1834 research outputs found
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Evaluating the importance of mangroves as fish nurseries in selected warm temperate South African estuaries
No full textThe value of mangrove habitats as fish nurseries was assessed by comparing communities of early stage and juvenile fishes between estuaries with and without mangroves. Early stage fishes were sampled using boat-based plankton towing while juveniles were sampled by seine netting. Sampling took place at five sites spaced 1 km apart starting near the estuary mouth in four estuaries along the temperate coastline of the Eastern Cape Province of South Africa. Four estuaries were selected based on shared similarities which included catchment area, estuarine area and shared habitats barring the presence of mangroves which occupied the river margins of two systems. Results revealed that early stage and juvenile fish communities (both marine- and estuary-spawned) were similar between systems with and without mangrove habitats. Differences in fish communities among estuaries were rather attributed to axial salinity gradients associated with greater freshwater input, while season and temperature produced significant variances in fish densities with Generalised Additive Models revealing responses of communities to these variables. A common estuarine-dependent fish, Rhabdosargus holubi (Family Sparidae), was further investigated to determine habitat use, residency and dietary patterns in different mangrove habitats. High habitat residency in this species was revealed during a short-term tagging study using Visible Implant Elastomer tags and long-term isotope analysis in juveniles sampled from two contrasting mangrove habitats. A wider feeding niche was observed in an eelgrass-red mangrove connected habitat when compared with more exposed white mangrove areas. Low dependence on mangrove habitats in temperate estuaries is likely due to their tidally dominated inundation and limited refuge potential due to smaller area coverage by mangroves in temperate estuaries. Relatively lower primary productivity in warm temperate mangrove areas, relative to their tropical counterparts, provides no significant feeding advantage or refuge opportunities relative to other available habitats in these estuaries. Warm temperate estuaries, which are both spatially and temporally highly variable, instead host species which are habitat generalists, able to capitalise on these highly dynamic environments.National Research Foundatio
NRF open access statement : implications for grantees’ research output submissions and dissemination
No full textSouth African Research Chairs initiative, North West & Limpopo Regional Workshop
Venue: NRF, Albert Luthuli Auditorium, 2 March 2017
The global eye: international relations and cooperation newsletter edition three 2017
No full textThe Global Eye: International Relations and Cooperations Newsletter. Third Edition, 2017, Science: Africa: Societ
Scaling patterns and drivers of anuran diversity across the afrotropics
No full textUnderstanding the broad scale patterns and environmental determinants of amphibian richness
(α-diversity) and turnover (β-diversity) is becoming ever more crucial as communities,
ecosystems and landscapes are increasingly threatened by anthropogenic processes and climate
change. Spatial scale, the grain at which sampling takes place or analysis occurs, confounds
understanding of such diversity patterns and the relationships these exhibit with environmental
processes. This is because various processes operate at different spatial scales resulting in
different patterns emerging at different spatial scales. This is problematic, because patterns, and
pattern-process’ relationships which emerge at one scale may not hold at another scale thereby
confounding our understanding of how biotic patterns are generated and maintained, thus leading
to misguided conservation strategies and policies. The focus of the present study was thus to
examine the relationship between present patterns of anuran richness and turnover, the
relationship of these with several contemporary environmental processes, and how these patterns
and pattern-process relationships are influenced by spatial grain.
Using IUCN range data for the Afrotropical region, amphibian richness and turnover patterns
were generated using a Geographic Information System and quantified using the recently
formulated zeta diversity partitioning method (ζ). These patterns were then related to several
contemporary environmental variables/processes hypothesised to govern amphibian diversity
across a range of spatial scales using both the global Ordinary Least Squares (OLS) method and
local spatial Geographically Weighted Regression (GWR) across three nested spatial grains.
The results show that amphibian richness and turnover patterns (visual & empirical) and the
relationships these exhibit with environmental conditions were sensitive to spatial grain.
