East African Coast Research Articles

Teniky: enigmatic architecture at an archaeological site in southern Madagascar

ABSTRACT Teniky is an isolated inland archaeological site in the Isalo massif of southern Madagascar, with enigmatic rock-cut architecture that is unique in all of Madagascar and the wider East African coast. In the first half of the twentieth century visitors described archaeogical structures within a fluvial cirque (i.e. an amphitheatre-shaped valley formed by fluvial erosion), which included man-made terraces, rock-cut niches in the steep cliffs and a rock shelter delimited by walls consisting of carved sandstone blocks. Our investigations at Teniky have led to the discovery of further archaeological structures beyond the cirque. These structures include further terraces, rock-cut niches, stone basins and carved sandstone walls on a hill 2.5 km to the west, as well as sandstone quarries and dry stone walls in the valley in between. AMS radiocarbon dating of charcoal found during excavations at the newly discovered rock-cut niches and carved sandstone walls indicates that they were constructed in the late first millennium/early second millennium c. tenth to twelfth century AD. Pottery sherds at Teniky include Chinese and Southeast Asian ceramics dating to broadly the eleventh to fourteenth centuries, concordant with the radiocarbon ages. The presence of imported ceramics indicates that those living at Teniky participated in Indian Ocean trade networks in medieval times, despite being over 200 km from the nearest coast. The closest stylistic parallels to the enigmatic rock-cut architecture at Teniky are found in present-day Iran, particularly in the Fars region, where rock-cut niches dating to the first millennium AD or earlier have been attributed to Zoroastrian communities. We tentatively interpret the rock-cut architecture at Teniky as part of a former necropolis made by settlers with Zoroastrian origins. More archaeological research is required to test this hypothesis and to address questions such as: where and when did these settlers first arrive on the coast of Madagascar; why and when did they move inland; how did they live and how did they interact with other populations on the island; and why and when was the site deserted?

Treasures in our backyard: unleashing the biotechnological potentials of endophytic fungi from Tanzanian mangroves

Endophytic fungi are useful in a variety of biological processes and may find value in pharmaceutical settings. However, there hasn’t been much research done on the bioactive compounds produced by mangrove fungal endophytes from the East African coast. Our previous research revealed a significant number of mangrove endophytic fungi in Dar es Salaam, Tanzania. This study explores the antimicrobial and cytotoxic properties of these endophytic fungi. Crude extracts of 34 mangrove endophytic fungal isolates were screened, with thirteen showing antimicrobial activity against tested microorganisms. MIC and cytotoxicity tests revealed varying bioactivity. Aspergillus fumigatus (HMD45) was particularly potent against tested organisms (MIC = <0.195 to 0.391 mg/ml) and (LC50 = 36.001). GC-MS evaluation of HMD45 extracts indicated the existence of compounds including dodecanoic acid, n-heptadecanol-1, and n-hexadecanoic acid, which may contribute to its bioactivity. These findings offer insight into the bioactivity of mangrove endophytic fungi and trigger interest for further research.

A review and analysis of the nomenclature and taxonomy of the genus-rank synonyms of Kalanchoe (Crassulaceae subfam. Kalanchooideae) published between 1763 and 1956

The genus name Kalanchoe, which is in use for about 200 tetramerous-flowered infrageneric taxa, species, and infraspecific taxa of Crassulaceae subfam. Kalanchooideae that are indigenous to Madagascar, some Indian Ocean islands off the African east coast, most of sub-Saharan Africa, and the Near, Middle, and Far East, was validly published in 1763 by Michel Adanson (1727–1806) and is legitimate. Genus names that are included in the synonymy of Kalanchoe are assessed and assigned to the appropriate subgenera recognised in the genus, and their nomenclature is reviewed. In chronological sequence the genus names in question are: (1) Vereia (1798), (2) Physocalycium (1820), (3) Baumgartenia (1821), (4) Meristostylus (1861), and (5) Geaya (1908); and (6) Bryophyllum (1805) is the basionym of K. subg. Bryophyllum (1919), and (7) Kitchingia (1881) is the basionym of K. subg. Kitchingia (2018). When Bryophyllum is treated as a synonym of Kalanchoe—a view followed here—the nothogenus name (8) ×Bryokalanchoe (1956) is a synonym of Kalanchoe.

