Sea trout adapt their migratory behaviour in response to high salmon lice concentrations.

Sea trout face growth-mortality trade-offs when entering the sea to feed. Salmon lice epizootics resulting from aquaculture have shifted these trade-offs, as salmon lice might both increase mortality and reduce growth of sea trout. We studied mortality and behavioural adaptations of wild sea trout in a large-scale experiment with acoustic telemetry in an aquaculture intensive area that was fallowed (emptied of fish) synchronically biannually, creating large variations in salmon lice concentrations. We tagged 310 wild sea trout during 3 years, and gave half of the individuals a prophylaxis against further salmon lice infestation. There was no difference in survival among years or between treatments. In years of high infestation pressure, however, sea trout remained closer to the river outlet, used freshwater (FW) habitats for longer periods and returned earlier to the river than in the low infestation year. This indicates that sea trout adapt their migratory behaviour by actively choosing FW refuges from salmon lice to escape from immediate mortality risk. Nevertheless, simulations show that these adaptations can lead to lost growth opportunities. Reduced growth can increase long-term mortality of sea trout due to prolonged exposure to size-dependent predation risk, lead to lower fecundity and, ultimately, reduce the likelihood of sea migration.

Are hybrids between Atlantic salmon and brown trout suitable long-term hosts of Gyrodactylus salaris during winter?

The monogenean parasite Gyrodactylus salaris poses serious threats to many Atlantic salmon populations and presents many conservation and management questions/foci and challenges. It is therefore critical to identify potential vectors for infection. To test whether hybrids of native Atlantic salmon (Salmo salar) × brown trout (Salmo trutta) are suitable as reservoir hosts for G. salaris during winter, infected hybrid parr were released into a natural subarctic brook in the autumn. Six months later, 23.9% of the pit-tagged fish were recaptured. During the experimental period, the hybrids had a sixfold increase in mean intensity of G. salaris, while the prevalence decreased from 81% to 35%. There was high interindividual hybrid variability in susceptibility to infections. The maximum infrapopulation growth rate (0.018 day-1 ) of G. salaris throughout the winter was comparable to earlier laboratory experiments at similar temperatures. The results confirm that infrapopulations of G. salaris may reproduce on a hybrid population for several generations at low water temperatures (~1 °C). Wild salmon-trout hybrids are undoubtedly susceptible to G. salaris and represent an important reservoir host for the parasite independent of other co-occurring susceptible hosts. Consequently, these hybrids may pose a serious risk for G. salaris transmission to nearby, uninfected rivers by migratory individuals.

Transmission dynamics of the monogenean Gyrodactylus salaris under seminatural conditions.

Tracking individual variation in the dynamics of parasite infections in wild populations is often complicated by lack of knowledge of the epidemiological history of hosts. Whereas the dynamics and development of Gyrodactylus salaris Malmberg, 1957, on Atlantic salmon, Salmo salar L., are known from laboratory studies, knowledge about infection development on individual wild fishes is currently sparse. In this study, the dynamics of an infection of G. salaris on individually marked Atlantic salmon parr was followed in a section of a natural stream. During the 6-week experiment, the prevalence increased from 3.3 to 60.0%, with an average increase in intensity of 4.1% day(-1) . Survival analyses showed an initially high probability (93.6%) of staying uninfected by G. salaris, decreasing significantly to 37% after 6 weeks. The results showed that even at subarctic water temperatures and with an initially low risk of infection, the parasite spread rapidly in the Atlantic salmon population, with the capacity to reach 100% prevalence within a short summer season. The study thus track individual infection trajectories of Atlantic salmon living under near-natural conditions, providing an integration of key population parameters from controlled experiments with the dynamics of the epizootic observed in free-living living populations.

A planktivorous specialist turns rapacious: piscivory in invading vendace Coregonus albula.

Following invasion and establishment in a subarctic watercourse, small-sized vendace Coregonus albula were surprisingly found to include fish prey in their diet. The zooplankton resource was severely depleted and only made a minor dietary contribution.

Antenatal ultrasound and postnatal autopsy findings in terminations after 12 weeks' gestation due to fetal abnormality: population-based study in Western Norway, 1988-2002.

BACKGROUND: Ultrasound screening has been part of antenatal care for several decades, and warrants high expertise to meet the criteria for a worthwhile screening program. In particular, the rate of false positives should be low. PURPOSE: To examine time trends of pregnancy terminations for fetal abnormality after 12 weeks' gestation, and to assess the agreement between antenatal ultrasound and post-termination autopsy findings for the main pathologies leading to termination. MATERIAL AND METHODS: During the period 1988 to 2002, 198 pregnancies were terminated for fetal abnormality after 12 weeks' gestation. We reviewed the case notes for those 151 who were autopsied (male/female/undetermined ;= ;91/56/4). Annual rates of live births and stillbirths were retrieved from the Medical Birth Registry of Norway. RESULTS: Antenatal ultrasound provided a correct diagnosis of the major abnormality in 149/151 cases (99%), based on post-termination autopsy findings. The annual rate of terminations after 12 weeks' gestation varied between 0.6 and 3.4 (mean 1.8) per 1000 live births, with a trend toward higher rates over the study period (P=0.001, chi-square test for linear-by-linear association). CONCLUSION: The specificity of antenatal ultrasound for major abnormalities was high, as compared to postnatal autopsy findings. The mean annual rates of termination after 12 weeks' gestation tended to increase over the 14-year study period.

