Southeastern Africa Research Articles

Crustal seismic structure and anisotropy of Madagascar and southeastern Africa using receiver function harmonics: interplay of inherited local heterogeneities and current regional stress

SummaryThis study investigates the seismic structure and anisotropy in the crust beneath Madagascar and southeastern Africa, using receiver functions. The understanding of seismic anisotropy is essential for imaging past and present deformation in the lithosphere–asthenosphere system. In the upper mantle, seismic anisotropy mainly results from the orientation of olivine, which deforms under tectonic (fossil anisotropy) or flow processes (in the asthenosphere). In the crust, the crystallographic alignment of amphiboles, feldspars (plagioclase) or micas or the alignment of heterogeneities such as fractures, add to a complex geometry, which results in challenges to understanding the Earth's shallow structure. The decomposition of receiver functions into backazimuth harmonics allows to characterize orientations of lithospheric structure responsible for azimuthally varying seismic signals, such as a dipping isotropic velocity contrasts or layers of azimuthal seismic anisotropy. By analysing receiver function harmonics from records of 48 permanent or temporary stations this study reveals significant azimuthally varying signals within the upper crust of Madagascar and southeastern Africa. At 30 stations crustal anisotropy dominates the harmonics while the signature of a dipping isotropic contrast is dominant at the remaining 18 stations. However, all stations’ backazimuth harmonics show complex signals involving both dipping isotropic and shallow anisotropic contrasts or more than one source of anisotropy at shallow depth. Our calculated orientations for the crust are therefore interpreted as reflecting either the average or the interplay of several sources of azimuthally varying signals depending of their strength. However, comparing information between stations allows us to draw the same conclusions regionally: in both southern Africa and Madagascar our measurements reflect the interplay between local, inherited structural heterogeneities and crustal seismic anisotropy generated by the current extensional stress field imposed by the southward propagation of the East-African Rift System. A final comparison of our crustal orientations with SKS orientations attributed to mantle deformation further probes the interplay of crustal and mantle anisotropy on SKS measurements.

Climate change risk to southern African wild food plants

Climate change is a threat to food security. Wild-harvested food plants (WFPs) are important for the diets of millions of people and contribute to food security, especially in rural and low-income communities, but little is known about climate change risk to WFPs. Using species distribution models, we examined climate change risk to 1190 WFP species used by 19 native language groups in southern Africa. We project that 60% of species will experience an increase (40% a decrease) in range extent within southern Africa by 2060–2080 under a low warming scenario (Representative Concentration Pathway (RCP) 2.6), while range reductions for 66% of species are projected under a high warming scenario (RCP 8.5). Decreases in geographic range are projected for > 70% of WFP species traditionally used by some language groups. Loss of suitable climatic conditions is projected to decrease WFP species richness most in north-eastern southern Africa—with losses of > 200 species—while increases in species richness are projected in the south and east of South Africa. Availability of WFP species for food security during lean times is also projected to change. In south-eastern South Africa, local diversity of WFPs is projected to increase, while maize and sorghum yields decrease. However, this potential WFP nutritional safety net may be lost in central parts of the region, where declines in both crop yield and WFPs are projected. By looking beyond conventional crops to the exceptional diversity of WFPs, this research helps understanding linkages between WFPs, traditional knowledge, food security and climate change adaptation.

Mortality among birds and bats during an extreme heat event in eastern South Africa

AbstractHeat‐related mortality events involving birds and bats are projected to occur more frequently as a result of anthropogenic global heating. Reports of mass mortalities associated with extreme heat have, over the last decade, mostly involved Australian birds and pteropodid flying‐foxes. Here, we report a mortality event involving ~110 birds and fruit bats in eastern South Africa in early November 2020 when maximum air temperatures (Tmax) reached 43–45°C and relative humidities were 21–23%. The mortalities included 47 birds of 14 species, all but three of which were passerines, and ~60 Wahlberg’s epauletted fruit bats (Epomophorus wahlbergi). This mortality event occurred on a single very hot day preceded by several cooler days (Tmax = 37–39°C at one location) and involved weather conditions similar to those associated with at least one recent flying‐fox die‐off in Australia. The disproportionately high representation of passerines among the avian mortalities supports recent predictions that songbirds are more vulnerable to lethal hyperthermia on account of the relative inefficiency of panting as an avenue of evaporative heat dissipation. As far as we are aware, this is the first documented heat‐related mortality event involving wild birds and bats in southern Africa.

