SPATIAL COMPARISONS OF POPULATIONS OF AN INDIGENOUS LIMPET SCUTELLASTRA ARGENVILLEI AND AN ALIEN MUSSEL MYTILUS GALLOPROVINCIALIS ALONG A GRADIENT OF WAVE ENERGY

In the 1970s, the Mediterranean mussel Mytilus galloprovincialis invaded the South African coast and spread rapidly to dominate much of the West Coast, indicating either the opportunity to occupy a vacant niche or its superior competitive capability over indigenous species. In Namaqualand on the West Coast it appears to compete with a large indigenous limpet, Scutellastra argenvillei, which is capable of forming dense, almost monospecific stands low on the shore. A survey on the Namaqualand coast indicated that the abundance of M. galloprovincialis changes with wave exposure. At wave-exposed locations, the mussel covered up to 90&#37 of the primary substratum, whereas in semi-exposed situations it was never abundant. As the cover of M. galloprovincialis increased, the abundance and size of S. argenvillei on rock declined and it became confined to patches within a matrix of mussel bed. Both species were absent from sheltered shores and diminished where wave action was extreme. Comparisons with previous surveys indicated that exposed sites now largely covered by the alien mussel were once dominated by dense populations of the limpet. Therefore, the results of this survey provide circumstantial correlative evidence of a competitive interaction between M. galloprovincialis and S. argenvillei, and suggest that wave action mediates the strength of this interaction. The presence of mussel beds provides a novel settlement and living substratum for recruits and juveniles of S. argenvillei, albeit at much lower densities than in limpet patches. Adult limpets were virtually excluded from the mussel beds owing to their large size, which indicates the unsuitability of this habitat as a replacement substratum after competitive exclusion from primary rock space.Afr. J. mar. Sci. 25: 195–21

TEMPORAL CHANGES IN AN INTERACTION BETWEEN AN INDIGENOUS LIMPET SCUTELLASTRA ARGENVILLEI AND AN ALIEN MUSSEL MYTILUS GALLOPROVINCIALIS: EFFECTS OF WAVE EXPOSURE

A previous survey of 15 sites off the Namaqualand coast on the west coast of South Africa provided evidence of a competitive interaction between an alien mussel Mytilus galloprovincialis and an indigenous limpet Scutellastra argenvillei, and indicated that wave action mediates the strength of this interaction. In this study, the temporal persistence of these patterns was tested by selecting six sites, ranging from sheltered to very exposed, and monitoring them over a two-year period. The patterns remained consistent over time. Both S. argenvillei and M. galloprovincialis were perpetually absent from the most sheltered site. The limpet consistently dominated rock space at the semi-exposed site where mussel cover was always low. At exposed sites, M. galloprovincialis was dominant but its percentage cover varied temporally as a result of wave action, creating free space and allowing temporary expansion of limpet patches. However, with time the mussel recolonized the cleared rock space and repeatedly displaced the limpet from it. This provides additional observational evidence of competition for space between the alien invader and the indigenous limpet. It is concluded that S. argenvillei has a spatial refuge from M. galloprovincialis in areas with moderate wave action. However, the limpet is likely to become locally extinct on exposed shores because mussels outcompete it there and rapidly recolonize patches from which they have been temporarily eliminated by wave action.Afr. J. mar. Sci. 25: 213–22

The recoverability of fingerprints on paper exposed to elevated temperatures - Part 1: comparison of enhancement techniques