[Transvaginal ultrasonography. Diagnosis and treatment of pelvic abscesses]. / Transvaginal ultrasonografi. Diagnostikk og behandling av bekkenabscessar.

In recent years, transvaginal ultrasound has revolutionized the diagnosis of many gynaecological diseases. During the last four years we have introduced transvaginal ultrasound in the diagnosis of pelvic abscesses. The diagnosis of pelvic abscess can be made with certainty by ultrasound-guided puncture. Usually it is possible to empty the abscess by aspiration of the content without the need of a general anaesthetic. The method thus requires few resources, and is furthermore organ-conserving. Our experience of the method is good, based on the treatment of about 50 patients so far.

Congenital absence of the nose: a case report and literature review.

A case of congenital absence of the nose is presented. The etiology of this rare condition is unknown. A review of the literature reveals that the previously applied terms, e.g. 'arhinia', are unclear. In the reviewed cases there seems to be a pattern of facial anomalies associated with nasal absence. In most cases, one could probably expect a lack of the olfactory bulbs and tracts. We suggest a new terminology and summarize the aims of the radiological evaluation of this condition.

Treatment of ectopic pregnancy by local injection of hypertonic glucose: a randomized trial comparing administration guided by transvaginal ultrasound or laparoscopy.

OBJECTIVE: To study local treatment of ectopic pregnancy by injection of hyperosmolar (50%) glucose, guided either by transvaginal ultrasound or by laparoscopy. METHODS: Eighty women were randomized, 39 into the sonography and 41 into the laparoscopy group. Criteria for inclusion were 1) ectopic pregnancy < or = 4 cm seen by transvaginal ultrasound, 2) hCG < or = 3000 IU/l, and 3) little or no intraabdominal bleeding. In the sonography group, patients were treated by one skilled ultrasound investigator, whereas injections by laparoscopy were performed by several colleagues. The former group were offered a second glucose injection if hCG levels were rising. Those successfully treated were offered hysterosalpingography (HSG) for evaluation of tubal patency. RESULTS: Twenty-nine (74.4%) women were successfully treated in the sonography group by one single injection, compared to 21 (51.2%) in the laparoscopy group. Eight women in the sonography group received a second glucose injection because of a rising hCG, increasing the success rate in this group to 82.1% (32 of 39 women). Six patients in the laparoscopy group were not injected due to technical difficulties during the operation, and the success rate for those injected were 60% (21 of 35 women). The overall success rate was 66.3%. Of the 28 women investigated by HSG, both tubes were normal in 19 (67.8%), and in 25 patients (89.3%) the treated tube was open. CONCLUSIONS: Local injection of hyperosmolar glucose guided by transvaginal ultrasound by one skilled investigator is an effective treatment for ectopic pregnancy. Most women preserve tubal patency after treatment.

Echogenic material in the fetal gallbladder and fetal disease.

The presence of echogenic material within the gallbladder is probably a rare finding in the fetus, and the list of predisposing factors known for postnatal life seems not to be applicable to prenatal diagnosis. In the present study 1656 obstetric scans were performed on referrals to the Unit of Fetal Medicine. No echogenic gallbladder contents were found before 28 weeks. In the subgroup of 523 fetuses who were examined during gestational weeks 28-42, six fetuses were found to have echogenic material in the gallbladder. The echogenicities were found in patients who had the following: extra-amniotic hematoma with intrauterine growth retardation and oligohydramnios, tetralogy of Fallot, trisomy 21 with atrioventricular septal defect and transient ascites, early abnormally distended fetal gallbladder, chromosomal aberration (translocation 10; 11) with bilateral clubfoot, and gastroschisis. Echogenic densities had disappeared at ultrasound scans performed during early postnatal life in four cases, were absent at five weeks in one case, and still present as calculi 8 months after birth in one case. Although no causative conclusions can be drawn from the report, these conditions are suggested as possible predisposing factors for the presence of echogenic material in the fetal gallbladder.

Neonatal lethal dwarfism with distinct skeletal malformations--a separate entity?

We describe a case of neonatal lethal dwarfism characterised by short trunk, short, stick-like tubular bones, deficient ossification of the axial skeleton and broad, sclerotic horizontal ribs. Two similar cases have previously been reported as examples of the Neu-Laxova syndrome. However, the radiological findings of the Neu-Laxova syndrome, as reported in 16 out of 40 documented cases, show a heterogeneous pattern of minor features, which differ distinctively from those found in the previous two cases and by us. A literature research did not reveal similar cases, and we therefore suggest that our case, together with the two previous cases, may represent a new distinctive form of neonatal lethal dwarfism.