bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mate choice in the monogamous and polychromatic Midas cichlid, Cichlasoma citrinellum
Authors: Barlow G. W. 
Published: January 2006

Choice of mate in the Midas cichlid, Cichlasoma citrinellum (Günther, 1864), has been examined from a number of perspectives, proceeding from general species attributes to individual differences.The Midas cichlid discriminates against closely‐related, highly‐similar Cichlasoma, and recognizes sex, probably chemically in both cases. It is polychromatic and changes from the normal (N) pattern to gold (G) or even white at almost any age. Gold colouration inhibited attack and made it difficult to mate an N female with a G male; the inhibiting effect was cancelled by using a larger N female.Because the Midas cichlid is also biparentally monogamous, early experience could easily influence later choice of mate. G females of G × G parents preferentially spawned adjacent to G males; N females of N × N spawned mainly before N males. N females of G × G pairs, however, showed no preference.Groups of females were reared by all four combinations of two colours and two sexes, or by no parents. Females reared by identically pure‐coloured parents responded most to males of those colours, whereas females raised by mixed‐colour parents did not discriminate. Females reared without parents preferred N males. Regardless of their own or their parents' colour, juveniles spent more time with N juveniles and behaved less aggressively towards them, compared to G juveniles.Fish were offered a choice among potential mates that differed in aggressiveness, size or breeding experience. Males did not choose on the basis of those traits. Females preferred large, aggressive, experienced males. Pairs with large aggressive males more readily kept a breeding territory, and aggressive experienced males guarded young more effectively. All females were equally aggressive in protecting their young.
Fine structure and cytochemistry of the endothelial cells and rodlet cells in the bulbus arteriosus in species of Cichlidae (Teleostei)
Authors: Leknes I. L. 
Published: January 2006

The ultrastructure of endothelial cells and rodlet cells in the bulbus arteriosus of specimens representing six genera of Cichlidae is described. The former are very closely packed by membrane–bound and mainly electron–dense inclusion bodies (0.3–0.7μm).In Apistogramma ramirezi I observed numerous subendothelial rodlet cells throughout the entire length of the bulbus arteriosus. These cells penetrate the endothelium and connect to the latter by desmosomes and tight junctions. The luminal part of the cell contains numerous vesicles and tubules (width 50–100 nm), whereas the basal part is occupied by a number of membrane–bound, club–like inclusions (length ≤ 5 μm). Between these two layers there occurs a layer of small, elongated mitochondria. Peripherally, these cells consist of a filamentous wall, except in the apical area.The endothelial and rodlet cell inclusion bodies do not react with phosphotungstic acid (pH 1) or Sudan black B stain. The endothelial cells react strongly with periodic acid–Schiff (PAS) stain, whereas the rodlet cells are only moderately coloured by this stain.The present results are discussed and compared with those reported previously for endothelial/ endocardial cells and rodlet cells in bony fish.
Haematological and haematopoietic response to sodium chloride stress in a freshwater air‐breathing fish Channapunctatus Bloch
Authors: Dheer J. M. S. , Dheer T. R. , Mahajan C. L. 
Published: January 2006

Results of experiments to determine the sensitivity of Channa punciatus to different levels of sodium chloride (NaCl) (1.2, 3.2 and 6.2g 1−1) are reported. It was found that C. punctatus which is otherwise considered a hardy fish is more sensitive to higher levels of sodium chloride stress. Thus 10% of the LC50 96 h value (1.2 g 1−1 NaCl) was found stressful as evidenced by loss in body weight, while 25 and 50% of the LC50 96 h value (3.2 and 6.2 g 1−1 NaCl) even resulted in mortality. Haematological and associated haematopoietic investigation confirmed stress symptoms in all the parameters tested. Thus microcytic hypochromic anemia together with leucopenia was indicated at the two higher sublethal levels, i.e., 25% and 50% of LC50 96 h value. Differential leucocyte count showed that leucopenia is mainly contributed by thrombocytic and neutrophilic decrease. Other cell types, viz., eosinophils, basophils, large and small lymphocytes, showed a relatively significant (P < 0.01) increase in number.Haematopoietic studies revealed that the two penultimate stages in both RBC and neutrophil development closely follow the trend of their counterparts in the peripheral blood. However, the stem cells of both these cell types recorded significant increase under sodium chloride stress, which indicated homeostatic response. Biochemical studies revealed a depletion in blood glucose level as well as in liver and muscle glycogen reserves.Restoration to normal control conditions after 6 weeks of exposure to different levels of sodium chloride stress resulted in a cessation of mortality (if any), gain in body weight and more or less normality in all the haematological parameters within a period of 2 weeks.
The effects of various diets on chitinase and ß‐glucosidase activities and the condition of cod, Gadus morhua (L.)
Authors: Danulat E. 
Published: January 2006

