European Bitterling Rhodeus Sericeus Research Articles

Taste Preferences of Cyprinid Fishes (Cyprinidae). A Comparative Study

Palatability of various substances (amino acids, carboxylic acids, some organic acids, and basic taste substances) is presented for eight species of cyprinids (Cyprinidae): bream Abramis brama, European bitterling Rhodeus sericeus amarus, sunbleak Leucaspius delineatus, crucian carp Carassius carassius, common bleak Alburnus alburnus, dace Leuciscus leuciscus, chub L. cephalus, and tiger barb Puntigrus tetrazona. The taste sensitivity to certain substances has been estimated for these species. A comparative analysis has been performed considering the published data on other species of the family; as a result, a high specificity of the taste spectra of cyprinids is obtained. No obvious relationship of taste preferences with the fish lifestyle, their diet, and phylogenetic similarity has been revealed. All cyprinids keep food objects in their oral cavity the longer, the most is the food object palatability. The number of orosensory testing events performed with a food object differs in fish of different lifestyles and belonging to different trophic categories, but does not correlate with the taste properties of the food object. During orosensory testing, the first retention of the grasped object in the oral cavity is longer than subsequent ones. Retentions are many times longer if the object is finally swallowed than when the fish refuse to consume. The great similarity of behavior in cyprinids during orosensory testing of food indicates the conservatism of the feeding behavior compared to taste reception.

Morphological characteristics, reproduction, and food habits of European bitterling Rhodeus sericeus amarus (Cyprinidae) in the Alatyr River

The data on the morphology, reproduction, and diet of European bitterling Rhodeus sericeus amarus in the Alatyr River (the Sura tributary) are presented. Differences between females and males have been revealed with respect to the complex of morphometric characters. It is assumed that the deviations of some meristic characters from those that are typical of European bitterling are due to the habitation of this population at the boundary of the species distribution. The species reaches sexual maturity at the age of 1–2 years; the individual fecundity is 103–525 (354) eggs. Bitterling is a typical phytophage.

Relative abundance of Ponto-Caspian gobiids in the lower Vistula River (Poland) 3- to 4 years after first appearance

In the years 2000–2001, specimens of two Ponto-Caspian gobiids (racer goby Neogobius gymnotrachelus and monkey goby Apollonia fluviatilis) were recorded for the first time in the lower Vistula River, which is a part of the central inland corridor used by Ponto-Caspian species to migrate in Europe. In 2004, seine net surveys were made in the river course to examine relative abundance of the non-indigenous gobiids in the local small-fish community. Altogether 4420 specimens with total lengths ranging from 10 to 340 mm (mostly <100 mm) belonging to 18 species were recorded in 70 hauls. Monkey goby was one of the subdominant species (18.1% of total number of fish captured; 64.3% frequency of occurrence in hauls) together with bleak Alburnus alburnus (21.0, 54.3), roach Rutilus rutilus (18.2, 67.1) and three-spined stickleback Gasterosteus aculaetus (17.3, 37.1). Racer goby was less abundant but quite common (2.5, 32.9), similar to common bream/white bream Abramis brama/Blicca bjoerkna (6.4, 47.1), Eurasian perch Perca fluviatilis (5.7, 57.1), dace Leuciscus leuciscus (4.2, 40.0) and European bitterling Rhodeus sericeus amarus (3.4, 27.1). The study shows that Ponto-Caspian gobiids dispersed successfully in the lower Vistula, becoming species common to its nearshore zone 3- to 4 years after their first appearance.

The importance of species interactions in conservation: the endangered European bitterling Rhodeus sericeus and its freshwater mussel hosts

AbstractSpecies conservation may be complicated in symbiotic interactions. Sub‐lethal impacts of human activities on one species may be lethal to other species on which they depend. We investigated the impact of two aspects of eutrophication – changes in phytoplankton and oxygen levels – on the interaction between a freshwater fish that is endangered in several countries, the European bitterling, Rhodeus sericeus, and the unionid mussel hosts that they require for spawning. Reduced concentrations of algae and oxygen each led to a greater proportion of bitterling embryos being ejected prematurely from the mussel hosts. Reduced algal concentrations also led to reductions in mussel ventilation rates and to mussels spending less time with their valves open. Bitterling mortality may have been due to three causes: direct effects of environmental conditions on embryonic survival, active expulsion by mussels when stressed and through responses by mussels that created internal conditions that bitterling embryos could not survive. Our study shows that the sub‐lethal effects of pollution on one species can have lethal effects on another species with which it interacts. Such interactions need to be considered in conservation programmes.

