Jagsch A. , Honsig‐Erlenburg W. , Weiss S.
Published: April 2005

The European grayling Thymallus thymallus is widely distributed in Austria, occurring in all eight rural provinces. However, in recent years, an increasing number of studies report severe declines in population sizes. Since 1997, the grayling has had the status of an endangered species in Austria. In 1997 the multidisciplinary research programme ‘Local Adaptation, Threat, and Conservation of European Grayling’ has carried out three projects in Upper Austria, Salzburg, and Carinthia. Research has included repeated electro‐fishing in selected stretches of eight rivers and the collection of data on habitat characteristics, fish species composition, population abundance and size distribution, growth and body condition, as well reproductive timing, and migratory activities of grayling. Furthermore, genetic and morphological variation among grayling populations has been studied as well as the number, habitat use and feeding activity of cormorants. Evidence is provided for the existence of distinct negative effects caused by single factors or combinations of factors on grayling stocks in each of the river stretches studied.
Influence of population decline, fishing, and spawner variability on the recovery of marine fishes
Authors: Hutchings J. A.
Published: April 2005

Based on an analysis of 90 marine fish populations, collapses (the greatest proportional reduction in spawner biomass over 15 years) are predicated typically by dramatic increases in fishing mortality and recoveries are more likely to occur when exploitation is reduced. However, among populations for which fishing mortality declined after collapse, recovery was independent of exploitation rate, even when fishing mortality (F) post‐collapse was expressed as a function of each population's maximum growth rate (r). After a period of 15 years, many populations that experienced 15 year declines >60% exhibited little or no recovery, despite considerable reductions in fishing mortality. This suggests that factors other than fishing may be considerably more important to recovery, and fishing less important, than previously thought. Furthermore, among populations for which fishing mortality decreased post‐collapse, rate of population decline was a reliable predictor of recovery. With the possible exception of clupeids, variation in marine fish breeding population size was found to differ little from that of other vertebrates, and such variability appears to have no effect on rate of recovery. In addition to providing an empirical framework for the study of population collapse and recovery, the analyses presented here provide a means of assessing the precautionary nature of various population‐decline thresholds used to assign extinction risks to marine fish.
The Irish pollan, Coregonus autumnalis: options for its conservation
Authors: Harrod C. , Griffiths D. , McCarthy T. K. , Rosell R.
Published: April 2005

The ecology of four relict Irish populations of pollan (Coregonus autumnalis) is compared with that of the species elsewhere, and used to advocate conservation. The threats to these populations from introduced/invasive species, habitat degradation, climate warming and commercial exploitation are summarized and the legislation governing conservation of the stocks is reviewed. Conservation options (legislation, habitat restoration, stock translocation and stock augmentation) are outlined and their practicality and efficacy considered. A preliminary search indicates that there are a number of lakes that appear to be suitable for pollan translocation.
Luteinizing hormone and sexual steroid plasma levels after treatment of European sea bass with sustained‐release delivery systems for gonadotropin‐releasing hormone analogue
Authors: Mañanós E. , Carrillo M. , Sorbera L. A. , Mylonas C. C. , Asturiano J. F. , Bayarri M. J. , Zohar Y. , Zanuy S.
Published: April 2005

Spermiating male European sea bass Dicentrarchus labrax were treated with gonadotropin‐releasing hormone agonists (GnRHa), either a GnRHa injection (IN; 25 μg kg−1 body mass) or one of three types of controlled‐release GnRHa‐delivery systems: fast release implants (EVAc; 1OO μg kg−1), slow release implants (EVSL; lOO μg kg−1) and slow release microspheres (MC; 50 μg kg−1). Luteinizing hormone (LH) release was highly stimulated by all GnRHa treatments, with elevated plasma levels lasting for 2 days in injected fish (IN) and 2, 4 and 6 weeks in controlled‐release‐treated fish (EVAc, MC and EVSL, respectively), correlating with a 1, 3, 5 and 5 week period of stimulation of milt production, respectively. Plasma levels of the androgens testosterone (T) and 11‐ketotestosterone (11‐KT), were not significantly affected by the GnRHa treatments. Plasma T was high at early spermiation and declined sharply near the end of this period. Plasma 11‐KT levels declined continuously throughout the experiment. Levels of 17,20β‐dihydroxy‐4‐pregnen‐3‐one (17,20β‐P), a proposed maturation‐inducing steroid (MIS) in European sea bass, fluctuated around 0.2–1 ng ml−1 and were not greatly affected by the treatments. These results indicated a close correlation between sustained stimulation of LH release, achieved by GnRHa‐delivery systems, and long‐term enhancement of milt production. They also show an absence of changes in the common sex steroids, associated with elevated LH and enhanced spermiation.
Using stable isotopes to confirm the trophic ecology of Arctic charr morphotypes from Lake Hazen, Nunavut, Canada
Authors: Guiguer K. R. R. A. , Reist J. D. , Power M. , Babaluk J. A.
Published: April 2005