Regional foraging areas of green turtles (Chelonia mydas) nesting at Aldabra Atoll: insights from stable isotopes and satellite telemetry

Sea turtles spend the majority of their lives at foraging grounds. These areas are important for population persistence but generally occur in coastal habitats, which are under increasing human pressure. Identifying key foraging areas is therefore an important step to understanding critical sea turtle habitats, and therefore their threats. Isotope ratios (δ15N, δ13C) from skin tissues of 90 green turtles (Chelonia mydas) nesting at the regionally important rookery of Aldabra Atoll, Seychelles, were analyzed with samples collected during two periods: 51 samples from March to September 2021, and 39 samples from January to April 2022. These analyses were complemented by nine satellite tracks to identify key foraging areas. Hierarchical clustering and discriminant function analysis identified two main foraging areas: the East African coast (Tanzania and Somalia) and northern Madagascar. Isotopic values indicated that the majority of green turtles nesting at Aldabra forage at one of these two areas, with slightly more green turtles visiting the East African coast. Geographical isotopic patterns were not found latitudinally, suggesting a potential limit to this approach for coastal areas in the Western Indian Ocean. However, we found longitudinal variation of δ13C and δ15N that few studies have reported. This is the first study in this region to combine satellite telemetry and stable isotope analysis to assign likely foraging areas of green turtles and advances understanding of the complex migration patterns and foraging ecology of this species. We demonstrate the potential and the limitations of stable isotope analysis for identifying/characterizing green turtle foraging areas in this region.

Interannual variability of the East African Coastal Current associated with the El Niño-Southern Oscillation

Abstract The East African Coastal Current (EACC) is an important western boundary current of the tropical South Indian Ocean and plays an important role in the ocean circulation and biogeochemical cycles in the Indian Ocean. This study investigates the interannual variability of the EACC and its dynamical mechanisms. The result shows that the EACC has interannual variability associated with the El Niño-Southern Oscillation (ENSO) during 1993-2017. The EACC shows a significantly positive correlation with the Niño3.4 index with a correlation coefficient of 0.65, lagging the Niño3.4 index by 18 months. During the decaying phases of El Niño (La Niña) events, the negative (positive) sea level anomaly (SLA) propagates westward as upwelling (downwelling) Rossby waves from the southeast Indian Ocean to the southwest Indian Ocean, and then strengthens (weakens) the EACC due to zonal SLA gradient off the East African coast under geostrophic equilibrium. The SLA gradually weakens in the southeast Indian Ocean during its westward propagation but strengthens in the southwest Indian Ocean promoted by local wind stress curl anomaly. This study can improve our understanding of the relationship between the western boundary current of the tropical South Indian Ocean and large-scale ENSO air-sea processes, and is important for managing marine fisheries and ecosystems on the East African coast.

Microplastic pollution in the Thumbprint emperor (Lethrinus harak) from Tanzanian coastal waters: Occurrence, abundance, characterization, and relevance as a monitoring species

In the present study we collected the Thumbprint emperor (Lethrinus harak) from seven landing sites from the coastal waters around Dar es Salaam and Zanzibar (Tanzania) to (i) quantify and characterize microplastics (MPs) in their digestive tracts and (ii) use previously assessed environmental levels in nearshore surface waters and seabed sediments to determine whether L. harak could be a relevant biomonitor for MP pollution in the region. L. harak (n=387) had an overall frequency of occurrence (FO%) of 48 % and displayed spatial variation between sites with Kunduchi (FO=66.7 %) and Mijimwena (FO=17.1 %) having the highest and lowest FO%, respectively. Fish from Mjimwema had a mean MP content of 0.17 ± 0.38 MPs individual-1 whilst fish from Kizimkazi had the highest MP abundance (1.75 ± 2.33 MPs individual-1). Fibers (overall 64.7 %, range across sites 48–86 %) and fragments (17.9 %, 5–25 %) were the most dominant MP types whilst black (46.9 %, 40–58 %) and blue (22.5%, 7–36 %) MPs were the most common colours. Fish length (ρ= -0.09, p=0.09) or weight (ρ=0.07, p=0.18) did not significantly correlate to MP abundance in fish (Spearman rank correlations). Neither MP occurrence nor abundance was linked to MP concentrations in either surface waters or seabed sediments (Spearman rank correlation), but MPs in the fish better reflected MPs in the sediment compared to surface water (two-way ANOVA on ranked data). Whilst L. harak presents as a promising candidate to monitor MP pollution along the East African coast due to its ecology, overall, it lacks reliability. Nonetheless, the present study fills important knowledge gaps both geographically on the East African Coast and with an underrepresented taxonomic family (Lethrinidae ‘Emporer fishes’).

