125 Changing Environmental Conditions and Changes in the Abundances of Rocky Intertidal Seaweeds on Southern California Shores

In a recent study of the North American biogeography of the red algae genus Hildenbrandia , the presence of group I introns were noted in the nuclear SSU rRNA gene of the marine species H. rubra (Hildenbrandiales). Group I introns in the nuclear encoded rRNAs have been previously reported in the Hildenbrandiales as well as the Bangiales. All reported introns within the red algae have been identified as belonging to the IC1 subclass and occur at two insertion sites in the nuclear small subunit rRNA (516 and 1506). However, an unclassified intron was discovered at position 989 in the nuclear SSU rRNA gene of a collection of H. rubra from British Columbia, Canada. We have determined that the intron is a member of the IE subclass and this is the first report of an IE intron and an intron in position 989 in the red algae. Phylogenetic analyses of the intron sequences reveal a close relationship between this group IE intron and similar ascomycete and basidiomycete fungal IE introns in the nuclear SSU rRNA genes at positions 989 and 1199. In addition, a common unique helix (structural signature) in the P13 domain of the Hildenbrandia intron and those of the fungi at the 989 and 1199 IE positions in the nuclear SSU rRNA gene also indicates a close relationship. Hence, this study provides evidence for a possible lateral transfer of the IE intron in position 989 between fungal and red algal nuclear SSU rRNA genes.     

Mechanisms Influencing the Spread of a Native Marine Alga

Like invasive macrophytes, some native macrophytes are spreading rapidly with consequences for community structure. There is evidence that the native alga Caulerpa filiformis is spreading along intertidal rocky shores in New South Wales, Australia, seemingly at the expense of native Sargassum spp. We experimentally investigated the role physical disturbance plays in the spread of C. filiformis and its possible consequences for Sargassum spp. Cleared patches within beds of C. filiformis (Caulerpa habitat) or Sargassum spp. (Sargassum habitat) at multiple sites showed that C. filiformis had significantly higher recruitment (via propagules) into its own habitat. The recruitment of Sargassum spp. to Caulerpa habitat was rare, possibly due in part to sediment accretion within Caulerpa habitat. Diversity of newly recruited epibiotic assemblages within Caulerpa habitat was significantly less than in Sargassum habitat. In addition, more C. filiformis than Sargassum spp. recruited to Sargassum habitat at some sites. On common boundaries between these two macroalgae, the vegetative growth of adjacent C. filiformis into cleared patches was significantly higher than for adjacent Sargassum spp. In both experiments, results were largely independent of the size of disturbance (clearing). Lastly, we used PAM fluorometry to show that the photosynthetic condition of Sargassum spp. fronds adjacent to C. filiformis was generally suppressed relative to those distant from C. filiformis. Thus, physical disturbance, combined with invasive traits (e.g. high levels of recruitment and vegetative growth) most likely facilitate the spread of C. filiformis, with the ramifications being lower epibiotic diversity and possibly reduced photosynthetic condition of co-occurring native macrophytes.     

Heading for New Shores: Projecting Marine Distribution Ranges of Selected Larger Foraminifera