Stable isotopes of carbon and nitrogen were used to examine differences in the feeding ecology of sympatric morphotypes of Arctic charr Sahelinus alpinus from Lake Hazen, Ellesmere Island, in the Canadian High Arctic. Large and small morphotypes possessed significantly different carbon and nitrogen signatures with large‐form Arctic charr being more depleted in 13C and more enriched in 15N than the small‐form. Isotope and stomach content analyses yielded consistent results and indicated short‐ and long‐term reliance on fish as a food for large Arctic charr. Large‐form individuals predate on juveniles but do not predate on small‐form individuals ≥ 250 mm. The observed cannibalism by large‐form individuals, therefore, does not act to maintain the bimodal length‐frequency distribution in Lake Hazen. Bimodality is argued to arise for ecological reasons connected with differing habitat use by the morphotypes and the associated differences in resource consumption opportunities.
Growth response of pikeperch larvae in relation to body size and zooplankton abundance
Authors: Ljunggren L.
Published: April 2005

The most critical period at onset of feeding in pikeperch Stizostedion lucioperca is short (<5 days at 20° C). The larvae are sensitive to prey density during the first week of exogenous feeding. First‐feeding larvae of 6.5 mm total length (LT) needed prey densities of >585 prey l−1 to maintain mass (Cmaint), whereas 5 days older larvae of 7 mm LT Cmaint= 55 prey l−1 and for 11 mmLT larvae Cmaint<10 prey 1−1. Changes in specific growth rates for larvae of 7 and 11 mm were similar to a type‐II functional response curve reaching a specific growth rate of 26 and 30% day−1, respectively, at 1000 prey l−1, whereas the 6·5 mm larvae showed a linear growth response reaching a specific growth rate of only 9% day −1 at 1000 prey l−1. The results suggest that prey density is a limiting factor, which might contribute to the high variation between year‐class Strengths.
Induction of gynogenesis and gonad development in the muskellunge
Authors: Rlnchard J. , Garcia‐Abiado M. A. , Dabrowski K. , Ottobre J. , Schmidt D.
Published: April 2005

Muskellunge Esox masquinongy eggs activated with UV‐irradiated yellow perch Perca flavescens sperm were subjected to heat shock at 31 ± 1° C for 6 min, 20 min after fertilization in three experiments. Survival at eyed stage was 1·7 ±1·6, 6·8 ± 4·8 and 2·3 ±0·5% in experiments I, II and III, respectively. After rearing the gynogenetic muskellunge in troughs and then in ponds, the sex ratio of gynogens in experiment I did not significantly (P>0·05) differ from the expected ratio 0:1 (male: female), however, one male and one intersex were observed. In experiments II and III, the sex ratio of gynogens differed significantly from expected (0 : 1). Three months after hatching, the growth of females did not significantly (P>0·05) differ among control and gynogenetic groups, whereas male growth was significantly (P<0·01) higher in the control v. gynogenetic group. The histological structures of the gynogenetic fish gonads in both sexes were similar to those described in the gonads of control muskellunge. After the overwintering period, signs of active spermatogenesis were observed in the testis of 1 + year old gynogenetic fish, whereas ovaries contained only oocytes at the perinucleolar stage. At this stage, plasma sex steroids testosterone (T) and oestradiol‐17β (E2) cannot be used to discriminate the sex of gynogenetic muskellunge, as intersex, male and female fish had similar levels of T and E2.
Phagocytosis and giant cell formation at 0° C by macrophage (MØ) of Notothenia coriiceps
Authors: Silva J. R. M. C. , Staines N. A. , Hernandez‐Blazquez F. J. , Porto‐Neto L. R. , Borges J. C. S.
Published: April 2005

