West Coast Of South Africa Research Articles

Fostering Family Resilience: A Community Participatory Action Research Perspective

ABSTRACT Theoretically, increasing family resilience, may contribute to an increase the resilience of communities. However families in South Africa experience challenges to their resilience, often owing to a variety of historic, socio-economic, and political factors. Research and intervention planning that attempts to ameliorate the effects these factors, especially upon families who live within disenfranchised communities, should begin with a consideration of the relationships between researcher and community stakeholders. The aim of this paper is to discuss lessons learned during the process of intervention development in which the whole community (should they choose to) can participate. The Family Resilience Strengthening Programme is an intervention that was developed with the aim of strengthening family resilience processes using a participatory action research approach (PAR). Participants of this project were from a small, rural community from the West Coast of South Africa. We argue that PAR can be used to foster family resilience and, in so doing, can mobilise communities and their resources to increase community resilience. Key lessons learned during this project is discussed and addresses aspects important in community engagement such as the quality of communication and a unifying of different stakeholder community groups. Moreover, we encourage researchers and practitioners engage with the value that communities contribute to research and intervention planning, and the need to maintain, and further develop, those relationships both throughout and after the research process.

Modelling changes in trophic and structural impacts of alien ecosystem engineers on a rocky-shore island

Between 1980 and 2012, successive arrivals by three alien ecosystem engineers on a rocky shore community at Marcus Island on the west coast of South Africa led to substantial changes in species composition and diversity. An ecosystem analysis of this open intertidal system was developed using Ecopath with Ecosim to determine the impacts of these aliens and the services they provide on the native community. A baseline Ecopath model of the community in 2015 was generated using values of biomass, production/biomass, consumption/biomass and the dietary composition of 30 functional groups. Ecosim, a time-dynamic modelling routine, was then used to simulate the changes in biomass of native species. A 1980 model (pre-invasion) was constructed and 22 simulations were run up to 2015 by systematically adding (1) biomass time series for non-native species; (2) relative biomass time series for native species; (3) mediation functions that mimicked biomass impacts due to changes in substrate, shelter and feeding grounds created by the alien ecosystem engineers; and (4) the effects of wave action as a source of mortality. Positive or negative influences of these ecological processes on diversity and the final biomasses of all groups in 2015 were assessed. Trophic impacts by the alien species affected diversity and biomass at the end of all simulations, but the addition of shelter or a combination of all three ecosystem services provided by ecosystem engineers (shelter, substrate and feeding grounds) resulted in 2015 model ecosystems that most closely matched the diversity and individual group biomasses empirically measured on Marcus Island in 2015. Wave action had only a minor impact. Marcus Island's rocky shore community was therefore driven mainly by the fixed input of alien species biomass and made more realistic by the incorporation of their ecosystem services. However, structural complexity and zonation, explored in a follow-up paper invoking spatial modelling, need to be represented for a more complete realisation of the ecosystem.

Estimation of the environmental impact of Military Exercises on a bombing range by employing radionuclide mapping and drone imaging

A Gamma In Situ Potable Device (GISPI) was used to map naturally occurring radionuclides in an abandoned South African Air Force (SAAF) bombing range on the west coast of South Africa. The concentrations of potassium and radioactive progeny of thorium and uranium were measured and plotted with the help of QGIS software. The results demonstrated changes in radionuclide concentrations in specific areas of the ranges. These areas were correlated with areas where weapon testing and live bombing exercises were conducted. The areas were also surveyed and photographed with a drone. The article finally draws conclusions as to the environmental impact of the bombing on the area. This method can be used to investigate other bombing ranges in future quickly and effectively.

