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Estuaries supply direct and indirect multi-sectoral opportunities including for transport, natural resource use and climate protection. These provisions support livelihoods and contribute to social and economic development. The Bons Sinais Estuary in Zambézia Province, central Mozambique, is adjacent to the provincial administrative capital Quelima...
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... three decades there was an overall increase in cultivated crop, development and intertidal mudflat categories, with a decline in wetlands, mangrove and cultivated tree areas (Fig. 4). Figure 5 presents the changes in the LU/LC main categories using sets of inter-annual comparisons. Except for the first interval (1991)(1992)(1993)(1994)(1995)(1996)(1997)(1998), all were changes over five-year spans, compared with the overall change ...
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... three decades there was an overall increase in cultivated crop, development and intertidal mudflat categories, with a decline in wetlands, mangrove and cultivated tree areas (Fig. 4). Figure 5 presents the changes in the LU/LC main categories using sets of inter-annual comparisons. Except for the first interval (1991)(1992)(1993)(1994)(1995)(1996)(1997)(1998), all were changes over five-year spans, compared with the overall change ...
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... Our report is the second documented consumption of a member of the genus Arthroleptis by any night adder species -and it is also the first predator-prey interaction for these species and genera in Mozambique. Clearly, documentation and reporting of these types of interaction is important and relevant to our knowledge of food webs throughout the Afrotropics, especially given the uncertainty posed by direct, humaninitiated habitat loss (Furaca et al., 2021) and the impact of strong cyclones (such as the recent devastating Cyclones Idai and Freddy; Charrua et al., 2021) and the dire need for conservation action. ...
... In general, urbanization threatens the loss of biodiversity, such as the loss of most bird species [1]. Urbanization is also one of the factors causing the loss of wetland habitat in Bons Sinais Estuary, Mozambique [2]. Land clearing for plantation areas has been the cause of the extinction of endemic species in Costa Rica [3]. ...
As the capital city of Indonesia, Jakarta has eight satellite cities as the supporting areas, namely Bogor Regency, Bogor City, Depok City, Tangerang City, Tangerang Regency, South Tangerang City, Bekasi City, and Bekasi Regency. The rapid urbanization in Jakarta is driving the growth of these areas. One of the impacts of urban growth is the land cover change that can be observed through multitemporal satellite imagery. This study analyses the land cover change within 20 years in urban and non-urban areas. The data used are Landsat satellite imagery and Indonesian base maps validated by ESRI World Imagery. In this study, satellite imagery is processed into predetermined classes. The analysis process by comparing land cover classes between 2001 and 2021 and calculating the area of each class in each regency/city. The results show that dense and evenly distributed urban growth occurs throughout the “City” area. Attention must be given to the government of Bekasi City, Tangerang City, South Tangerang City, and Depok City because the built area already exceeds 70% of the city area.
... Local inhabitants rely heavily on the ecosystem goods and services provided by the estuary, including fish, mangrove wood for fuel and construction, and floodplains for planting rice and other crops or for salt production or aquaculture (Mazzilli, 2015;Francisco et al. 2021). These activities encroach on the estuarine functional zone and contribute to pollution, siltation and the degradation of ecologically important habitats (Furaca et al. 2021). An understanding of the estuary circulation pattern is therefore crucial for developing deeper insights and management strategies. ...
The residual circulation in estuaries determines the net exchange of water, heat, salt, fine sediments and drifting biological organisms between estuarine and nearshore marine waters. The Bons Sinais Estuary in central Mozambique is ~ 30 km long with the city of Quelimane and an industrial port on the northern bank of its upper reaches. To investigate residual circulation in the estuary, seasonal (wet, dry and transition season) CTD profiling data were collected at 11 fixed stations between the upper estuary and mouth, and vertical current profiles were measured over a full tidal cycle at a fixed mid-estuary station. Strong longitudinal gradients in salinity and density indicated that the estuary was river-dominated during the wet season and tide-dominated during the dry season, but the water column remained partially mixed. Tidally averaged vertical profiles from the mid-estuary station revealed: uniform vertical temperatures, warmest during the wet season; depth-stratified salinity during the wet season, but uniform profiles during the dry and transition seasons with highest salinity during the dry season when the density was also highest. The density was uniform and somewhat lower in the transition season, and in the wet season the density was even lower, but stratified. The vertical velocity profile showed a classical two-layer circulation model, with downstream flow intensifying at the surface, and upstream flow at the bottom, during the wet and transitory seasons, when freshwater discharges into the estuary. The flow velocities obtained from a calibrated Hansen and Rattray model fitted the observed data well, confirming that a simplified modelling approach is adequate to describe the residual flow of the Bons Sinais Estuary. The residual circulation model provides insights useful for fisheries research and predicting the spread of water-borne pollutants in the estuary.