Visually, spatial patterns were more distinct at finer grains, but visibly smooth at the coarser
grains. The statistics describing these patterns suggest that the scaling behaviour follows an
increasing linear and nonlinear trend across spatial grain. Results from both the OLS and GWR
models confirm that contemporary environmental conditions are significant determinants of both
anuran richness and turnover patterns across spatial grain. Precipitation was the strongest
determinant of anuran richness while topographic complexity best explained turnover. The
relationship between both diversity components and environmental conditions, however, was
scale dependent with environmental conditions explaining a greater proportion of the variation in
these biotic patterns at coarser than finer grains. Studies conducted across multiple grains is thus
recommended to improve current understanding of biodiversity patterns and the relationship they
exhibit with environmental processes.National Research Foundatio
Supercontinuum pulse characterisation and compression
No full textThis project centers around the development of infrastructure, speci cally a broadband
white light source, for integration into non-linear microscopes. The broadband light source
needed for such an instrument comprises an all-normal dispersion photonic crystal bre
(ANDi PCF) (which produces a supercontinuum) and a pulse compressor (which produces
the needed ultra short pulses).
Polarisation and power characteristics of the ANDi PCF are investigated in order to
establish the optimal working conditions with the broadest spectral output coinciding
with the highest power throughput. The bandwidth can be increased from about 12 nm
to 200 nm (depending on the pump power) and enables us to decrease the pump pulse
length from about 80 fs to below 10 fs if we are able to fully compress the full bandwidth.
A particularilly suitable pulse characterisation technique, multiphoton intrapulse interference
phase scan (MIIPS), is used to characterise and compress the supercontinuum
pulses produced by the PCF. The e cacy of this technique is computationally and experimentally
tested through computer simulations and laboratory experiments. From the
simulations we see that the MIIPS technique is able to adequately reconstruct the phase
of the supercontinuum pulses which can then be used to compress the pulses.
Experiments performed on bandwidths around ∼ 80 nm, show that the MIIPS algorithm
is able to reconstruct the supercontinuum pulse's phase and in the process compress
it. A measurement of the GVD of a SF6 glass cube with known dispersion is used as supplementary
evidence of the e ectiveness of the MIIPS technique.
A SLM assisted IFROG measurement is performed on the compressed pulses to further
test the degree of compression after MIIPS. This measurement shows a decrease in pulse
length from picosecond regime to ∼ 23 fs. This is near to the Fourier limit of ∼ 12 fs for
these bandwidths.National Research Foundatio
Glocalisation within the media landscape: a study of selected reality television franchises in South Africa and transnational broadcaster Multichoice
No full textSeveral debates have arisen on the concept of globalisation within diverse cultural backgrounds and its consequences on various aspects of culture and social life. These propelled the need for this study. Out of the desire to examine the integrations of these perspectives, glocalisation as a subset of globalisation became the main focus of the study. Glocalisation – a hybrid of global and local ‘consequences’ – serves to bring to view how important elements of a global entity and a local entity can converge to form something inherently unique to each local context as a result of varying practices and norms of different cultures. The implication of this is that those in charge of ‘global entities’ attempt to find ways they can modify ‘global practices’ into diverse ‘local contexts’ while at the same time seek to maintain semblance with the global entity. Therefore, this study conceptualised these entities, practices and consequences within South Africa as a local context, in order to trace how the global entities (transnational corporations as Endemol Shine Africa, Fremantle Media, 19 Entertainment and transnational broadcaster MultiChoice) have adjusted global practices (global reality television franchises as Big Brother, Idols and Survivor) and their consequences (homogenisation/similarities and heterogenisation/uniqueness) within local contexts (the South African media landscape) and how these are guided by certain rules (media regulations on local programmes within South Africa). This was achieved through a desk research of media reports, social media channels, the Internet and literature from scholars on transnational media exchanges. The focus of this study was to identify those factors that made such glocal adaptations different from global formats. These were guided by the theoretical approaches of cultural proximity, the circuit of culture and the political economy of communication in the media. The study ascertained that indeed there are considerations of various local contexts through the identification of glocalised features of the shows. It highlighted the manner MultiChoice has balanced global and local needs and the regulations that guide South African media contents. However, these glocal franchises are still vehicles of the global ideologies of global formats rather than promotion of more cultural and local features.National Research Foundatio