Macrophages adhered to round glass coverslips that had been implanted into the abdominal cavity of Notothenia coriiceps, collected from Admiralty Bay, King George Island, and removed and incubated in vitro for 4 h at 0° C at various intervals. The macrophages phagocytosed yeast Saccharomyces cerevisiae cells suspended in saline. Bi‐nuclear macrophages were first observed after 6 h. The formation of giant cells and their phagocytic activity was observed only in fish which had been injected with 1 ml of Bacillus of Calmette and Guerin (BCG)‐suspension 24 h before coverslip implantation and the coverslips removed 15 days after the implantation. Phagocytosis and the formation of giant cells in an Antarctic fish at 0° C is described for the first time.
Length of herring larvae in relation to age and time of hatching
Authors: Geffen A. J.
Published: April 2005

The lengths of newly hatched herring Clupea harengus larvae were generally larger than the lengths of embryos released from eggs on the same day. Over subsequent days, the daily increase in length was higher in groups that were released from the eggs as opposed to groups that hatched naturally. Thus by the end of the hatching period (18 days after fertilization) there were no significant differences in mean lengths.
Seasonal pattern of filial cannibalism by Apogon doederleini mouthbrooding males
Authors: Takeyama T. , Okuda N. , Yanagisawa Y.
Published: April 2005

In temperate waters of southern Japan, mouthbrooding males of the cardinal fishApogon doederleinisometimes ate their entire brood within a day of spawning. In spite of annual variation in age structure and length of the breeding season, however, the annual cannibalism rate (broods cannibalized to total broods spawned) was nearly constant, 12–16%. Fish 1 year old frequently cannibalized early broods of the season, especially the first brood, whereas the cannibalism rate by 2 year‐old fish did not vary within the season. In contrast, the cannibalism by older males increased late in the season. This tendency was attributed to their different allocation patterns to growth and reproduction. For 1 year‐old fish, which can enhance future reproductive success by growth and cannibalizing on early broods instead of mouthbrooding (at relatively low temperatures), this may be a tactic for investing energy in growth. For fish 3 years, which have more breeding cycles and grow little, cannibalizing late broods may be energetic compensation for their poor somatic condition. No seasonal variation of cannibalism by 2 year‐old fish can be explained by their intermediate nature of growth and reproduction. Multiple mate availability is one factor facilitating the cannibalism by 2 and 3 + year‐old fish whose operational sex ratio is female‐biased.
Spatially varying natural selection in a fish hybrid zone
Authors: Crespin L. , Berrebi P. , Lebreton J‐D.
Published: April 2005

A capture‐mark‐recapture (CMR) study in a hybrid zone between two species of barbel,Barbus barbusandBarbus meridionalis, in the Lergue River (southern France) failed to reject the null hypothesis of no difference in survival among phenotypes. Power calculations indicated that very intensive fieldwork should be carried out if this hypothesis was to be investigated again. The study demonstrated, however, that there were marked differences in survival between upstream and downstream sites. It is suggested that there is an environmental gradient of selection along the hybrid zone (extrinsic component of natural selection).
Effects on acid‐base balance, methaemoglobinemia and nitrogen excretion of European eel after exposure to elevated ambient nitrite
Authors: Huang C.‐Y. , Chen J.‐C.
Published: April 2005

Haemoglobin, methaemoglobin, blood nitrite concentration and acid‐base balance were measured in European eel Anguilla anguilla following exposure to 0 (control), 0·142, 0·356, 0·751 and l·549 mM nitrite in fresh water for 24 h. Blood GOT (glutamate oxaloacetate transaminase) and GPT (glutamate pyruvate transaminase) activities and whole animal ammonia‐N and urea‐N excretions were also measured. Blood nitrite, methaemoglobin, PO2 (oxygen partial pressure), GOT, and whole animal ammonia‐N excretion and urea‐N excretion increased directly with increasing ambient nitrite concentrations, whereas blood pH, PCO2, and HCO−3 were inversely related to ambient nitrite concentration. An accumulation of nitrite in the blood of A. anguilla following 24 h exposure to elevated ambient nitrite as low as 0·751 mM increased its blood methaemoglobin, PO2, GOT and nitrogen excretion, but decreased its PCO2 (carbon dioxide partial pressure), HCO−3 and functional haemoglobin.
Effects of capture and transmitter attachments on the swimming speed of large juvenile lemon sharks in the wild
Authors: Sundström L. F. , Gruber S. H.
Published: April 2005

