Confirmation of the southern African distribution of the marine sponge Hymeniacidon perlevis (Montagu, 1814) in the context of its global dispersal.

Background: Intertidal rocky shore surveys along the South African coastline (∼3,000 km) have demonstrated the presence and abundance of the encrusting orange sponge Hymeniacidon perlevis (Montagu, 1814), a well-known globally distributed species. After analysing the southern African populations, we gained a better understanding of the genetic structure of this now-accepted global species. Apart from confirming the presence of a single population of H. perlevis, we also determined its distribution in the southern African intertidal rocky shore ecosystem, compared its genetic diversity to congeners, predict its global distribution via environmental niche modelling, and discussed possible underlying mechanisms controlling the species' global distribution. Methods: We surveyed the South African coastline and sampled sponges at 53 rocky shore sites spanning over 3,000 km, from Grosse Bucht south of Lüderitz (Namibia) to Kosi Bay on the east coast of South Africa. DNA sequences of the nuclear rDNA internal transcribed spacer (ITS1) and the COI mitochondrial gene were obtained from 61 samples and compared them to a world-wide sample of other H. perlevis sequences. Using environmental predictor variables from the global dataset BIO-ORACLE, we predicted the probability of global occurrence of the species using an ensemble of eight distribution models. Results: South African specimens were found to be 99-100% identical to other populations of H. perlevis (=H. sinapium) from other world-wide regions. The presence of a single population of H. perlevis in southern Africa is supported by genetic data, extending its distribution to a relatively wide geographical range spanning more than 4,000 km along the temperate southern African coast. The predicted global occurrence by ensemble model matched well with the observed distribution. Surface temperature mean and range were the most important predictor variables. Conclusion: While H. perlevis appears to have been introduced in many parts of the world, its origins in Europe and southern Africa are unclear.

Acoustic detectability of whales amidst underwater noise off the west coast of South Africa.

Anthropogenic underwater noise has been shown to negatively affect marine organisms globally; yet little to no noise research has been conducted in most African waters including South Africa's. This study aimed to quantitatively describe sources of underwater noise and effects of underwater noise on the acoustic detectability of Antarctic blue, fin, minke, humpback, and sperm whales off South Africa's west coast. Noise from vessel traffic (<35 km to the location of recorders) dominated the soundscape below 500 Hz while wind-generated noise increased with wind speed above 5 m s-1 and dominated the soundscape above 500 Hz. Acoustic detectability of humpback, minke and sperm whales decreased with increasing ambient noise levels whereas blue and fin whale acoustic detectability increased with the ambient noise levels. We provide baseline information on underwater noise sources and the effects of underwater noise on whale acoustic detectability off the west coast of South Africa.

Traditional medicine among the community of Gash-Barka region, Eritrea: attitude, societal dependence, and pattern of use.

BACKGROUND: Despite the growing conventional healthcare coverage in Eritrea, traditional medicine (TM) remains an essential source of healthcare service to the population. This study, therefore, aims at exploring the attitude, societal dependence, and pattern of TM use of the Gash-Barka community. METHODS: A cross-sectional study was conducted between December 2018 and January 2019 in Gash-Barka region, one of the six regions of Eritrea. Two-stage stratified cluster sampling design was used to provide representative sample of households. The data collected through face-to-face interview using a structured questionnaire was entered twice and analyzed using CSPro7.2 and SPSS 23, respectively. Both descriptive and analytical analyses were performed to test statistical significance. RESULTS: Of the total 210 participants, 202 completed the interview with a response rate of 96.2%. Almost 97% of the respondents were aware of the general existence of TM. About half of the respondents (47.4%) had visited traditional health practitioners (THPs) at least once in their lifetime. The majority of the respondents claimed their medical condition had been improved (63.2%), were satisfied with the outcome (76.8%), and had not encountered complications (95.2%) due to TM use. Around 40% of the respondents admitted they do not disclose previous TM use to conventional health practitioners. Females are more likely to have had ever visited THPs (AOR = 1.85, CI: 1.01, 3.38) and use TM in the future (AOR = 2.26, CI: 0.92, 5.14) than males. Moreover, those who had visited THPs before (COR = 8.30, CI: 3.25, 21.20) are more likely to use TM as a primary treatment choice and prefer to use TM in the future (AOR = 4.40, CI: 1.97, 9.83) than those who had never visited THPs. About 61% of the total families claimed they had circumcised at least one female child, and 96.8% disclosed they had circumcised at least one male child. Out of which, 89.2% of the circumcisions were done by THPs. CONCLUSION: TM is popular and widely relayed upon by Gash-Barka residents with exposure of children to harmful TM practices. Since the reliance of the community on TM is expected to continue, further representative studies are recommended to inform regulatory interventions and integrate TM into the health system.