Using multiple tracers and geological techniques to determine the connectivity between aquifer systems, West Coast, South Africa

Langebaan Road and Elandsfontein aquifer found in the West Coast of South Africa was used as the case study. Previous studies on groundwater excluded focusing on ideal methods used to determine aquifer connectivity which is the focus on the current study. Aquifer connectivity in this case study is vital as there are human activities and ecosystems which are proved to be groundwater dependent. Aquifer-aquifer interaction refers to the hydraulic connection between the two aquifers. Factors affecting aquifer connectivity are well known, however appropriate techniques to establish the extent of connectivity remain poorly understood and hence the need to employ various techniques so that the extent of connectivity between the two aquifers is established. A quantitative approach was taken where hydrogeochemical and geological mapping techniques were used to produce a detailed geological conceptual model to describe the groundwater flow direction and aquifer leakage was highlighted. Results showed that Langebaan and Elandsfontein aquifer units have similar chemical signatures with pH ranging from 7.4 to 8.2, EC values ranging from 47 to 379 mS/m, and temperature between 24.6 °C and 28.0 °C. Stable isotope signatures δ18O vs δ2H showed a mixing between confined and unconfined aquifers. Frequency VLF and magnetometer techniques indicated the presence of geological structures that formed preferential groundwater pathways. Results confirmed the lower aquifer units were linked vertically at site-specific and laterally at the confined units. The vertical leakage between the aquifers through the clay layer was more apparent in some areas compared to others. The study has shown that hydrochemical and geophysical techniques seem appropriate techniques to show the connectivity between aquifer units in the groundwater system. Only two techniques were used, the study recommends using a range of techniques in establishing the interaction between aquifer units in a groundwater system.

Holocene variability in climate and oceanic conditions in the winter rainfall zone of South Africa—inferred from a high resolution diatom record from Verlorenvlei

ABSTRACTWe present a diatom record from a well‐dated 15.25 m composite sedimentary core from Verlorenvlei, a shallow coastal lake on the west coast of South Africa. We show that fluctuations in the diatom record occur in response to changes in sea level, ocean–atmosphere interactions and latitudinal shifts in the wind belts. During the early to mid‐Holocene, the system primarily responds to sea level changes. A marine community that favours high nutrients is evident, particularly during 9200–8000, 7420–7000 and 6200–5600 cal a bp, corroborating periods of Benguela upwelling linked to fluctuations in the southeast trade winds. Increases in bioproductivity (%TOC, C/N) and fresher‐water diatoms are associated with wetter conditions over the region and the northward migration of the southern westerly wind belt, most notably between 8000 and 7500 cal a bp and over the last 700 years. The latter trends are concomitant with changes in the extent of Antarctic sea ice and availability of moisture in southern South America. During the late Holocene, as sea levels stabilised to modern levels, climate variability is more strongly evident. The body of evidence further reveals the sensitivity of the region to high‐latitude atmospheric mechanisms, but also showcases the significance of the southeast trade winds.

Origin and genetic diversity of the invasive mussel Semimytilus algosus in South Africa, relative to source populations in Chile and Namibia

Worldwide, the spread of alien species in marine ecosystems has increased, with mussels frequently being involved. In South Africa, 91 alien and 39 cryptic marine and estuarine species, from 17 taxonomic groups, are known. Of these, three are associated with major invasions, including the Pacific mussel, Semimytilus algosus, which has rapidly spread and colonised the lower portions of rocky shores on the west coast. Semimytilus algosus is indigenous to Chile and has been introduced to Namibia. To determine the source and likely mode of introduction of S. algosus, we analysed the population genetic structure of eight populations on the west coast of South Africa and Namibia, as well as three populations in the native Chilean range. Using cytochrome c oxidase subunit I, we collected sequence data from 226 individuals sampled across the 11 localities. We detected no evidence for founder effects, as the South African and Namibian populations had comparable genetic variation to those sampled in Chile, pointing to large effective population sizes and high propagule pressure in the region. It is probable that the Namibian population originated from Chile, and that introduction took place from there to South Africa via a single and substantial natural larval dispersal that breached the biogeographic barrier created by the Luderitz upwelling cell; but we cannot discount the possibility that introduction associated with oyster aquaculture played a role. Based on comparisons with Mytilus galloprovincialis, we predict S. algosus will continue to spread in South Africa but will be confined to temperate regions; reduce limpet abundance by monopolising primary substratum and because it is too small for them to occupy its shells; and supplement food sources for predators such as oystercatchers and dogwhelks.