Land snail biogeography and endemism in south-eastern Africa: Implications for the Maputaland-Pondoland-Albany biodiversity hotspot.

Invertebrates in general have long been underrepresented in studies on biodiversity, biogeography and conservation. Boundaries of biodiversity hotspots are often delimited intuitively based on floristic endemism and have seldom been empirically tested using actual species distributions, and especially invertebrates. Here we analyse the zoogeography of terrestrial malacofauna from south-eastern Africa (SEA), proposing the first mollusc-based numerical regionalisation for the area. We also discuss patterns and centres of land snail endemism, thence assessing the importance and the delimitation of the Maputaland-Pondoland-Albany (MPA) biodiversity hotspot for their conservation. An incidence matrix compiled for relatively well-collected lineages of land snails and slugs (73 taxa in twelve genera) in 40 a priori operational geographic units was subjected to (a) phenetic agglomerative hierarchical clustering using unweighted pair-group method with arithmetic means (UPGMA), (b) parsimony analysis of endemicity (PAE) and biotic element analysis (BEA). Fulfilling the primary objective of our study, the UPGMA dendrogram provided a hierarchical regionalisation and identified five centres of molluscan endemism for SEA, while the PAE confirmed six areas of endemism, also supported by the BEA. The regionalisation recovers a zoogeographic province similar to the MPA hotspot, but with a conspicuous westward extension into Knysna (towards the Cape). The MPA province, centres and areas of endemism, biotic elements as well as the spatial patterns of species richness and endemism, support the MPA hotspot, but suggest further extensions resulting in a greater MPA region of land snail endemism (also with a northward extension into sky islands—Soutpansberg and Wolkberg), similar to that noted for vertebrates. The greater MPA region provides a more robustly defined region of conservation concern, with centres of endemism serving as local conservation priorities.

Climate‐sensitivity of sugarcane yield in the southeastern Africa lowlands

AbstractWe have analysed the relationships between local and regional climate and sugarcane yield over the southeastern Africa lowlands (31°–23.5°S, 28.5°–32.5°E) for the period 1970–2017. The temporal associations for preceding December–May rainfall and temperature, and indices of the Pacific El Niño Southern Oscillation and Indian Ocean Dipole, demonstrate the climate‐sensitivity of sugarcane yield and its proxy: the Palmer Drought Severity Index (PDSI). The composite differences revealed how the atmospheric circulation over the Mozambique Channel shifts the moisture gradient over southeastern Africa. Predictors of sugarcane yield were identified in point‐to‐field maps of global sea surface temperature, sea level air pressure, and upper winds with respect to the PDSI. It was found that four climate predictors account for half of the PDSI variance at 1 year lead time. We also investigated the long‐term change using coupled model simulations. These exhibit weak drying trends but large year‐to‐year swings in soil moisture. Our research offers a basis for mitigating climate variability for the benefit of the sugar industry in southeastern Africa, through statistical forecasts that inform crop management.

Spatial Risk Analysis of Batrachochytrium dendrobatidis, A Global Emerging Fungal Pathogen.

