Chondrostoma Toxostoma Research Articles

Early Development of the Sofie, Chondrostoma toxostoma

The developmental biology of embryos, larvae and juveniles of sofie, Chondrostoma toxostoma, reared from artificial insemination, was examined under controlled laboratory conditions, using both in-vivo and preserved specimens. The complete remodelling process (metamorphosis) was described and interpreted according to the theory of saltatory ontogeny, providing a model within which the highly complex ecological niche and behaviour (habitat use, diet, etc.) of the free embryos and larvae can be evaluated. The sofie ova were relatively opaque and the free embryos presented a small yolksac. Consequently, the free embryo steps were short and the free embryos emerged rapidly from the substratum. The circulatory system appeared early and was simple, which suggests that sofie free embryos require well oxygenated water. The remodelling of the mouth from a superior to inferior position characterised changes in the sofie's diet during early life history, which is typical of the genus. Differences in development relative to the nase, C. naus, are discussed.

Long-term recovery of macrobenthos and fish assemblages after water pollution abatement measures in the River Petite Baïse (France).

Riverine ecosystems are subject to a large variety of man-made influences, and in recent years a new public awareness of the need to protect rivers has emerged within the industrialized world. The present study focuses on the effect of abatement of pollution from one factory on the recovery of fish and macroinvertebrate species richness in the River Petite Baïse over a 20-year period (1973-1993). Until 1973, the Petite Baïse (75 km in length) received not only factory waste (nitrogenous rich effluents) but also the untreated sewage of many villages and agricultural runoff from the river's catchment. In 1970, macroinvertebrates and fishes were absent in the river despite having initially been classified as of the barbel Barbus barbus zone, and extensive efforts were made by the factory to reduce pollution to allow the riverine community to recover. Regular surveys between 1973 and 1993 revealed a progressive improvement in water quality and the recolonization of the river by macrobenthic and fish populations. Macrobenthic fauna species richness gradually increased from zero in 1970 to level 8 or 9 in 1993 (Verneaux and Tuffery method), reflecting improvements in river water quality. Fish were not observed until 40 km downstream of the factory in 1978, 16 km in 1980, and approximately 5 km by 1990. Fish species richness increased from five in 1978 (barbel, chub Leuciscus cephalus, stone loach Barbatula barbatula, minnow Phoxinus phoxinus, gudgeon Gobio gobio) to eight in 1990 (the carnivorous brown trout Salmo fario, the omnivorous chub, and six benthophagous fishes: gudgeon, barbel, minnow, stone loach, sofie Chondrostoma toxostoma, carp Cyprinus carpio). Fish biomass 45 km downstream the factory increased from 1 g/m2 in 1978 to more than 5 g/m2 by 1990. Recolonization of the river, in particular those areas furthest downstream from the factory, occurred as a result of reductions in the nitrogen inputs emanating from the factory.

Current status of the riverine fishes of the French Mediterranean basin

We have undertaken a study of current knowledge on the distribution and abundance of 10 freshwater fish species with a restricted geographical range, recorded since 1950 from French rivers flowing into the Mediterranean, including those in Corsica. In order of decreasing abundance these are: Leuciscus (Telestes) souffia, Chondrostoma toxostoma, Barbus meridionalis, Zingel asper, Blennius fluviatilis, Aphanius fasciatus, Alosa fallax rhodanensis, Aphanius iberus, Valencia hispanica and Cottus petiti. Distribution maps for the first seven taxa have been produced on the basis of 3124 fisheries surveys included within Fisheries Orientation Schemes carried out in French départements. These taxa are distributed in three different zoogeographical regions: a northern mainland region, a southern mainland region and the island of Corsica. The distribution of these taxa in the major rivers is shown on maps by means of lines of varying thickness and for the minor river courses by shading. The detailed habitat preferences of the first three species have been determined, showing a succession of Barbus meridionalis, Leuciscus (Telestes) souffia and Chondrostoma toxostoma going downstream within the southern mainland region. Following a discussion of the requirements of each of these species and of the threats that they face within the study area, their status is defined according to the International Union for the Conservation of Nature definitions.