The Nones of Mombasa: Religious Disbelief and Disaffiliation on the East African Coast

Abstract Religious disbelief (RDb) and religious disaffiliation (RDa), which describe the intellectual, cultural, and social lives of contemporary citizens referred to as “Nones” (i.e., “none of the above” as a respondent’s choice among religious options), are emerging as sociological categories of increasing interest to religious studies scholars. Much of the research done thus far focuses on Western nations and religions. This study and the observations herein apply some of these same interests and methods to the African nonreligious scene. As a field site, the cosmopolitan city of Mombasa (pop. 1.2 million) on the Kenyan coast has for many recent generations been home to a variety of African, Arab, Indian-Asian, and European races, cultures, and religions. African Traditional Religions (ATRs), Islam(s), Indian religions, and Christianities all have a presence in this religiously pluralistic milieu. In this cosmopolitan context, we should expect to find among urban Africans some representation of trends found across the world, one of which is a potentially growing, if silent and low-profile, population called “Nones.”

An overview of the current status of Lake Jipe and its biodiversity dilemma

AbstractLake Jipe, is a shared water resource between Kenya and Tanzania located at the East African Coast is under multiple pressures. The present study assessed the current state of Lake Jipe and its biodiversity dilemma. Random sampling was conducted at 14 sampling points set at equidistant parallel to each other. Sampling depths and location coordinates were measured using Solar Transducer and GPSMAPS® 65 s. In situ water quality parameters were measured using YSI Pro Plus multiparameter; water samples for nutrients analysis were collected and preserved in cooler boxes prior transportation to Kenya Marine and Fisheries Research Institute (KMFRI) laboratory for analysis according to ALPHA 2005. Socio‐economic data in relation to status of Lake Jipe ecology were generated using Key Informants Interviews at identified beaches along Kenya and Tanzania. Present findings indicated that the lake has receded from the original 108.72 Km2 to 27.32 Km2 with annual temperatures, dissolved oxygen and conductivity of 28.58 ± 0.95, 5.19 ± 00 and 799.24 ± 69.41, respectively, for dry season. Wet season recorded 31.21 ± 0.31, 4.16 ± 0.01 and 882.44 ± 57.41 for temperature, dissolved oxygen and conductivity, respectively. Agricultural activities have significantly (90%) contributed to the lake levels decline and further affected the lakes' aquatic biodiversity. Among the most affected are the commercially important endemic fish species of the lake of which Oreochromis jipe has experienced the greatest decline. Overfishing, use of illegal unreported and unregulated fishing gears, intensified fishing along protected fish breeding areas as well as poor management and uncoordinated conservation efforts have significantly contributed to the decline of fish catches from 348 kg of O. jipe in 2016 to 90 kg daily catches in 2022. Consequently, the lake is in the verge of extinction if no action is taken. This calls for awareness on the significance of the L. Jipe ecosystems and its immediate and long‐term benefits. Further, there is need to revive and promote alternative economic activities including sustainable aquaculture and agriculture to local communities.

Inference on the biological history of the Comoros archipelago using the CD4 Alu/STR compound system

The Comoros Archipelago is located at the northern end of the Mozambique Channel between Madagascar and the East African coast. Its settlement would have been influenced by contacts and possibly migratory waves that would have come from the East African coast, Middle East and Southeast Asia. This finding was the conclusion of various previous genetic studies carried out on Comorian populations to answer the question of its settlement and its biological history. These studies have used many kinds of molecular markers, although the autosomal markers (Alu/STR CD4) used in the present study have never been studied on the archipelago's populations. Nevertheless, they have been used on populations all over the world and have provided valuable information on genetic affinities and differentiation between populations and have also shed more light on the origins of modern human.In this study, we aimed to characterize for the first time the populations of the 3 main islands of the Comoros Archipelago using the CD4 Alu/STR compound system. Due to its robustness, this system allowed us to include, in our comparative analyses, populations having shared a common history with Comoros islanders (through migrations, commercial relations, or others).Our results showed by island, peculiar frequencies of STR and Alu alleles, as well as haplotypic ones. Genetic diversity values at the allelic level, ranged between 0.798 and 0.836 for the STR, and between 0.254 and 0.327 for the Alu. The most frequent haplotypes were 85+, followed by 115+ and 120+ in all the three islands. Phylogenetic and comparative analyses highlighted that our populations exhibit more affinities with sub-Saharan populations especially the Kenyans. However some Middle Eastern signals are perceptible in Anjouan Islanders through 90+ and 110− haplotypes.Finally, the results obtained contribute to a further understanding of the biological history of the Comoros population and provide new insights into the gene flows such as haplotypes of Middle Eastern origin.