Field processing and transport costs in shellfish gathering along the Cape west coast

The discard of shells in visible heaps, shell middens in our terminology, need not reflect the consumption locations, but may rather be field processing sites prior to the transport of edible flesh elsewhere, likely inland. The comparison of shell midden locations, sizes and contents from a well-studied section of the Cape west coast of South Africa, against the framework of Metcalf and Barlow's (1992) model of the ‘optimal trade-off between field processing and transport’ leads us to suggest that through time different decisions were made by local shellfish gatherers. In particular, the millennium between 2000 and 3000 years ago stands out as one of deliberate and intense field processing, compared with earlier and later millennia.

Magmatic clasts in the Saldanha ignimbrites, and Trekoskraal beach pebbles: missing pieces from the volcanic puzzle in the Cape Granite Suite

Abstract Previous studies have shown that the 542 Ma Saldanha eruption centre, situated on the west coast of South Africa, consists of the basal Saldanha Ignimbrite, which is partly intermingled with and partly overlain by the Jacobs Bay Ignimbrite, both having S-type characteristics. Together, the Saldanha eruption centre and the Postberg eruption centre (to the south, across Saldanha Bay) form part of the volcanic phase of the Cape Granite Suite. The lowermost parts of the Jacob’s Bay Ignimbrite contain magma clasts that are chemically dissimilar to their host ignimbrites. Some clasts are recrystallized ignimbrites that are chemically distinct from any unit that has outcrop expression, and are inferred to form part of a previously unrecognised volcanic event. Other clasts are non-fragmental, hypabyssal rocks that were evidently intruded prior to the explosive intracaldera eruptions that formed the Saldanha ignimbrites. Beach cobbles and pebbles, sampled from the Trekoskraal coastal area, include three texturally and chemically distinct groups – rhyolitic ignimbrites, rhyolitic hypabyssal rocks and dacitic hypabyssal rocks or lavas. Only a minority of these rocks (from the rhyolitic ignimbrite group) show some chemical affinities with the Saldanha Bay ignimbrites. The other pebble types show neither chemical nor textural similarities with the rocks of either the Saldanha or the Postberg eruption centres. The pebbles and cobbles also have no chemical affinities with any of the granitic intrusive rocks of the region. Their chemical and isotopic characteristics suggest that a variety of different magma batches were formed through partial melting of heterogeneous Malmesbury Group metamorphic rocks, at depth. LA-ICP-MS dating of igneous zircon crystals from two of the pebbles (a low-silica rhyolite ignimbrite and a dacite) yielded magmatic ages of 540 ± 4 Ma and 533 ± 4 Ma, respectively. Taking uncertainty brackets into account, these new dates suggest that there may have been a 3 Myr hiatus in eruptive activity, between the eruptions responsible for the exposed Saldanha ignimbrites and the eruptions that produced the volcanic units from which the pebbles were derived. This confirms the inference that there was a previously unidentified, later, volcanic event associated with the Cape Granite Suite in the Saldanha area.

Seasonal acoustic occurrence, diel‐vocalizing patterns and bioduck call‐type composition of Antarctic minke whales off the west coast of South Africa and the Maud Rise, Antarctica

AbstractSeasonal occurrence, diel‐vocalizing patterns, and call‐types of Antarctic minke whales are described using bio‐acoustic recordings from the west coast of South Africa and the Maud Rise, Antarctica. In Antarctica, minke whale bioduck calls were detected in seven of nine months of hydrophone deployment (peaking in May and September) while downsweeps were only detected in June. Bioduck calls were sporadically detected in South African waters with peak calling in September/October, and no bioducks were detected from March through August. Bioduck call occurrence was high during daytime in Antarctica but there was no diel‐vocalizing pattern in South African waters. We split bioduck B call‐type into two subtypes: B1 with 13 ± 1 pulses (Dominello & Širović, 2016) and B2 with 9 ± 1 pulses (this study). Bioduck B2 was detected both in Antarctic and South African waters, with harmonics up to 2 kHz. Similar bioduck call‐types were detected in Antarctic and South African waters, with bioduck A2 being the most common. Month of the year was the most important predictor of bioduck occurrence both in Antarctic and South African waters. This is the first study to describe the seasonal occurrence, diel‐vocalizing behavior and call‐types of Antarctic minke whales off the South African west coast and eastern Weddell Sea.