Groups of cod, Gadus morhua (L.), were fed exclusively on fish, crustaceans, or crustacean shells for a period of 3 weeks. Chitinase and ß‐glucosidase activities were measured in enzyme extracts of stomach contents, stomach tissue, pyloric caeca, intestinal contents, and intestine tissue, and compared to the enzyme activities of control fish starved over the same period. Fulton's condition factor K, liver lipid content and liver water content were determined to estimate the effects of the diets on the condition of cod.general, the highest chitinase activities were measured in samples of cod that had been fed on whole crustaceans. In this feeding group, there was also a remarkable increase of activity by a factor of four to eight in the pyloric caeca, compared to the group fed on fish and the control group, respectively.Measurements of ß‐glucosidase activity revealed no similar dependence on food quality, ß‐glucosidase occurrence seemed to be mainly restricted to the pyloric caeca and the intestine of cod.
Changes in selected haematological parameters in juvenile chinook salmon subjected to a bacterial challenge and a toxicant
Authors: Iwama G. K. , Greek G. L. , Randall D. J. 
Published: January 2006

An infection and a toxicant were presented singly and in combination to juvenile chinook salmon. The fish were challenged with Renibacterium salmoniarum and exposed to two levels (0.05 and 0.50 × 96 h LC50) of the toxicant sodium pentachlorophenate. The experiment comprised measurement of seven blood parameters and observations on mortality and behaviour at 4‐day intervals over a period of 40 days.All fish receiving the combined treatment of bacterial challenge and higher level of toxicant died 12 days post‐infection on the 8th day of toxicant exposure. Mortalities also occurred in the groups of diseased fish and fish receiving the toxicant alone. There were no mortalities in the appropriate control groups of unchallenged fish in clean water.Most of the haematological changes pointed to a general haemodilution probably arising from progressive damage to the kidney and haematopoietic tissue by bacteria but which did not appear to be greatly affected by combined exposure to the toxicant. The blood parameters of the fish in clean water as well as those exposed to just the toxicant remained relatively constant. Higher mortality and sustained lower values of haematocrit, haemoglobin and glucose concentrations as well as red blood cell counts were present in both the diseased group of fish held in clean water and the disease plus low level toxicant group compared to the control fish; white blood cell counts were low initially but increased markedly as the infection progressed. This latter treatment combination also produced lower total protein and blood urea nitrogen concentrations.
Activation of rainbow trout macrophages
Authors: Chung S. , Secombes C. J. 
Published: January 2006

Rainbow trout peritoneal macrophages were stimulated in vitro using Concanavalin A (Con A) and in vivo using formalin‐killed Aeromonas salmonicida in Freund's incomplete adjuvant (FIA). Whether these cells had been activated was determined by the measurements of oxygen anions (NBT reduction), H2O2 production (oxidation of phenol red), RNA synthesis (3H‐uridine incorporation), acid phosphatase activity and bactericidal activity. In vitro‐stimulated macrophages showed an increased NBT reduction and 3H‐uridine incorporation over a range of Con A concentrations, compared with untreated control macrophages, but no detectable increases in H2O2 production or bactericidal activity were observed. On the other hand, in vivo‐stimulated peritoneal cells showed increases in all the assays compared with FIA‐elicited control cells, and were considered to have been activated.
Induction of immunosuppression to bacterial antigens in carp, Cyprinus carpio
Authors: Wishkovsky A. , Avtalion R. R. 
Published: January 2006

