•Subtropical-temperate coastal forested wetlands of Africa are threatened.•These swamp and floodplain forests are very likely Critically Endangered.•Traditional conservation methods have failed to ...protect these wetlands.
Africa’s range-restricted and transitional subtropical-temperate coastal forested wetlands are facing interlinking threats of climate and anthropogenic pressures. We assessed their conservation status using the criteria of the International Union for Conservation of Nature (IUCN). Their total areal extent was hind-casted to the reference epoch 2000, followed by the quantification of subsequent total losses in areal extents for the epochs 2005, 2008, 2011 and 2017. South Africa had 120 km2 of coastal swamp and floodplain forests in 2000 of which the majority (116.5 km2) occurred on the Maputaland Coastal Plain (MCP). By 2011, 20% of the areal extent was lost, and at the lowest rate of decline we estimate that ≥ 80% of the rest will be lost in the next 50 years. An ecosystem collapse assessment therefore indicated that the habitat is very likely Critically Endangered. Fragmentation and types of transformations were used as degradation indices to show functional collapse. These results showed that forest patches became increasingly fragmented, from 511 to 1145 patches between 2000 and 2017 and that > 23% of the areal extent showed severe transformation. Several faunal species, with a close association to the forested wetlands of the MCP, are considered threatened with numbers declining because of transformation to timber plantations or agriculture and coupled with a prolonged drought. Of these, a sub-species of the Samango monkey, Cercopithecus mitis erythrarchus, considered to be a primary ecosystem engineer of the habitat, was red listed with a restricted distribution, being endemic, Near Threatened and declining. Also under pressure, because of habitat fragmentation and degradation is the Peregrine crab (Varuna litterata), a euryhaline species requiring connectivity across the land-seascape, ranging from freshwater forested wetlands to estuarine and off-shore environments. Functionally, these coastal forested wetlands are therefore also considered Critically Endangered. The final IUCN conservation status of South Africa’s subtropical-temperate coastal forested wetlands are recommended to be very likely Critically Endangered. Irrespective of 62% of the areal extent of these forested wetlands being within protected areas, severe degradation (metrics of fragmentation and transformation) were observed even inside these areas for the past two decades. The conservation conundrum is that despite existing legislation and management measures, there has been no stop or reversal of the negative trends to date. As a supplementary method, we therefore recommend a transdisciplinary community-based approach to conservation practice, continued and improved monitoring of the habitat losses, the identifying priority areas for rehabilitation and addressing data deficiencies in important species associations.
The monthly responses of macrophytes in the East Kleinemonde Estuary were examined in relation to changes in physical factors between March 2006 and March 2007. The East Kleinemonde is a small ...temporarily open/closed system where the mouth breaches in response to high water levels (>2
m amsl) or following high river inflow. On breaching there is a rapid drop in water level that causes the submerged macrophytes to be exposed and they die as a result of desiccation. Salt marsh plants then establish in the vacant habitat. Correlation analysis showed that water level and duration of inundation influenced macrophyte cover abundance. Inundation for 3
months caused die-back of intertidal salt marsh. Under open and tidal conditions, intertidal salt marsh increased at a maximum monthly expansion rate of 25% change in cover. Supratidal salt marsh expanded at maximum monthly rates of 33% change in cover. Because of its position at a relatively high elevation compared to other vegetation, supratidal salt marsh was only affected by water levels of >1.8
m amsl and only after being inundated for 1–2
months. Submerged macrophytes developed in inundated areas when stable water levels were present for longer than 2
months at a monthly maximum expansion rate of 23% cover change. In this study macrophytes responded quickly to water level fluctuations and indicate that monthly monitoring is needed to provide an understanding of macrophyte response. This is the first study that reports on rates of macrophyte habitat development in temporarily open/closed estuaries. These data can be used in mouth management plans and freshwater requirement studies to predict the growth and establishment of a diversity of macrophyte habitats.
Light is a fundamental cue regulating a host of biological responses. The artificial modification thereof demonstrably impacts a wide range of organisms. The use of artificial light is changing in ...type, extent and intensity. Insect vector-borne diseases remain a global scourge, but surprisingly few studies have directly investigated the interactions between artificial light and disease vectors, such as mosquitoes. Here we briefly overview the progress to date, which highlights that artificial light must be considered as a modulator of mosquito-borne disease risk. We discuss where the mechanisms may lie, and where future research could usefully be directed, particularly in advancing understanding of the biological effects of the light environment. Further understanding of how artificial light may modulate mosquito-borne disease risk may assist in employing and redesigning light regimes that do not increase, and may even mitigate, already significant disease burdens, especially in the developing world.
