Turban Snails as Habitat for Foliose Algae: Contrasting Geographical Patterns in Species Richness

Understanding patterns of species richness is a major goal for ecologists, especially in space-limited habitats where many organisms live on top of others (epibiosis, e.g. by algae growing on gastropods in marine environments). We tested the hypotheses that species richness of epiflora on the gastropod Turbo torquatus would not differ between regions with similarly rich algal floras, and that epifloral richness would increase with increasing gastropod size. Macroalgal floras of Hamelin Bay (HB), Marmion (M), Jurien Bay (JB) and Kalbarri (K), Western Australia, ranged from ~20 to 40 species reef–1 (JB = HB = M ≥ K). Epiflora on small T. torquatus (shell areacm2) did not differ among regions but epifloral richness increased with increasing basibiont size. Large T. torquatus (\u3e150 cm2) were only found in Hamelin Bay and Marmion, where epifloral richness differed substantially. Epifloral richness was positively related to basibiont size in Marmion but not in Hamelin Bay. However, densities of patellid limpets on large T. torquatus were ~4× higher in Hamelin Bay than in Marmion, implying that limpet grazing suppresses epifloral richness. Epifloral richness on turbinids is not simply associated with regional species pools or gastropod size; rather, biological interactions at the scale of individual basibionts apparently govern broad scale patterns of epibiosis

Assemblage turnover and taxonomic sufficiency of subtidal macroalgae at multiplespatial scales

Spatial variability in the structure of subtidal macroalgal assemblages in southwest Australia was examined at multiple spatial scales using a three-factor hierarchal design. Spatial extents ranged from metres (between quadrats) to many hundreds of kilometres (between regions), and the study encompassed N2000 km of temperate coastline. In addition, the influence of taxonomic resolution, from species level data to class level, on spatial patterns was investigated to assess the potential evolutionary timescales of the pattern and for developing cost effective regionally applicable surrogates for biodiversity monitoring. Almost 300 species were identified from 14 sites, representing considerable biodiversity and a significant subset of the total benthic macroalgal diversity in the region (∼1000 species). Multivariate variability was significant at all spatial scales examined, but most prominent at smallest spatial scales, regardless of taxonomic resolution. Assemblage and species turnover was pronounced at scales of metres to hundreds of metres. Generally, small scale patchiness was a ubiquitous pattern for all individual taxa examined, regardless of taxonomic resolution, while variability at the scale of 10s of km was less important. Even so, differences in spatial variability between taxa were observed, and ecological and historical reasons for such differences are proposed. Taxonomic aggregation to family level had minimal effect on spatial patterns, but aggregation to order level led to changes in some aspects of patterns of assemblage structure. The unique and speciose macroalgal assemblages on subtidal reefs in southwest Australia are shaped by a complex array of historical and contemporary processes that act at multiple spatial (and temporal) scales. Understanding the relative importance of these processes requires that further manipulative and correlative work is conducted across a range of ecologically-important spatial scales

Sediment burial stress response, bio-indicators and thresholds for a tropical multi-species seagrass assemblage: Report of Theme 5 - Project 5.5.2 prepared for the Dredging Science Node

Changes to the amount of light and burial by the deposition of suspended sediments are presumed to be major mechanisms by which dredging can impact seagrasses. This report presents findings from a controlled burial experiment that aimed to determine the effects of burial by sediments on the growth of two seagrass species found in the northwest of Western Australia (NW WA). The report provides guidance and protocols for the application of the research outputs (e.g. seagrass burial stress:response relationships, sub-lethal and lethal bio-indicators and thresholds) to the prediction, assessment, monitoring and management of dredging programs in NW WA..

Response and recovery of a mixed tropical seagrass assemblage to variation in the frequency and magnitude of light deprivation. Report of Theme 5 - Project 5.5.3 prepared for the Dredging Science Node

The capacity of seagrasses to cope with episodes of light deprivation from overlying turbid waters may not only depend on the absolute quantity of light they receive during that episode, but also on how the light deprivation varies through time. For example, turbidity and therefore light reduction may be relatively constant over the episode or it may fluctuate depending on the frequency of pulsed turbidity events. This report presents findings from a controlled mesocosm experiment that aimed to determine the responses of seagrasses to, and recovery from, differences in the pattern of the delivery of light. The study focussed on two seagrass species found in the northwest of Western Australia (NW WA). The report provides guidance and protocols for the application of the research outputs (e.g. light stress frequency and response relationships, recovery potential, sub-lethal and lethal bio-indicators and thresholds) to impact prediction, monitoring and/or management of dredging programs in NW WA..

Social and Economic Stress Related to the HIV/AIDS Epidemic in Botswana

The paper describes the consequences of HIV/AIDS in Botswana; the country with the highest HIV prevalence rate in Africa. In addition to frequently experienced trauma due to sickness and death, many households experience rising health expenditures and a sharp deterioration of incomes. High levels of morbidity and mortality among workers result in depressed returns on investment, reduced productivity and increased expenditure on training and replacement of workers. As the health care system finds it increasingly difficult to cope, home-based care provides an inadequate solution since the home infrastructure of many households is inadequate for proper care of seriously ill patients. The stigma associated with AIDS often isolates fragile households and provides an environment in which abuse of infected individuals and of orphans whose parents have died of AIDS is not uncommon. The quality of education also suffers, resulting in an ill prepared skilled manpower, with adverse consequences for social, economic, and political development as well as for good future governance of the country

Seagrass Halophila ovalis is affected by light quality across different life history stages

