bluuebunny/crossref_metadata_2025_split huggingface dataset:
Water and ion balance in hydrating oocytes of the grey mullet, Mugil cephalus (L.), during hormone‐induced final maturation
Authors: Watanabe W. O. , Kuo C‐M. 
Published: January 2006

Sequential changes in water content and inorganic ion concentrations occurring in intra‐ovarian oocytes of the grey mullet, Mugil cephalus L., during hormone‐induced final maturation are described. Post‐vitellogenic oocytes have a water content of 59.4%. During final maturation, oocyte water increases rapidly to a maximum of 84.8% at oviposition. Hydration is accompanied by a relatively small increase in dry matter due to the concurrent uptake of inorganic ions and an apparent uptake of organic matter.Net uptake of Ca2+ during hydration is negligible. Net uptake of Mg2 + and Na+ occurs in less than equimolar proportions. Net uptake of K+ and Cl− occurs in greater than equimolar proportions prior to ovulation, returning to equimolarity at oviposition. Hence, hydration results in a dilution of intracellular Ca2+, Mg2+ and Na+ to minimum concentrations at oviposition. In contrast, K+ and Cl− concentrations are slightly elevated prior to ovulation, returning to initial levels at oviposition. A 1:1 stoichiometric relationship in net uptake of K + andCl− is evident.Intracellular osmotic pressure in post‐vitellogenic oocytes is 203.4 ± 18.0 mOsmolkg−1. Osmotic pressure rises to a peak of 421.3+ 17.3 mOsmol kg−1 prior to ovulation, then declines to 313.3 ± 15.0 mOsmol kg−1 at oviposition. This rise in osmotic pressure prior to ovulation cannot be accounted for solely on the basis of inorganic ion uptake and must be attributed to changes in intracellular concentrations of organic solutes as well. An apparent increase in non‐ash dry matter during hydration suggests that a net uptake of organic solute is involved. A relatively small organic molecule with high osmotic activity (e.g., amino acids) is implicated.
Experimental evidence for geomagnetic orientation in juvenile salmon, Oncorhynchus tschawytscha Walbaum
Authors: Taylor P. B. 
Published: January 2006

Juvenile chinook salmon, Oncorhynchus tschawytscha, kept under artificial light in a rectangular holding tank aligned east/west for 18 months, showed a preferred temporal and directional orientation of 270° with respect to water flow and the source of food.Individual fish transferred from the holding/training tank to an unfamiliar circular test arena in another room devoid of local directional cues showed a mean of means preferred unimodal orientation of 264°.Controlled re‐introduction of individual stimuli revealed a hierarchy of orientation cues; one of these was a response to magnetism. A 90° clockwise shift in the horizontal component of the earth's magnetic field was followed by a significant change in the mean of means axial orientation, for the fish under test, from 258°/78° to 354°/174°. After restoration of the normal magnetic field the mean of means axial orientation reverted to 274°/94°.
Migrations of sea trout, Salmo trutta L., from the Vardnes river in northern Norway
Authors: Berg O. K. , Berg M. 
Published: January 2006

During the periods 1956–1963 and 1967–1970 traps were operated to catch upstream‐ and downstream‐migrating sea trout, Salmo trutta L. A total of 15 788 sea trout were tagged, using Carlin tags. The number of recaptures made in the traps was 4481, of which 1796 were recaptured more than once.The distribution of the 2122 recaptures in the sea provides a picture of the sea‐migration pattern. Of the sea recaptures, 52.8% were reported as within a distance of 3 km from the river mouth, compared to 0.7% more than 80 km away. All the different size‐groups of sea trout were represented among both the long‐distance and the short‐distance migrants. The results of this study of sea trout migrations are discussed in relation to the published results for Atlantic salmon, Salmo salar L., and sea charr, Salvelinus alpinus (L.), from the same river.The four highest values recorded for mean distance of daily travel away from the river were 20, 8, 8 and 6km day−1 by smolts and 6, 6, 5 and 5km day−1 by larger‐sized sea trout.Recaptures of tagged sea trout in rivers other than the Vardnes totalled 506, of which 306 had been tagged as smolts. The calculated minimum percentage of stray is 15.5%. The proportion of sea trout from the Vardnes river that actually spawn in other rivers is not known. No significant difference in length distribution was found between the sea trout caught in the Vardnes river and those caught in other rivers. An hypothesis concerning the selective advantages of straying by anadromous salmonids living in small rivers is discussed.
Some effects on the growth of brown trout from exposure to aluminium at different pH levels
Authors: Sadler K. , Lynam S. 
Published: January 2006

