Literatura científica selecionada sobre o tema "Maputo Bay (Mozambique) - Fiction"

Mangroves are critical to maintaining human well-being and global biodiversity. Eastern and western African shores present major environmental contrasts that reflect on mangrove forests’ structure and the ecosystem services they provide to human communities. This study compares the mangrove forest structure and condition, ecosystem services, and uses of resources in Maputo Bay (Mozambique in eastern Africa) and Príncipe Island (São Tomé and Príncipe in western Africa). Five mangrove species were identified in Maputo Bay, Avicennia marina, Bruguiera gymnorhiza, Ceriops tagal, Rhizophora mucronata, and Xylocarpus granatum, and the importance value index was higher for A. marina. Mangroves in Príncipe were exclusively dominated by Rhizophora harrisonii. In Maputo Bay, a weak regeneration characterized by a low quantity of seedlings was observed, although in Príncipe the sites were characterized by a low regeneration rate but well-established forests. The comparison of the mangrove structure between Maputo Bay and Príncipe Island presented statistically significant differences for mean DBH and height, whereas the trees in Príncipe presented higher values for both parameters. Strong human disturbance (through cutting) was identified in almost all sites in Maputo Bay but was rarely observed on Príncipe Island. In Maputo Bay, more than 90% of the coastal human community is involved in activities related to the surrounding mangroves, with a diversified exploitation of forest resources. On Príncipe Island, the exploitation of mangroves targets only tannin from the mangrove bark to dye fishing nets and small boats. The economic value of mangroves in Maputo Bay has subsistence and commercial importance, in contrast to Príncipe, which revealed no major economic value to the community.

A floristic analysis of the grass species assemblages of the Licuati Forest and Maputo Elephant Reserves south of Maputo Bay, Mozambique, is presented. Sampling of grass data was undertaken in six previously described, major vegetation types. TWINSPAN divisions distinguished grass assemblages that are characteristic for these major vegetation types of the study area. The results were supported by an Indirect Gradient Analysis. Further TWINSPAN divisions of a larger Maputaland data set indicated a floristic relationship between grass assemblages of similar major vegetation types in the study area and South Africa. This relationship was supported by high similarity values ( 65%), obtained with Sorenson's Coefficient. The coefficient also indicated varying degrees of similarity between grass assemblages of different major vegetation types within the study area. A rich diversity of 115 grass species and infraspecific taxa was recorded for the study area. The Chloridoideae and Panicoideae dominate the grass diversity and the genera with the most species include Eragrostis, Panicum and Digitaria. Most grass species in the study area are perennials and have a tufted growth form, but this varies considerably between vegetation types.

The Macaneta area lies in the Incomati River estuary in northern Maputo Bay, Maputo Province, southern Mozambique. The 56 km2 area of study was selected based on access from tracks and follows no formal boundaries. The site comprises a 10 km stretch of ocean beach, coastal dunes with patchy thicket forest, and low lying wet grasslands inland to the Incomati River. The wetlands have complex hydrology offering diverse salinity and temporal conditions. The peninsula of Praia de Macaneta is also included in the study site but with few data. Improved access to the site in Oct 2016 enabled over 200 field ornithological visits Oct 2016-Oct 2020 and the sightings are analysed and reported herein. A total of 295 species was recorded including eight Globally Threatened birds (three Endangered, five Near-threatened) and Internationally Important numbers of White-breasted Cormorant Phalacrocorax carbo and Whiskered Terns Chlidonias hybrida were found. Three new birds for Mozambique were discovered; Sharp-tailed Sandpiper Calidris acuminata (first for Africa), White-rumped Sandpiper C. fuscicollis and Pearl-breasted Swallow Hirundo dimidiate. An annotated checklist of selected species is presented. The Sharp-tailed Sandpiper in particular drew much birder interest with 254 international visitor days over the 12 weeks of its first visit Feb-Apr 2018, contributing over US$12,000 into the local economy. The bird returned for two further seasons but it was not possible to gather further data.