... The geographical setting, history of settlement, ecosystems and socio-ecological importance of the estuary were summarized by Groeneveld et al. (2021). Hoguane et al. (2020; described estuarine circulation patterns, and Furaca et al. (2021) used remote sensing maps to infer changes in land use and land cover adjacent to the estuary over the past 27 years, including the growth of Quelimane city and its intrusion into the estuarine functional zone. ...
Small-scale fisheries in estuaries of the Western Indian Ocean form a key component of socio-ecological systems (SES) and food security, yet they remain poorly understood. This study describes the estuarine fisheries of the Bons Sinais Estuary in Mozambique based on fisheries and biological data collected by monitors between 2007 and 2016. Multiple gears were used, including beach seines (78 % of sampled fish), chicocota nets (12 %), gillnets (5 %), and hook and line (4 %). Landings were dominated by small pelagic fishes (Engraulidae 29 %, Pristigasteridae 16 %, Clupeidae 11 %) and prawns (Penaeidae 29 %). Monthly averaged fishing effort, landings and catch per unit effort of beach seine and chicocota nets peaked during the dry season, in April and July to October. The proportion of penaeid prawns in landings increased moderately at the end of the wet season, between January and March. The species and size composition selected by beach seine and chicocota nets overlapped, with chicocota nets also retaining marginally smaller individuals. Both gears exploited low trophic level species near the base of the food web, with low trophic values of 2.8 for chicocota and 3.0 for beach seine nets. The small-scale fishery in the Bons Sinais Estuary followed a ‘balanced harvest’ approach in which unselective fishing gear is used to exploit a mix of species and sizes proportional to natural productivity and relative abundance.
... The area has been settled for millennia by a succession of civilizations (Mosha and Plevoets, 2020) and is a highly productive part of the coast that supplies local and distant markets with fish and agricultural products (Mkama et al., 2010). SES at the Ruvu Estuary, as elsewhere in the WIO, are dominated by fish-based farming (FBF) systems (Hamerlynck et al., 2020;Francisco et al., 2021;Furaca et al., 2021;Mwamlavya et al., 2021), in which households derive some 30 to 50 % of their income from fisheries and engage in a wide livelihood portfolio, including farming, use of mangrove products, livestock herding, bee keeping and operating small business enterprises (Hamerlynck et al., 2020). ...
Ecosystem goods and services derived from estuaries have sustained coastal livelihoods in the Western Indian Ocean (WIO) region throughout recorded history. Estuaries provide fertile and seasonally irrigated space for planting crops, mangrove products for construction and fuel, and fish as a protein source. Human population growth and an escalating demand for natural resources threaten estuarine critical habitats and their functioning, exacerbated by the effects of climate change. Decadal and seasonal land-use and land-cover (LULC) changes in the Ruvu Estuary in Tanzania were investigated through analysis of Landsat 5/8 and Sentinel-2 satellite images. The estuary is river-dominated and truncated near the coast during high river flow, with tidal influence extending approximately 12 km upstream during low river flow. LULC change detection targeting nine classes (water, developed, barren, forest, grasslands, cultivated, mangroves, wetlands and mudflats) showed that estuary-associated wetlands and mangroves had declined significantly over the past two decades (1995-2016) making way for developed land (growth of Bagamoyo Town), cultivated land (agricultural expansion with increasing population) and grasslands (coastal habitat changes). Seasonal LULC changes were conversion of wetlands to cultivated land after the wet season, and transformation of fallow wetlands to grasslands. The estuarine fishery relied on a small number of mainly freshwater and marine migrant species, compared to a highly diverse mix of mainly marine species in the nearby coastal fishery. The sparsity of quantitative fisheries data, spectral confusion when modelling land-cover change, and absence of household survey data to assess livelihood activities remain major information gaps. Generalized recommendations for improving socio-ecological change studies in WIO estuarine systems are provided.
... In the Western Indian Ocean (WIO), FBF systems in estuarine deltas (termed deltaic fish-based farming systems) are characterised by brackish water habitats, use of mangroves forest products and a high diversity of fish and crustacean species in catches (often juvenile or small individuals). Deltaic FBF systems occur, inter alia, in the Bons Sinais Estuary in Mozambique (Furaca et al., 2021;Mugabe et al., 2021), Tana Estuary in Kenya (Manyenze et al., 2021;Mwamlavya et al., 2021) and Ruvu Estuary in Tanzania (Groeneveld et al., 2021a;2021b). System-associated farming activities include tree crops (coconut, banana, mangos, various fruits and palms), maize and root crops such as cassava (Hamerlynck et al., 2010; and tidal or mangrove Abstract Households in estuarine deltas of the Western Indian Ocean depend on small-scale fishing, farming in flood-recession and adjacent areas, and mangrove forest products for food security, energy and an income in so-called deltaic fish-based farming (FBF) systems. ...