Investigating the effects of management practice on mammalian co-occurrence along the West Coast of South Africa.

The subtle and cascading effects (e.g., altered interspecific interactions) that anthropogenic stressors have on local ecological assemblages often go unnoticed but are concerning given their importance in ecosystem function. For example, elimination of buffalo from the Serengeti National Park is suggested to have driven increased abundance of smaller antelope as a result of release from competition. The perceived low abundance of small antelope in the contractual Postberg section of the West Coast National Park (the park) has been an ongoing management concern which has been anecdotally attributed to predation by a mesopredator (the caracal, Caracal caracal). However, we hypothesized that the historical overstocking, and consequent overgrazing by larger-bodied managed ungulates would influence small antelope abundance. Using camera traps, we investigated species co-occurrence and temporal activity between small antelope, managed ungulates and caracals in Postberg as well as another part of the park (Langebaan) and a farm outside of the park. Results suggest that small antelope and managed ungulates have a high degree of temporal overlap (Δ = 0.74, 0.79 and 0.86 for the farm, Langebaan and Postberg respectively), while temporal partitioning between small antelope and caracal is apparent (Δ = 0.59). Further, small antelope and managed ungulates appear to occur independently of one another (SIF = 0.91–1 across areas). Managed ungulates were detected almost three times more frequently on fallow lands when compared to the more vegetated sites within the park suggesting that segregated food/cover resources allow for independent occurrence. Small antelope had a much higher probability of occurrence outside of the protected area (e.g., ψ = 0.192 and 0.486 for steenbok at Postberg, Langebaan compared to 0.841 on the farm), likely due to less variable (more intact) habitat outside of the protected area. There is not sufficient evidence to currently warrant management intervention for predators. The small size of the protected area provides limited scope for spatial replication thus reducing possibilities to infer the cause and effect for complex interactions (which would historically have taken place over much larger areas) with negative implications for adaptive management. We recommend continued monitoring over multiple seasons and a wider area to determine the spatial information requirements to inform management of small protected areas.

Singing in South Africa: monitoring the occurrence of humpback whale (Megaptera novaeangliae) song near the Western Cape

ABSTRACT Humpback whales (Megaptera novaeangliae) are highly vocal, producing a wide repertoire of sounds often organised into song. Song is prolific at breeding sites but also documented along migration routes and at feeding sites, including along the west coast of South Africa (28°–34°S). Here we examine the occurrence of humpback whale song within False Bay, South Africa, using intermittent recording periods from moored hydrophones spanning September 2016 to January 2018. Recordings from four locations were scrutinised for humpback whale vocalisations using long-term spectral averages (LTSAs). In total, 7205 h were examined, with song identified in 3% (211 h) of recording hours. Song was exclusively documented in September and October 2016 and was more prevalent at the most westerly sites. Diel patterns of song presence were modelled, showing the likelihood of detection was higher in the early morning and late evening (GAM: p < 0.05). On 15 occasions, two or more singers were detected with temporally overlapping song components. These results indicate prevalent, albeit seasonal, song production by humpback whales off the coast of South Africa and highlight the utility of passive acoustic monitoring to indicate their presence, behaviour, and potential population linkages in the region.

Measuring the effect of wind-driven processes on coastal dunes: a study of the Atlantis and Geelbek dune fields along the West Coast of South Africa

Dunes are dynamic features that can change location, shape or extent depending on wind direction and strength, the vegetation cover, temperature and moisture. This study focus on the primary factors impacting the change dynamics of sand dunes which are wind direction and wind strength. Two methods exist for measuring and detecting sand dune movements, namely, in situ surveys and change detection through remote sensing. This study applied change detection through remote sensing by using satellite imagery as methodology to monitor the movement and extent of change of two prominent coastal sand dunes located along the West Coast of South Africa. The significance of this study is to highlight the changes that occurred in the Atlantis and Geelbek coastal dune fields over the period 1998 to 2018 ascribable to the effect of wind-driven processes. The results showed that both these two dunes experienced more or less the same extent of movement and the direction of movement correlated well with the direction of the stronger summer wind-driven processes on the West Coast. However, it was also recorded that the extent of change of the dune fields were irregular.

