Metabolic responses of fish larvae [Rutilus vutilus (L.)] to forced activity (Cyprinidae, Teleostei)

Larvae of Rutilus rutilus (L.) weighing approx. 40 mg were exercised for 5 min by mechanical stimulation. Individual larvae were taken before and immediately after stimulation, and during 2 h of recovery. The concentrations of glucose, glucose-6-phosphate, pyruvate, lactate, 2-oxoglutarate, and ascorbic acid were determined in individual larvae. The larvae recovered faster from forced activity than juvenile roach, recovery being complete after 1 h. Larvae also differed from juveniles in that metabolite levels increased less during activity. It is suggested that the combination of low glycolytic, and high oxidative capacity was responsible for the specific metabolic responses of the larvae.     

A search for introgressive hybridization in the rudd, Scardinius erythrophthalmus (L.), and the roach, Rutilus rutilus (L.)

Rudd, roach and their hybrids from an interbreeding population at Norwich were examined electrophoretically for seven enzymes; an examination of pharyngeal teeth supplemented the data. The rudd were compared to rudd from Lake Trawsfynydd, Wales, a lake free from roach. No differences were observed between the rudd from the two localities and no evidence was found of introgression within the fish from Norwich.     

Reproductive disturbance in a roach (Rutilus rutilus) population affected by cooling water discharge

To analyse a recruitment failure in a roach ( Rutilus rutilus ) population exposed to cooling water from a Swedish nuclear power plant, histopathological examinations were made on female gonads. Several disorders were documented, corresponding to effects previously seen in Lithuanian, Moldavian and Russian heated waters, The relative gonad size (GSI) was generally lower in the exposed population. Oocyte degeneration was observed in about 50% of the females, potentially seriously reducing their reproductive capacity. The gameto- and gonadogeneses also were clearly affected and generally occurred at a faster rate. Sexual maturity was earlier and was accompanied by an increased occurrence of asynchionic gonad and oocyte growth. A normal gonad development should pass through different stages, coupled to the seasons, and the difference between individuals in a population should be small. However, in some exposed fish, the sequence of seasonal development was disturbed and a simultaneous, intensive, growth of sex cells in different stages of development could be seen. An increase of variation in gonad development both within, as well as between, fish thus was documented. Conclusively, the histopathological analysis provided evidence that the observed recruitment deficit could be related to gonad failure.     

Histochemical characterization of myotomal muscle in the roach, Rutilus rutilus (L.)

A histochemical study of the myotomal muscles in the roach revealed three main muscle regions: red, intermediate and white. These were distinguished on the basis of glycogen content, succinate dehydrogenase (SDH), and myofibrillar ATPase (mATPase) activity. Except for the red fibre region, none of these described regions is homogeneous. The principal new findings are the toniclike fibre, the presence of a transitional zone with two fibre types, and the mosaic organization of the white fibre region. The significance of this type of myotome architecture in relation to the locomotion of the species is discussed.     

Hybrids of Abramis brama with Scardinius erythrophthalmus and Rutilus rutilus from Lake Volvi, Macedonia, Greece

Two specimens of the hybrid Abramis brama × Scardinius erythrophthalmus and a single specimen of the hybrid A. brama × Rutilus rutilus are reported and described from Lake Volvi, Macedonia, Greece. This is the first occurrence of either hybrid in Greek fresh waters.     

额尔齐斯河流域湖拟鲤寄生指环虫——中国分布新记录种十字花指环虫

2021年7月在额尔齐斯河哈巴河河段于湖拟鲤（Rutilus rutilus lacustris）鳃部发现有指环虫寄生。进行形态比较,发现其形态与国内记载寄生于湖拟鲤的指环虫差异明显：本研究采集虫体的交接管基部膨大呈“8”字形,随后管径均匀,延伸呈弯曲状,形似“6”形;中央大钩内突长超过外突长,背连接片呈“一”字型且中部弯曲,腹联结片呈蝶形。与已报道指环虫形态数据比较,本研究采集的虫体偏小,其后吸器与Dactylogyruscaballeroi的形态最为接近,但交接器不同;与其余指环虫相比,十字花指环虫（D. crucifer）的腹联结片呈蝶形,而极小指环虫（D. rarissimus）呈倒“T”字型,湖拟鲤指环虫（D.rutili）呈“十”字型,双髻指环虫（D.sphyrna）和维氏指环虫（D.vistulae）没有腹联结片。在背联结片形态中,十字花指环虫（D.crucifer）呈现“一”字型,而维氏指环虫呈“V”字型。本研究所采集的虫体结构特征明显不同于国内已记载寄生在湖拟鲤上的双髻指环虫、维氏指环虫和湖拟鲤指环虫,而与俄罗斯记载的寄生于湖拟鲤鳃部的十字花指环虫形态高度相似。28S...     