The swimming speed of seven large juvenile lemon sharks Negaprion brevirostris following attachment of an external speed‐sensing ultrasonic transmitter was significantly higher during the first 18 h after release compared to the average swimming speed obtained >48 h after release. The external speed‐sensing transmitter can be used to monitor the voluntary swimming speed of large fishes in the field, but data during the first 24 h period should be excluded from analysis of natural speeds, at least from species similar in behaviour to N. brevirostris.
A comparison of staining techniques to improve precision of age estimation from fish otoliths
Authors: Alagador D. , Murta A. G.
Published: April 2005

A total of 30 pairs of sagitta otoliths of horse mackerel Trachurus trachurus were sampled from three length‐classes, and five staining methods were applied to each pair. Ten age estimates were obtained per fish, method and length‐class. Significant differences in age estimates were found between methods, due to the variable enhancement in the otolith pattern produced by each method. A method using amido‐schwartz as the staining reagent produced the best results in terms of precision of the age estimates.
Demonstration of a new calibration standard for strontium measurements in otoliths based on high energy Sr ion implantation
Authors: Gauldie R. W. , Markwitz A.
Published: April 2005

A new Sr measurement standard is given for biominerals based on implanting an exactly known number of Sr atoms into an otolith section using ion‐beam implantation and pre‐ and post‐implantation ion beam (PIXE) scanning.
Isolation of freshwater and deep‐sea type opsin genes from the common Japanese conger
Authors: Zhang H. , Futami K. , Yamada Y. , Horie N. , Okamura A. , Utoh T. , Mikawa N. , Tanaka S. , Okamoto N. , Oka H. P.
Published: April 2005

Two rod‐like opsin genes, conf and cond, were isolated from the common Japanese conger Conger myriaster. The predicted proteins of conf and cond consisted of 354 and 350 amino acid (aa) residues respectively, and the aa identity was 87.4%. Phylogenetic analysis suggested that conf and cond are homologous to the freshwater type and the deep‐sea type rod opsin genes of freshwater eels. RT‐PCR analyses revealed that in both juveniles and adults cond is expressed in the retina and pineal complex, while conf is only expressed in the pineal complex at a low level.
Nest orientation patterns in Salaria fluviatilis
Authors: Vinyoles D. , Côté I. M. , De Sostoa A.
Published: April 2005

The entrances of nests established under small stones by male river blennies Salaria fluviatilis in two rivers of the Ebro Basin in eastern Spain were randomly oriented in slow‐flowing sites. In fast‐flowing stretches or under large stones, however, nest entrances tended to open at an angle of c. 30° relative to current flow direction, i.e. near a south‐east direction. As current velocity increased, males positioned their nest entrance closer and closer to the direction of flow. Selective nest entrance orientation reduced significantly the speed of current reaching the nest entrance such that current velocity was similar (5–7 cm s−1) for all nests, regardless of stone size, prevailing current speed, or study site. Male mating success, measured as egg clutch area, however, was not related to current speed at the nest entrance but instead, it increased with nest stone size and decreased with deviations from a south‐east direction. The reasons for female river blenny preference for this specific nest orientation are unknown but may be related to patterns of water flow, and hence oxygenation of the eggs, in the nest.
Maturation, spawning and growth of rock soles off Kodiak Island in the Gulf of Alaska
Authors: Stark J. W. , Somerton D. A.
Published: April 2005

Northern rock sole Lepidopsetta polyxystra females from the Kodiak Island area, Alaska, reached 50% maturity at 328 mm LT and an average age of 7 years. In contrast, southern rock sole Lepidopsetta bilineata females reached 50% maturity at 347 mm LT and an average age of 9 years. Spawning started in midwinter for northern rock sole and peaked during the spring, while spawning for southern rock sole occurred during the summer. The bottom depth for spawning northern rock sole ranged from 43 to 61 m and averaged 45 m; spawning depth for southern rock sole ranged from 35 to 120m and averaged 78m. Both species appeared to develop a single stock of oocytes and to ovulate them in a single spawning. Northern rock sole females grew faster overall (K=0.24) than southern rock sole females (K=0.12) but reached a smaller maximum length (L∞=430 mm) than southern rock sole (L∞=520mm). Males of both species grew more slowly than females after 5 years of age and reached a smaller maximum length.
Ligulosis associated with mortality in largescale suckers
Authors: Shields B. A. , Groves K. L. , Rombaugh C. , Bellmore R.
Published: April 2005