This research investigates the recoverability of fingerprints which have been exposed to elevated temperatures in order to mimic the environment a piece of paper may be exposed to within an arson scene. Arson is an expensive crime, costing the UK economy, on average, £53.8 million each week [1]. Anything which may give rise to the identity of the fire setter should be analysed and as such, unburnt paper may be a potential source of fingerprints. While it is true that even a moderate fire will obscure and render partially useless some types of evidence, many items, including fingerprints, may still survive [2-4]. This research has shown that fingerprints are still retrievable from paper which has been subjected to the maximum testing conditions of 200˚C for 320min. In fact, some fingerprints naturally enhance themselves by the heating process. This investigation has also shown that the most effective enhancement technique was found to be 1,8-diazafluoren-9-one (DFO) for exposure temperatures upto 100˚C. Physical developer (PD) is the most effective enhancement technique for exposure temperatures from 100˚C to 200˚C. For porous surfaces, there are fingerprint development techniques which are effective at enhancing fingerprints exposed upto a temperature of 200˚C, irrespective of the firefighting extinguishing technique, as PD, in addition to developing fingerprints exposed to high temperatures, is one of the few processes which will enhance fingermarks on wetted surfaces

The recoverability of fingerprints on paper exposed to elevated temperatures - Part 2: natural fluorescence

Previous work by the authors [1] investigated the recoverability of fingerprints on paper which had been exposed to elevated temperatures by comparing various chemical enhancement techniques (ninhydrin, 1,8-diazafluoren-9-one (DFO), and physical developer (PD)). During that study, it became apparent, as a consequence of observations made in operational work [2], that fingerprints on paper subjected to 150˚C fluoresced under examination with green light of waveband 473-548nm with a 549nm viewing filter. This work examined the three types of prints (eccrine, sebaceous, and ungroomed) after 20 min exposure to the temperature range 110˚C to 190˚C (in 10˚C increments) and found that the eccrine fingerprints fluoresced more brightly. This indicated that it was a component of the eccrine deposit which was causing the fluorescence. Luminance measurements found that the maximum fluorescence was experienced at 170˚C on both types of paper. As a consequence, eccrine heat-treated fingerprints were viewed under violet-blue (350-469nm), blue (352-509nm), and green light (473-548nm) which indicated that the greatest luminance intensities were obtained under blue light and the smallest under green light. In order to determine what component of the eccrine fingerprint was causing this fluorescence, five of the most prevalent amino acids (alanine, aspartic acid, glycine, lysine, and serine) [3-4] were exposed to this temperature range. The luminance measurements were taken under exposure to the green light in order for the minimum fluorescence to be observed, with an assumption that blue-violet or blue illumination will provide brighter fluorescence in practice. The results indicated that four of the amino acids are behaving similarly across the temperature range, but with slightly different luminance measurements, but all are exhibiting some level of fluorescence. Thermal degradation products of alanine and aspartic acid have been suggested by Richmond-Aylor et al. [5]. The structure of these thermal degradation products is cyclic in nature, and as such, there is a possibility that two of these products would fluorescence. Sodium chloride and urea were also exposed to the temperature range and they also fluoresced to some extent. This work shows that eccrine fingerprints that have been exposed to temperatures of between 130˚C to 180˚C will fluoresce under violet-blue, blue, and green light. This level of fluorescence for ungroomed fingerprints is much less but this will be dependent on the individual, the more eccrine the deposit, the stronger the fluorescence. This work shows that the amino acids, sodium chloride, and urea present in fingerprint deposits are all contributing to the fluorescence of the print, but may not be the sole contributor as other eccrine components have not yet been tested

Defining fishers in the South African context: subsistence, artisanal and small-scale commercial sectors