Seagrass meadows provide crucial ecosystem services to the coastal zone but are threatened globally. Seagrass loss to date has mainly been attributed to anthropogenic activities that reduce light quantity (amount of photosynthetic photon flux density), such as dredging, flooding and eutrophication. However, light quality (wavelengths of light within the visible spectrum) is also altered by these anthropogenic stressors. This study addressed the effect of light quality changes on seagrasses. Aquarium-based experiments were conducted to determine whether the seagrass Halophila ovalis (R.Br.) Hook f. responds to different light quality treatments. Separate experiments were performed in which adults, seeds or seedlings were subjected to monochromatic light treatments in the blue (peak λ %= 451 nm), green (peak λ = 522 nm), yellow (peak λ = 596 nm) and red (peak λ = 673 nm) wavelengths with a control of full-spectrum light (λ = 400 - 700 nm, at 200 µmol photons m-2 s-1). This study is unique in that it measured seagrass responses to light across several plant scales (physiology, productivity, morphology and biomass) as well as across life-history stages (seeds, seedlings, adults and flowering). Adult plants responded differently to seeds and seedlings but were generally consistent with terrestrial angiosperms: blue light decreased below-ground productivity; green light influenced morphology (through increased rhizome internode length); red light enhanced seed germination and survival. The findings indicate that both natural and human-induced changes in light quality could significantly affect seagrass growth and reproduction. As a range of anthropogenic activities are currently contributing to the global losses of seagrasses, this research provides timely information on how light quality influences different seagrass life history stages

Synthesis Report: Defining thresholds and indicators of primary producer response to dredging-related pressures: Report of Theme 5 prepared for the Dredging Science Node

Seagrasses form a small component of a diverse group of organisms termed ‘benthic primary producers’. Benthic primary producers are organisms that grow on the sea-bed that obtain some or all of their energy needs from photosynthesis. This includes animals such as scleractinian corals and some sponges that host microscopic intercellular algae, coralline and turf algae, and the larger seaweeds such as the kelps and sargassum. Seagrasses are marine flowering plants, more closely related to land plants than seaweeds and algae. Seagrasses live mostly in soft sediments, and can be found from the shallow intertidal zone through to a depth of 60 m when waters are exceptionally clear allowing sufficient sunlight to reach the seafloor. Some species form persistent underwater meadows, while others form transitory meadows, and occur in low-density patches or as understorey species. Seagrasses typically require more light than algae to survive because of the respiratory demand of the underground roots and rhizomes. Seagrasses provide many important services. As primary producers, they contribute to the base of the marine foodweb and the habitats they form are important nursery areas for commercially-important prawns and provide shelter and foraging grounds for many species of fish. Seagrasses also play an important role in recycling nutrients, filtering water, sequestering carbon from the atmosphere and protecting the coastline from erosion. Because they are sensitive to change, they make useful indicators of environmental health. Furthermore, tropical seagrasses are essential food sources for dugong which is a marine mammal of particular conservation and Indigenous cultural interest..

Ariel - Volume 12(13) Number 4

Co-Editors Gary Fishbein Lynn Solomon Business Manager Rich Davis Assistant Business Manager Jeff Lavanier Layout Editors Paul J. Berlin Tracy A. Glauser Photography Editor Ben Alma

A comparative analysis of perceived stigma among HIV-positive Ghanaian and African American males

The purpose of this paper was to address two questions: (i) Do Ghanaian and African American males with HIV/AIDS experience different types and degrees of stigma? and (ii) Is the impact of stigma associated with HIV/AIDS on the self different for Ghanaian and African American males? A quantitative method was used, and the four dimensions of stigma (social rejection, financial insecurity, internalised shame, and social interaction) were identified and measured using combination Likert-type questionnaires. Data regarding positive feelings of selfworth and self-deprecation, stress related to body image, and personal control were also collected in Ghana and the southeastern USA.The sample consisted of 55 men from Ghana and 55 men from the southeastern USA. Results indicate that values for the scales measuring stigma and self-perception were significantly higher for the Ghanaian sample than for the African American sample.Thus we conclude that the Ghanaian sample living with HIV/AIDS experienced a greater amount of negative self-perception and stigma-related strife than the African American sample.Keywords: stigma, HIV/AIDS, social rejection, financial insecurity, internalised shame, cultureRésuméLe but de cette communication est d'aborder deux questions, à savoir: (i) Est-ce que les hommes Ghanéens et Afro-Américains vivant avec le VIH/SIDA éprouvent de types et de degrés différents de stigmatisation? et (ii) Estce que l'impact de stigmatisation liée au VIH/SIDA sur le moi est différent chez les Ghanéens en comparaison aux Afro-Américains? Une méthode quantitative a été employée et les quatre dimensions de stigmatisation (le rejet social, l'insécurité financière, la honte intériorisée et l'interaction sociale) ont été identifiés et mesurés grâce à une combinaison des questionnaires Likert-type. Des données concernant des sentiments positifs de la valeur personnelle et d'auto-dénigrement, le stresse lié à l'image corporel et le contrôle de soi-même ont été recueilles au Ghana et au sud-est des États Unis. L'échantillon consistait de 55 hommes du Ghana et 55 hommes du sud-est des États Unis. Les chiffres des barèmes utilisées pour mesurer la stigmatisation et la perception de soi-même étaient sensiblement élevés pour l'échantillon ghanéen par rapport à l'échantillon afro-américain. L'échantillon ghanéen vivant avec le VIH/SIDA a davantage de perception négative de soi-même ainsi que la lutte liée à la stigmatisation par rapport à l'échantillon afro-américain.Mots clés: stigmatisation,VIH, SIDA, rejet social, insécurité financière, honte intériorisée, culture SAHARA J (Journal of Social Aspects of HIV/AIDS Research Alliance) Vol. 2(3) 2005: 344-35