Species distribution modelling of Bryde's whales, humpback whales, southern right whales, and sperm whales in the southern African region to inform their conservation in expanding economies.

In southern African waters, information about species distribution and habitat preferences of many cetacean species is limited, despite the recent economic growth that may affect them. We determined the relative importance of eight environmental variables (bathymetry, distance to shore, slope, chlorophyll-a, salinity, eastwards sea water velocity, northwards sea water velocity and sea surface temperature) as drivers of seasonal habitat preferences of Bryde's whales (Balaenoptera brydei), humpback whales (Megaptera novaeangliae), southern right whales (Eubalaena australis) and sperm whales (Physeter macrocephalus). Using presence only data from multiple sources, we constructed predictive species distribution models (SDMs) consisting of ensembles of seven algorithms for these species during both summer and winter. Predicted distribution for all cetaceans was high in southern Africa and, in particular, within the South African Exclusive Economic Zone (EEZ). Predictive models indicated a more pronounced seasonal variation for humpback, sperm and southern right whales than for Bryde's whales. Southern right whales occurred closer to shore during winter, humpback whales were more likely to occur along the east coast in winter and the west coast in summer, and sperm whales were more concentrated off the shelf in winter. Our study shows that ensemble models using historical, incidental and scientific data, in conjunction with modern environmental variables, can provide baseline knowledge on important environmental drivers of cetacean distribution for conservation purposes. Results of this study can further be used to help develop marine spatial plans and identify important marine mammal areas.

Modelling the effects of environmental conditions on the acoustic occurrence and behaviour of Antarctic blue whales.

Harvested to perilously low numbers by commercial whaling during the past century, the large scale response of Antarctic blue whales Balaenoptera musculus intermedia to environmental variability is poorly understood. This study uses acoustic data collected from 586 sonobuoys deployed in the austral summers of 1997 through 2009, south of 38°S, coupled with visual observations of blue whales during the IWC SOWER line-transect surveys. The characteristic Z-call and D-call of Antarctic blue whales were detected using an automated detection template and visual verification method. Using a random forest model, we showed the environmental preferences pattern, spatial occurrence and acoustic behaviour of Antarctic blue whales. Distance to the southern boundary of the Antarctic Circumpolar Current (SBACC), latitude and distance from the nearest Antarctic shores were the main geographic predictors of blue whale call occurrence. Satellite-derived sea surface height, sea surface temperature, and productivity (chlorophyll-a) were the most important environmental predictors of blue whale call occurrence. Call rates of D-calls were strongly predicted by the location of the SBACC, latitude and visually detected number of whales in an area while call rates of Z-call were predicted by the SBACC, latitude and longitude. Satellite-derived sea surface height, wind stress, wind direction, water depth, sea surface temperatures, chlorophyll-a and wind speed were important environmental predictors of blue whale call rates in the Southern Ocean. Blue whale call occurrence and call rates varied significantly in response to inter-annual and long term variability of those environmental predictors. Our results identify the response of Antarctic blue whales to inter-annual variability in environmental conditions and highlighted potential suitable habitats for this population. Such emerging knowledge about the acoustic behaviour, environmental and habitat preferences of Antarctic blue whales is important in improving the management and conservation of this highly depleted species.