Yearling brown trout, Salmo trutta L., were exposed to various concentrations of inorganic aluminium (0–3.7 μM1−1) over a pH range of 4.3–6.5 in a flow‐through bioassay apparatus using synthetic test media. Low pH, in the absence of aluminium, produced little effect on growth or survival except at the lowest pH tested (4.3). At pH less than 5.5, concentrations of total aluminium in excess of 1 μM 1−1 (27μg 1−1) were found to retard growth. The effects of a given aluminium concentration were markedly reduced at pH above 5.5.The change in aluminium toxicity with pH must be related to changes in aluminium chemistry. When growth rates are correlated with the different aluminium species, calculated using thermodynamic equilibrium constants given in the literature, it appears that the Al(OH)2 + species is the most toxic, with a small contribution also coming from polymeric complexes.
The vertical and transverse distribution of larval herring in the River Blackwater estuary, Essex
Authors: Henderson P. A. 
Published: January 2006

The vertical and transverse distributions of spring‐spawned larval herring were studied in the River Blackwater estuary, Essex. Sampling was undertaken during May when larval densities within the estuary were at a maximum for the year. At this time, larval lengths were in the range 7–16 mm. No clear diel pattern in the vertical distribution was found, although larval distribution at night was more even.The tides were found to influence the vertical distribution. Surface waters (< 1.5 m in depth) were avoided during both flood and ebb tides, but used during slack water. Larval densities at ebb were higher near the sea bed than during the flood tide. It was concluded that this behaviour will tend to transport larvae into and retain them within the estuary.
Morphological and sensory specializations of five New Zealand flatfish species, in relation to feeding behaviour
Authors: Livingston M. E. 
Published: January 2006

The morphology of the feeding apparatus and sensory systems of flatfish species Rhombosolea plebeia (Richardson, 1843), Rhombosolea leporina Günther, 1862, Peltorhamphus novaezeelandiae Günther, 1862, Pelotretis flavilatus Waite, 1911 (f. Pleuronectidae) and Arnoglossus scapha (Forster, in Bloch & Schneider, 1801) (f. Bothidae) are described. The four pleuronectid species have asymmetric jaws and non‐toothed gill rakers typical of benthic‐feeding flatfish, while the bothid has symmetric jaws and toothed gill rakers typical of midwater‐feeding flatfish. R. plebeia, R. leporina and P. novaezeelandiae have extensive external taste bud systems which facilitate non‐visual prey location. External tastebuds are lacking in P. flavilatus and A. scapha; however, these two species have relatively large, prominent eyes which facilitate visual prey location. The lateral line is well‐developed in all five species, but R. plebeia, R. leporina and particularly P. novaezeelandiae have additional free neuromasts on their blind sides, which probably assist in prey location.The feeding habits of these flatfish species closely reflect their morphological and sensory specializations. A detailed feeding study in Wellington Harbour, New Zealand showed that R. plebeia, R. leporina and P. novaezeelandiae have closely overlapping diets consisting of largely sedentary or inactive invertebrates living in the bottom sediments. In contrast, P. flavilatus and A. scapha have specialized diets of one or two species only. While the latter two species differ in that P. flavilatus is a benthic feeder and A. scapha is pelagic feeder, both are visual feeders and therefore more specialist than the other three species.
Post‐larval growth in the lateral white muscle of the eel, Anguilla anguilla
Authors: Romanello M. G. , Scapolo P. A. , Luprano S. , Mascarello F. 
Published: January 2006