Evolution of a new policy for the management of marine fisheries in South Africa led to the Marine Living Resources Act of 1998 (MLRA). Among other innovations, this requires that management strategies be developed for subsistence fisheries. As a prerequisite, definitions and criteria are needed to identify and distinguish them. To achieve this, the Chief Director of Marine & Coastal Management (MCM), the authority responsible for managing marine fisheries, appointed a Subsistence Fisheries Task Group (SFTG) to make recommendations about definitions and modes of management. The process involved successive surveys and consultations with fishing communities, communication with MCM, and a national workshop of all participants. This led to consensus about the following definition: Subsistence fishers are poor people who personally harvest marine resources as a source of food or to sell them to meet the basic needs of food security; they operate on or near to the shore or in estuaries, live in close proximity to the resource, consume or sell the resources locally, use low-technology gear (often as part of a long-standing community-based or cultural practice), and the kinds of resources they harvest generate only sufficient returns to meet the basic needs of food security. This definition builds on the facts that existing subsistence fisheries are usually: (1) local operations; (2) customary, traditional or cultural; (3) undertaken for personal or family use; (4) primarily for nutritional needs (though excess resources may be sold to ensure food security); (5) based on minimal technology; and (6) undertaken by people with low cash incomes. They are specifically non-commercial and non-recreational. The definition was designed to allow protection of the rights of these people and sustainability of the resources. While developing this definition, it became obvious that the definition of “commercial fishing” in the MLRA is also inadequate, and a new definition was developed. Commercial fisheries span a wide spectrum, and the SFTG defined “small-scale commercial fishers” as a distinct component that has not received adequate attention, and for whom specific management plans need to be developed. They are distinguished by living on or close to the coast, having a history of involvement with fishing, being personally involved in hands-on day-to-day running of their enterprises, operating with limited amounts of capital investment and low levels of technology, and employing small numbers of people.Keywords: defining subsistence, fisheries management, subsistence fishersAfrican Journal of Marine Science 2002, 24: 475–48

Morphological and genetic differentiation of Patella granularis (Gastropoda: Patellidae): recognition of two sibling species along the coast of southern Africa

Morphological and isozyme variations between 13 populations of the species hitherto named Patella granularis were investigated to see whether differences in shell structure between the west coast versus the south and east coasts of southern Africa are supported by other morphological features or by genetic differences. The shells showed a definite decrease in size from west to east, but this is correlated with productivity and is of no diagnostic use in distinguishing between populations. Discriminant functions analysis based on shell morphometrics failed to separate populations from the three coastal regions. Shells from the northern east coast do, however, have shell nodules with a dark pigmentation, distinctly separating them from those further south and west. No differences in radular or soft part morphology were detected between the populations, but the four northernmost populations on the east coast have a significantly shorter Z looping of the gut than the other populations along the coast. Significant microstructural differences in the sperm were also detected between these two groups of populations. Electrophoretic analysis of 16 enzyme loci failed to detect any significant differences between the west and south coast populations, but revealed a genetic identity (Nei) of 0.528 as well as four diagnostic alleles between the four northernmost populations from the east coast compared with those to the south and west. The two genetically distinct forms occurred sympatrically at one of the study sites on the east coast (Coffee Bay). It was concluded the two groupings were sufficiently different to warrant the recognition of a separate species, which is centred in KwaZulu-Natal on the east coast and extends south to Coffee Bay, from where it is replaced by P. granularis. There is, however, no evidence at all that the west coast populations are in any way separable from the remaining populations of P. granularis on the south coast

SN 2005hj: Evidence for Two Classes of Normal-Bright SNe Ia and Implications for Cosmology

HET Optical spectra covering the evolution from about 6 days before to about 5 weeks after maximum light and the ROTSE-IIIb unfiltered light curve of the "Branch-normal" Type Ia Supernova SN 2005hj are presented. The host galaxy shows HII region lines at redshift of z=0.0574, which puts the peak unfiltered absolute magnitude at a somewhat over-luminous -19.6. The spectra show weak and narrow SiII lines, and for a period of at least 10 days beginning around maximum light these profiles do not change in width or depth and they indicate a constant expansion velocity of ~10,600 km/s. We analyzed the observations based on detailed radiation dynamical models in the literature. Whereas delayed detonation and deflagration models have been used to explain the majority of SNe Ia, they do not predict a long velocity plateau in the SiII minimum with an unvarying line profile. Pulsating delayed detonations and merger scenarios form shell-like density structures with properties mostly related to the mass of the shell, M_shell, and we discuss how these models may explain the observed SiII line evolution; however, these models are based on spherical calculations and other possibilities may exist. SN 2005hj is consistent with respect to the onset, duration, and velocity of the plateau, the peak luminosity and, within the uncertainties, with the intrinsic colors for models with M_shell=0.2 M_sun. Our analysis suggests a distinct class of events hidden within the Branch-normal SNe Ia. If the predicted relations between observables are confirmed, they may provide a way to separate these two groups. We discuss the implications of two distinct progenitor classes on cosmological studies employing SNe Ia, including possible differences in the peak luminosity to light curve width relation.Comment: ApJ accepted, 31 page

