The food niche overlap of five fish species in the Úpoř brook (Central Bohemia)

Abstract

The diet and food niche overlap of five fish species in the Úpoř brook was evaluated. The supply of food represented by benthos was studied, and the proportion of total food particles in the intestine of brown trout Salmo trutta L., chub Squalius cephalus (L.), dace Leuciscus leuciscus (L.), bullhead Cottus gobio (L.) and stone loach Barbatula barbatula (L.) was measured. Evaluations were performed using a new index (Mtot p ). All fish species except stone loach exhibited a balanced consumption of the food supply. The food components were systematically grouped, but no differences in the ingestion of these groups were found. However, a new approach in the evaluation of food competition based on observation of species-specific preferences/avoidance in ingestion of food particles was applied. The particles were divided into four ecological categories according to their availability for fish. Brown trout concentrated on easily accessible sources of benthos or that hiding below stones, and also distinctly preyed on terrestrial insects. Chub displayed a similar feeding habit, though concentrating more on drift and allochthonous sources. The food spectrum of dace was mostly composed of easily accessible benthic organisms, consuming fewer hidden benthos and terrestrial insects. The food of bullhead and stone loach was similar, both preferring benthos. Bullhead consumed hidden species while stone loach consumed more accessible species rather than hidden ones. l'exception de la loche franche présentaient une consommation équilibrée de la nourriture disponible. Les composants alimentaires ont été regroupés suivant les ordres ou classes, mais aucune différence dans l'ingestion de ces groupes n'a été trouvée. Cependant, une nouvelle approche dans l'évaluation de la compétition alimentaire basée sur l'observation des préférences / évitement à l'ingestion de particules alimentaires spécifiques à chaque espèce a été appliquée. Les particules ont été réparties en quatre catégories écologiques en fonction de leur disponibilité pour les poissons. La truite se tourne vers des sources facilement accessibles du benthos ou cachées en dessous des pierres, et significativement vers les insectes terrestres. Le chevesne affiche des habitudes alimentaires similaires, bien que se concentrant plus sur la dérive et les sources allochtones. Le spectre alimentaire des vandoises était principalement composé d'organismes benthiques facilement accessibles, consommant moins de benthos cachés et d'insectes terrestres. La nourriture du chabot et de la loche franche étaient similaires, les deux préfèrent le benthos. Le chabot consomme des espèces cachées alors que la loche franche consomme des espèces accessibles, plutôt que celles qui sont cachées. RÉSUMÉ

Pro-ecological and conservation activities are not always beneficial to nature: a case study of two lowland streams in Central Europe

“…The roach, being eurytopic, is frequently dominant in degraded watercourses, while the degree of dominance may be an indicator of the level of aquatic system transformation 1 , 6 , 27 , 29 , 76 . The brown trout and the bullhead are very sensitive to changes in environmental parameters 77 – 81 , which was confirmed by the results of studies conducted by the authors of this paper. Here an increase in water temperature, sanding of gravel pits, as well as a reduced mosaic pattern of microhabitats following the construction of retention basins has resulted in the disappearance of these two fish species.…”

Hepatic Steatosis in a Bullhead (Cottus gobio) Population from a High-Mountain Lake (Carnic Alps): Adaptation to an Extreme Ecosystem?

“…Indeed, Hirudinea and Oligochaeta taxa are also present in this lake [19], but more endobenthic than Chironomidae, thus more difficult to hunt, justifying the bullhead preference for Chironomidae. Generally, C. gobio prey on a wide range of insect larvae as Plecoptera, Trichoptera, Ephemeroptera, and Diptera [21][22][23][24], as recorded in Degano Creek. Nevertheless, bullhead was found to be predominantly food generalists, with an ability to shift their feeding strategy towards specialization when exposed to environmental disturbances [25].…”

Benthic grazing in a eutrophic river: cascading effects of zoobenthivorous fish mask direct effects of herbivorous fish

“…Another explanation for these results is that the strong effects are due to the relatively high density of the large omnivorous fish European chub ( S. cephalus ) and dace ( L. leuciscus ). Both species feed to a considerable proportion on benthic prey ( Vlach, Švátora & Dušek, 2013 ) and might therefore have reduced benthic grazers on the tiles accessible to fish.…”