The distribution of modern symbiont-bearing larger foraminifera is confined to tropical and subtropical shallow water marine habitats and a narrow range of environmental variables (e.g. temperature). Most of today''s taxa are restricted to tropical and subtropical regions (between 30°N and 30°S) and their minimum temperature limits are governed by the 14 to 20°C isotherms. However, during times of extensive global warming (e.g., the Eocene and Miocene), larger foraminifera have been found as far north as 50°N (North America and Central Europe) as well as towards 47°S in New Zealand. During the last century, sea surface temperatures have been rising significantly. This trend is expected to continue and climate change scenarios for 2050 suggest a further increase by 1 to 3°C. We applied Species Distribution Models to assess potential distribution range changes of three taxa of larger foraminifera under current and future climate. The studied foraminifera include Archaias angulatus, Calcarina spp., and Amphistegina spp., and represent taxa with regional, superregional and global distribution patterns. Under present environmental conditions, Amphistegina spp. shows the largest potential distribution, apparently due to its temperature tolerance. Both Archaias angulatus and Calcarina spp. display potential distributions that cover currently uninhabited regions. Under climate conditions expected for the year 2050, all taxa should display latitudinal range expansions between 1 to 2.5 degrees both north- and southward. The modeled range projections suggest that some larger foraminifera may colonize biogeographic regions that so far seemed unsuitable. Archaias angulatus and Calcarina spp. also show an increase in habitat suitability within their native occurrence ranges, suggesting that their tolerance for maximum temperatures has yet not been fully exploited and that they benefit from ocean warming. Our findings suggest an increased role of larger foraminifera as carbonate producers and reef framework builders in future oceans.     

Biogeographic Variability in the Value of Mussel Beds as Ecosystem Engineers on South African Rocky Shores

Ecological engineers have important effects on biodiversity because they often increase habitat complexity and moderate environmental conditions, implying that their influence on associated fauna will vary across gradients of environmental stress. To test this, we quantified the positive effects of mussel beds on associated benthic communities around the entire South African coastline (~3500 km). We hypothesised that molluscan assemblages would show stronger affinities to the presence of mussel beds with increasing levels of heat-stress. Biomimetic loggers used to characterise thermal properties within and outside mussel beds found that solitary mussels experienced significantly greater daily maximum temperatures than mussels within beds across all locations. However, the magnitude of such differences did not appear to vary with latitude or time of year but rather was strongly influenced by biogeographic region. Differences in the abundance, diversity and community structure of molluscs within and outside mussel beds showed similar biogeographic variability, with differences in total molluscan abundances being most pronounced along the cool temperate west coast during summer and least pronounced along the warm temperate south coast during winter. Greater affinity of molluscan assemblages for mussel beds within cooler biogeographic regions suggests that evolutionary history and/or other abiotic factors may be the primary cause for the stronger influence of mussel beds on the west coast. This highlights the complex, context-dependant nature of ecosystem engineering and the varying degrees to which associated organisms affiliate with these biogenic structures. Such findings have important implications for the use of ecosystem engineers as umbrella species in ecological conservation.     

Quantitation of microRNAs using a modified Invader assay

The short lengths of microRNAs (miRNAs) present a significant challenge for detection and quantitation using conventional methods for RNA analysis. To address this problem, we developed a quantitative, sensitive, and rapid miRNA assay based on our previously described messenger RNA Invader assay. This assay was used successfully in the analysis of several miRNAs, using as little as 50-100 ng of total cellular RNA or as few as 1,000 lysed cells. Its specificity allowed for discrimination between miRNAs differing by a single nucleotide, and between precursor and mature miRNAs. The Invader miRNA assay, which can be performed in unfractionated detergent lysates, uses fluorescence detection in microtiter plates and requires only 2-3 h incubation time, allowing for parallel analysis of multiple samples in high-throughput screening analyses.     

Southern Sea Otter as a Sentinel of Marine Ecosystem Health

The southern sea otter (Enhydra lutris nereis) is listed as threatened under the Endangered Species Act (ESA) and is a keystone species, strongly influencing the abundance and diversity of the other species within its kelp forest ecosystem. This is accomplished primarily by preying upon urchins that eat the kelp stipe and holdfast, which can reduce a kelp forest to an urchin barren. Sea otters are very susceptible to marine pollutants such as petroleum, which may be directly toxic and/or alter their furs insulating properties. Sea otters are an excellent sentinel species. They eat approximately 25% of their body weight per day in shellfish and other invertebrates, and can concentrate and integrate chemical contaminants. In addition, they appear to be susceptible to a number of diseases and parasites that may have anthropogenic origins, and shellfish may serve as an intermediary for some of these infections. Many of the shellfish the otters eat are also harvested for human food. In their role as sentinels, sea otter health has implications for human health, economic sustainability of shellfisheries, as well as overall marine ecosystem health. The recent southern sea otter decline has been viewed with some alarm by conservationists and, indeed, recovery seems a long way off. High mortality rather than depressed recruitment appears to underlie the decline. A good deal of debate has centered on the role of infectious diseases and parasites, exposure to contaminants, nutrition and prey availability, net and pot fishery interactions, and other sources of mortality. Current research is being done related to major classes of mortality, various types of pollutants and some specific organisms causing southern sea otter mortality, and their implications for marine ecosystem health and sustainability.     