Chytridiomycosis, a leading cause for the global decline in the number of amphibians, is caused by the fungal pathogen Batrachochytrium dendrobatidis. In this study, global distribution data of B. dendrobatidis were collected from January 2009 to May 2019. Space-time scan statistics and the maximum entropy (MaxEnt) model were used to analyze the epidemic trends and aggregation of the pathogen, and predict B. dendrobatidis distribution through its relationships with climate factors, wind speed, and solar radiation. The results of space-time scan statistics show seven clusters of data for the distribution of B. dendrobatidis. The time was mainly concentrated in 2009, 2013, 2015, and 2016, and the regions were primarily concentrated in southeastern Canada, southwestern France, Nigeria, Cameroon, eastern Brazil, southeastern Brazil, central Madagascar, and central and eastern Australia. MaxEnt showed that annual precipitation had the largest contribution percentage in the model, and annual mean temperature highly influenced the distribution of B. dendrobatidis. The global high-risk areas of B. dendrobatidis distribution were mainly observed in western Canada, southern Brazil, Chile, the United Kingdom, Japan, the Republic of Korea, eastern South Africa, eastern Madagascar, southeastern Australia, and southern China.

Quaternary landscape evolution in a tectonically active rift basin (paleo-lake Mweru, south-central Africa)

Located between the Northern Province of Zambia and the southeastern Katanga Province of the Democratic Republic of Congo, Lakes Mweru and Mweru Wantipa are part of the southwest extension of the East African Rift System (EARS). Fault analysis reveals that, since the Miocene, movements along the active Mweru-Mweru Wantipa Fault System (MMFS) have been largely responsible for the reorganization of the landscape and the drainage patterns across the western branch of the EARS. To investigate the spatial and temporal patterns of fluvial-lacustrine landscape development, we determined in-situ cosmogenic 10Be and 26Al using Accelerator Mass Spectrometry. A total of twenty-six quartzitic bedrock samples were collected from knickpoints across the Mporokoso Plateau (south of Lake Mweru) and the eastern part of the Kundelungu Plateau (north of Lake Mweru). Samples from the Mporokoso Plateau and close to the MMFS provide evidence of temporary burial. By contrast, surfaces located far from the MMFS appear to have remained uncovered since their initial exposure as they show consistent 10Be and 26Al exposure ages ranging up to ~830 ka. Reconciliation of the observed burial patterns with morphotectonic and stratigraphic analysis reveals the existence of an extensive paleo-lake during the Pleistocene. Through hypsometric analyses of the dated knickpoints, the potential maximum water level of the paleo-lake is constrained to ~1200 m asl. High denudation rates (up to ~40 mm ka−1) along the eastern Kundelungu Plateau suggest that footwall uplift, resulting from normal faulting, caused rapid river incision, thereby controlling paleo-lake drainage. The complex exposure histories recorded by 10Be and 26Al may be explained because of lake water-level fluctuations caused by active normal faulting along the MMFS coupled with intense climate variations across southeastern Africa.

New faunistic and taxonomic data on oribatid mites (Acari, Oribatida) inhabiting soil and termite nests in the Golden Gate Highlands National Park (eastern South Africa)

ABSTRACT The present study is based on oribatid mite material collected from soil and nests of the termite, Trinervitermes trinervoides of the Golden Gate Highlands National Park in South Africa. A list of identified taxa, including 49 species, belonging to 41 genera and 24 families, is presented; of these, 13 species, eight genera and two families are found in South Africa for the first time. The faunistic comparison of mites from soil and termite nests showed higher abundance and species richness in soil than in the nests. Soil samples contain dominant species Oppiella nova, Tectocepheus velatus sarekensis, Africoribates pilosus, Afroleius lucidus and Scheloribates elsi versus Ausoribula bloemfonteinensis and Coetzeella navalensis in termite nests. One new species, Urubambates ueckermanni sp. nov. (Scheloribatidae) is described as differing from all known species of the genus by the presence of monodactylous legs. http://www.zoobank.org/urn:lsid:zoobank.org:pub:48FD196B-5FED-43AC-AB1E-1F3A3E0C2C78

