Selective coral mortality associated with outbreaks of Acanthaster planci L. in Bootless Bay, Papua New Guinea

Population outbreaks of crown-of-thorns sea star (Acanthaster planci L.) remain one of the most significant biological disturbances on tropical coral reefs although the increasing attention given to other threats has greatly limited recent progress in understanding the cause and consequences of this phenomenon. In September 2005 dramatic increases in the abundance of A. planci were observed on reefs within Bootless Bay, Central Province, Papua New Guinea, where few crown-of-thorns have previously been reported. Densities of A. planci peaked at 162 sea stars per hectare and caused extensive coral mortality. This outbreak killed upwards of 55% of live corals, reducing overall coral cover from 42.4% in 2005 down to just 19.1% in March 2006. Declines in coral cover were largely driven by widespread mortality of Acropora spp. which dominated reef assemblages prior to the outbreak. The extensive depletion of Acropora spp. greatly altered the coral composition as well as the physical structure of reef habitats. In the absence of any other major disturbances these coral communities are likely to quickly recover, but this outbreak highlights the ongoing contribution of A. planci to degradation of coral reef environments.     

Plankton dynamics due to rainfall,eutrophication, dilution,grazing and assimilation in an urbanized coastal lagoon

After a prolonged summer dry period, the effects of a distinctive and continuing rainfall on the nutrients and plankton of an urban coastal lagoon were investigated over 2 months. The lagoon filled up over 5 weeks from <10% of its maximum volume until it broke open to the sea. Nutrients (ammonia and oxidised nitrogen) significantly increased the day after initial rainfall, before returning to pre-rainfall conditions within 5 days. Phytoplankton biomass grew 10 fold within a week after initial rainfall in the 25–30 °C water and declined to near initial levels 2 weeks later. The assemblage of phytoplankton and zooplankton changed dramatically after 1 day and again by 6 days later, gradually returning to the original community by 2 weeks after the initial rainfall. Zooplankton responded within a day with a two fold increase in the adult stages of the calanoid copepod Oithona sp., followed a week later by nauplii and adult Acartia bispinosa. The influx of adult Oithona indicates resting populations that were previously under sampled by our plankton net. The plankton community returned to the initial state by 2 weeks, to being dominated by a centric diatom and A. bispinosa after 5 weeks. Dilution of the lagoon reached a maximum of 0.25 d⁻¹, while growth rates of the phytoplankton population reached a maximum of 1 d⁻¹, and A. bispinosa nauplii growth of 2.5 d⁻¹. Declines in chlorophyll biomass from the maximum 10 μg l⁻¹, at a rate of approximately 10% d⁻¹ are consistent with the modelled uptake by zooplankton. The nutrients from runoff, growth and the influx of new zooplankton into the water column, resulted in a depleted δ¹³C and δ¹⁵N stable isotope signature of A. bispinosa by 2–4 ppt within 1–2 weeks, consistent with diatom growth and the terrestrial supply of depleted nutrients. δ³⁴S of A. bispinosa was enriched by 2 ppt for 1–2 weeks after rainfall, but unlike C and N, returned to pre-rainfall levels by the end of the study period. We suggest that plankton studies in coastal lakes with variable water levels that are not tidally driven, should account for the influence of changes in water levels to help explain data variability.     

Ultraminiature X-ray fluorescence spectrometer for in-situ geochemical analysis on Mars

Determination of the surface composition at various sites on the planet Mars will provide information essential to a better understanding of the geologic history of this complex planet. A spectrometer based upon the X-ray fluorescence method of elemental analysis has been developed in an ultraminiature, rugged form suitable for a spacecraft mission to Mars. The instrument employs two radioisotope sources (⁵⁵Fe and¹⁰⁹Cd) which irradiate adjacent areas on a regolith sample. Fluorescent X-rays emitted by the sample are detected by four thin-window proportional counters. Using pulse-height discrimination, the energy spectra are determined. Virtually all elements above sodium in the periodic table are detected if present at sufficient levels. Minimum detection limits range from 30 ppm to 2%. depending upon the element and the matrix. For most elements, they are below 0.5%. Accuracies also depend upon the matrix, but are generally better than ± 0.5% for all elements of atomic number greater than 14. Elements below sodium are also detected, but as a single group. Ambiguities of identification of the elements producing the observed spectra are minimal. Exotic geological materials are, therefore, just as susceptible to analysis as are the more common rocks. A computer model of the instrument has been developed and tested. This model was used to optimize instrument parameters during the design phase, and has now been expanded to perform automatic analysis of the output data.     

