Do green and golden bell frogs (Litoria aurea) occupy habitats with fungicidal properties?

The Green and Golden Bell frog Litoria aureo is in major decline in Australia, where its distribution is now confined mainly to the east coast of New South Wales (NSW). Infection by the newly emerged amphibian fungal pathogen Batrachochytrium dendrobatidis has been identified as one of the main threats affecting L. aurea. Surprisingly, some of the sites in NSW sustaining the largest populations of this species are industrial and urban habitats that are often disturbed and polluted, which could protect L. aurea from chytrid infection if pollution had fungicidal capacity.The aim of this study was to characterise the trace metal concentration of several L. aurea breeding sites in the Sydney and IIlawarra regions of NSW and to evaluate the fungicidal efficacy of the main "'ace metals identified. Selected L. aurea sites were sampled throughout the breeding season (September to February) to establish the concentration of trace metals in both surface sediment and waters. Physico-chemical parameters including pH and salinity were also measured. Of the trace metals identified, copper and zinc were consistently elevated across sites. Over 50% of sites exceeded the National Sediment Quality Guideline for both copper and zinc concentration, and over 90% of sites exceeded the National Water Quality Guideline for these metals. Consequently, we evaluated their effect on the growth and survival of a laboratory culture of B. dendrobatidis,These tests were performed in media containing dissolved metal concentrations of 0.02 - 0.65 mgL^-1 Cu and 0.24 - 5.0 mgL^-1 Zn. Growth rates were inferred by total fungal density in liquid culture (based on spectral absorbance measurements), final dry weight, and the density of zoospores in fungal cultures grown for 28 days. Both copper and zinc were found to reduce the growth and proliferation of B. dendrobatidis, but in a non-linear manner. This suggests that L. aurea may be gaining some protection from B. dendrobatidis infection at several of the sites examined.

Reproductive development, GnRHa-induced spawning and egg quality of wild meagre (Argyrosomus regius) acclimatised to captivity

The objective of the study was to acclimatise wild-caught meagre (Argyrosomus regius) to captivity to produce viable eggs for aquaculture production. Twelve meagre (3 males and 9 females, mean weight = 20 ± 7 kg) were caught and transported to a land-based facility on 26 October 2006. During, March to June 2007, all three males were spermiating and five of the nine females were in vitellogenesis with mean maximum oocyte diameter ≥550 μm. No spontaneous spawning was observed. Two hormone treatments, either a single injection of gonadotropin-releasing hormone agonist (GnRHa, 20 μg kg−1 for females and 10 μg kg−1 for males) or a slow-release implant loaded with the same GnRHa (50 μg kg−1 for females and 25 μg kg−1 for males), were used to induce spawning on three different dates on 26 March 2007, 4 May 2007 and 18 April 2008. From each spawning event, the following parameters were determined: fecundity, number of floating eggs, egg size, fertilisation and hatching success, unfed larval survival, and proximal composition and fatty acid profile of the eggs. In 2007, two females that were injected on 26 March and 4 May spawned a total of 5 times producing 9,019,300 floating eggs and a relative fecundity of 198,200 eggs kg−1 and two different females that were implanted on the same dates spawned 14 times producing 12,430,000 floating eggs and a relative fecundity of 276,200 eggs kg−1. In 2008, a pair that was implanted spawned five times producing a total of 10,211,900 floating eggs and a relative fecundity of 527,380 eggs kg−1. The latency period was 48–72 h. Parameters were compared between hormone treatments, date of hormone induction and parents determined by microsatellites. Percentage hatch and egg size were 70 ± 0.3% and 0.99 ± 0.02 mm, respectively, for GnRHa-implanted fish and were significantly higher (P < 0.05) compared to 30 ± 0.3% and 0.95 ± 0.03 mm, respectively, for injected fish. Few differences were observed in proximal composition and fatty acid profile and for all spawns mean (% dry weight) lipid content was 17.3 ± 3.0%, carbohydrate was 4.4 ± 1.9% and protein was 31.5 ± 6.4% and the essential fatty acids: Arachidonic acid (ARA, 20:4n-6) ranged between 0.9 and 1% (of total fatty acids), eicosapentaenoic acid (EPA 20:5n-3) 7.7–10.4% and docosahexaenoic acid (DHA 22:6n-3), 28.6–35.4%. All good quality spawns were obtained in the second and/or third spawn after GnRHa treatment, whereas all bad quality spawns were obtained either on the first spawn or after the fifth spawn. Both spawning protocols gave commercially viable (1,000,000+) numbers of good quality eggs that could form the basis of a hatchery production.

Analysis of fetal heart rate asymmetry before and after 35 weeks of gestation

In this study, we have investigated the evidence of fetal heart rate asymmetry and how the fetal heart rate asymmetry changes before and after 35 weeks of gestation. Noninvasive fetal electrocardiogram (fECG) signals from 45 pregnant women at the gestational age from16 to 41 weeks with normal single pregnancies were analysed. A nonlinear parameter called heart rate asymmetry (HRA) index that measures time asymmetry of RR interval time-series signal was used to understand the changes of HRA in early and late fetus groups. Results indicate that fetal HRA measured by Porta's Index (PI) consistently increases after 35 weeks gestation compared to foetus before 32 weeks of gestation. It might be due to significant changes of sympatho-vagal balance towards delivery with more sympathetic surge. On the other hand, Guzik's Index (GI) showed a mixed effect i.e., increases at lower lags and decreases at higher lags. Finally, fHRA could potentially help identify normal and the pathological autonomic nervous system development.