Deep Learning Approaches for Disease Detection in Groundnut Crops using CNN Models

A major oilseed crop grown in tropical and subtropical parts of the world, groundnuts are a major crop in India. In the sixteenth century, groundnuts were likely transported from Brazil to West Africa, later making their way to India and the African east coast. According to earlier research, various strategies are employed to prevent diseases of groundnut leaves. The main methods include artificial intelligence (AI), machine learning (ML), convolutional neural networks (CNN), and more. Several CNN techniques for leaf disease identification and methodology will be employed in this study. Different CNN models, such as MobileNet, VGG-16, and EfficientNet, are compared to determine which model is most frequently used to identify leaf disease. The accuracy and precision will be computed and presented as a result of utilizing the dataset.

Clientage, debt, and the integrative orientation of non-elites on the East African Swahili coast

Ceramic trends on Unguja Island in Zanzibar, Tanzania provide insights into non-elite political strategies on the East African Swahili Coast. Synthesizing imported ceramic data from two seasons of systematic field survey across rural Unguja with historical, ethnographic, and archaeological evidence from coastal East Africa, this paper argues that an integrative orientation toward power characterized bottom-up action on the Swahili Coast over the second millennium CE. While theories of bottom-up action have emphasized commoner autonomy and resistance to clientage, debt, and social inequality, evidence from the Swahili Coast attests to efforts by non-elites to seek entrance into cycles of reciprocal obligation as a means for recognition and social mobility—a specifically non-egalitarian orientation toward power. In response, elites competed with one another to accumulate wealth-in-people, resulting in a competitive patron-client system that prevented political consolidation. Elucidating these dynamics contributes to an understanding of how non-elite political strategies have shaped sociopolitical systems globally.

An Outport for Gedi?—Archaeological Survey in Mida Creek, Kenya

Communities of the East African coast have had a long history of international interaction. Swahili maritime networks linked African port towns across the Indian Ocean seaboard, thus enabling merchandise to reach the hinterlands of the continent. One of these Swahili towns is the ancient city of Gedi, located on the central Kenyan coast near the medieval town of Malindi. Located inshore, 6 km from the main ocean to the southeast and 3 km from Mida Creek to the southwest, Gedi’s lack of seaward connectivity has perplexed scholars. To effectively function within the vibrant Indian Ocean maritime trade networks of the 10th to 16th centuries CE, Gedi needed access to the sea. Inevitably goods had to be transported overland from a port or landing place. The ‘MUCH to Discover in Mida Creek’ project carried out an archaeological survey around the Creek to form a broader understanding of the region’s maritime past. The study identified a range of sites that evidence past coastal activity. In particular, a concentration of contemporary house sites at Chafisi near the closest point on the Creek to Gedi would suggest it may have acted as an outport for the stone town.

Swahili Cultural Heritage: Origins, Development and Influences

This paper examines the cultural heritage of the Swahili of East Africa based on an analysis of archaeological, historical and anthropological literature. The intricate history of Swahili interaction with the maritime environment, their immediate neighbours and the outside world since the last quarter of the first millennium BC produced a distinct cultural heritage. Coupled with internal dynamics, these interactions led to the rise and fall of a civilization characterized by a unique socio-cultural, economic and political pattern on the East African coast. Swahili cultural heritage reflects this interaction. This examination analyses a selection of tangible and intangible aspects, including ruined buildings, wooden crafts, and Swahili modes of dress, literary art and communication, music and dance. The paper concludes by examining the influence of Swahili cultural heritage on world culture.