The reproductive ecology of the European bitterling (Rhodeus sericeus)

AbstractThe European bitterling Rhodeus sericeus Pallas is a freshwater fish belonging to the Acheilognathinae, a subfamily that has an unusual spawning symbiosis with freshwater mussels. Female bitterling possess long ovipositors that they use to place their eggs onto the gills of a mussel through the mussels' exhalant siphon. Males fertilize the eggs by releasing sperm into the inhalant siphon of the mussel. The embryos develop inside the mussel for approximately a month, eventually leaving the mussel as actively swimming larvae. Because they use a discrete spawning site that can be readily manipulated they have recently been used in studies to understand oviposition choice with respect to mate and spawning site quality, host–parasite coevolution, alternative male mating tactics, and linking behavioural decisions with population dynamics. The current state of knowledge of bitterling reproductive ecology is reviewed and synthesized, and future directions for research on this species are proposed.

The bitterling–mussel interaction as a test case for co‐evolution

The European bitterling Rhodeus sericeus(Cyprinidae) spawns in the gills of freshwater mussels (Unionidae) and shows some obvious adaptations to this type of spawning, such as the development of an ovipositor. Furthermore, recent studies have shown that the fish avoid species of mussels that have a high likelihood of ejecting their eggs prematurely. This leads to the question of whether the interaction between bitterling and mussels could represent a case of co‐evolution, involving evolutionary responses by both species to selection imposed by the other. The evidence for and against co‐evolution is reviewed, incorporating new results from two sets of experiments designed to test for adaptive choices by bitterling according to the mussels’ sex and reproductive state, as well as a preliminary study of potential benefits for mussels from exposure to bitterling. Host preferences by bitterling, both among and within mussel species, may indeed have evolved in response to differences in benefits for offspring survival. There is no evidence yet for any benefits to mussels from receiving eggs, whereas there are costs due to reduced ventilation rates when the gills contain bitterling eggs. While there are differences among mussel species and individuals in their tendency to reject bitterling embryos, these differences do not provide strong evidence for co‐evolution. For example, they may reflect differences in host physiology such as ventilation rate and generalized responses to expelling objects from their gills. Therefore, while bitterling are well adapted for their obligate spawning relationship with mussels, it has been much more difficult to find evidence for adaptations by mussels for dealing with bitterling. This suggests that any co‐evolutionary dynamics between bitterling and mussels may be asymmetric, with stronger responses to selection by the fish than by mussels.

Effects of phosphate on the reproductive symbiosis between bitterling and freshwater mussels: implications for conservation

Summary We examined the effects of phosphorus, an important pollutant in fresh waters, on mussels Anodonta anatina and embryos of European bitterling Rhodeus sericeus amarus. These species are involved in an unusual symbiosis, with the fish depositing eggs inside the mussels' gills, where the embryos develop for 3–6 weeks until the larvae leave the mussel. High concentrations of phosphate (500 μg L−1 and higher) caused a significant increase in the rate of premature expulsion and emergence of bitterling embryos from the mussels, with a concomitant increase in fish mortality. At concentrations of 750 μg L−1 and higher, mussels reduced their frequency of ventilation and movements through the substratum. These results have implications for understanding the nature of the symbiosis between the fish and their mussel hosts, showing that mussels have control over bitterling developing in their gills. The premature expulsion of bitterling embryos at high phosphate levels is detrimental to the fish that they harbour. Recommendations for the conservation of bitterling and species of mussels, which are threatened or endangered over parts of their ranges, include reductions in levels of phosphorus in natural habitats and the need for low levels in reintroduction sites for the fish and their mussel hosts.

Biology of the European bitterling Rhodeus sericeus (pisces: cyprinidae) in the Bronx River, New York, USA: An apparently benign exotic species

Selected aspects of the biology of the European bitterling Rhodeus sericeus in southern New York were investigated as a preliminary determination of the impact of this species on the native ecosystem. There are about 900 bitterlings in the only extant North American population. The oldest specimen was in its fourth summer (III +) and all were mature in their first year. Fecundity is low, less than 60 eggs per female. Bitterlings feed primarily on diatoms and the digestive system is typical of a surface-scraping herbivore. Impact of this exotic species on the ecosystem appears minimal. It is unlikely that the species would cause appreciable negative impact on any habitat in the northeastern United States.