Impact of Geographic Region on the COMMANDER-HF Trial

ObjectivesThis study sought to compare patient characteristics, outcomes, and treatment effects among regions in the COMMANDER-HF trial. BackgroundGlobalization of cardiovascular trials increases generalizability. However, regional differences may also introduce heterogeneity in results. MethodsIncidence rates and interactions with treatment were recorded in pre-specified regions: Eastern Europe, Western Europe and South Africa, North America, Asia-Pacific, and Latin America. ResultsMost patients (n = 3,224; 64.2%) were from Eastern Europe; 458 (9.1%) were from Western Europe and South Africa; 149 (3.0%) were from North America; 733 (14.6%) were from Asia-Pacific; and 458 (9.1%) were from Latin America. Compared with patients from Eastern Europe, patients from Western Europe and South Africa, North America, and Asia-Pacific were older and more likely to have coronary interventions and cardiac devices. Patients from Eastern Europe had the lowest event rates. For the primary outcome of myocardial infarction (MI), stroke, or all-cause death, event rates (100/year) were 11.6 in Eastern Europe (10.8 to 12.5); 19.5 (16.5 to 23.0) in Western Europe and South Africa; 14.2 (10.5 to 19.2) in North America; 17.7 (15.4 to 20.3) in Asia-Pacific; and 18.6 (15.6 to 22.1) in Latin America. There was a lower incidence of bleeding in Eastern Europe. Blood concentrations of rivaroxaban (Xarelto, Titusville, New Jersey) at 4 weeks were undetectable in 21% patients from Eastern Europe (n = 128) compared to 5% in other regions (n = 42). There was no evidence of treatment-by-region heterogeneity for the primary outcome (interactionp = 0.14), but a favorable effect on the secondary outcome of MI, stroke, or cardiovascular death was observed in Western Europe and South Africa, North America, and Latin America but not in Eastern Europe and Asia-Pacific (interactionp = 0.017). ConclusionsIn the COMMANDER-HF study, patients from Eastern Europe had a lower risk profile and fewer cardiovascular and bleeding events, possibly related to lower treatment adherence. Those differences might have influenced the effect of rivaroxaban therapy. (A Study to Assess the Effectiveness and Safety of Rivaroxaban in Reducing the Risk of Death, Myocardial Infarction or Stroke in Participants With Heart Failure and Coronary Artery Disease Following an Episode of Decompensated Heart Failure [COMMANDER HF]; NCT01877915)

Glacial to interglacial climate variability in the southeastern African subtropics (25–20° S)

Abstract. We present a continuous and well-resolved record of climatic variability for the past 100 000 years from a marine sediment core taken in Delagoa Bight, off southeastern Africa. In addition to providing a sea surface temperature reconstruction for the past ca. 100 000 years, this record also allows a high-resolution continental climatic reconstruction. Climate sensitive organic proxies, like the distribution and isotopic composition of plant-wax lipids as well as elemental indicators of fluvial input and weathering type provide information on climatic changes in the adjacent catchment areas (Incomati, Matola and Lusutfu rivers). At the transition between glacials and interglacials, shifts in vegetation correlate with changes in sea surface temperature in the Agulhas Current. The local hydrology, however, does not follow these orbitally paced shifts. Instead, precipitation patterns follow millennial-scale variations with different forcing mechanisms in glacial vs. interglacial climatic states. During glacials, southward displacement of the Intertropical Convergence Zone facilitates a transmission of northern hemispheric signals (e.g., Heinrich events) to the southern hemispheric subtropics. Furthermore, the southern hemispheric westerlies become a more direct source of precipitation as they shift northward over the study site, especially during Antarctic cold phases. During interglacials, the observed short-term hydrological variability is also a function of Antarctic climate variability; however, it is driven by the indirect influence of the southern hemispheric westerlies and the associated South African high-pressure cell blocking the South Indian Ocean Convergence Zone related precipitation. As a consequence of the interplay of these effects, small-scale climatic zones exist. We propose a conceptual model describing latitudinal shifts of these zones along the southeastern African coast as tropical and temperate climate systems shift over glacial and interglacial cycles. The proposed model explains some of the apparent contradictions between several paleoclimate records in the region.