Variability in intertidal communities along a latitudinal gradient in the Southern Ocean

Despite being one of the most intensely studied habitat types worldwide, the intertidal region around Antarctica has received little more than superficial study. Despite this, the first detailed study of a single locality on the Antarctic Peninsula reported previously unanticipated levels of species richness, biomass and diversity in cryptic intertidal habitats. The current study extends the coverage achieved from this single locality. The intertidal zone at sites in the Scotia Arc, the Falkland Islands and the Antarctic Peninsula was investigated. At all the study sites selected, a wide range of macrofauna was found inhabiting the littoral fringe. These communities, although generally cryptic and occupying predominantly the undersides of boulders and protected interstices, at some locations and sites were rich at multiple taxonomic levels. Across the study locations species richness in the intertidal zone ranged from 7 to 30 species. The highest species richness and diversity were found at high latitude localities, which experienced the highest physical disturbance due to ice scour, and appeared superficially to be denuded of life. Species assemblages varied with latitude with Adelaide Island having a high proportion of bryozoans relative to all other localities.     

Child fostering as a reproductive strategy among Southern African pastoralists

Information on child fosterage was obtained on 1902 individuals in the course of collecting 611 reproductive histories from Herero and Mbanderu pastoralists in northwestern Botswana in southern Africa. The hypothesis that women foster out their children as a strategy for increasing the number of children they produce is tested. Analysis of these data indicate that sex and birth year of children and parents' marital status significantly influence a child's risk of being fostered, but the relationship of fostering to fertility is unclear. More recently born individuals, females, and children born to parents who were not married to each other are more likely to be fostered than older individuals, males, and children born to parents who were married to each other. A child's risk of being fostered does not appear to be influenced by mother's age if the parents were married to each other, while children born to parents who were not married to each other are more likely to be fostered if the mother is very young, but this pattern is not clear. No association between fostering and mortality was found.     

Southern Ocean Biogeography of Tintinnid Ciliates of the Marine Plankton

Ciliate microzooplankton are important grazers in most pelagic ecosystems and among them, tintinnids, with their largely species‐specific loricas, allow relatively easy assessment of questions of diversity and distributions. Herein, we present the results of a survey of species records of tintinnids from the Southern Ocean (locations below 40°S) reported in 56 publications yielding 2,047 species records (synonyms included) from 402 locations. The 192 species reported can be parsed into two main groups: 32 endemic Southern Ocean species, known only from 40°S and further south, and a second group of 181 widespread species, forms with extensive geographic ranges extending into the Southern Ocean. Widespread species reported from the Southern Ocean can be further divided into a group of 81 species, each recorded multiple times in the Southern Ocean waters and 70 apparent “stray” species which have only been found but once. The endemic and widespread species of the Southern Ocean show both distinct distributional patterns and morphological differences. The assemblage of Southern Ocean endemics is found mostly within the Antarctic zone delimited by the average location of the Polar Front and contains a relatively large portion of wide‐mouthed forms. We give suggestions for future study.     