Typical primary antibody responses were found after injecting carp maintained at 25°C with formalin‐killed (Fk) Vibrio anguillarum bacteria, but not in fish injected with the same antigen held at 12° C. There were no significant increases over the primary responses in fish receiving a second injection 60 days after the first injection.The differences in the results between fish groups receiving three V. anguillarum antigens at two dosages were found to be insignificant in most of the experiments. A comparison of the antibody titres of fish groups after challenge with Fk bacteria showed no difference from control fish receiving a single injection similar to the challenge dose or fish receiving a previous injection with the antigens emulsified in complete Freund's adjuvant (CFA) at 25° C. However, significant immunosuppression was found in fish that were given the primary injection intracardially at 25° C or 12° C, or with CFA emulsion at 12° C.
Age and growth rate determination of southern bluefin tuna, Thunnus maccoyii, using otolith banding
Authors: Thorogood J. 
Published: January 2006

Otoliths of southern bluefin, Thunnus maccoyii, of between 42 cm and 167 cm f.l., taken from waters off New South Wales, South Australia, and Western Australia were prepared to reveal annual banding. Methods of preparation and examination are detailed.Otolith growth was demonstrated to be directly proportional to fish growth over the size range studied. Sampling over 13 months provided validation of the annual nature of bands for fish in their 3rd, 4th and 5th year of growth. Band formation of fish in their 2nd, 6th, 7th, 8th and 9th years of growth also appeared to be annular, though samples were available from an insufficient number of months for confident validation.Von Bertalanffy growth parameters derived from determined age‐at‐length are LL, 261.3cm;k, 0.108,t0, –0.157.
Composition and ultrastructure of elasmobranch granulocytes. I. Dogfishes (Squaliformes)
Authors: Hine P. M. , Wain J. M. 
Published: January 2006

The blood granulocyte composition of 10 species of dogfish is given, together with ultrastructural observations made on Etmopterus baxteri Leydig organ and blood, and on spleens of Oxynotus bruniensis, Deania calcea, Scymnodon plunketi and blood of Centroscymnus crepidator. Neutrophilic granulocytes, which were common, had spherical granules that developed a dense core, which then lost contents to become lucent. Eosinophilic granulocytes had ovoid or elongated granules with a fibrillar content that became aligned longitudinally, and rarely formed an axial rod. Eosinophils had large spherical granules that were electron‐dense but in early stages had a disorganised fibrillar content. These cells correspond to the neutrophils, heterophils and eosinophils, respectively, of other elasmobranchs.Dogfish granulocytes are compared with those of other elasmobranchs, and their lack of similarity to those of higher vertebrates is noted.
Composition and ultrastructure of elasmobranch granulocytes. III. Sharks (Lamniformes)
Authors: Hine P. M. , Wain J. M. 
Published: January 2006

The peripheral blood granulocyte composition of five species of shark is given together with ultrastructural observations made on the epigonal organ and blood of Mustelus lenticulatus and spleen of Apristurus sp. Three granulocyte lineages occurred in Mustelus. Ultrastructurally, eosinophilic granulocytes contained granules that were very variable in size and contained parallel fibrillar arrays that were unidirectional in small granules, but which were often orientated in several directions in larger granules. This dense core material sometimes formed angular crystalloids.Eosinophils had ovoid or irregular granules that were usually uniformly electron‐dense, but some had an eccentric ovoid area of greater electron‐density. Some eosinophils enter the blood where they are phagocytic, but others, in blood and epigonal organ, showed an unusual but characteristic process of disintegration, leaving a ragged cell full of cellular debris.The third granulocyte type had features of mast cells and basophils of higher vertebrates and was tentatively identified as belonging to that lineage. The inter‐relationships of these cells, and of them with granulocytes of other elasmobranchs, are discussed.
The effect of feeding frequency on utilization of algal nutrients by the marine herbivore, the luderick, Girella tricuspidata (Quoy and Gaimard)
Authors: Anderson T. A. 
Published: January 2006