Microhabitat use by fish in the upper Rio Matarraña, Spain, 1984–1987

Abstract– We evaluated the microhabitat use and abundance of Barbus graellsii, Bardus haasi, Chondrostoma toxostoma, Noemacheilus barbatulus, Oncorhynchus mykiss and Rutilus arcasii between 1984 and 1987 in the upper Rio Matarraña, Spain. The mean abundance classes for all species ranged from 1.8 to 3.0 (where 1=1–6, 2=6–10, 3=11–20 and 4=>20 specimens, respectively). Mean abundance was consistently higher in 1984–1985 (2.4–3.0) than during 1986–1987 (1.8–2.8). The decreases noted in 1986–1987 were attributable to declines in abundance of O. mykiss (introduced in winter 1984) and B. haasi. Barbus graellsii and Ch. toxostoma, however, remained abundant throughout the entire 4‐year study. We only observed N. barbatulus and R. arcasii irregularly in the study site. Analyses of microhabitat availability data indicated that the study site contained more silt and less algae/debris during spring 1985 and early and late summer 1986 than in the majority of the remaining season. The converse was true for late summer 1985 (i. e., less silt and more algae/debris than the majority of seasons). Principal component analyses showed that B. graellsii and Ch. toxostoma generally occupied deeper microhabitats with low to average velocities, higher amounts of depositional substrata and lower quantities of erosional substrata. B. haasi tended to avoid microhabitats with rubble substrata and occurred in those with higher amounts of algae/debris. O. mykiss occupied shallower areas with slightly higher velocities and a heterogeneous substratum. With the exception of B. haasi, microhabitat use by assemblage members was similar from 1984 to 1987. B. haasi, however, was not as strongly affected by depth in the latter two years of the study as it was during 1984–1985. Seasonal and annual analyses of intraspecific microhabitat use showed that most changes were due to variations in microhabitat availability. Nonetheless, all species exhibited minor seasonal shifts in microhabitat use. Size‐related analyses indicated that both smaller B. graellsii and Ch. toxostoma occupied shallower microhabitats with slower velocities than larger specimens. Intersite differences in microhabitat use for B. graellsii and Ch. toxostoma showed that most differences in substratum use were attributable to disparities in substratum availability. Both species occurred closer to the substratum in the site with higher velocities (i. e., upper reach), although this response was more pronounced in Ch. toxostoma. Interspecific analyses indicated that B. graellsii and Ch. toxostoma did not consistently occupy statistically differentiable microhabitats, although both species occurred farther from the substratum and refuges than did B. haasi. O. mykiss occupied shallower microhabitats with more gravel than either B. graellsii or Ch. toxostoma. The lack of microhabitat shifts by native species during the study period indicates that interactions with either B. haasi or O. mykiss did not play a strong role in microhabitat use by the remaining assemblage members.

Modifications in habitat use patterns and trophic interrelationships in the fish fauna of an oligotrophic artificial lake: Sainte Croix (Provence, France)

Lake Sainte-Croix is a hydro-electric reservoir on the river Verdon that came into operation about 16 years ago. The area of the lake is about 22 km2 and the volume about 767 Mm3. The water level drops by as much as 16 m in winter. Sainte-Croix is a warm monomictic oligotrophic lake. The indigenous fish fauna of the Verdon originally included 8 species. Successive stocking has raised this number to 17. In catches made in 1976–1977 with 27 mm mesh nets, 80 to 90% of the fish with a body size of between 15 and 25 cm were of the four main species indigenous to the river before the dam was built: Leuciscus cephalus, Barbus fluviatilis, Chondrostoma toxostoma, Salmo trutta. Catches made at same period with 14 mm mesh nets gave only Chondrostoma toxostoma and Leuciscus cephalus. Changes in the fish fauna were apparent from catches made in 1984 and 1987 with nets of the same mesh size. There was a marked demographic increase of roach, and more recently of bleak and gudgeon, all three species introduced after the construction of the dam. At the same time, there was a decrease in catch frequency of Ch. toxostoma, L. cephalus and B. fluviatilis in the downstream area of the lake. Stomach content analysis carried out in different seasons on the six most abundant species of the lake (roach, toxostome, chub, bleak, perch and gudgeon) provided evidence on the trophic organisation of the fish fauna. We have measured niche breadth for each species by the Simpson diversity index and niche overlap by the Pianka index. Bleak is the only species to feed on zooplankton in open water. Roach is a particularly opportunistic feeder, sometimes taking plankton, but at Sainte-Croix it is exclusively herbivorous and benthophagous. Niche overlap between these two species is slight or null, depending on the season. On the other hand, there is a high degree of overlap between roach and chub and between roach and toxostome. The decrease in toxostome and chub frequency in the downstream area of the lake, where roach is most abundant, would appear to be a competitive exclusion phenomenon. There is high niche overlap between bleak and young perch, which partly explains the low abundance of the latter species; other contributory factors are the scarcity of zooplankton inshore, and the scarcity of zoobenthos resulting from the drop in the water level in winter.