Temporarily open/closed estuaries typically open to the sea due to freshwater inflow coupled with storm surge events. In September 2008, in the absence of freshwater inflow, the mouth of the East ...Kleinemonde Estuary breached in response to a storm surge. The mouth of the estuary closed the following day at a high level. Marine overwash events following the breach introduced large volumes of saline water into the estuary and raised the water level by 0.07–0.33
m. Salinity was significantly higher in the 15 month closed phase after the breach (31
±
0.9) compared to 21.9
±
0.9 in the closed brackish phase before the breach. The historical average salinity for the estuary during a closed period is 23–25. The increase in salinity has reduced submerged macrophytes
Ruppia cirrhosa and
Chara vulgaris cover by 38.1%. Macroalgal cover of species such as
Dictyota dichotoma,
Caulacanthus ustulatus,
Codium tenue and
Ulva spp. have increased by 7.9%. The saline high water levels have also significantly reduced supratidal salt marsh cover by 15.2%, and reed and sedge cover by 19.7%. Loss of these habitats may result in bank destabilisation and erosion. This is the first record of an extended saline period in the 15 years the estuary has been monitored. Sea level rise in association with climate change, together with localised freshwater inflow reduction is likely to result in an increase in marine overwash events. The frequency and duration of closed saline periods are likely to increase in this type of estuary. A loss of submerged macrophytes may have significant impacts on faunal composition and abundance and on the subsequent functioning of temporarily open/closed estuaries. This has serious ecological implications since these estuaries represent 70% of the different types of estuaries found in South Africa.
The seed banks of two temporarily open/closed estuaries in South Africa were quantified in this study. Charophyte öospores represented almost 72% of the sexual propagules in the sediment with a mean ...öospore density of 31,306
öospores
m
−2. This was followed by the seeds of the intertidal salt marsh plant
Sarcocornia perennis (18%) (7929
seed
m
−2) and the submerged angiosperm
Ruppia cirrhosa (7%) (2852
seeds
m
−2). The remaining 3% was made up of a mixture of species such as
Salicornia meyeriana,
Sporobolus virginicus,
Stukenia pectinata,
Bolboschoenus maritimus and terrestrial species. Although seed density did not differ significantly with depth, seeds still occurred at 20
cm depth providing a regeneration source in the event of sediment disturbance. Three salinity (0, 17 and 35
PSU) and moisture treatments (exposed, waterlogged and submerged) were applied to collected sediment to determine how fast species would germinate.
S. perennis germinated after 3 d to a maximum of 82%. Submerged species began to germinate only after 18 d (
Chara vulgaris and
R. cirrhosa) and had low germination percentages of between 11 and 15% after 91 d. Results from this study indicate that in the event of unpredictable disturbance events such as water level fluctuations, large sediment seed reserves would ensure habitat persistence.
Spartina alterniflora Loisel., widely recognised as an aggressive invader of estuaries and salt marshes around the world, was discovered growing in the temporarily open/closed Great Brak Estuary on ...the southern Cape coast of South Africa in 2004. This is the first record of this invasive plant in Africa as well as its first occurrence in an estuary that closes to the sea. Plant traits and sediment characteristics were measured in 2009 and 2011 and found to be comparable to those reported elsewhere. Prior to the 2011 sampling, S. alterniflora stands had been flooded for almost eight months. As a result, sediment redox potential (−268 + 4 mV) was significantly lower in 2011. Sediments were mostly clay in 2009 (71 ± 0.01%) compared to a predominance of sand in 2011 (40 ± 0.02%). These differences were related to the artificial breaching of the estuary one month prior to sampling in March 2011. The grass currently occupies 1.1 ha in the salt marsh, sandflat and mudflat habitats of the estuary where its cover is expanding at a rate of 0.162 ha y
−1
. Individual stands numbered about 12 in 2006, but have increased to 24 in 2011. These stands are expanding laterally at 0.9 m y
−1
although the long period of inundation during 2010 reduced this to 0.6 m y
−1
. Expansion is due to vegetative spread as an analysis of the sediment seed bank showed no S. alterniflora seeds and very few salt marsh seeds (1 132 seeds m
−2
). If left unchecked, S. alterniflora has the potential to replace 42.9 ha or 41% of the total estuary habitat in the Great Brak Estuary, but also has the potential to invade other estuaries in South Africa, especially those with extensive intertidal habitat and containing S. maritima (19 estuaries in total). This study illustrates the adaptive potential of this invasive marsh plant and indicates the possibility of invasion in seasonally closed estuaries in other locations around the world.