Mestrado em Ciências do Mar e das Zonas Costeiras
Maputo Bay is a tidally-energetic embayment in Mozambique, influenced by strong rainfall and associated river runoff during the wet season. Previous investigations have suggested the arrestment of the freshwater plume related to high mixing during spring tide, eroding stratification and preventing an efficient exchange with the shelf due to the hampering of density currents. It was suggested that, with decreasing mixing towards neap tide, the bay would re-stratify, releasing the estuarine plume. The objective of this dissertation was to find out whether and under which conditions this arrestment of the estuarine plume occurs in Maputo Bay. A 3-dimensional hydrodynamic model was applied to the bay, improving a previously published model through vertical and temporal refinement and recalibration. It is shown that now the model reproduces more accurately the semidiurnal and fortnightly stratification-mixing cycles occurring during the wet season. However, the model still predicts salinities lower than those found in observations. Uncertainties increase towards the mouth of the Maputo River, for which only modelled river flow data was available to force the bay dynamics, indicating this input as a possible source of the underestimation of salinity. The effect of varying river discharges, varying timings of discharge as well as varying discharge ratios on flushing times was investigated through a set of experiments of varying Maputo and Incomati river flows as well as timings of discharge during the spring-neap cycle. The results suggest that when no discharge or a small discharge is introduced, flushing times are smallest during spring tide, when barotropic forcing is strong. Largest flushing times are found approximately 40 hours before neap tide, when tidal forcing is relatively weak. Flushing times for model runs with larger discharge were smaller due to the addition of flushing from river water. Here, flushing times were especially small during neap tide, when the decreased tidal mixing lead to stratification through which a classical estuarine circulation could develop, leading to an efficient bay-shelf exchange. Maximum flushing times for high-discharge runs during wet season were found for spring tide. Shelf-bay exchange was most efficient when the discharge of the Maputo River was larger than the discharge of the Incomati River, due to its location opposite the bay opening, thus influencing a larger area before leaving the bay. Timing of the discharge of the freshwater had only small effects, influencing the amount of mixing induced on the freshwater when first entering the bay. It is concluded that the estuarine plume of Maputo Bay is in fact arrested during spring tide due to the large mixing inhibiting density currents and is released when mixing decreases, inducing stratification and baroclinic circulation. The potential energy stored in the bay is larger for a larger discharge of the Maputo River.
A Baía de Maputo, em Moçambique, é uma baía com marés energéticas, influenciada pelo escoamento dos rios associado a forte precipitação durante a estação húmida. Investigações anteriores têm sugerido que o aprisionamento da pluma de água doce está relacionado com a elevada mistura durante a maré viva, que por sua vez provoca a erosão da estratificação e impede a troca eficiente com a plataforma continental, dificultando o estabelecimento de correntes de densidade. Foi sugerido que com a diminuição da mistura durante a maré morta a baía seria re-estratificada, libertando a pluma estuarina. O objetivo desta dissertação foi averiguar se, e em que condições, este aprisionamento da pluma estuarina ocorre na baía de Maputo. Foi aplicado um modelo hidrodinâmico 3-d para a baía, resultante do melhoramento de um modelo publicado anteriormente, através do refinamento vertical e temporal e recalibração. É demonstrado que agora o modelo reproduz com mais precisão os ciclos de estratificação/mistura semidiurnas e quinzenais que ocorrem durante a estação chuvosa. No entanto, o modelo ainda prevê salinidades inferiores as encontradas em observações. As incertezas aumentam próximo da foz do Rio Maputo, para o qual existem apenas dados de modelos de bacia para forçar o modelo, indicando esta entrada como uma possível causa da subestimação da salinidade. Foi definido um conjunto de experiências de diferentes descargas dos Rios Maputo e Incomati, sendo estes introduzidos no modelo em fárias fases do ciclo da maré. Foi investigado o efeito da variação da duração das descargas fluviais e da proporção do Maputo e do Incomati nos tempos de renovação da água na baía. Os resultados sugerem que quando há uma pequena descarga dos rios, os tempos de renovação são menores durante a maré viva, quando o forçamento barotrópico é forte. Os maiores tempos de renovação encontram-se cerca de 40 horas antes da maré morta. Os tempos de renovação para as corridas com maior descarga são menores devido à adição de descargas de água do rio. Neste caso, os tempos de renovação foram especialmente pequenos durante a maré morta, quando a diminuição da mistura pela maré induz estratificação, criando condições para o desenvolvimento da circulação estuarina clássica, e escoando a baía eficiente. Tempos máximos de renovação para corridas de alta descarga durante a estação chuvosa foram encontrados em condições mistas de maré viva. O intercâmbio entre a baía e a plataforma continental foi mais eficiente para uma maior proporção do Rio Maputo em relação ao Rio Incomati. Este padrão justifica-se pela maior distância da foz do Rio Maputo à entrada da baía. A variação do momento da descarga de água doce em relação à fase da maré tem efeitos pouco significativos (ou pouco relevantes), determinando apenas o grau de mistura que influencia a água doce nas primeiras horas a seguir da descarga. Concluiu-se que existe um aprisionamento da pluma estuarina da Baía de Maputo. Este aprisionamento ocorre durante a elevada mistura de maré viva. A energia potencial armazenada na baía é maior para uma descarga maior do Rio Maputo.