Interactive effects of pH and temperature on native and alien mussels from the west coast of South Africa

Global warming and ocean acidification influence marine calcifying organisms, particularly those with external shells. Among these, mussels may compensate for environmental changes by phenotypic plasticity, but this may entail trade-offs between shell deposition, growth and reproduction. We assessed main and interactive effects of pH and temperature on four mussel species on the west coast of South Africa (33°48′ S, 18°27′ E) in October 2012 by comparing shell dissolution, shell growth, shell breaking force and condition index of two native species, the ribbed mussel Aulacomya atra and the black mussel Choromytilus meridionalis, and two aliens, the Mediterranean mussel Mytilus galloprovincialis and the bisexual mussel Semimytilus algosus. Live mussels and dead shells were exposed for 42 days to seawater of pH 7.5 or 8.0, at 14 °C or 20 °C. Low pH, high temperature and their combination increased shell dissolution of the two aliens but their growth rates and condition indices remained unchanged. Aulacomya atra also experienced greater shell dissolution at a low pH and high temperature, but grew faster in low-pH treatments. For C. meridionalis, shell dissolution was unaffected by pH or temperature; it also grew faster in low-pH treatments, but had a lower condition index in the higher temperature treatment. Shell strength was not determined by thickness alone. In most respects, all four species proved to be robust to short-term reduction of pH and elevation of temperature, but the native species compensated for greater shell dissolution at low pH by increasing growth rate, whereas the aliens did not, so their invasive success cannot be ascribed to benefits accruing from climate change.

Oxygen and temperature influence the distribution of deepwater Cape hake Merluccius paradoxus in the southern Benguela: a GAM analysis of a 10-year time-series

Generalised additive models (GAMs) were applied to survey data to assess the influence of dissolved oxygen, water temperature and year of sampling upon the presence/absence of small (≤15 cm TL), medium (16–34 cm TL) and large (≥35 cm TL) size classes of deepwater Cape hake Merluccius paradoxus captured off the west coast of South Africa. Data were obtained from surveys using the RV Dr Fridtjof Nansen conducted in 2003 and from 2005 to 2013 during summer (January–February). Among the variables investigated, oxygen was the most important for the small size class (juveniles), with both low and high constraints (two-sided, ‘just right’ option), whereas for the medium and large size classes the oxygen effects were one-sided (avoiding lows). This finding, in combination with other published information, suggests that the Orange Banks is a nursery ground for juvenile M. paradoxus and that the area covered by this nursery ground can vary with the optimal oxygen concentration. The temperature constraint was generally wider and weaker than that for oxygen, being two-sided for the small and medium hake and one-sided (avoiding highs) for the large hake. The medium hake displayed the greatest tolerance to the investigated variables, which resulted in the widest distribution for this size class. Temperature, oxygen and sampling year play an important role in determining the distribution of M. paradoxus, but details of the biology (life cycle) of the species, such as its pelagic–demersal transition and associated movements, are no less important.

Variability in stable isotope values of South African Laminariales, Ecklonia maxima and Laminaria pallida, over different spatial and temporal scales