The role of phosphorus release by roach [Rutilus rutilus (L.)] in the water quality changes of a biomanipulated lake

SUMMARY 1. Following fish removal, the water quality in biomanipulated lakes often improves concomitant with decreased phosphorus (P) levels. Because the decrease in P concentrations derives most probably either directly or indirectly from fish, which are the main target of biomanipulation, this study examined the P release of 0+, 1+ and 2+ roach [Rutilus rutilus (L.)] and changes in the P release during summer in a shallow eutrophic lake in Finland. 2. The P release was separated into P derived from benthic and littoral food items and into recycled P derived from feeding on zooplankton, to estimate the contribution of net P additions to the water column by the fish to the increase in P concentrations of the lake water (75–110 mg P m^?3) in summer 1991–96. 3. Individual P release of roach by both egestion and excretion was estimated with a bioenergetics model. The size of the roach population was estimated with a depletion method and the proportions of different age groups from catch samples, using a programme separating mixtures of normal distributions. The sensitivity of the release estimates to variation in the growth data was estimated with the jackknife technique. 4. The biomass‐specific P release by 0+ roach (0.36–0.54 mg P g^?1 day^?1) was higher than that by older roach (0.07–0.16 mg P g^?1 day^?1) throughout the summer. The P release by the whole roach population deriving from benthic and littoral food items (0.7–2.7 mg m^?3 during July to August, representing a net addition to the water column) was 5–19 times lower in 1991–96 than the recycled P release deriving from zooplankton (8.9–25.7 mg m^?3), and too low to explain the increase in the P concentration of the lake water during the summer. Because the biomass‐specific P release and roach diet composition vary with fish age, it is important to consider the age structure of fish populations to obtain correct estimates of P release and net additions to the water column. 5. The removal of roach by fishing diminished the roach stock greatly, but the fish‐mediated P release to the water column changed little. This effect was because of the high compensation capacity of the roach population, leading to high recruitment of young fish with higher biomass‐specific P release rates. 6. External loading is very low during summer months and therefore it cannot explain the increase in the P concentration of water during that time. Internal loading from the sediment might be as high as 10.2 mg P m^?2 day^?1, i.e. 50 times higher than the maximum net P addition by the total roach population.     

Behaviour of roach (Rutilus rutilus L.) altered by Ligula intestinalis (Cestoda: Pseudophyllidea): a field demonstration

1. We studied the influence of a cestode parasite, the tapeworm Ligula intestinalis (L.) on roach ( Rutilus rutilus L.) spatial occupancy in a French reservoir (Lake Pareloup, South-west of France).
2. Fish host age, habitat use and parasite occurrence and abundance were determined during a 1 year cycle using monthly gill-net catches. Multivariate analysis [generalized linear models (GLIM)], revealed significant relationships ( P  < 0.05) between roach age, its spatial occupancy and parasite occurrence and abundance.
3. Three-year-old roach were found to be heavily parasitized and their location toward the bank was significantly linked to parasite occurrence and abundance. Parasitized fish, considering both parasite occurrence and abundance, tended to occur close to the bank between July and December. On the contrary, between January and June no significant relationship was found.
4. These behavioural changes induced by the parasite may increase piscivorous bird encounter rate and predation efficiency on parasitized roach and therefore facilitate completion of the parasite's life cycle.     

Consumption, growth and respiration of bleak, Alburnus alburnus (L.), and roach, Rutilus rutilus (L.), during early ontogeny

Three components of the energy budget, consumption ( C ), production ( P ) and respiration ( R ) in juvenile roach and bleak kept under controlled food ( Anemia salina , 2400 ind. l⁻¹) and temperature (20° C) conditions were measured in a study aimed at defining differences between the two species and elucidating the patterns of energy partitioning during ontogeny.
Daily food consumption rates (J day⁻¹ fish⁻¹) increased allometrically ( C =a W ^b) with body size ( W , mg dry weight) in both species. Covariance analysis indicated no differences in slope or intercept for the two regression lines ( P ≤ 0.05, n = 82). However, the two species grew at significantly different rates, roach faster than bleak.
The dependence of the respiration rate (μmol h⁻¹ fish ⁻¹) on body weight ( W ) can be described by an allometric function: R = a W ^b, where a ± 95% C.L. = 0.17 ± 0.15 for roach and 0.18 ± 0.20 for bleak. The slope for roach (b ± 95% C.L. = 0.78 ± 0.01) is slightly higher than that for bleak (0.69 ± 0.03).
Assimilation efficiency [AE = ( P + R ) C ⁻¹] was significantly higher in roach than in bleak. Different levels of AE correlated with differences in relative gut length (gut length as percentage of body length). Due to the shorter relative gut length above a weight of 5 mg, bleak has lower powers of digestion, which may explain lower production rates. These differences in energetic performance between the two species indicate mechanisms leading to niche differentiation in the early life history of the fishes.