Foraging Behavior of Subantarctic Fur Seals Supports Efficiency of a Marine Reserve's Design.

Foraging behaviour of marine top predators is increasingly being used to identify areas of ecological importance. This is largely enabled by the ability of many such species to forage extensively in search of prey that is often concentrated in oceanographically productive areas. To identify important habitat in the Southern Indian Ocean within and around South Africa's Prince Edward Islands' Marine Protected Area (MPA), satellite transmitters were deployed on 12 lactating Subantarctic fur seals Arctocephalus tropicalis at Prince Edward Island (PEI) itself. Switching state space models were employed to correct ARGOS tracks and estimate behavioural states for locations along predicted tracks, namely travelling or area restricted search (ARS). A random forest model showed that distance from the study colony, longitude and distance from the Subantarctic Front were the most important predictors of suitable foraging habitat (inferred from ARS). Model-predicted suitable habitat occurred within the MPA in relatively close access to the colony during summer and autumn, but shifted northwards concurrently with frontal movements in winter and spring. The association of ARS with the MPA during summer-autumn was highly significant, highlighting the effectiveness of the recently declared reserve's design for capturing suitable foraging habitat for this and probably other marine top predator species.

Spatial dynamics of the bearded goby and its key fish predators off Namibia vary with climate and oxygen availability.

Hypoxia [O2 < 2.0 mL L-1 (87 µmol kg-1)] and severely hypoxic water masses [O2 < 0.5 mL L-1 (21.8 µmol kg-1)] are increasing in coastal marine ecosystems due to eutrophication and warming. Here, we investigate the response of the suboxic-tolerant endemic fish, Sufflogobius bibarbatus, to variations in the thermal and oxygen environment, as well as to predation pressure, using 22 yr worth of satellite and in situ data. We show that environmental variation and predation pressure affect the goby population, which has expanded over the last decade while that of horse mackerel has contracted. These changes co-occurred with a general warming in the north and central shelf areas (north of 24.5°S). Spring warming positively affected both goby and hake abundances, but not the horse mackerel, suggesting different responses to surface temperature. The goby habitat contracted when predators were abundant, particularly in the north, which is the fringe of its distributional area. The implications of the differential tolerance of gobies and their predators for climate variations are discussed.

Size evolution of gold nanoparticles in a millifluidic reactor.

The size evolution of gold nanoparticles in a millifluidic reactor is investigated using spatially resolved transmission electron microscopy (TEM). The experimental data is supported by numerical simulations, carried out to study the residence-time distribution (RTD) of tracers that have the same properties as Au ions. Size and size distribution of the particles within the channels are influenced by the mixing zones as well as the RTD. However, the Au nanoparticles obtained show a broader size distribution even at the shortest investigated residence time of 3.53 s, indicating that in addition to surface growth reaction kinetics also plays an important role. The comparison of time resolved particle growth within the millifluidic channel with flask-based reactions reveals that the particle size can be controlled better within millifluidic channels. Overall, the results indicate potential opportunities to utilize easy to fabricate millifluidic reactors for the synthesis of nanoparticles, as well as as for carrying out time resolved kinetic studies.

Hybrid integration of injector and detector functions for microchip gas chromatography.

Hybrid microchips containing high aspect ratio gas chromatograph (GC) columns with an integrated on-chip split injection and a flame ionization detector were developed. Two different column configurations, spiral and serpentine, both 1 m long by 50 µm wide and 500 µm tall, were fabricated out of electrodeposited nickel. The hybrid chip allowed injection plugs on the order of 1-2 ms, which lowered the height equivalent to theoretical plates (HETP) and allowed a comparison of system level band broadening between the two column configurations. The gas phase band broadening was estimated by measuring the flow characteristics and peak broadening of an unretained compound, and the results were compared with kinetic models. Experimental results show that both spiral and serpentine column layouts had similar flow and band broadening, suggesting that gas phase band broadening may be independent of column layout. The necessity for narrow injection bands for fast micro-chip chromatographic analysis was demonstrated, which emphasized the importance of component integration in designing powerful micro-analytical systems.