Investigations of a fish kill at an irrigation reservoir in the Deschutes River basin, Oregon, documented at least 153 dead largescale suckers Catostomus macrocheilus, all heavily infected with large Ligula intestinalis (Cestoda). Moribund fish nearshore were similarly infected, with no evidence of secondary disease or infection. Morbidity and mortality in all cases was probably due to severe mechanical damage to internal host organs resulting from infection with multiple, large L. intestinalis. The pathology of L. intestinalis documented in largescale sucker in this study contrasts sharply with previous accounts and may represent a new and emerging disease for largescale suckers.
Sinusoidal cycling swimming pattern of reservoir fishes
Authors: čEch M. , Kubečka J.
Published: April 2005

A circular split‐beam transducer (7°, nominal angle), fixed on the bottom close to the deepest point (c. 36 m) of the Rimov Reservoir and beaming up towards the surface showed that most fishes stayed in the epilimnion during the summer. The majority (83%) of larger fish individuals (136–359 mm Ls; maximum target strength, TSmax, ranged from −42.2 to −34.1 dB) in open water performed very characteristic sinusoidal movements in the vertical plane during July and August. As they crossed the sonar beam (3–4 m wide), the fishes changed their depth several times (frequency 1.3–10.1 cycles min−1) with amplitude of 19—321 cm. The trajectory of fish vertical oscillations was in many cases greater than the trajectory of their horizontal movement. Fishes started to swim up‐and‐down after sunrise and continued doing so during daytime. The sinusoidal movement pattern was replaced by direct movement before sunset. A number of descriptive parameters of up‐and‐down movement is proposed and their ranges are given. Variation of target strength indicates active changes of fish tilt (30° on average) in transient phases of the sinusoidal cycle rather than changes of swim bladder volume. Up‐and‐down fish swimming is likely to be an efficient way of visual inspecting a larger volume of the epilimnion for prey, mainly large zooplankton (Daphnia, Leptodora), whose epilimnetic density in the Rimov Reservoir is low and patchy in summer time.
Isolation and characterization of strains of Flavobacterium columnare from Brazil
Authors: Figueiredo H C P , Klesius P H , Arias C R , Evans J , Shoemaker C A , Pereira D J , Peixoto M T D
Published: April 2005

Flavobacterium columnare is an important pathogen of freshwater fish, implicated in skin and gill disease, often causing high mortality. An outbreak of skin disease in fingerling and adult Nile tilapia, Oreochromis niloticus (L.), cultivated in a recirculation system, was investigated. Four strains were isolated and characterized by biochemical reactions, enzyme production, fatty acid profile and analysis of the 16S‐23S rDNA intergenic spacer region. All strains were identified as F. columnare. Experimental infection assays with one of these strains (BZ‐5‐02) were conducted and pathogenicity (by intramuscular route) was demonstrated in Nile tilapia and channel catfish, Ictalurus punctatus (Rafinesque). This is the first report of characterization of Brazilian strains of F. columnare.
Isolation of lymphocystis disease virus from sole, Solea senegalensis Kaup, and blackspot sea bream, Pagellus bogaraveo (Brünnich)
Authors: Alonso M C , Cano I , Garcia‐Rosado E , Castro D , Lamas J , Barja J L , Borrego J J
Published: April 2005

Two viruses were isolated from cultured sole, Solea senegalensis, and wild blackspot sea bream, Pagellus bogaraveo, and preliminarily characterized as lymphocystis disease viruses (LCDVs). Viral isolates were characterized by morphological, biochemical and biophysical properties. In addition, the susceptibility of four fish cell lines was also tested. LCDV isolates developed cytopathic effects on the SAF‐1 cell line at 5 and 6 days post‐infection and reached titres of 106 TCID50 mL−1. The antigenic and structural protein analysis of the two new LCDV isolates showed identical profiles to that obtained for LCDV strain Leetown NFH (ATCC VR‐342), used as a reference viral strain, and for an LCDV isolate collected from gilt‐head sea bream, Sparus aurata, cultured in southern Spain. Molecular confirmation was performed by polymerase chain reaction. Specific primers for LCDV produced a 270‐bp DNA fragment, the expected size for LCDV.
Cutaneous antibodies from channel catfish, Ictalurus punctatus (Rafinesque), immune to Ichthyophthirius multifiliis (Ich) may induce apoptosis of Ich theronts
Authors: Xu D‐H , Klesius P H , Shoemaker C A
Published: April 2005