The spatial distribution of mangroves in the Mngazana Estuary under sea level rise induced by climate change, together with different substrate elevation change scenarios was predicted for 2020, 2050 ...and 2100. The present inundation frequency tolerance range was from 0.8 to 31.2 %, equivalent to substrate elevation thresholds of 1.1 and 1.7 m amsl. These thresholds were measured by field surveys and analysis of a gauge station situated near the mouth of the estuary. The predictions were based on the assumption that the inundation frequency tolerance range of mangrove stands remains constant in the future. Through the use of a digital elevation model an initial increase of 2.10 ha year⁻¹ was found in mangrove area between present and 2020 (from 122.6 to 143.6 ha). This was due to habitat becoming available that is currently too compacted for seedling establishment to occur. This compaction resulted from human and cattle traffic for grazing. Thereafter there would be a mean loss of 0.66 ha year⁻¹ from 2020 through 2100. Landward migration of mangroves would not take place due to the elevation limit of adjacent non-mangrove areas. In addition, the loss rate would increase to 1.01 ha year⁻¹ under insufficient sediment accretion, but would decrease to 0.18 ha year⁻¹ under thriving mangroves condition. The analysis of sea storm event in September 2008 showed that local water level increased by 28 cm and maximum affected area was 87.0 ha (about 71 % of mangrove stands). The inundation continued over 5 days. The results indicated that the combination impact of sea level rise, substrate elevation change and sea storm would possibly be a threat to tropical African estuaries with large flat intertidal areas and mangroves.
► The growth and phenology of two submerged macrophytes were monitored in a small estuary. ► The estuary has large variations occur in water level and salinity. ► Water level increased life cycle ...length and reproductive output. ► Plants make use of stable conditions in an unpredictable environment.
The study investigated the phenology of Ruppia cirrhosa (Petagna) Grande and Chara sp. in the East Kleinemonde Estuary, a warm temperate temporarily open/closed estuary (TOCE) along the south-eastern coastline of South Africa. Monthly growth and sexual reproduction were monitored over a 17 month period, including environmental conditions. The estuary was closed to the sea for the duration of the study and inundation of the submerged habitat ranged from 6 to 86cm. Both species began to germinate in Autumn 2009 (April and May) once the submerged habitat had been flooded for one month. R. cirrhosa began to produce viable seed after five months and production occurred over a four month Spring–Summer period. Maximum seed production occurred in late Spring (26,242±3401seedsm−2). It took C. sp. three months to start producing viable oogonia with production taking place over seven months, from late winter late Summer with a maximum of 196,998±48,004oogoniam−2 produced. Peak biomass was attained during Spring to mid-Summer when R. cirrhosa reached 2248±388gDWm−2 and C. sp. 142±34gDWm−2, eight and six months after germination, respectively. Multivariate analysis showed that both biomass and reproductive output increased as water level and pH did. In conclusion, the high biomass and reproductive output of both submerged species under continued water permanence maintains large seed banks for habitat persistence during open mouth states when submerged beds are lost through exposure. This is an important survival strategy in small estuaries where water level fluctuates in response to unpredictable mouth breaching and mouth closure events.
Transferability of economic evaluations to low- and middle-income countries through adaptation of models is important; however, several methodological and practical challenges remain. Given its ...significant costs and the quality-of-life burden to patients, adjuvant treatment of early breast cancer was identified as a priority intervention by the South African National Department of Health. This study assessed the cost-effectiveness of docetaxel and paclitaxel-containing chemotherapy regimens (taxanes) compared with standard (non-taxane) treatments.
A cost-utility analysis was undertaken based on a UK 6-health-state Markov model adapted for South Africa using the Mullins checklist. The analysis assumed a 35-year time horizon. The model was populated with clinical effectiveness data (hazard ratios, recurrence rates, and adverse events) using direct comparisons from clinical trials. Resource use patterns and unit costs for estimating cost parameters (drugs, diagnostics, consumables, personnel) were obtained from South Africa. Uncertainty was assessed using probabilistic and deterministic sensitivity analyses.
The incremental cost per patient for the docetaxel regimen compared with standard treatment was R6774. The incremental quality-adjusted life years (QALYs) were 0.24, generating an incremental cost-effectiveness ratio of R28430 per QALY. The cost of the paclitaxel regimen compared with standard treatment was estimated as −R578 and −R1512, producing an additional 0.03 and 0.025 QALYs, based on 2 trials. Paclitaxel, therefore, appears to be a dominant intervention. The base case results were robust to all sensitivity analyses.
Based on the adapted model, docetaxel and paclitaxel are predicted to be cost-effective as adjuvant treatment for early breast cancer in South Africa.
•A range of methods for transferability of economic evaluations are available; however, many methodological and practical challenges remain. Using cost data from South Africa in an adapted UK model suggests that docetaxel-containing chemotherapy regimens (docetaxel, doxorubicin, cyclophosphamide) produce an additional 0.24 quality-adjusted life years (QALYs) at an extra total cost of R6774 per patient compared to standard non-taxane regimens (fluorouracil, doxorubicin, cyclophosphamide). This is expected to generate R8.3 million of net monetary benefit for 1000 women over a 35-year period.•A paclitaxel regimen (doxorubicin, cyclophosphamide, paclitaxel) is less costly and more effective compared with standard non-taxane regimen (doxorubicin, cyclophosphamide). This is expected to produce additional 0.025 to 0.03 QALYs while reducing cost by R578 to R1512 per patient, leading to a net monetary benefit of R2.5 to R3.0 million per 1000 women over a 35-year period.•Model adaptation from high-income countries to middle-income countries contexts is possible but not easy and may need considerable resources.
PDF