Community structure and trophic relations in marine tufa stromatolite pools of the Eastern Cape
No full textMicrobialites were the dominant life-form of most shallow oceans during the Precambrian. These
structures are formed by the deposition of calcium carbonate by cyanobacteria as well as the binding and
trapping of sediment by these and other microalgae. In modern environments they are scarce due to several
factors, including grazing pressures by metazoans, altered calcium carbonate saturation states of seawater
and competition with macroalgae. The recent discovery of an extensive network of actively accreting
layered microbialites (stromatolites) along the South African coastline is potentially informative from this
perspective. These stromatolites form within the peritidal zone, at the interface of groundwater seepage
and periodic marine incursion, forming pools trapped by the accreting fabric. The aim of this thesis was to
characterise the ecosystem dynamics of a representative selection of the South African locations. During a
comprehensive monthly assessment over an annual cycle, as well as for additional seasonal collections,
physico-chemical measurements were monitored together with biological components such as benthic and
pelagic microalgae as well as the invertebrate fauna inhabiting the stromatolite pools. These components
were then assessed in terms of the potential physical and biological drivers which might explain patterns of
variability. Finally, to link all of the ecosystem components, a food-web analysis was conducted, to
determine the trophic linkages and, importantly, the reliance by the various consumer organisms on the
stromatolite material as a food resource.
Results show that the stromatolite pools are driven by a regular interplay between freshwater and marine
salinity states, this being determined by tidal amplitude and ocean storm cycles. Furthermore, marine
incursion represents the primary source of phosphorus for the stromatolite pools, while available nitrogen
is consistently provided by the freshwater inlet stream at each site. This results in an optimum zone of
primary biomass within the main stromatolite pool supported by nutrient conditions, while the shifts in
salinity state occurring over a weekly tidal schedule likely exclude organisms and macrophytes that are not
halotolerant. This is reflected in the benthic microalgae that form the stromatolite accretions in that they
are primarily driven by salinity conditions, in addition to seasonal patterns. Interestingly, the variable
nutrient conditions, both between sites and temporally, did not contribute as an important driver of the
benthic microalgae but did significantly relate to the pelagic microalgae (phytoplankton). This, together
with the higher biomass of benthic microalgae compared to its pelagic counterpart, suggests that the
stromatolite pools are a benthic-driven system. The short duration of water retention within the
stromatolite pools as a result of the constant freshwater inflow, likely also precludes nutrient build-up and
favours the benthic, sessile ecosystem component, especially the stromatolite-forming microalgae.
In terms of the metazoan infauna, the South African stromatolite pools support a persistent assemblage.
This might be surprising given the apparently destructive influence of grazing and burrowing animals on
microbial mats in terms of restricting the formation of layered accretions. However, metazoans that burrow
within the stromatolite fabric were observed to coexist with clear, layered accretions. This supports the
observations in some other modern microbialite habitats to suggest that metazoan disruption is clearly not the only or primary factor responsible for modern microbialite scarcity. When assessing the possible
drivers of the metazoan community occupying the stromatolite matrix, both salinity patterns and resource
conditions in terms of nutrient supply and macroalgal cover were consistently best related to infaunal
abundance and presence/absence. This further demonstrates the role of salinity conditions in terms of
providing a habitat that is restrictive to most metazoan organisms, while also suggesting that the metazoans
are responding to macroalgal rather than the stromatolite microalgal conditions. To further develop this
observation, the results from the stable isotope work clearly reflect a dominance of pool macroalgae in the
diets of invertebrate consumers, with little to no stromatolite material consumed. This suggests that there is
limited apparent destructive grazing influence by the metazoans on the stromatolite matrix, in addition to
the burrowing bioturbation mentioned previously. Furthermore, the metazoan grazers may be indirectly
benefitting the stromatolites by restricting macroalgal biomass, which might otherwise outcompete its
microalgal counterpart.