Entre o Império do Mali e o «Islão marítimo». O impacto dos legados e das literacias islâmicas na África portuguesa

The article presents the impact of the Islamicate populations and literacies in Portuguese colonial literature and scholarship. The main ethnic group that focused the attention of the colonisers were the aggressive, dominant Fulani portrayed in the novels of Fausto Duarte, Auá and A Revolta. Their usages and traditions were studied by the first Portuguese ethnographers and ethnohistorians with almost satisfactory results. On the other hand, Islam in the oriental part of the Portuguese colonial empire (Mozambique) was much less understood. The Portuguese paid greater attention to the aggressive, jihadist movements in West Africa than to the relatively less conspicuous Sufi movements that developed in the port cities and islands along the East African coast. Overall, the process of Islamicization of the territories controlled by the Portuguese went on unhindered or even accelerated during the colonial period.

The value of multibeam bathymetry in marine spatial planning in South Africa: A review

Given a growing global population and shift to embrace the blue economy, a need for marine spatial planning (MSP) has emerged in South Africa to sustainably resolve the rising conflicts over the use of marine and seabed resources and services. A well-developed marine spatial plan yields numerous ecological, social and economic benefits. These are achieved through mediating between spatially conflicting economic drivers’ interests (e.g. commercial fishing, tourism, mining), preventing their activities from compromising thresholds of an environment’s sustainability. Within the MSP framework, high-resolution geospatial datasets are required to document and describe the seabed in the highest possible detail. At any scale, integrated analysis of seabed geomorphology and habitats is anticipated to greatly improve the understanding of ecosystem functioning from a multidisciplinary perspective, whilst improving MSP procedures and management of marine space. South Africa is the first of few African countries to have an approved and implemented MSP framework, but is still somewhat behind globally in implementing large-scale regional hydroacoustic surveys to cover the country’s vast offshore territory. The deficiency of hydroacoustic surveys is perhaps due to a relative lack of funds and poor communication about the value of multibeam echo-sounder (MBES) derived data, whilst marine geoscience remains a scarce skill in the country. This review paper presents a geological perspective of MSP and explores (1) the value that seabed mapping offers MSP specifically and (2) the need to increase seabed mapping with MBES, using a recently initiated project from the South African east coast as a case study. Significance: The collected MBES data (our case study) provides unprecedented seabed detail of the complex reef habitat and adjacent areas within specific management zones of the uThukela Banks Marine Protected Area. We reveal seabed features and their spatial distribution at a scale not possible using earlier (singlebeam) seabed mapping techniques. These high-resolution data will enable a better understanding of east coast marine habitats whilst contributing to improved spatial management of areas within and around the uThukela Banks Marine Protected Area.

Insights into the genetic makeup of French Polynesian peripheral populations of the small giant clam Tridacna maxima

Abstract The small giant clam, Tridacna maxima, is distributed from the Red Sea and East African coast to French Polynesia. Across this widespread Indo‐Pacific range, T. maxima shows strong population structure, in agreement with its limited dispersal abilities. Peripheral populations may have smaller effective population sizes, increasing their vulnerability under any environmental changes. Understanding evolutionary processes at play in such regions located at the edges of T. maxima distribution is a prerequisite in the context of transfers and restocking programmes. In this study, giant clams were sampled from 14 atolls and islands within four archipelagos in the peripheral region of French Polynesia, in 2001–2002 and/or in 2012–2013, then genotyped at the COI gene and at nine microsatellite loci. Mitochondrial lineages of T. maxima from French Polynesia diverged from those sampled in Micronesia, Melanesia, the Coral Triangle and the Red Sea by 6.6–7.3%. Within French Polynesia, significant genetic structure was found, indicating restricted gene flow, and it was stable through time. Most of the genetic variation at microsatellite loci was between archipelagos. The most differentiated archipelago was the most geographically isolated (the Austral Islands). The current patterns of genetic structuring of T. maxima in French Polynesia probably result from long‐term genetic isolation with limited dispersal ability. In addition, these results underlined that sufficiently large populations of T. maxima have persisted in the Central Pacific during the last sea‐level regression. Strategies to optimize transfers and restocking programmes should be designed to preserve the genetic diversity and structure observed here, to avoid the risks of altering the genetic structure, allele loss and/or introduction of maladapted alleles in the receiving populations.

