Rickard Bjerselius

Male goldfish reproductive behaviour and physiology are severely affected by exogenous exposure to 17β-estradiol

Mature male goldfish were exposed to different concentrations of the natural hormone 17beta-estradiol (E2). Two methods of exposure were employed, via ingestion at 0, 1, 10 and 100 microg/g food and via the water at 0, 1 and 10 microg/l. The fish were exposed for 24-28 days during the spawning period. The males were then paired with an artificially induced, spawning female and their sexual behaviour was observed during a 15 min period. The physiological status of the fish was also examined with respect to GSI, presence of milt and spawning tubercles and the blood plasma concentration of E2. Despite the relatively short exposure period, exposure to physiological levels of E2 was shown to severely affect the male goldfish reproductive behaviour and physiology. In conclusion, the results from this study and the ability to interpret the effects on this well-studied species, show that the effects of E2, and possibly other estrogenic EDCs, have severe effects at several vital levels of male goldfish reproduction. The results also suggests that the hormone E2 can act as an endocrine disrupting chemical (EDC) in the environment.

Responses of Acilius sulcatus (Coleoptera: Dytiscidae) to chemical cues from perch (Perca fluviatilis)

Abstract In this study we tested the hypothesis that the presence of chemical stimuli from a hungry predator would initiate anti-predator responses, while stimuli from a satiated predator would not. We used chemical stimuli released from starved perch (Perca fluviatilis) and from satiated perch (predator). As prey we used adult Acilius sulcatus (Coleoptera: Dytiscidae). The reaction of the beetles to different predator conditions was tested during daytime. We also tested the reaction to starved perch during the night. A. sulcatus activity decreased when it was exposed to stimuli released from starved perch during daytime when visibility was poor, due to the presence of artificial vegetation. There was, however, no reaction to satiated perch under the same experimental conditions. These results indicate that A. sulcatus can discriminate between chemical cues from hungry and satiated fish predators. When visibility was good and the concentration of chemical cues was constant, the beetles did not react to starved perch in the daytime, but their activity decreased at night in response to stimuli released from starved perch. Visual as well as chemical cues seem to be important for detecting a potential predator. When visibility is good, beetles seem to rely on visual stimuli, while in darkness they seem to use chemical stimuli to detect the presence of predators.

The effect of Cu(II) on the electro-olfactogram (EOG) of the Atlantic salmon (Salmo salar L) in artificial freshwater of varying inorganic carbon concentrations

The effect of inorganic copper species was studied by recording the receptor potential, electro-olfactogram (EOG), from the olfactory epithelium of Atlantic salmon (Salmo salar L). In a series of experiments, the olfactory organ was irrigated with aqueous copper solutions with concentrations of the free cupric ion (Cu2+) ranging from 0.2 to 9.7 microM. The diverse copper species were created by varying the amount of bicarbonate (NaHCO3) in artificial freshwater solutions of equal total copper concentrations. In general, these copper solutions induced a slow depolarization of the baseline followed by a hyperpolarization. The amplitudes of these variations in baseline potentials increased with increasing concentrations of Cu2+ ion, i.e., decreasing concentrations of NaHCO3. Stimulating the olfactory epithelium with L-alanine during the copper exposure evoked atypical EOG responses. The amplitudes and form of the EOGs changed drastically with increasing Cu2+ concentrations, with significant correlation between the reduction in EOG amplitudes and the Cu2+ concentration. The results indicate that among the copper species tested the toxic effect is caused mainly by the dissolved Cu2+ ion. The results also suggest that the Cu2+ ion exerts its toxic effects on the transduction mechanisms of the olfactory receptor cells. The different EOG profiles obtained in response to varying Cu2+ concentrations indicate that this ion affects the transduction mechanisms at different stages.

Both Ovarian Fluid and Female Urine Increase Sex Steroid Hormone Levels in Mature Atlantic Salmon (Salmo salar) Male Parr

We compared the ability of urine and ovarian fluid from female Atlantic salmon (Salmo salar) to stimulate increase in plasma concentrations of sex steroid hormones in mature conspecific male parr (priming effect of the stimuli). We also tested the hypothesis that prostaglandin F2α (PGF2α) may act as a priming pheromone in the tested stimulants. Individual males of salmon parr were exposed to female urine, ovarian fluid, urine–ovarian fluid mix, or PGF2α. Plasma concentrations of the sex steroids of 17,20β-dihydroxy-4-pregnen-3-one (17,20β-P) were higher in males exposed to urine, ovarian fluids, and PGF2α compared to control males. PGF2α and a mixture of urine and ovarian fluid also gave increased concentrations of 11-ketotestosterone (11-KT). Concentrations of PGF2α were higher in ovarian fluids than in urine. A behavior test with mature male parr in a fluviarium showed neither attraction to nor avoidance of 0.1 nM PGF2α, but plasma levels of 17,20β-P were significantly higher in exposed males compared to controls.