Microhabitat use in a mediterranean riverine fish assemblage : Fishes of the upper Matarraña.

We examined microhabitat use in Barbus graellsii, Barbus haasi, Chondrostoma toxostoma, Rutilus arcasii, and Salmo gairdneri over a 19 month period in the upper Rio Matarraña, Spain. B. graellsii and Ch. toxostoma exhibited non-random microhabitat use during all seasons and preferentially occupied deep microhabitats with heterogeneous substrates. During the majority of seasons in which they were present, B. haasi and R. arcasii occurred in microhabitats similar to those occupied by B. graellsii and Ch. toxostoma. S. gairdneri was over-represented in high velocity microhabitats with erosional substrates. We did not observe any evidence of interspecific interference competition or avoidance. Substrate composition did not appear to affect microhabitat use outside of its covariation with depth and velocity. Seaonal variation in microhabitat use by B. graellsii, B. haasi and Ch. toxostoma was strongly correlated with seasonal changes in microhabitat availability. S. gairdneri, however, occurred closer to the substrate when average velocities were high. Larger B. graellsii and B. haasi sometimes occupied deeper, higher velocity microhabitats than did smaller specimens. Larger B. graellsii also occasionally occurred farther from shelter than did smaller specimens; the reverse was true for B. haasi. Larger Ch. toxostoma sometimes were found farther from both the substrate and shelter than smaller individuals, whereas smaller specimens occasionally inhabited deeper areas with more depositional substrates than did larger Ch. toxostoma. During Late Summer 1985, smaller Ch. toxostoma also occupied microhabitats with higher velocities than did larger specimens. A comparison of microhabitat use for two species present in both upper and lower portions of the Matarraña indicated that most differences in microhabitat use could be attributed to inter-site differences in microhabitat availability. The data suggest, hovever, that both species shifted to more protected microhabitats in the higher velocity site. Assemblage members generally occupied statistically distinguishable microhabitats and could be classified as: 1) high-velocity upper water column (S. gairdneri), 2) low velocity lower water column (B. graellsii, Ch. toxostoma and R. arcasii), and 3) shelter-oriented benthic (B. haasi). The introduction of S. gairdneri during Winter 1984 did not produce microhabitat shifts in any of the native species. Whether or not the native species affected microhabitat use in S. gairdneri is unknown. Interspecific competition for space, however, did not appear to strongly influence microhabitat use among the native species.

Microhabitat use in a mediterranean riverine fish assemblage : Fishes of the lower Matarraña.

Over a 22 month period Barbus graellsii, Chondrostoma toxostoma, Cyprinus carpio, Esox lucius, Gobio gobio, and Leuciscus cephalus displayed non-random microhabitat use in the Rio Mattarraña, Spain and generally were overrepresented in deep microhabitats with low or undetectable flow velocities. Substrate composition did not strongly affect microhabitat use outside of its covariation with depth and velocity. Most seasonal differences in microhabitat use were attributable to seasonal changes in microhabitat availability, although all species selectively occupied deeper microhabitats during Spring 1984, 1985, and Early Summer 1984. Smaller specimens of B. graellsii, Ch. toxostoma, G. gobio, and L. cephalus all occurred closer to the substrate than larger specimens. Smaller specimens also tended to occupy shallower areas with greater amounts of erosional substrates (except for Ch. toxostoma). Assemblage members occupied statistically distinct microhabitats and could be classified as: 1) upper water column (L. cephalus), 2) mid-water column (Ch. toxostoma, C. carpio), 3) lower water column (B. graellsii), or 4) benthic (G. gobio, E. lucius). We hypothesize that the observed pattern of vertical segregation was produced by a combination of predator avoidance and differential evolutionary adaptation rather than by interspecific competition for space.

The chromosomes of 11 species of cyprinidae and one cobitidae from Italy, with some remarks on the problem of polyploidy in the cypriniformes

The present paper gives a detailed description of the morphology of the karyotype of 11 Cyprinidae and 1 Cobitidae indigenous to Italian inland waters. The data relating to Chondrostoma toxostoma, C. soetta, Phoxinus phoxinus, Rutilus rubilio, Barbus meridionalis and Cobitis taenia are new from a karyological point of view; as regards Leuciscus cephalus, L. souffia, Alburnus alburnus, Scardinius erythrophtalmus, Tinca tinca and Barbus barbus the already known diploid numbers are confirmed and the morphology of the karyotypes is specified. The data on the morphology of the karyotype are used in discussing the problem of polyploidization of the chromosomal complement in both the Cyprinidae and the whole order Cypriniformes.