Effects of a Major Tree Invader on Urban Woodland Arthropods

Biological invasions are a major threat to biodiversity; however, the degree of impact can vary depending on the ecosystem and taxa. Here, we test whether a top invader at a global scale, the tree Robinia pseudoacacia (black locust or false acacia), which is known to profoundly change site conditions, significantly affects urban animal diversity. As a first multi-taxon study of this kind, we analyzed the effects of Robinia dominance on 18 arthropod taxa by pairwise comparisons of woodlands in Berlin, Germany, that were dominated by R. pseudoacacia or the native pioneer tree Betula pendula. As a negative effect, abundances of five arthropod taxa decreased (Chilopoda, Formicidae, Diptera, Heteroptera, Hymenoptera); 13 others were not affected. Woodland type affected species composition of carabids and functional groups in spiders, but surprisingly did not decrease alpha and beta diversity of carabid and spider assemblages or the number of endangered species. Tree invasion thus did not induce biotic homogenization at the habitat scale. We detected no positive effects of alien dominance. Our results illustrate that invasions by a major tree invader can induce species turnover in ground-dwelling arthropods, but do not necessarily reduce arthropod species abundances or diversity and might thus contribute to the conservation of epigeal invertebrates in urban settings. Considering the context of invasion impacts thus helps to set priorities in managing biological invasions and can illustrate the potential of novel ecosystems to maintain urban biodiversity.     

Responses of Marine Bacteria Under Starvation Conditions at a Solid-Water Interface

Size changes during starvation of 17 marine bacterial isolates at a solid-water interface and in the liquid phase were examined. Twelve rod-shaped, hydrophilic bacteria decreased in size more rapidly at the solid surface than in the liquid phase, a result parallel to that observed previously for one of the strains at an air-water interface. On the other hand, three rod-shaped, hydrophobic bacteria diminished in size more rapidly in the liquid phase than at the solid-water interface. The rapid size decrease (defined here as the dwarfing phase) in either situation appeared to be an active process which occurred more rapidly when the cells were in an early stage of logarithmic growth at the onset of starvation. Dwarfing was reversibly inhibited by low temperature and low pH but was not inhibited by chloramphenicol. Three coccoidal bacteria showed little tendency to become smaller upon starvation in the liquid phase or at a surface.     

Abrupt shifts in African savanna tree cover along a climatic gradient

Aim To describe patterns of tree cover in savannas over a climatic gradient and a range of spatial scales and test if there are identifiable climate‐related mean structures, if tree cover always increases with water availability and if there is a continuous trend or a stepwise trend in tree cover. Location Central Tropical Africa. Methods We compared a new analysis of satellite tree cover data with botanical, phytogeographical and environmental data. Results Along the climatic transect, six vegetation structures were distinguished according to their average tree cover, which can co‐occur as mosaics. The resulting abrupt shifts in tree cover were not correlated to any shifts in either environmental variables or in tree species distributions. Main conclusions A strong contrast appears between fine‐scale variability in tree cover and coarse‐scale structural states that are stable over several degrees of latitude. While climate parameters and species pools display a continuous evolution along the climatic gradient, these stable structural states have discontinuous transitions, resulting in regions containing mosaics of alternative stable states. Soils appear to have little effect inside the climatic stable state domains but a strong action on the location of the transitions. This indicates that savannas are patch dynamics systems, prone to feedbacks stabilizing their coarse‐scale structure over wide ranges of environmental conditions.     

Aquaculture Can Promote the Presence and Spread of Antibiotic-Resistant Enterococci in Marine Sediments