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 628:55-71 (2019) - DOI: https://doi.org/10.3354/meps13096 Variability in stable isotope values of South African Laminariales, Ecklonia maxima and Laminaria pallida, over different spatial and temporal scales David C. Dyer1,*, Mike J. Butler2, Albertus J. Smit3,4, Robert J. Anderson1,5, John J. Bolton1 1Biological Sciences Department, University of Cape Town, Private Bag X3, Rondebosch, 7701, South Africa 2Environmental Isotope Laboratory, iThemba LABS, Private Bag 11, WITS, Johannesburg, 2050, South Africa 3Biodiversity and Conservation Biology Programme, University of the Western Cape, Private Bag X17, Bellville, 7535, South Africa 4South African Environmental Observation Network, Elwandle Coastal Node, Port Elizabeth, 6031, South Africa 5African Centre for Coastal Palaeoscience, Nelson Mandela University, PO Box 77000, Port Elizabeth, 6031, South Africa *Corresponding author: dcdyer007@gmail.com ABSTRACT: Kelp forests are some of the most productive habitats in the oceans, supporting diverse, ecologically, and often commercially, important ecosystems. This study of 8 geographically separate sites in 2 seasons highlights the natural variability of stable isotope values (δ13C and δ15N), at different spatial and temporal scales, within the 2 dominant kelp species along the west coast of South Africa. Additionally, stable isotope variability was investigated within and among different tissues within both kelp species. Within a kelp plant, δ13C values had a variance of 1.7‰ for Ecklonia maxima and 1.5‰ for Laminaria pallida. The δ15N values had a variance of 3.8‰ for E. maxima and 4.2‰ for L. pallida. There were also consistent variability patterns along the length of a single frond in both species, for both isotopes. Among the localities, E. maxima and L. pallida were highly variable with variances in δ13C (9.4‰ and 11.2‰) and δ15N (3.4‰ and 4.5‰) for the 2 species respectively. The δ13C values of L. pallida and E. maxima displayed a clear pattern coinciding with depth, particularly for L. pallida. Within-site variability was a major contributor to the overall spatial variability for both species. This study provides further evidence for the importance of understanding basal variability of stable isotope values when determining the carbon sources of bottom-up controlled ecosystems. KEY WORDS: δ13C · δ15N · Laminariales · South Africa Full text in pdf format PreviousNextCite this article as: Dyer DC, Butler MJ, Smit AJ, Anderson RJ, Bolton JJ (2019) Variability in stable isotope values of South African Laminariales, Ecklonia maxima and Laminaria pallida, over different spatial and temporal scales. Mar Ecol Prog Ser 628:55-71. https://doi.org/10.3354/meps13096 Export citation Mail this link - Contents Mailing Lists - RSS Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 628. Online publication date: October 10, 2019 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2019 Inter-Research.

Prevalence of Kudoa thyrsites (Myxozoa) in South African sardine Sardinops sagax, kingklip Genypterus capensis, and Cape hakes Merluccius capensis and M. paradoxus

Prevalence of infection with the myxozoan parasite Kudoa thyrsites is not well documented in sardine Sardinops sagax, the Cape hakes Merluccius capensis and M. paradoxus, and kingklip Genypterus capensis. Quantitative polymerase chain reaction assays were used to determine the prevalence of K. thyrsites in wild-caught S. sagax (n = 296), Merluccius spp. (n = 162) and G. capensis (n = 70), harvested in 2015. Sardinops sagax were harvested from the east, south and west coasts of South Africa, whereas M. capensis, M. paradoxus and G. capensis were taken from the west coast only. Relationships between K. thyrsites infection prevalence and fish capture locality, season, sex and size were determined with Chi-square tests. Prevalence was highest in S. sagax (91%), followed by M. capensis and M. paradoxus (87%) and G. capensis (40%). Prevalence was independent of sex of the host for all fish species. In the case of S. sagax only, the prevalence of infection was independent of locality of capture but depended on season, with prevalence lowest during spring and highest during autumn. No significant relationship (p > 0.05) was found between infection prevalence and host size for any of the fish species.

Age, growth and per-recruit stock assessment of southern mullet Chelon richardsonii in Saldanha Bay and Langebaan Lagoon, South Africa