The post‐larval growth of lateral white muscle was studied in eels at different stages of post‐larval development (glass, yellow and silver eels) by means of histochemical methods for myosin‐ATPase (mATPase) activity, immunohistochemistry (for myosin isoforms) and electron microscopy.Morphological, histo‐ and immunohistochemical data reveal a uniform appearance of white muscle in glass eels, whereas in following stages the typical mosaic appearance is present. Small‐diameter fibres show a more acid‐labile mATPase activity than large fibres and react with anti‐F, anti‐FHC and anti‐S sera, but not with anti‐SHC serum. In the silver stage, the small fibres tend to decrease in number as the size of the eels increases.Electron microscopy reveals the presence of satellite cells at every stage: in glass eels there are also ‘activated’ elements showing scarce myofilaments in their cytoplasm; in yellow eels very small fibres are present, enveloped within the basal lamina of well‐differentiated muscle fibres; in silver eels there are no fibres showing signs of immaturity.Presumably the post‐larval development of white muscle involves in juvenile eels a substantial recruitment of fibres from the satellite cell population; later the hyperplasia decreases or ceases and hypertrophy remains the only mechanism for muscle growth.
An anomalous specimen of Rhamdia guatemalensis (Günther, 1864)
Authors: Cabrera J. , Martinez G. , Alforo A. 
Published: January 2006

In March of 1984 an immature Rhamida guatemalensis(Günther, 1864) lacking the right pectoral fin (Fig. 1) was captured in the Sangregado sector, Arenal Dam, Guanacaste, Costa Rica (10°28′ N, 84°46′W) The body colouration and morphometric characteristics were as described for this species (Bussing 1966; Zúñga, 1980). X‐ray examination revealed the absence of the radial bones and the fin rays of the right peoctoral fin. External examination of the tegument of this region showed no scars or evidence of accidental loss of the appendage, indicating that the fin had never developed.Morphometric data from this abnormal specimen are: total length, 14.25 cm, standard length, 11.98cm; maximum height of body, 22.35 cm; maximum width of body, 2.40 cm, caudal peduncle width, 1.27 cm; head length, 3.00cm.
Morphometric, meristic character and electrophoretic analyses of two Irish populations of twaite shad, Alosa fallax (Lacépède)
Authors: O'Maoileidigh N. , Cawdery S. , Bracken J. J. , Ferguson A. 
Published: January 2006

Since 1911 a rare lacustrine form of twaite shad, Alosa fallax killarnensis Regan (1916), has been known to occur in the Killarney Lakes. During the summers of 1985 and 1986 a gill netting programme in Lough Leane for brown trout, Salmo trutta L., yielded 32 shad (1985) and 64 shad (1986) as a by‐catch. These fish were deep frozen and compared with a sample of 59 marine twaite shad, taken on rod and line from St Mullin's, Co. Carlow, which had entered the River Barrow to spawn.Morphometric, meristic and electrophoretic character analyses were carried out on the two populations. The three analyses, particularly the isoelectric focusing, confirmed a high degree of genetic similarity. The two major differences found were the dwarfed size of the Killarney shad and the increased numbers of gill rakers carried on the first branchial arch. The merits and demerits of assigning the term subspecies to the Killarney shad are discussed in the light of the available evidence produced.
The effects of aluminium and low pH on chloride fluxes in the brown trout, Salmo trutta L.
Authors: Battram J. C. 
Published: January 2006

Juvenile brown trout acclimated to fresh water of 0‐3 mEq 1‐1 calcium and neutral pH were exposed to pH 4‐0 for 2 h at 10°C. Chloride influx was reduced by 66% and a 144% stimulation of chloride efflux recorded. The effect on chloride influx was reversed by returning the medium pH to 7‐0, restoring the influx rate to 89% of its former value.After a control period without aluminium, chloride influx and efflux were measured at 10°C at pH 7‐0 in the presence of aluminium at a final concentration of 6‐5 μM. The experiment was repeated at pH 5‐5, and subsequently pH 4‐0. At pH 7‐0, aluminium stimulated chloride efflux by 105% but influx was not affected. At pH 4‐0, efflux was not affected but influx reduced to 55%. At pH 5‐5, influx was reduced by 62% and efflux was increased by 67‐5%.Thus, the effects of aluminium on chloride fluxes are shown to be separate from those of low pH alone, and the presence of aluminium in natural waters may have a detrimental effect on chloride balance which is most evident at pH 5‐5.
Cohort sampling, anaesthesia and stocking‐density effects on plasma cortisol, thyroid hormone, metabolite and ion levels in rainbow trout, Salmo gairdneri Richardson
Authors: Laidley C. W. , Leatherland J. F. 
Published: January 2006