Aquaculture is an expanding activity worldwide. However its rapid growth can affect the aquatic environment through release of large amounts of chemicals, including antibiotics. Moreover, the presence of organic matter and bacteria of different origin can favor gene transfer and recombination. Whereas the consequences of such activities on environmental microbiota are well explored, little is known of their effects on allochthonous and potentially pathogenic bacteria, such as enterococci. Sediments from three sampling stations (two inside and one outside) collected in a fish farm in the Adriatic Sea were examined for enterococcal abundance and antibiotic resistance traits using the membrane filter technique and an improved quantitative PCR. Strains were tested for susceptibility to tetracycline, erythromycin, ampicillin and gentamicin; samples were directly screened for selected tetracycline [tet(M), tet(L), tet(O)] and macrolide [erm(A), erm(B) and mef] resistance genes by newly-developed multiplex PCRs. The abundance of benthic enterococci was higher inside than outside the farm. All isolates were susceptible to the four antimicrobials tested, although direct PCR evidenced tet(M) and tet(L) in sediment samples from all stations. Direct multiplex PCR of sediment samples cultured in rich broth supplemented with antibiotic (tetracycline, erythromycin, ampicillin or gentamicin) highlighted changes in resistance gene profiles, with amplification of previously undetected tet(O), erm(B) and mef genes and an increase in benthic enterococcal abundance after incubation in the presence of ampicillin and gentamicin. Despite being limited to a single farm, these data indicate that aquaculture may influence the abundance and spread of benthic enterococci and that farm sediments can be reservoirs of dormant antibiotic-resistant bacteria, including enterococci, which can rapidly revive in presence of new inputs of organic matter. This reservoir may constitute an underestimated health risk and deserves further investigation.     

Unraveling the complex maternal history of Southern African Khoisan populations

The Khoisan populations of southern Africa are known to harbor some of the deepest‐rooting lineages of human mtDNA; however, their relationships are as yet poorly understood. Here, we report the results of analyses of complete mtDNA genome sequences from nearly 700 individuals representing 26 populations of southern Africa who speak diverse Khoisan and Bantu languages. Our data reveal a multilayered history of the indigenous populations of southern Africa, who are likely to be the result of admixture of different genetic substrates, such as resident forager populations and pre‐Bantu pastoralists from East Africa. We find high levels of genetic differentiation of the Khoisan populations, which can be explained by the effect of drift together with a partial uxorilocal/multilocal residence pattern. Furthermore, there is evidence of extensive contact, not only between geographically proximate groups, but also across wider areas. The results of this contact, which may have played a role in the diffusion of common cultural and linguistic features, are especially evident in the Khoisan populations of the central Kalahari. Am J Phys Anthropol 153:435–448, 2014. © 2013 Wiley Periodicals, Inc.     

New Records of Marine Fishes in the Waters of Southern Vietnam

Journal of Ichthyology - New data on distribution of seven fish species from the families Argentinidae, Scorpaenidae, Cepolidae, Pinguipedidae and Tetraodontidae are presented. Argentina...     

Potential Future Impact of a Partially Effective HIV Vaccine in a Southern African Setting

Background

It is important for public health and within the HIV vaccine development field to understand the potential population level impact of an HIV vaccine of partial efficacy—both in preventing infection and in reducing viral load in vaccinated individuals who become infected—in the context of a realistic future implementation scenario in resource limited settings.

Methods

An individual level model of HIV transmission, progression and the effect of antiretroviral therapy was used to predict the outcome to 2060 of introduction in 2025 of a partially effective vaccine with various combinations of efficacy characteristics, in the context of continued ART roll-out in southern Africa.

Results

In the context of our base case epidemic (in 2015 HIV prevalence 28% and incidence 1.7 per 100 person years), a vaccine with only 30% preventative efficacy could make a substantial difference in the rate with which HIV incidence declines; the impact on incidence in relative terms is projected to increase over time, with a projected 67% lower HIV incidence in 2060 compared with no vaccine introduction. The projected mean decline in the general adult population death rate 2040–2060 is 11%. A vaccine with no prevention efficacy but which reduces viral load by 1 log is predicted to result in a modest (14%) reduction in HIV incidence and an 8% reduction in death rate in the general adult population (mean 2040–2060). These effects were broadly similar in multivariable uncertainty analysis.

Interpretation

Introduction of a partially effective preventive HIV vaccine would make a substantial long-term impact on HIV epidemics in southern Africa, in addition to the effects of ART. Development of an HIV vaccine, even of relatively low apparent efficacy at the individual level, remains a critical global public health goal.