... Key among these are reduced freshwater input from upstream catchments (Duvail et al., 2017) and change in land use and land cover (both upstream and in the estuarine zone) to accommodate the needs of growing human populations (Mwaguni et al., 2016;Furaca et al., 2021). These threats are exacerbated by overexploitation of estuarine habitats (mangrove cutting and clearing) and fish resources (Bosire et al., 2016;Diop et al., 2016) ...
... com). The estuary is surrounded by a mosaic of cultivated croplands and tree plantations, wetlands, mangroves and intertidal mudflats and built-up areas (Furaca et al., 2021). Five villages between the mouth and upper estuary were sampled ( Fig. 1): Marrubune and Gazelas in a rural area near the estuary mouth; ...
Households in estuarine deltas of the Western Indian Ocean depend on small-scale fishing, farming in flood-recession and adjacent areas, and mangrove forest products for food security, energy and an income in so-called deltaic fish-based farming (FBF) systems. It was hypothesized that the relative importance of household activities would depend on location along the Bons Sinais Estuary in Mozambique, diversifying in peri-urban settings. Semi-structured interviews were undertaken at five sites, including rural sites near the estuary mouth and upstream, and peri-urban settings near Quelimane city. Fishing contributed the most to FBF livelihoods (54 %) followed by farming (15 %), small business operators (14 %), collection and use of mangrove products (6 %) and other activities such as wage-earning or formal employment (10 %). The highest diversity of activities was at a peri-urban site, Chuabo Dembe, which differed from all other sites in Cluster and Principal Components Analyses. Fishing dominated activities at four of five sites, with the highest preponderance near the estuary mouth. Women played an important role in generating household income, mainly through farming and operating small businesses in peri-urban areas. The education level declined in rural settings. Overexploitation and degradation of natural ecosystems to provide for an increasing urban population around Quelimane threaten estuarine functioning, making deltaic FBF systems vulnerable. Rural development programmes should focus on improving education levels and the efficiency of food production, processing and distribution systems.
Monitoring the ichthyofauna is crucial to detect changes in aquatic communities for fisheries management and conservation. This study aimed to identify the most effective gear for ichthyofauna studies in the estuary. Thus, the performance of the beach seine (active gear) and chicocota (fixed gear), common fishing gears used by artisanal fishers in the Bons Sinais estuary (BSE), were used to characterise fish assemblage structure. Monthly surveys were conducted at two fixed sample points of the BSE to assess the composition of the fish assemblage. The analysis revealed statistical differences in abundance, biomass, and the presence/absence of different species between gear regardless sampling months. At ecological level differences among gears were explained by different modus operandi, technological features and also different sampling habitats where gears operate, beach seine is catching bottom-bound and littoral fish while Chicocota is sampling the pelagic assemblage of the mid-channels. The frequency of occurrence of the 13 most abundant species differed between gears. Both gears were little size-selectivity in size with the mean total length and mean body height of these species statistically differed between gears due to the habitat-specific operation of each gear. A total of 92 fish species were identified. No statistical differences were observed among gears for species richness, diversity and evenness. Both fishing gears captured several local socio-economically important species in the BSE. In particular, 13 of the most important species accounted for more than 54% and 60% of the total abundance and biomass in beach seine and chicocota, respectively. The complementary use of fixed and active fishing gears for studying fish community structure in estuaries is recommended. This multi-gear sampling approach enhances the capacity to detect changes in fish communities and provides valuable data for fisheries management and conservation efforts.
The article describes study of the hydrochemistry of Taldykol lake system, consisting of the Big and Small Taldykol lakes, in the city of Nur-Sultan. The aim of the work is to assess the anthropogenic impact on the ecosystem of steppe wetlands located in the center of the developing capital. Sampling was carried out from 8 sites of the lake system in autumn 2020. The results of hydrochemical analysis of water samples made it possible to assess the level of chemical pollution and anthropogenic impact on the ecosystem, which, due to rapid urbanization, the lakes have been exposed to for decades. Now, due to the artificial fragmentation of lakes, the surface communication between the sites is disrupted, as evidenced by the different composition of pollutants in water bodies. Nevertheless, to draw up a complete picture and assess the anthropogenic impact on the Taldykol lake ecosystem, it is necessary to consider the results of a comprehensive study of lakes, which includes a number of additional works.