The ecology and population biology of bottlenose and humpback dolphins inhabiting the Maputo Bay, Southern Mozambique were studied through boat based photoidentification surveys and behavioural methods between December 1995 and December 1997. Data from preliminary surveys carried out in 1992 are also included. Bottlenose dolphins occurred throughout the year in Maputo Bay, but were sighted infrequently (36% of surveys). Their occurrence and group size were significantly larger during winter. Group size of bottlenose dolphins not differ significantly between months, daylight hours, semi-lunar tidal cycles and depth. Most identifiable bottlenose dolphin individuals had low site fidelity, but nursing females had relatively high site fidelity, implying that Maputo Bay is a nursing area. The group dynamics of bottlenose dolphins suggests a fluid (fission-fusion) social organisation. Age and sex appears to influence the degree of association between individuals. An influx of bottlenose dolphins occurred during winter and influenced group size and occurrence. Bottlenose dolphins occurred in restricted areas of the Bay, preferring the north eastern area (the pass between the Bay and the Ocean), and along the 3 km strip from the east coast of Inhaca Island. Their distribution here did not vary with depth, although they did not occur in intertidal areas. Feeding dominated both frequency and proportion of time of bottlenose dolphin behaviour. Social behaviour accounted for a small proportion of time (10%) and was greater in open unsheltered areas. Neither season, nor depth, nor daylight, nor tides influenced the proportion of time allocated to the types of behaviours. Non directional movement occurred on most of the sightings of bottlenose dolphins, but smaller groups of dolphins moved inshore at high tide late in the afternoon. Few bottlenose dolphin births were observed and the numbers of animals born varied between years. Recruitment rates at six months and one year were low and mortality rates of calves appeared high, but were probably inaccurate because the fate of mother-calf pairs that left the area could not be established. Population estimates of the bottlenose dolphins varied between 170 and 526 individuals. The precision of these estimates was poor, because of high proportion of transient individuals which almost certainly violated some model assumptions. Humpback dolphins occurred throughout the year in Maputo Bay, but were sighted infrequently (21% of surveys). The occurrence and group size of humpback dolphins were not influenced by season, months, daylight, semi-lunar tidal cycles and depth. Groups of humpback dolphins in Maputo Bay were the largest observed along the east coast of Southern Africa. Most identified humpback dolphin individuals showed low site fidelity, but a relatively high proportion of individuals (including nursing females) had high site fidelity. Humpback dolphin groups had a fluid (fission- fusion) social organisation, but there was a large proportion of stable associations between resident individuals. Age and sex appears to influence the degree of association between individuals. An influx of humpback dolphin individuals occurred during summer but did not change group size or occurrence, suggesting the occurrence of an outflux of other individuals. Humpback dolphins in the Bay ranged between the deep north eastern Maputo Bay to the southern intertidal areas. Most sightings occurred within 1 km from shore along the eastern coast of Inhaca Island, at variable depth. Humpback dolphins spent more time feeding (57%) and travelling (30%) than socializing and resting, because of their movements between extensive intertidal areas and deep channels. Social behaviour contributed a small proportion of time (10%), but increased when humpback dolphins moved towards and within shallow sheltered areas. Neither season, nor depth, nor daylight, nor tides influenced the proportion of time allocated to the types of behaviours of this species. Non directional movement occurred on most of the sightings of humpback dolphins, thought this was significantly influenced by diurnal tides. Few humpback dolphin births were observed and their numbers varied between years. Recruitment rates at six months and one year were low and mortality rates appeared high, but were probably inaccurate because the fate of mother-calf pairs that left the area could not be established. Population estimates of humpback dolphins varied between 105 and 308 individuals, but their precision was poor, because of a high proportion of transient individuals which almost certainly violated some model assumptions. Maputo Bay is a feeding, breeding and nursing area for bottlenose and humpback dolphins. These species are threatened by intense fishing activity, habitat degradation, coastal development and disturbance by powerboats and other activities (tourism, port) carried out in and around Maputo Bay. Their low estimated growth rates imply the implementation of precautionary conservation measures. The actual distribution of these species may reflect the deterioration of the habitats in the western part of the Bay. A coastal zone management plan to address environmental problems affecting the dolphin species need to be formulated and implemented.
Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2008.

M.Sc.
The KaNyaka barrier island system consists of the vegetated KaNyaka and Portuguese Islands, and various partially exposed sandbars. It is situated in south-easternmost Mozambique where it forms a barrier between Maputo Bay in the west and the Indian Ocean in the east. It forms part of the northern most limit of the Maputaland Group, which consists of Pliocene to Holocene sediments. The island system is an example of a compound barrier island since it comprises a stacked succession of several ancient shoreline marine and aeolian sedimentary rock units and sediments, along with various active sedimentary environments. This thesis describe the general geology of the island system, the petrography of the various rock and sedimentary units and provide information on provenance of sediment based on detrital zircon age populations. It also provides several new 14C age dates of shell fossils and calcified rhizoliths. KaNyaka Island consists of two high north-south trending dune cordons along its eastern and western shores, with a low-lying dune-covered area in between. The Western dune cordon consists of aeolian calcareous quartz arenite of the Ridjene Formation unconformably overlain by calcified aeolian dunes of the Alto Pocuane Formation in turn overlain by the unlithified red dunes of the Barreira Vermelha Formation. The core of the Eastern dune cordon consists of the calcareous quartz arenite of the Cabo Inhaca Formation comprised of stacked calcified aeolian dunes, the marine and tidal deposits of the Ponta Mazondue and Ponta Torres formations form the eastern and south-western flanks of the Eastern dune cordon. The formations are overlain by unlithified red to orange sands of the Changana Formation and partially lithified light grey to yellow sands of the Muamuluago Formation. The area between these two dune cordons is covered by low-lying aeolian dunes of the Alto Chumine Formation, ancient sandbar and beach deposits of the Chunhe Formation and both modern and paleo-intertidal flat deposits. Modern sedimentary environments include high-energy beaches, intertidal flats, sand spits, sandbars and aeolian dunes. The presence of aeolian deposits extending below the present sea-level, and marine deposits up to 3m above it, indicates that the KaNyaka barrier island system records a long history of sea-level change. 14C dating of marine and freshwater shell fossils and a rhizolith collected from several of the formations on the KaNyaka barrier island system assist in defining the history of the island with reference to sea-level fluctuations. Results from two freshwater shell fossils in the aeolian Alto Pocuane and Cabo Inhaca Formations indicate that they were deposited and subsequently calcified 47 000 and 30 000 years ago respectively, at times when the sea-level was 40 - 60 m lower than at present. The red sand of the Barreira Vermelha and Changana formation overlying these calcified dunes are suggested to have formed when climate was drier and sea-level even lower, during the Last Glacial Maximum (LGM) around 17 000 years ago. 14C ages on formations overlying the red sand deposits all postdate the Last Glacial Maximum and record sediment deposition of the past 7 000 years when the sea-level was either rather similar or somewhat higher than the present. Detrital zircon age populations, determined by laser ablation inductively coupled mass spectrometry (LA-ICP-MS), indicate that the majority of the sediment building the barrier island system was derived from the Grenvillian (~1100 Ma) and the Pan-African (~500 Ma) orogenic belts situated along the eastern side of Africa. Sediment was probably transported from exposed rock successions of these belts by large rivers like the Zambezi in the north and the Tugela in the south. The sediment was then dispersed along the coast by the south flowing Agulhas Current and northward directed long-shore current. Rivers feeding into Maputo Bay, like the Phongola, Umbeluzi and Incomati, draining the Kaapvaal Craton and Karoo Supergroup provided very little sediment to the barrier island system.