The effect of serial removal of fish from aquaria, anaesthesia and stocking density on plasma cortisol, thyroid hormone, metabolite and ion levels was examined in rainbow trout, Salmo gairdneri, to determine the consequences of normal handling and maintenance procedures on the activity of the pituitary‐adrenal and pituitary‐thyroid axes in the species.The capture and handling associated with serial removal of fish from an aquarium resulted in a rapid elevation of plasma cortisol concentrations and a slower rise in plasma glucose, Mg2+ and Na+ concentrations; plasma K.+ levels showed a transient fall shortly after commencing the sampling, followed by a significant increase.A lethal concentration of 3‐aminobenzoic acid ethyl ester (MS 222) of 125 mgl−1 (but not a sublethal concentration of 62.5 ng 1−1) prevented the capture stressor‐associated changes in most of the measured parameters, including plasma cortisol levels, although plasma protein and ion concentrations were elevated in fish sampled after MS 222‐anaesthesia.Stocking densities from 1 to 64 fish 80 1−1 aquarium did not appear to effect changes in the measured parameters, except for plasma T3/T4 ratios which decreased with increasing stocking density. The exception was found in fish which were stocked in pairs: one member of each pair had a markedly elevated plasma cortisol level and there was a high incidence of mortality, probably related to aggressive social interaction.
Morphological effects of mercury exposure on windowpane flounder gills as observed by scanning electron microscopy
Authors: Pereira J. J. 
Published: January 2006

Windowpane flounder, Scophthalmus aquosus Mitchill, were exposed for 60 days to 5 or 10 μg 1−1 mercury and gill samples were examined by scanning electron microscopy. The response of the gill epithelium was different at the two levels of mercury exposure. The number of chloride cell apical pits and gill filaments bearing ‘cratered’ epithelial cells increased at the 5‐μg 1−1 level and decreased at the higher exposure level.Focal swellings demonstrated a dose‐dependent relationship, their numbers being greatest at the higher exposure level. Marked fragmentation of pavement cell microridge patterns and swelling of the respiratory epithelial cells was evident at the 10‐μg 1−1 exposure level.
The reproductive success of pike, Esox lucius: aspects of fecundity, egg density and survival
Authors: Wright R. M. , Shoesmith E. A. 
Published: January 2006

Power‐law relationships have been estimated between fecundity and fish length, weight and age for pike from two gravel pit lakes (Main Lake and St Peter's Lake) in Buckinghamshire, England. Relative fecundity, estimated at 17.6 eggs g−1 for Main Lake pike and 19.4 g−1 for St Peter's Lake pike, did not differ significantly between the lakes. Population fecundity for the Main Lake was estimated at 10.6 million eggs and 6.4 million eggs in 1986 and 1987, respectively.Experimental work involving samples of eggs from 18 artificially fertilized Main Lake female pike showed a significant relationship between egg diameter and female length, and a significant difference between mean egg diameters for 41‐cm and 101‐cm females. No significant relationships were found between mean egg size and mean fry size, nor between fry length and adult length. Mean size differences between newly hatched, 18‐day‐old and 41‐day‐old fry from the 41‐cm and 101‐cm females were not significant.Samples of eggs taken at 2‐day intervals from 6 April to 5 May in a pike spawning area of the Main Lake revealed clumped distributions of eggs, with average egg densities ranging from 1 to 47 eggs per 0.071 m2 (14–671 m 2) on sand and silt substrata. The maximum egg density of 51 per 0.071 m2 (729 m−2) was found on flooded grass. The stages of development of the eggs were identified over the sampling period. Survival from stage 1 to fry was estimated at 3–6%. Egg losses were estimated at 9–10% day−1.Egg survival experiments gave overall hatching success rates of 11 % on sand/silt compared with 2.5% on aquatic plants (1986), and 18.9% on undisturbed sand/silt compared with 7.9% on disturbed sand/silt (1987). The effect of siltation on egg hatching is discussed.
The ontogeny of the alimentary tract of coregonid larvae: normal development
Authors: Loewe H. , Eckmann R. 
Published: January 2006