This study provides a valuable understanding of benthic-driven peritidal stromatolite ecosystems, and also,
from a geological perspective of past stromatolite habitats, suggests some of the mechanisms as to why
metazoans may be able to coexist with layered microbialites. Given the threats to similar habitats globally,
especially in terms of water resources, management measures necessary to ensure stromatolite persistence
in modern environments such as these are proposed. The possible ecological role of peritidal stromatolite
habitats within the broader environment, as well as recommendations for future work, is also
contextualised.National Research Foundatio
Community perceptions of child sexual assault : case study of Ngangelizwe community In Mthatha Eastern Cape
No full textNumerous studies have been done on child sexual violence/abuse (CSV/A). Sexual victimization of minors remains a constant problem globally. Section 28(1) (d) of the Constitution of the Republic of South Africa, Act 108 of 1996 (South Africa, 1996) provides that every child has the right to be safeguard from ill-treatment, desertion, exploitation and degradation. November 2014 marked the 25th anniversary of the United Nations (UN) Convention on the Rights of the Child (CRC). On this occasion, the South African Human Rights Commission (SAHRC) called on the
South African government to once again prioritise children’s rights as a key government agenda, to commit to its obligations under the CRC, to uphold the promise made to South Africa’s children by the late Nelson Mandela, and to heed his powerful words: “History will judge us by the differences we make in the everyday lives of children”.
In-depth interviews were conducted with 20 community members of Ngangelizwe Township in Mthatha, Eastern Cape province. The interviews were held in the period August 2016 - September 2016. The aim of the investigation was to determine the social, biological, and psychological effects of child sexual offences on children and as well as their parents, families, and the community at large. The study explored the authentic views of Township people, as there is limited scholarly literature on child sexual abuse and particularly on the experiences of Township residents of this atrocious act. Community members shared their views on the effects of child sexual assault, and there was common agreement that the sexual abuse of a child destroys the psychological and physical well-being not only of the child, but also of the parents. Sexually abused children show signs of depression, anxiety, suicidal thoughts, mental disturbance, and post-traumatic stress disorder. They also lose focus at school and they often isolate themselves from other children. These children lose trust not only in the person who sexually abused them, but in all older people, as it is usually adults who perpetrate this crime. Sexually abused children experience memory loss, always live in fear, and experience anxiety disorders long after the event.National Research Foundatio
Thermal sensitivity of the crab Neosarmatium africanum in tropical and temperate mangroves on the east coast of Africa
No full textMangrove forests are amongst the tropical marine ecosystems most severely affected by rapid environmental change, and the activities of key associated macrobenthic species contribute to their ecological resilience. Along the east coast of Africa, the amphibious sesarmid crab Neosarmatium africanum (=meinerti) plays a pivotal role in mangrove ecosystem functioning through carbon cycling and sediment bioturbation. In the face of rapid climate change, identifying the sensitivity and vulnerability to global warming of this species is of increasing importance. Based on a latitudinal comparison, we measured the thermal sensitivity of a tropical and a temperate population of N. africanum, testing specimens at the centre and southern limit of its distribution, respectively. We measured metabolic oxygen consumption and haemolymph dissolved oxygen content during air and water breathing within a temperature range that matched the natural environmental conditions. The results indicate different thermal sensitivities in the physiological responses of N. africanum from tropical and temperate populations, especially during air breathing. The differences observed in the thermal physiology between the two populations suggest that the effect of global warming on this important mangrove species may be different under different climate regimes.Intra-European Fellowship (ex Marie Curie) Number 221017, FP