Utilization of whole algae, lipid, protein and total nitrogen and total carbon by the luderick, Girella tricuspidata, fed ad libitum were found to be comparable with published results obtained for other species. Periods of food deprivation were found to cause reduced efficiency of utilization for all nutrients measured, with a 4–day deprivation period having a greater effect than a 24–h deprivation period.Only animals fed ad libitum were able to obtain a greater amount of lipid from their food than was defaecated. Utilization of protein and non–protein nitrogen is similar in fish fed ad libitum, but a greater reliance upon the non–protein nitrogen content of the food for nutrition is apparent when the fish are subjected to periods of food deprivation. Nitrogen utilization, relative to other nutrients, by fish subjected to periods of food deprivation is greatest immediately after a feeding bout. Total carbon utilization relative to other nutrients increases with increasing time of deprivation following a feeding bout.It is suggested that these changes in nutrient utilization with time after feeding are the result of rapid utilization of the nitrogen–rich cell contents, followed later by utilization of the algal cell wall.
Influence of photoperiod on growth changes in juvenile Atlantic salmon, Salmo salar L.
Authors: Villarreal C. A. , Thorp J. E. , Miles M. S. 
Published: January 2006

During their first 6 months sibling Atlantic salmon parr, Salmo salar L., grew larger under constant light than under natural photoperiod or simulated natural photoperiod (control). When rate of change of photoperiod was accelerated after midsummer, ×2, ×3 and ×4, there were no growth differences between the three groups, but all were smaller than the control population. Under constant autumn photoperiod of 8 h light: 16 h dark growth was less than under all other experimental photoperiod conditions. Mean length was directly correlated with total hours of daylight experienced, excluding those fish kept under constant light.Fish reared from first feeding under photoperiod regimes delayed 6 and 9 months out of phase with the natural light cycle were smaller than the controls, whereas those under a regime 3 months out of phase did not differ from the controls. The clear segregation of modal length groups within the 3, 6 and 9 months out‐of‐phase populations occurred 1, 4 and 4 months, respectively, after the segregation in the control group. Under constant light, and under constant 12 h light: 12 h dark (12 LD), the segregation was delayed 3 and 4 months, respectively. The proportion of the population which maintained growth (upper modal group) was significantly less in the 9 and 6 months out‐of‐phase and 12 LD groups (39, 40 and 42%, respectively) than in the other three groups (82.5‐85%). Acceleration of photoperiod change also resulted in decreased growth.The results support a model of salmon development in which, 2‐3 months after first feeding, growth is maintained if feeding opportunities at that time are above a threshold level, and in which this critical timing is influenced by photoperiod. It is suggested that the delays reflect a synchronizing effect of photoperiod on an endogenous rhythm of appetite and growth. The differences in upper modal group proportions observed in the present experiments, reflect the relative feeding opportunities available at the critical period in July‐August.
Age, growth and reproduction of the barbel, Barbus sclateri (Günther, 1868), in a first‐order stream in southern Spain
Authors: Herrera M. , Hernando J. A. , Fernandez‐Delgado C. , Bellido M. 
Published: January 2006

This study was based on examination of 1476 barbels from a first‐order stream located in the Guadalquivir River basin (38°N, 4°43′W). This stock comprised nine age groups of male and 11 of females. No growth was recorded between October and March, most occurring in April–June and, to a lesser extent, in July–September. A classification analysis revealed that this stock had the lowest growth rate of 37 different European barbel populations. Length–weight relationships were obtained for 12 barbel categories and used to estimate both condition and instantaneous growth rate. Relative condition (before and after subtracting gonad weight) was similar in both sexes and was affected by gonad growth and environmental summer conditions.Spawning occurred during the second half of May (15 May is suggested as the birthday). Gonads began to develop in September (females) and in February (males). Males matured at between 7 and 9 cm fork length (f.l.) (2–4 years old) and females between 11 and 16 cm (6–7 years). The fecundity of this stock was represented by the formula F=6.07 10 4 f.l. (mm)3.0667. Larger and older fish showed a higher fecundity and bigger eggs. The overall sex ratio did not differ from 1:1.
Bioenergetics of growth of a cyprinid, Phoxinus phoxinus: the effect of ration, temperature and body size on food consumption, faecal production and nitrogenous excretion
Authors: Cui Y. , Wootton R. J. 
Published: January 2006