This study explored the existence of apoptosis (programmed cell death) in Ichthyophthirius multifiliis Fouquet (Ich) theronts and determined the effect of cutaneous antibodies in skin culture fluid from fish immune to Ich on theront apoptosis. Apoptosis was detected in theronts and was clearly distinguished by fluorescent microscopy after staining with acridine orange and propidium iodide. The apoptotic theronts showed characteristic chromatin condensation and nuclear fragments containing chromatin pieces. The externalization of phosphatidylserine on the plasma membrane of apoptotic theronts was detected with fluorescein isothiocyanate‐conjugated annexin using flow cytometry. Theront apoptosis was induced using the skin culture fluid from fish immune to Ich, which contained cutaneous antibodies against Ich. The highest apoptosis appeared in theronts exposed to immune skin culture fluid at a 1:10 dilution, compared with those at 1:20 and 1:40 dilutions. A direct correlation was noted between the percentage of apoptotic theronts and exposure duration to immune skin culture fluid. The study indicated that antibody reaction with theronts (immobilization) played an important role in theront apoptosis, but it could not be excluded that other components released from the excised skin had effects on theronts.
Adhesion to sole, Solea senegalensis Kaup, mucus of microorganisms isolated from farmed fish, and their interaction with Photobacterium damselae subsp. piscicida
Authors: Chabrillón M , Rico R M , Balebona M C , Moriñigo M A
Published: April 2005

Most studies carried out to select microorganisms as candidate probiotics have focused on in vitro antagonism tests, such as the production of inhibitory compounds against pathogenic microorganisms. However, attachment to mucous surfaces could be another criterion to be considered when selecting potential probiotics for aquaculture. Nineteen isolates obtained from farmed Senegalese sole, Solea senegalensis Kaup, and gilthead sea bream, Sparus aurata L., have been evaluated for their capacity to adhere to skin and intestinal mucus of Senegalese sole, and their antagonistic effect against Photobacterium damselae subsp. piscicida, an important pathogen for farmed sole. The isolates from gilthead sea bream showed the highest percentage of adhesion to sole mucus, whilst the pathogenic microorganisms assayed and the isolates from sole showed, in general, a lower ability to adhere to sole mucus. The results suggest that the adhesion to fish mucus was more dependent on the isolate tested than on the host mucus. The isolates from gilthead sea bream also showed a higher antagonistic activity against P. damselae subsp. piscicida than those from Senegalese sole. Four isolates were selected, on the basis of their adhesive ability and antagonistic effect on P. damselae subsp. piscicida, to study their interactions with the pathogen in respect of adhesion to skin and intestinal mucus under exclusion, competition and displacement conditions. The results obtained show the ability of three isolates to reduce the adhesion of P. damselae subsp. piscicida to sole mucus under displacement and competition conditions. The adhesion of the pathogen to sole intestinal mucus was also significantly reduced when three isolates were assayed under exclusion conditions.
Evidence for disruption of Na+‐K+‐ATPase and hsp70 during vibriosis of sea bream, Sparus (=Rhabdosargus) sarba Forsskål
Authors: Deane E E , Woo N Y S
Published: April 2005

Osmoregulation via the sodium pump (Na+‐K+‐ATPase) and cytoprotection via expression of different families of heat shock protein (hsp) were studied at transcriptional/translational levels during progressive vibriosis in silver sea bream, Sparus (=Rhabdosargus) sarba Measurements of Na+‐K+‐ATPase activity showed that an early and drastic decline occurred in the kidney of infected fish. This reduction in Na+‐K+‐ATPase activity was not caused by transcriptional downregulation of genes coding for either the Na+‐K+‐ATPase α or β subunits. Using specific antibodies, data from immunoassays showed that the decreased sodium pump activity was caused by the specific loss of the translated glycosylated Na+‐K+‐ATPase β subunit. Data from immunoassays of different hsp families demonstrated that the expression of hsp90 and hsp60 remained unchanged throughout vibriosis whereas expression of the hsp70 family decreased in kidney and liver tissues. As hsp70 is a multigene family, the expression of the constitutive (hsc70) and inducible (hsp70) members of the hsp70 family were studied and it was found that hsp70 and hsc70 expression decreased from an early stage of infection in the kidney and the liver respectively. Reverse transcriptase‐polymerase chain reaction analysis of the hsp70 transcription‐inducing factor, hsf1, demonstrated that loss of cytoprotective function during vibriosis was mediated by a downregulation of hsf1 transcription.
Molecular Variability and Distribution of Cassava Mosaic Begomoviruses in Nigeria
Authors: Ariyo O. A. , Koerbler M. , Dixon A. G. O. , Atiri G. I. , Winter S.
Published: April 2005