SNLS Spectroscopy: Testing for Evolution in Type Ia Supernovae

Aims: We present a quantitative study of a new data set of high redshift Type Ia supernovae spectra, observed at the Gemini telescopes during the first 34 months of the Supernova Legacy Survey. During this time 123 supernovae candidates were observed, of which 87 have been identified as SNe Ia at a median redshift of z=0.720. Spectra from the entire second year of the survey and part of the third year (59 total SNe candidates with 46 confirmed SNe Ia) are published here for the first time. The spectroscopic measurements made on this data set are used determine if these distant SNe comprise a population similar to those observed locally. Methods: Rest-frame equivalent width and ejection velocity measurements are made on four spectroscopic features. Corresponding measurements are presented for a set of 167 spectra from 24 low-z SNe Ia from the literature. Results: We show that there exists a sample at high redshift with properties similar to nearby SNe. No significant difference was found between the distributions of measurements at low and high redsift for three of the features. The fourth feature displays a possible difference that should be investigated further. Correlations between Type Ia SNe properties and host galaxy morphology were also found to be similar at low and high z, and within each host galaxy class we see no evidence for redshift-evolution in SN properties. A new correlation between SNe Ia peak magnitude and the equivalent width of SiII absorption is presented. We demonstrate that this correlation reduces the scatter in SNe Ia luminosity distances in a manner consistent with the lightcurve shape-luminosity corrections that are used for Type Ia SNe cosmology. Conclusions: We show that this new sample of SNLS SNe Ia has spectroscopic properties similar to nearby objects. (Abridged)Comment: Accepted for publication in Astronomy and Astrophysic

Helium Emission in the Type Ic SN 1999cq

We present the first unambiguous detection of helium emission lines in spectra of Type Ic supernovae (SNe Ic). The presence of He I lines, with full width at half maximum ~ 2000 km/s, and the distinct absence of any other intermediate-width emission (e.g., Halpha), implies that the ejecta of SN Ic 1999cq are interacting with dense circumstellar material composed of almost pure helium. This strengthens the argument that the progenitors of SNe Ic are core-collapse events in stars that have lost both their hydrogen and helium envelopes, either through a dense wind or mass-transfer to a companion. In this way, SN 1999cq is similar to supernovae such as SN 1987K and SN 1993J that helped firmly establish a physical connection between Type Ib and Type II supernovae. The light curve of SN 1999cq is very fast, with an extremely rapid rise followed by a quick decline. SN 1999cq is also found to exhibit a high level of emission at blue wavelengths (< 5500 A), likely resulting from either an unusually large amount of iron and iron-group element emission or uncharacteristically low reddening compared with other SNe Ic.Comment: 17 pages (AASTeX V5.0), 4 figures, accepted for publication in the Astronomical Journa

Analytic Inversion of Emission Lines of Arbitrary Optical Depth for the Structure of Supernova Ejecta

We derive a method for inverting emission line profiles formed in supernova ejecta. The derivation assumes spherical symmetry and homologous expansion (i.e., $v(r) \propto r$), is analytic, and even takes account of occultation by a pseudo-photosphere. Previous inversion methods have been developed which are restricted to optically thin lines, but the particular case of homologous expansion permits an analytic result for lines of {\it arbitrary} optical depth. In fact, we show that the quantity that is generically retrieved is the run of line intensity $I_\lambda$ with radius in the ejecta. This result is quite general, and so could be applied to resonance lines, recombination lines, etc. As a specific example, we show how to derive the run of (Sobolev) optical depth $\tau_\lambda$ with radius in the case of a pure resonance scattering emission line.Comment: 6 pages, no figures, to appear in Astrophysical Journal Letters, requires aaspp4.sty to late