<p><strong><em>Mallocybe africana</em> (Inocybaceae, Fungi), the first species of <em>Mallocybe</em> described from Africa</strong></p>

The family Inocybaceae has been poorly studied in Africa. Here we describe the first species of the genus Mallocybe from West African and Zambian woodlands dominated by ectomycorrhizal trees of Fabaceae and Phyllanthaceae. The new species M. africana is characterized by orange-brown fruitbodies, a fibrillose pileus, a stipe tapered towards the base and large ellipsoid basidiospores. It resembles many north and south temperate species of Mallocybe but is most closely related to the southeast Asian tropical species, M. errata. M. africana is widely distributed in West Africa (Benin, Togo, Burkina Faso and Ivory Coast) extending to South-eastern Africa in Zambia. Phylogenetic analyses based on 5.8S rDNA, nLSU and RPB2 sequence data confirm that M. africana is nested within Mallocybe. A complete morphological description and illustrations, including photographs and line drawings, are presented.

THE (IR)RELEVANCE OF BIBLICAL SCHOLARSHIP? A CHALLENGE, AND AN OPPORTUNITY

Has biblical scholarship become irrelevant to modern secular societies? Are the threats to the viability of biblical scholarship of the same nature as the threats to other areas of the humanities (history, philosophy, literature), or is there a qualitative difference? What about the role of technology in biblical research and biblical education? What is the future of the institutions of biblical scholarship such as universities, seminaries, journals, and academic presses? What is the role of biblical scholars in secular and post-secular societies, as contrasted with scholars in/from emerging communities? This essay argues that the problem of “validation” lies at the heart of biblical scholarship’s irrelevancy within the broader secularity of modern world and that this problem is even more evident in the scholarly discourse coming from regions like Eastern Europe and South Africa. However, the loss of authority of biblical scholarship more generally represents an opportunity for these communities. Rather than becoming enamoured of validation from the North Atlantic world, Bible-reading communities must cultivate their own forms of validation based in their unique histories with the Bible, and the affinities between their own histories/cultures and the cultures that produced the Old and New Testament texts.

Calibration of physicochemical parameters in aquaculture. A case study of tilapia breeding in Mozambique

This paper discusses the adequacy of methods used in monitoring the aquatic environment in aquaculture. It is assumed that the strategy of controlling each of the environmental parameters by observing their compliance with the technical limits established in aquaculture is not sufficient to highlight all the aspects that may compromise the quality of the process. Therefore, the univariate methods that are usually used in water monitoring in aquaculture cannot show aspects of the process derived from the joint variability between the parameters. Thus, a multivariate method for monitoring the aquatic environment in aquaculture based on Hotelling’s T2 chart was proposed in this paper. Data on four physicochemical parameters (oxygen, temperature, pH and transparency) were collected from four aquatic species breeding ponds at the company Aquapesca in Mozambique, located in southeastern Africa. The correlation structure evidenced in the four physicochemical parameters analyzed showed a strong and positive relationship between temperature and pH, oxygen and transparency are inversely correlated. This correlation structure indicates that a possible reduction in water temperature also reduces the pH and vice versa, while a reduction in transparency implies an increase in dissolved oxygen. The multivariate method used shows the relationship between the parameters and the strategies to manage them, as well as the control strategy of the multivariate structure through Hotelling’s T2 chart, pointing out and correcting all the aspects that may compromise the quality of the breeding of the species in aquaculture.

Potential Risk Levels of Invasive Fire Blight in Apple Orchards Around the World

Fire blight, a disease of apple trees caused by Erwinia amylovora, occurs worldwide except in South America, South-Central Africa, and most of Oceania. Ecological niche models can determine the potential distribution of species and measure the risk of pest invasion. This study aims to develop global climate suitability models using MaxEnt software for E. amylovora and to determine the regions in which apple cultivation and the bacterium are most likely to co-occur. Most occurrence data for E. amylovora (93%) are from the northern hemisphere, distributed between 63.90 to 14.56 degree days in regions of Africa, Central America, North America, Asia, and Europe. The only country in the southern hemisphere that this bacteria has been detected is New Zealand (Oceania). Apples are cultivated on every continent except Antarctica, between 61.55 to 44.41 degree days. We find that regions of South-Eastern Africa, Argentina, Australia, Southern Brazil, Bolivia, Chile, China, the United States, Madagascar, Morocco, Mexico, New Zealand, Peru, Tunisia, Uruguay, and the majority of Europe are suitable for both E. amylovora and apple cultivation. These results provide information on the potential worldwide distribution of E. amylovora in apple production area.