Ca2+ protects olfactory receptor function against acute Cu(II) toxicity in Atlantic salmon

Abstract The effects of Ca 2+ and Mg 2+ on the acute toxicity of inorganic Cu(II) on the olfactory sense of Atlantic salmon ( Salmo salar L.) was studied by recording electro-olfactogram (EOG), the receptor potential, from the olfactory epithelium. In a series of experiments, the olfactory organ was irrigated with aqueous Cu(II) solutions containing Ca 2+ at concentrations ranging from 400 μM to 4000 μM. The effect of Mg 2+ was also tested by adding MgCl 2 (3600 μM Mg 2+ ) to the solution with lowest Ca 2+ concentration (400 μM). Stimulating the olfactory epithelium with L-alanine during Cu(II) exposure evoked atypical EOG responses. The amplitude and form of the EOG changed drastically with decreasing ionic strength of the solution. Both high Ca 2+ and high Mg 2+ concentration significantly reduced the immediate effects of Cu(II) exposure. Following a 5 min Cu(II) exposure, the EOG gradually recovered. After this recovery period (29 min) the EOG response was higher if a high concentration of Ca 2+ was included in the solutions. There was a significant correlation between the Ca 2+ concentration and the EOG response after recovery. By contrast, 3600 μM of Mg 2+ had no effect on the recovery. However, high Mg 2+ concentration reduced the immediate effects of Cu(II) exposure, probably by increasing the ionic strength of the solution and, thus, lowering Cu 2+ activity. In fact, a significant correlation was found between the calculated free Cu 2+ activity and the EOG response after 4 min of Cu(II) exposure.

Mature Atlantic Salmon (Salmo salar L.) Male Parr Are Attracted to Ovulated Female Urine but Not to Ovarian Fluid

The behavioral responses to urine and ovarian fluids from conspecific and heterospecific ovulated females were studied in mature Atlantic salmon (Salmo salar) male parr in a two-choice fluviarium. The males reacted differently to the stimulants. They spent more time in water scented by urine from salmon or brown trout (Salmo trutta L.) females compared to the time in water with ovarian fluids from salmon females. Furthermore, the males were attracted to salmon female urine (different from an indifferent reaction). Males exposed to urine of either species had higher plasma concentrations of testosterone (T) compared to unexposed controls. Measurement of the concentrations of prostaglandin F2α (PGF2α) and its major metabolite 15-ketodihydro-prostaglandin F2α (15-ketodihydro-PGF2α) showed that the concentrations of the substances were higher in ovarian fluids of both species compared to those in urine. PGF2α showed a greater difference between ovarian fluid and urine than its major metabolite. The results suggest that urine of both species, in contrast to ovarian fluid, contain substances that attract mature Atlantic salmon male parr and that the active substances are neither PGF2α nor 15-keto-PGF2α.

Modeling relationships between Baltic Sea herring (Clupea harengus) biology and contaminant concentrations using multivariate data analysis.

Baltic Sea herring (Clupea harengus) is a pelagic, zoo-planktivorous fish and young (2-5 years old) individuals of this species are sampled annually in the Swedish marine monitoring program. This study determined concentrations of organochlorines (OCs) and brominated flame retardants (BFRs) in dorsal muscle from herring (n = 60) of varying age (2-13 years), weight (25-200 g), and body length (16-29 cm) caught at three locations in the Swedish part of the Baltic Proper. In order to ensure that the fish biology was as varied as possible, though still similar from all sampling sites, the fish to be chemically analyzed were selected from a large number of fish with determined biology using Multivariate Design. In statistical evaluation of the data, univariate and multivariate data analysis techniques, e.g. principal components analysis (PCA), partial least-squares regression (PLS), and orthogonal PLS (OPLS), were used. The results showed that the fish are exposed to a cocktail of contaminants and levels are presented. Significant OPLS models were found for all biological variables versus concentrations of OCs and BFRs, showing that fish biology covaries with fish contaminant concentrations. Correlation coefficients were as high as 0.98 for e.g. βHCH concentration (wet weight) versus the lipid content. Lastly, the OC concentrations in herring muscle were modeled against the BFR concentrations to determine whether concentrations of either could be used to predict the other. It was found that OPLS models allowed BFR concentrations to be predicted from OC concentrations with high, but varying, accuracy (R(2)Ys between 0.93 to 0.75). Thus, fish biology and contaminant concentrations are interwoven, and fish biological parameters can be used to calculate (predict) contaminant concentrations. It is also possible to predict the BFR concentrations in an individual fish from its concentrations of OCs with very high accuracy.