Temporal patterns of larval settlement and survivorship of two broadcast-spawning acroporid corals

Acroporid corals are the main reef-building corals that provide three-dimensional habitats for other reef organisms, but are decreasing on many reefs worldwide due to natural and anthropogenic disturbances. In this study, temporal patterns of larval settlement and survivorship of two broadcast-spawning acroporid coral species, Acropora muricata and A. valida, were examined through laboratory rearing experiments to better understand the potential for larval dispersal of this important coral group. Many larvae were attached (but not metamorphosed) to settlement tiles on the first examination 3–4 days after spawning (AS). The first permanent larval settlement (i.e. metamorphosed and permanently settled juvenile polyps) occurred at 5–6 days AS, and most larval settlement (85–97% of total) occurred within 9–10 days AS. Larval survivorship decreased substantially to around 50% by the first week of the experiment and to approximately 10% by the second to third week. The rates of larval attachment, settlement, and the initial drop in survivorship of larvae suggest that effective dispersal of some acroporid species may largely be completed within the first few weeks AS.     

Measurement of bisphenol A concentrations in human colostrum

Bisphenol A (BPA), an estrogenic endocrine disrupting chemical, has been reported to affect embryos and alter their postnatal development. In the present study, we measured the concentrations of BPA in human colostrum by a competitive enzyme-linked immunosorbent assay (ELISA) with the aim of understanding the present status of BPA burden in human breast milk in Shizuoka, Japan. Human colostral samples were collected from 101 healthy mothers within three days after delivery. The BPA concentrations of colostral samples were estimated by ELISA after the acetonitrile extraction and solid phase extraction column purification. BPA in 101 samples was detected in the concentration range of 1-7 ng ml(-1). The mean concentration of BPA was 3.41+/-0.13 (mean+/-SD) ng ml(-1). This is the first demonstration as to what BPA concentrations are in human colostrum. The BPA concentrations in colostrum were higher than those in blood sera samples obtained from healthy women in a previous study. In our study, there was no significant correlation between the concentrations of BPA in colostrum and the age and parity of mothers.     

Effects of elevated temperature on larval settlement and post-settlement survival in scleractinian corals, <Emphasis Type="Italic">Acropora solitaryensis</Emphasis> and <Emphasis Type="Italic">Favites chinensis</Emphasis>

We examined the effects of elevated temperature under different exposure periods on larval settlement and post-settlement survival in scleractinian corals, Acropora solitaryensis and Favites chinensis. In the first experiment with the subtropical coral, A. solitaryensis, the numbers of larvae settling and those dead were examined daily for 5 days at 20, 23 (ambient), 26 and 29°C conditions. Larval settlement of A. solitaryensis was initially greater at higher temperature conditions, but the peak in number of settled larvae shifted from 29 to 26°C by day 5, due to ca. 90% post-settlement mortality at 29°C condition. In order to determine the effects under short-term exposure, larvae of F. chinensis were exposed to 27 (ambient), 31 or 34°C only for one hour in the second experiment. The number of larvae settling for 24 h after the exposure and their survivorship over subsequent week was monitored in the ambient temperature condition. Larvae of F. chinensis exhibited greater settlement at higher temperature treatments and constantly low post-settlement mortalities (< ca. 17%) in all temperature treatments, resulting in the highest number of settled larvae at 34°C treatment. These results suggested two different effects of elevated temperature on the early stages of recruitment process of scleractinian corals; (1) the positive effect on larval settlement and (2) the negative effect on post-settlement survival under prolonged exposure.     

动态法测试空气净化器甲醛去除性能的研究

通过动态法测试水吸收型空气净化器A和活性炭过滤吸附型净化器B对甲醛的去除性能,探索更为合理的方法以评价空气净化器对气态污染物的去除性能.对净化器A去除甲醛的短期测试结果表明,净化器对甲醛浓度为0.3、0.5、0.8和1 mg/m3的连续空气流均有明显的净化效果,对甲醛的去除速率在0.91～2.78 mg/h之间.对净化...     

Reproduction and recruitment of scleractinian corals in a high-latitude coral community, Amakusa, southwestern Japan

Reproduction and recruitment in high-latitude coral populations in Japan have been little studied. A comprehensive study of the reproduction and early life history was conducted on nine common scleractinian coral species in Amakusa, southwestern Japan (32°N) from 2001 to 2003 including; (1) fecundity (the proportion of colonies with mature eggs), (2) timing and synchrony of spawning, (3) initial larval settlement pattern, (4) recruitment, (5) post-settlement mortality. The fecundity was high (76.7–100%) in six of seven species examined in 2002 and 2003. Annual spawning of the seven species occurred from mid July to August in 2001–2003, when seawater temperature was at the annual maximum. Spawning was highly synchronised among conspecific colonies and species in 2002 and 2003, with five species spawning five to nine nights after the full moon and another two spawning around the new moon. Temporal patterns of larval settlement of three spawning species during the first 10 days after spawning were similar to those of other spawning species from low latitudes. The number of scleractinian recruits on settlement plates, deployed from July to October (the major recruitment period at the study site), was low (2 recruits/m²) for the three consecutive years. Post-settlement mortality of 1–1.5 month old spat of five species ranged between 88 and 100% over 3–10 months in the field, similar to the values reported for both high and low latitude species (>94–99%). Among the key stages examined, the low recruitment rate may be the most important step in limiting successful reproduction and recruitment of these high-latitude scleractinian populations. The low recruitment rate may be attributable to (1) the reduced influx of larval supply from other coral populations, which are smaller and more isolated at high-latitudes and (2) the longer precompetent larval phase of broadcast-spawning corals which results in an increased chance of larvae being dispersed away from parent populations.