Open-Access Archaeological Predictive Modeling Using Zonal Statistics: A Case Study from Zanzibar, Tanzania

This paper presents a case study using zonal statistical analysis for archaeological predictive modeling with open-access software and free geospatial datasets. The method is applied to the rural landscapes of Zanzibar, Tanzania on the Swahili Coast. This study used QGIS (version 3.28) to perform zonal statistical analyses of environmental datasets weighted by settlement classes digitized from a 1907 historical map, to create predictive models for settlement across the island. These models were compared against the locations of major precolonial archaeological sites on the island and site data from a random stratified archaeological survey in an environmentally diverse region of northern Zanzibar. The results show strong correspondences between larger permanent site locations and areas of high likelihood for site detection in the predictive model. Additionally, there were correspondences between areas of lower likelihood for site detection and smaller, ephemeral sites related to agricultural production in swidden field plots. These results attest to Swahili rural complexity and enable an understanding of the specific environmental affordances that structured settlement and land use over the last millennium, in ways that shaped colonial contact in rural areas and altered the sociopolitical development of Zanzibar and the East African coast. The methods described here may be applicable for researchers and heritage managers in Africa and the Global South, where funding for large-scale field projects, expensive satellite imagery, or software licensing is limited.

LA‐ICP‐MS analysis of glass beads from Tié (12th–14th centuries), Kanem, Chad: Evidence of trans‐Sudanic exchanges

AbstractChemical analysis of glass from African archaeological sites has become a standard research tool over the past decades. Despite the multiplication of studies, the continent still exhibits vast unexplored regions. One of these is the surroundings of Lake Chad. This paper discusses the results of LA‐ICP‐MS analysis of recently excavated glass beads from the late medieval Chadian site of Tié. We demonstrate that the composition of those glass beads largely matches assemblages from along the East African coast. This indicates that most of the beads examined entered the region via a hitherto undocumented east–west Sudanic route linking Northeast Africa with Lake Chad.

Transoceanic Interconnectivities Between India- Tanzania Coastal Communities from the Antiquity to Contemporaries: The Archaeologic Perspectives from the Ancient Maritime Trade Connections via the Indian Ocean

The currently available archaeological and historical records indicate that since the prehistoric times, India and Tanzania shared a very long antiquity in terms of human civilization through the Indian Ocean maritime trade especially during the Neolithic period in aspects such as maritime trade links, ancient technology transfer, and intermarriages, expressly in monumental built heritage assets along the coast of the Indian Ocean. Outstandingly, the East African coast and its offshore islands preserve a lot of ancient remnants of built heritage assets, religious and symbolic entities, and socio-cultural traditions. Archaeologically, Swahili culture, which is one of the most powerful African civilizations along the coastal towns and littoral regions in East Africa is to some extent predisposed and inspired by Indian elements of early civilizations. The prehistoric contacts between the Indian Ocean communities of East Africa and Indian subcontinent have left some legacies in terms of language, crop and animal domestication, trade, architecture, and intermarriage. Some of these cultural elements are clearly visible in the forms of a spectacular series of historic stone towns along the coast and littoral regions of Tanzania for instance, especially ones that contain ruins of houses, mosques, and tombs built of coral limestones are typically Indian heritage inspired, which significantly influenced coastal and littoral societal socio-cultural developments in Tanzania.

Fishing Songs from Kilwa Kisiwani, Tanzania: A Case Study of Intangible Maritime Cultural Heritage on the Swahili Coast

Historically, fishers (both men and women) have engaged in different activities ranging from preparing fishing equipment (traps, nets, fishing vessels), weather forecasting, and sailing to fishing grounds and they continue to do so today. While sailing, fishers paddle collaboratively when the wind is low and when the boat is leaking, some crew will bail the vessel. Once they arrive at the fishing grounds, fishers cast anchor, mend the fishnets, and fix the boat foresheets. If successful, the fishers collect their catch, weigh the anchor, return to shore, and prepare to sell their fish. These fishing activities have always been accompanied by maritime customs, traditions, rituals, stories, and gestures. For instance, singing is one key tradition that has continued to accompany the fishing process from the start to the end. This paper documents and present the songs that have always been part of the fishing process in Kilwa Kisiwani, along the southern coast of Tanzania. The fishing songs are presented in the context of intangible cultural heritage of the east African Swahili coast.