The development of the alimentary tract in larvae of Coregonus fera fed with Anemia nauplii has been examined histologically from the 4th to the 24th day after hatching.Buccal cavity and oesophagus are nearly completely developed before the start of feeding. The stomach exists only as an ‘anlage’, but starts to store food during the study period. The intestinal absorptive cells are stuffed with fat vacuoles between the 7th and 13th day after the start of feeding. During this time the rectal absorptive cells contain one large supranuclear body consisting of protein. The occurrence of large vacuoles in the intestinal and rectal absorptive cells may be caused by a partial non‐functioning of the larval digestion; after two weeks of feeding this restriction seems to be overcome.
Disused docks as habitats for estuarine fish: a case study of Preston dock
Authors: Conlan K. , Hendry K. , White K. N. , Hawkins S. J. 
Published: January 2006

A netting and hydrographic study of Preston dock was undertaken between May 1987 and April 1988. Fish populations were assessed using Lundgren monofilament multimesh gillnets. The dock was a low‐salinity environment regularly replenished with estuarine water on spring tides. Influxes of higher‐salinity water caused intermittent saline wedges in the deeper regions. The dock water was poorly mixed in the summer, resulting in bottom water anoxia. The water was eutrophic, and blue‐green algal blooms were common for much of the year.Fourteen freshwater, marine‐estuarine, anadromous and catadromous species were present in the dock. No seasonal patterns in diversity were apparent, due to the dominance of the herring population. Changes in species composition and abundance seem to relate to seasonal migratory patterns and, in the case of the freshwater fish, estuarine salinity, rather than to water quality.The suitablity of docks for sampling estuarine fish assemblages is discussed.
The biology of the twaite shad, Alosa fallax fallax (Lacépède), in the Severn Estuary
Authors: Aprahamian M. W. 
Published: January 2006

The estuarine biology of the twaite shad was studied in the Severn Estuary. Adults enter the estuary at the start of the freshwater phase of their spawning migration between April and June. Peak immigration generally occurs in May and is associated with temperatures in the range 10.6–12.3°C. The mean (±s.d.) instantaneous mortality rate for the mature population was 0.53±0.18. The effect of additional mortality on the spawning population was modelled assuming constant recruitment and no density‐dependent effects.Juvenile twaite shad are present in the estuary from July until they emigrate seaward during the autumn. A portion of these fish re‐enter the estuary the following April–May and remain until late summer/early autumn before once more migrating seaward.The 0 + age group feed mainly on harpacticoid and calanoid copepods and mysids, the relative preponderance of these in the diet being apparently related to tidal conditions. The possible implications of the proposed tidal power barrage in the Severn Estuary on the twaite shad population are discussed in relation to movement, diet and additional mortality of the mature population.
Kinetic characteristics of the sodium uptake mechanism during the development of embryos and fry of Atlantic salmon, Salmo salar L., in an improved water quality
Authors: McWilliams P. G. , Shephard K. L. 
Published: January 2006

The kinetics of active sodium uptake in dechorionated embryos, yolk‐sac fry and start‐feed fry of Atlantic salmon were compared in two groups reared either in low conductivity, untreated, river water (conductivity ∼ 46 μS cm−1, pH 5.75), or in ‘improved’ river water buffered with sea water (conductivity ∼2200 μS cm 1, pH 6.56), the latter treatment often being used in commercial hatcheries to avoid problems associated with periodic acidification.Maximal transport rate (Vmax) increased during development in both groups but was always significantly higher in embryos and fry maintained in untreated river water. Values for Km were not seen to vary during development up to 12 weeks after hatching and were not significantly different between groups, or from values reported for adult Atlantic salmon in fresh water.The results are discussed with respect to the influence of Na+ concentrations in the perivitelline fluid of developing eggs and in the external medium surrounding fry on Vmax and Km. The ability of fry reared entirely in buffered river water to maintain sodium balance following transfer to untreated river water is also considered.
Histomorphological changes in some organs of the brown bullhead, Ictalurus nebulosus LeSueur, following short‐ and long‐term exposure to copper
Authors: Benedetti I. , Albano A. G. , Mola L. 
Published: January 2006

The effects of copper in solution on Icfalurus nebulosus was studied by means of acute short‐term bioassay and long‐term bioassay. Histomorphological and histochemical tests were performed on skin. liver, gills, gut and kidney; enzymatic tests were also performed on the liver.Morphological changes of skin. liver and gills are described. The results of the histoenzymatic tests on the liver agree with the histological findings and confirm a mild onset and slow evolution of liver distress.