Utilizing bycatch camera-trap data for broad-scale occupancy and conservation: a case study of the brown hyaenaParahyaena brunnea

AbstractWith human influences driving populations of apex predators into decline, more information is required on how factors affect species at national and global scales. However, camera-trap studies are seldom executed at a broad spatial scale. We demonstrate how uniting fine-scale studies and utilizing camera-trap data of non-target species is an effective approach for broadscale assessments through a case study of the brown hyaenaParahyaena brunnea. We collated camera-trap data from 25 protected and unprotected sites across South Africa into the largest detection/non-detection dataset collected on the brown hyaena, and investigated the influence of biological and anthropogenic factors on brown hyaena occupancy. Spatial autocorrelation had a significant effect on the data, and was corrected using a Bayesian Gibbs sampler. We show that brown hyaena occupancy is driven by specific co-occurring apex predator species and human disturbance. The relative abundance of spotted hyaenasCrocuta crocutaand people on foot had a negative effect on brown hyaena occupancy, whereas the relative abundance of leopardsPanthera pardusand vehicles had a positive influence. We estimated that brown hyaenas occur across 66% of the surveyed camera-trap station sites. Occupancy varied geographically, with lower estimates in eastern and southern South Africa. Our findings suggest that brown hyaena conservation is dependent upon a multi-species approach focussed on implementing conservation policies that better facilitate coexistence between people and hyaenas. We also validate the conservation value of pooling fine-scale datasets and utilizing bycatch data to examine species trends at broad spatial scales.

Cohort profile: the mature adults cohort of the Malawi longitudinal study of families and health (MLSFH-MAC)

PurposeThe Mature Adults Cohort of the Malawi Longitudinal Study of Families and Health (MLSFH-MAC) contributes to global ageing studies by providing a rare opportunity to study the processes of individual...

Middle Stone Age wood use in Rose Cottage Cave South Africa: Evidence from charcoal identifications

Here we present charcoal identifications for Rose Cottage Cave, Eastern Free State, from layers dated between about 96,000 and 35,000 years ago (~96 and ~35 ka ago). We then suggest plant community types that might have been established in the area in warm Marine Isotope Stage 5 (MIS5) versus cooler MIS4/MIS3 phases. The hypothesis is that frost-tender plants should occur in warm phases while hardy Leucosidea sericea, Protea spp. and Erica spp. should be more common during cooler phases more recent than ~74 ka ago. Leucosidea sericea thrives under moist conditions and its presence in late MIS4 and in several MIS3 layers at Rose Cottage implies that the area may have been moister than many other sites in the interior of southern Africa, thereby making it attractive for occupation. The charcoal identifications at ~96 ka ago included taxa like Buddleja salvifolia that need somewhat warmer conditions than taxa such as Leucosidea sericea. Taxa diversity based on the charcoal identifications is generally low at the site throughout the Middle Stone Age, but the vegetation from relatively warm MIS5 seems more diverse than that of MIS4 and MIS3. Some taxa identified, for example, Calodendrum capense, Leucosidea sericea, Erica caffra and Protea caffra no longer grow near the cave although they are commonly found in other parts of eastern South Africa.