Food consumption, faecal production and nitrogen excretion by minnows, Phoxinus phoxinus, weighing 1–5.5 g were studied at five rations ranging from starvation to ad libitum and four temperatures ranging from 5 to 15°C.The maximum rate of food consumption (Cmax) was related to body weight (W) and temperature (T) by the relationship: Cmax=aWb1Tb2. There were significant daily variations in Cmax, which tended to decline over time. Absorption efficiency increased with increasing ration size and decreasing temperature. Body weight had no significant effect on the faecal production. The equation F= aCb1eb2 T described the relationship between faecal production (F), food consumption (C) and temperature. Ammonia‐N predominated over urea‐N in the excreta of most experimental fish. The proportion of urea‐N in the total nitrogen excreted was generally higher at lower rations than at higher rations. Rates of nitrogen excretion increased with increased ration size and were, to a lesser extent, influenced by temperature. Body weight had no significant effect on the nitrogen excretion by feeding minnows. The equation N = a+blT+b2C described the effects of food consumption and temperature on nitrogen excretion (N) other than urea‐N excretion. The relationship between urea‐N excretion (Nu), food consumption and temperature was described by the equation Nu= aeb1T((C+1)b2.On the average, 11 % of food energy was lost in faecal production and nitrogen excretion by minnows feeding on whiteworms, Enchytraeus spp.
Choice of feeding station in Atlantic salmon, Salmo salar, parr: effects of predation risk, season and life history strategy
Authors: Huntingford F. A. , Metcalfe N. B. , Thorpe J. E. 
Published: January 2006

The current speed at which underyearling salmon parr held feeding stations was examined from late summer to early winter in laboratory flume tanks that offered a choice between (a) areas with high water flow, high food availability but high predation risk and (b) areas with low flow, little food but shelter from predators. In August, those fish that would become smolts aged 1 + (and which by late winter formed the upper modal group, UMG, of the bimodal size distribution) adopted positions in faster currents than did the fish which would take a further year to reach the smolt stage (the lower modal group, LMG). However, the chosen current speed of UMG fish decreased through the period of study, so that by December all fish were found in areas of low flow, and hence little food. Both date and water temperature had independent effects on the chosen current speed of UMG fish.The effect of predation risk was investigated using a model trout. A brief sight of this predator caused 47% of fish that had been in the main, exposed currents to move to slacker, sheltered areas; they took 1 h, on average, to return to their previous position. The fish that remained in position upon seeing the predator reduced their rate of tail beating, presumably increasing crypticity. Eventual UMG parr were less likely than were LMG fish to move away upon seeing a predator. The fish moved to faster currents than normal 2–3 h after seeing the predator, possibly compensating for the earlier reduction in feeding rate.
Ria de Alvor as a spawning place and a nursery ground
Authors: Antunes M. M. , da Cunha P. L. , Duarte A. P. , Mendonça E. P. 
Published: January 2006

Ria de Alvor is a small estuary between Lagos and Portimão on the south coast of Portugal, 37°7′–37°10′N, 8°35′–8°38′W.Samples were collected monthly in the period April 1985–March 1986 in an ichthyoplankton and ichthyofauna survey of the estuary. A WP‐2 plankton net was used for catching ichthyoplankton, and a beam trawl and a beach seine were used for catching ichthyofauna.Scaldfish, Arnoglossus laterna (Walbaum, 1792), even though the most abundant species in ichthyoplankton samples, was never found in ichthyofauna samples.From the results obtained, it is concluded that a great part of the fish species are temporary marine visitors using the Ria as a nursery ground, although this system appears to provide a spawning area for species with benthic eggs. No evidence was found of pelagic spawning.