The southern mullet Chelon richardsonii (Mugilidae) is the main target species of the inshore net fishery (gillnet and beach-seine) on the west coast of South Africa. The stock has displayed symptoms of overfishing, with a 28% reduction in the standardised catch per unit effort (CPUE) between 2008 and 2016, and a 36.5-mm reduction in mean total length (TL) of fish in the commercial catch between 1998 and 2017. The socioeconomic importance of the inshore net fishery and concern regarding stock status necessitated an assessment of the C. richardsonii stock. This work presents an update of the life-history parameters and the first stock assessment of C. richardsonii at the centre of its distribution—Saldanha Bay and Langebaan Lagoon—using CPUE standardisation and per-recruit analysis. The sexes exhibited distinctive growth, with females growing larger, and their length-at-first-maturity was estimated at 205 mm TL, corresponding to age 2 years. Estimated natural mortality was 0.718 y–1, total mortality was 1.599 y–1, and fishing mortality was 0.881 y–1. Current spawner- biomass-per-recruit was estimated at 24.5% of the pristine (unfished) levels, indicating a stock at risk of recruitment failure. An increase in the minimum stretched mesh size of the gillnets to 51 mm and a reduction in fishing mortality to 0.60 y–1 (approximately 30%) would facilitate the recovery of the spawner biomass to the target of 40% of pristine (SB40).

New species in the sponge genus Tsitsikamma (Poecilosclerida, Latrunculiidae) from South Africa.

The genus Tsitsikamma Samaai & Kelly, 2002 is to date exclusively reported from South Africa. Three species are known from the southern coast: Tsitsikamma favus Samaai & Kelly, 2002, from the Garden Route National Park Tsitsikamma Marine Protected Area (MPA) and Algoa Bay; T. pedunculata Samaai, Gibbons, Kelly and Davies-Coleman, 2003, collected from Cape Recife in St. Francis Bay, and T. scurra Samaai, Gibbons, Kelly and Davies-Coleman, 2003, collected from a wreck site in a small bay west of Hout Bay on the west coast of South Africa. Here two new species are described: Tsitsikamma michaeli Parker-Nance, sp. nov., a small green purse-like species, collected from Algoa Bay, and Tsitsikamma nguni Parker-Nance, sp. nov., from The Garden Route National Park, Tsitsikamma MPA. Additional morphological characteristics, spicule morphology, and distribution records are provided for T. favus and T. pedunculata from Algoa Bay. The phylogenetic relationship of these five Tsitsikamma species is investigated.

A modelling approach to improving water security in a drought-prone area, West Coast, South Africa

Due to severe droughts and rapid urbanization, Cape Town municipality including small towns along the West Coast of South Africa are facing water shortages. Managed aquifer recharge (MAR) seems to offer a solution to improve water security in this drought-prone area. This paper presents a conceptual framework within which numerical modelling of the aquifers system is operated to improve water security of West Coast. The ModelMuse software that included MODFLOW and MODPATH packages was used. Scenarios which considered recharge aspects were used to evaluate suitable sites and appropriate scheme of implementing MAR. The result showed that it is feasible to implement MAR in the upper unconfined aquifer unit (UAU) which had estimated available space for MAR of 915.7 million m3. For the semi-confined lower aquifer unit (LAU), the clay-missing window area located at west of Hopefield was a suitable site to implement MAR. However, the prevailing little space in LAU to store recharged water was a limiting factor to support the implementation of MAR scheme. Details on the possibility of implementing MAR scheme for West Coast aquifers system were discussed based of the simulations that were carried out. Although the modelling approach does not provide precise areas but a management tool, it provides key insights that are applicable in aquifer systems of similar characteristics.

Site Assessment for MAR through GIS and Modeling in West Coast, South Africa

Towns along the West Coast of South Africa are facing water shortages due to climate change and increasing water demand. Managed aquifer recharge (MAR) is considered as a solution to improve water security. This paper presents a two-step method of combining geographic information system (GIS) based analysis with numerical modeling to select suitable sites for implementing MAR in the West Coast area. Many factors were taken into account to generate the initial map for suitable sites through GIS based analysis. Subsequently, groundwater flow modeling was adopted to verify and optimize the suitable sites selected by GIS based analysis. The result showed that the map for suitable sites produced by the GIS based analysis was reasonable from a spatial aspect, but due to the lack of groundwater seepage information, the most suitable sites developed are not necessarily the optimal choices in practice. With the aid of both the spatial analysis in GIS and seepage simulation, this two-step analysis approach provides a reliable solution to identify suitable sites for implementing MAR. This approach provides a much better reference to the study of suitable sites and possible impacts of implementing MAR in an aquifer in similar areas with water stress.