Discovery of populations endemic to a marine biogeographical transition zone

AbstractAimBiogeographical transition zones are areas of overlap between the faunas of adjacent biogeographical entities. Particularly the well‐defined transition zones along linear coastlines are interesting natural laboratories to study dispersal and incipient speciation. Few studies have explored whether marine biogeographical transition zones harbour biodiversity that is distinct from that of the biogeographical entities they separate. The Wild Coast in eastern South Africa is a poorly studied transition zone between the region's warm‐temperate and subtropical faunas, and is generally considered to be an area of faunal overlap.LocationThe South African portion of the Western Indian Ocean.MethodsSequences of the DNA barcoding marker COI were generated from 306 estuarine sandprawns (Kraussillichirus kraussi) collected at 13 sites. Genetic structure and evolutionary history were assessed using a haplotype network and a Bayesian discrete phylogeographic analysis.ResultTwo populations were identified whose ranges are centred on the Wild Coast, a rare one in the northern portion and a more common one in the central and southern portion of this biogeographical transition zone. These populations are not closely related to each other, but descend from subtropical and warm‐temperate sister populations, respectively. Although genetic distances between populations were low, they exceeded within‐population distances, indicating the presence of a "barcoding gap."ConclusionsThis is the first study to indicate that the Wild Coast marine biogeographical transition zone is not merely an area of faunal overlap, and one of very few studies to have discovered genetically unique populations within a marine biogeographical transition zone. The Wild Coast may harbour additional unique biodiversity that remains to be discovered, including rare species that require protection. More research is required to understand how this environmentally dynamic marine biogeographical transition zone differs from the adjacent biogeographical provinces.

Temperature change in subtropical southeastern Africa during the past 790,000 yr

Abstract Across the glacial-interglacial cycles of the late Pleistocene (∼700 k.y.), temperature variability at low latitudes is often considered to have been negligible compared to changes in precipitation. However, a paucity of quantified temperature records makes this difficult to reliably assess. In this study, we used the Bayesian method CREST (Climate REconstruction SofTware) to produce a 790,000 yr quantified temperature reconstruction from a marine pollen record from southeast Africa. The results reveal a strong similarity between temperature variability in subtropical Africa and global ice volume and CO2 concentrations, indicating that temperature in the region was not controlled by local insolation, but followed global trends at these time scales, with an amplitude of ∼4 °C between glacial minima and interglacial maxima. The data also enabled us to make an assessment of the impact of temperature change on pollen diversity, with results showing there is no link between glacial-age temperatures/CO2 and a loss of diversity in this record.

Multivariate framework for the assessment of key forcing to Lake Malawi level variations in non-stationary frequency analysis

Lake Malawi in south eastern Africa is a very important freshwater system for the socio-economic development of the riparian countries and communities. The lake has however experienced considerable recession in the levels in recent years. Consequently, frequency analyses of the lake levels premised on time-invariance (or stationarity) in the parameters of the underlying probability distribution functions (pdfs) can no longer be assumed. In this study, the role of hydroclimate forcing factors (rainfall, lake evaporation, and inflowing discharge) and low frequency climate variability indicators (e.g., El Nino Southern Oscillation-ENSO and the Indian Ocean Dipole Mode-IODM) on lake level variations is investigated using a monthly mean lake level dataset from 1899 to 2017. Non-stationarity in the lake levels was tested and confirmed using the Mann-Kendall trend test (α = 0.05 level) for the first moment and the F test for the second moment (α = 0.05 level). Change points in the series were identified using the Mann-Whitney-Pettit test. The study also compared stationary and non-stationary lake level frequency during 1961 to 2004, the common period where data were available for all the forcing factors considered. Annual maximum series (AMS) and peak over threshold (POT) analysis were conducted by fitting various candidate extreme value distributions (EVD) and parameter fitting methods. The Akaike information criteria (AIC), Bayesian information criteria (BIC), deviance information criteria (DIC), and likelihood ratios (RL) served as model evaluation criteria. Under stationary conditions, the AMS when fitted to the generalized extreme value (GEV) distribution with maximum likelihood estimation (MLE) was found to be superior to POT analysis. For the non-stationary models, open water evaporation as a covariate of the lake levels with the GEV and MLE was found to have the most influence on the lake level variations as compared with rainfall, discharge, and the low frequency climatic forcing. The results are very critical in flood zoning especially with various planned infrastructural developments around the lakeshore.