A review of some radio and microwave searches for transient phenomena in relation to Vela gamma-ray bursts and supernovae

Radio systems with all sky viewing antennas at 151 MHz were operating at 5 widely spaced stations over the period 1970–1973, during which 19 Vela -ray bursts were detected. The records were analysed for each Vela time but no radio coincidences were recorded. A new experiment in the radio band operating at 408 MHz with similar objectives is now under construction and will be described.Five radiometers at 10 GHz have been tracking the Perseus cluster of galaxies for over one year. The supernova reported on 1 March in Perseus occurred during our oberving time but failed to give evidence from prompt emission in excess to 8×10^–11 erg cm^–2 event^–1, for event durations 0.3–100 s.Paper presented at the COSPAR Symposium on Fast Transients in X- and Gamma-Rays, held at Varna, Bulgaria, 29–31 May, 1975.     

Upper limits for the microwave pulsed emission from supernova explosions in clusters of galaxies

Between 1972 and 1975 an international collaborative search was carried out for prompt 10 GHz emission at the onset of supernovae. The motivations and techniques involved in this effort are described, and the results of the three years' work are summarized. No pulses from supernovae were detected, the best upper limit being 4×10⁴³ ergs in a 40 MHz band at 10 GHz for a pulse time-scale 0.5 s. Methods for improving this limit are briefly described.     

Seismic performance of non-structural components and contents in buildings: an overview of NZ research

This paper summarizes the research on non-structural elements and building contents being conducted at University of Canterbury in New Zealand. Since the 2010-2011 series of Canterbury earthquakes, in which damage to non-structural components and contents contributed heavily to downtime and overall financial loss, attention to seismic performance and design of non-structural components and contents in buildings has increased exponentially in NZ. This has resulted in an increased allocation of resources to research leading to development of more resilient non-structural systems in buildings that would incur substantially less damage and cause little downtime during earthquakes. In the last few years, NZ researchers have made important developments in understanding and improving the seismic performance of secondary building elements such as partitions, facades, ceilings and contents.     

Morphological change of natural pipe outlets in blanket peat

Peatlands are important carbon stores and many have natural pipes (tunnels) that transport water and carbon. Pipes are often viewed as passive and slowly changing features of peatland landscapes, particularly for sites that are relatively undisturbed by land management. However, there is a lack of data on pipe morphology change over time. This paper presents the first survey of natural pipe outlets in a peatland in which morphological changes in pipe outlets through time were measured. Three surveys of natural pipe outlets between 2007 and 2010 were conducted in a 17.4 ha, relatively undisturbed, blanket‐peat‐covered catchment in northern England. 27 of the 91 pipe outlets mapped in the first survey had perennial discharge and these outlets were significantly larger and shallower than those from ephemerally‐flowing pipes. The cross‐sectional area of 85% of pipe outlets changed (increased or decreased) during the study, with 20% of pipe outlet areas changing by more than 50 cm² (equivalent to a median 207 % change in area for this upper fifth of pipes) up to a maximum of 312 cm² for one pipe outlet. During the study, 18 pipe outlets completely infilled, while four new ones appeared. Mean pipe outlet area increased between August 2007 and July 2009 but decreased from July 2009 to April 2010. The largest changes in pipe morphology occurred between July 2009 and April 2010, which spanned the coldest winter for 31 years in the UK. During this period there was a significant increase in the proportion of vertically‐elongated pipes and a decrease in the proportion of circular pipes. Pipe outlet morphology in blanket peat catchments is shown to be dynamic and may respond relatively quickly to changes in flow or extreme events, linked to short‐term changes in weather and hence potentially to longer‐term changes in climate or land management. Copyright © 2011 John Wiley & Sons, Ltd.