Comparing RADseq and microsatellites to infer complex phylogeographic patterns, an empirical perspective in the Crucian carp, Carassius carassius, L.

The conservation of threatened species must be underpinned by phylogeographic knowledge. This need is epitomized by the freshwater fish Carassius carassius, which is in decline across much of its European range. Restriction site-associated DNA sequencing (RADseq) is increasingly used for such applications; however, RADseq is expensive, and limitations on sample number must be weighed against the benefit of large numbers of markers. This trade-off has previously been examined using simulation studies; however, empirical comparisons between these markers, especially in a phylogeographic context, are lacking. Here, we compare the results from microsatellites and RADseq for the phylogeography of C. carassius to test whether it is more advantageous to genotype fewer markers (microsatellites) in many samples, or many markers (SNPs) in fewer samples. These data sets, along with data from the mitochondrial cytochrome b gene, agree on broad phylogeographic patterns, showing the existence of two previously unidentified C. carassius lineages in Europe: one found throughout northern and central-eastern European drainages and a second almost exclusively confined to the Danubian catchment. These lineages have been isolated for approximately 2.15 M years and should be considered separate conservation units. RADseq recovered finer population structure and stronger patterns of IBD than microsatellites, despite including only 17.6% of samples (38% of populations and 52% of samples per population). RADseq was also used along with approximate Bayesian computation to show that the postglacial colonization routes of C. carassius differ from the general patterns of freshwater fish in Europe, likely as a result of their distinctive ecology

Exposure to carbamate fungicide iodocarb does not affect reproductive behavior or milt volumes in precocious male brown trout (Salmo trutta L.) parr

Previous studies with olfactory-disturbing pesticides resulted after exposure in disturbed behavior and physiology in fish. In the present experiment, reproductive behavior and milt volumes of precocious brown trout (Salmo trutta L.) male parr were studied in a large stream aquarium after exposure to the olfactory-disturbing fungicide 15 μg l-1 IPBC (iodocarb; 3-iodo-2-propynyl butyl carbamate) for 96 h. The statistical analyses did not reveal any significant differences for time attending females between controls and IPBC-exposed males. Furthermore, there were no significant differences in milt volumes. However, when taking all fish into consideration, there were significant differences in milt volumes between parr that had been attending females and those had not been attending females. Controls that had attended females had significantly higher milt volumes than controls or IPBC-exposed males that had not attended females. Taking all control and IPBC parr into consideration, there was a statistically significant positive correlation between time attended females and volume of milt and gonadosomatic index (GSI), respectively. In summary, 15 μg l-1 IPBC did not have any significant effects on mature male parr reproductive behavior and milt volumes

Feeding stimulants in an omnivorous species, crucian carp Carassiuscarassius (Linnaeus 1758)

Many fish are during feeding dependent on both an olfactory and gustatory sense. Olfaction that actsas the distance sense induces arousal, food search behaviour and attraction to the source, followed byexamination of food items by the gustatory sense. During buccal handling the fish decide if the feed willbe rejected or swallowed. Amino acids are often stimulatory to the gustatory sense and can act as feedingstimulants. There are, however, inter-species differences concerning what kinds of amino acids act asfeeding stimulants or deterrents. The species differences are probably dependent on the natural foodchoice. As feeding stimulating molecules increase feeding and growth, but deterrents have the reverseeffect, it is important to know what kind of molecules have either effect. In the present study we recordmouth handling time in the omnivorous crucian carp, Carassius carassius, of agar pellets containing waterextracts of meal consisting of ordinary food pellets, blue mussels or a commercial carp attractant. Thesetests were followed by testing with agar pellets with synthetic amino acids, based on the content of thewater extracts of the food pellets that was the only feeding stimulant. Neither extracts of mussel mealor of commercial carp attractants had a stimulating effect, i.e. no significant difference in handling timecompared to agar pellets with only water. A mixture of five of the major amino acids in the food pelletextract (40 mM alanine, 20 mM glycine, 20 mM arginine, 8 mM serine, 8 mM leucin) gave a significantlonger handling time compared to agar pellets with only water. The handling time was also longer for thethree amino acids that had the highest concentrations (40 mM Ala, 20 mM Gly, 20 mM Arg) and finallywith only alanine (128 mM). Agar pellets with only Ala gave, however, a significant shorter handlingtime compared to agar pellets with food pellet extract. The mussel meal extract had the same contentof free amino acids and their ranking order was the same as in extracts of food pellets, but at muchhigher concentrations. Based on the free amino acid content, the mussel extract should have stimulatedfeeding. This indicates that the mussel extract contained compounds that acted as feeding deterrents inomnivorous crucian carp that do not feed on blue mussels in their natural environment. Previous studieshave shown that blue mussel extracts act as feeding stimulants in several bottom feeding carnivorousfish. We finally tested betaine (100 mM) but the molecule had no significant stimulating effect that hasbeen observed in some other fish species

Chemical foraging stimulation in the omnivorous species crucian carp, Carassius carassius (Linnaeus 1758)

In fish aquaculture, great efforts are made to develop feed that excludes marine fish proteins and oils, or at least to decrease these parts to a minimum but the fish might not be attracted to or might not eat the alternative feed. Molecules detected by the olfactory sense can induce arousal and search behavior that attract the fish and induce foraging. In the present study, we have examined whether mussel extracts can induce foraging behavior in crucian carp, Carassius carassius. Free amino acids are present in high concentrations in mussels and they are detected at low concentrations by olfaction and induce food search behavior in several fish species. We studied the behavior responses to water extracts of mussel powder compared to extracts of a plant-based commercial carp feed. Extracts of different concentrations were administered in glass aquaria with individual fish. The tests began with 5 min with only tap water and this was followed by 5 min with extracts or amino acid solutions. The behavior was recorded with a video camera. The initial control period was compared to the following period with odors. No significant foraging response was observed with extracts of mussels, but the commercial carp feed extract induced increased bottom snapping. Synthetic mixtures of five nutritional amino acids present at high concentrations in both extracts did not give any significant foraging response. Our results show that mussels are not suitable as a protein source in feed to crucian carp. Keywords: Olfactory sense, Foraging behavior, Bottom snapping, Carp feed extracts, Mussel meal extract

Environmentally relevant concentrations of citalopram partially inhibit feeding in the three-spine stickleback (Gasterosteus aculeatus)

Selective Serotonin Re-uptake Inhibitors (SSRI) are mood-altering, psychotropic drugs commonly used in the treatment of depression and other psychological illnesses. Many of them are poorly degraded in sewage treatment plants and enter the environment unaltered. In laboratory studies, they have been demonstrated to affect a wide range of behaviours in aquatic organisms. In this study we investigated the effect of a three-week exposure to 0.15 and 1.5 μg/l of the SSRI citalopram dissolved in the ambient water on the feeding behaviour in three-spine stickleback (Gasterosteus aculeatus). Feeding, measured as the number of attacks performed on a piece of frozen bloodworms during a 10-min period, was reduced by 30–40% in fish exposed to both 0.15 and 1.5 μg/l citalopram. The effects of the environmentally relevant concentration 0.15 μg/l on feeding, an important fitness characteristic, suggests that the ecological significance of environmental SSRI exposure may be pronounced