Several begomovirus species and strains causing Cassava mosaic disease (CMD) have been reported from cassava in Africa. In Nigeria, African cassava mosaic virus (ACMV) was the predominant virus in this important crop, and East African cassava mosaic virus (EACMV), first reported from eastern Nigeria in 1999, was also found occasionally. A survey was conducted in 2002 to resolve the diversity of the virus types present in cassava in Nigeria and to further understand the increasing complexity of the viruses contributing to CMD. A total of 234 leaf samples from cassava with conspicuous CMD symptoms were collected in farmers’ fields across different agroecological zones of Nigeria and subjected to polymerase chain reaction (PCR) with type‐specific primers. In addition and, to provide a full characterization of the viruses present, DNA‐A genome components of several viruses and informative genome fragments were sequenced. In Nigeria, ACMV proved to be the dominant virus with 80% of all samples being positive for ACMV. The East African cassava mosaic Cameroon virus (EACMCV) prevalent in Cameroon and Ivory Coast was detected in single infections (2%) and in mixed infections (18%) with ACMV. There was no indication for other virus strains of EACMV present in the country. The EACMCV samples collected showed a high nucleotide sequence identity >98% and resembled the described sequence of a Cameroon isolate (EACMCV‐CM) more than an Ivory Coast isolate, EACMCV‐CM[CI]. Evidence is provided that the EACMCV has reached epidemiological significance in Nigeria.
Effects of Drip Irrigation on Population of Verticillium dahliae in Olive Orchards
Authors: López‐Escudero F. J. , Blanco‐López M. A.
Published: April 2005

Verticillium wilt of olive (Olea europaea L.), caused by Verticillium dahliae, is nowadays the most serious olive disease in Spain. The disease increments are being observed particularly in young olive plantations, favoured by several factors including inadequate cultural practices and crop production intensification, such as irrigation. Thus, three olive orchards affected by Verticillium wilt, with disease incidence ranging 30–50%, were selected to determine if the drip irrigation could favour the increase of pathogen in soil. Pathogen in soil was quantified in wet zones around the drippers and in dry zones out of them. Inoculum density in all experiments was higher in wet than in dry areas. After 4 months of watering, soil pathogen population increased considerably in wet and dry areas but inoculum density remained higher in the wet soil.
The Influence of the Inoculum Source of Rhizoctonia solani on Development of Black Scurf on Potato
Authors: Tsror (Lahkim) L. , Peretz‐Alon I.
Published: April 2005

Rhizoctonia solani, the causal agent of stem canker and black scurf on potato, survives as sclerotia on tubers, in soil and in plant residues. The objective of the present study was to evaluate the importance of inoculum source on disease development. Disease‐free minitubers and seed tubers contaminated with low levels of R. solani were planted in fumigated or artificially inoculated growth mixture in greenhouse experiments. Black scurf incidence and severity were significantly higher when the inoculum was present in both seed tubers and soil, compared with either of them separately. The severity of disease symptoms on the subterranean parts of the plant also were significantly higher in plots where both seed tubers and soil were contaminated, compared with plots where the inoculum source was either the seed tubers or the soil. Thus, both major sources of inoculum, seed tubers and soil, are important in disease development. However, when both sources are present, black scurf incidence and severity are increased, leading to economical damage to tuber yield and quality. Additional results from field trials support these findings. Disease incidence and severity on daughter tubers were correlated with levels of contamination in seed tubers and soil. When seed tubers and soil were heavily infested, the levels of black scurf incidence and severity on daughter tubers were very high; when seed tuber and soil infestation were very low, black scurf incidence and severity on progeny were also lower. Disease levels were reduced by in‐furrow fungicide treatment, but were less effective when the initial levels of the fungus on the seed tubers and in the soil were high.