Tropical coastal ecosystems, such as mangroves, have a great ecological and socioeconomic importance for adjacent systems and local populations, but intensive environmental impact monitoring is still lacking, mainly in East Africa. This study evaluated the potential anthropogenic disturbance on Palaemon concinnus population structure and fitness. Palaemon concinnus populations from one peri-urban (domestic sewage impacted) and two pristine mangrove creeks were studied by sampling nearly 100 shrimps per location every 15 days for 12 months. The shrimps at the peri-urban location were larger, experienced longer reproductive periods, presented higher proportion of ovigerous females and better embryo quality when compared with shrimps inhabiting pristine locations. Physiological indices (RNA/DNA ratio) were similar between shrimps at pristine and peri-urban mangroves. However, a higher level of parasitation by a Bopyridae isopod, Pseudione elongata indicated some degree of stress on the host at the peri-urban mangrove, with potential effects on the host population dynamics.

Concentrations of polychlorinated biphenyls, polyaromatic hydrocarbons, hexachlorobenzene, and DDE were determined by passive sampling (semipermeable membrane devices) with exposure times of 1–1.5 years at 0.1–5 km depth in the Irminger Sea, the Canary Basin (both North Atlantic Ocean), and the Mozambique Channel (Indian Ocean). The dissipation of performance reference compounds revealed a pronounced effect of hydrostatic pressure on the sampler-water partition coefficients. Concentrations in the Irminger Sea were uniform over the entire water column (0.1–3 km). At the Canary Basin site, concentrations were 2–25 times lower near the bottom (5 km) than at 1.4 km. Concentrations in the Mozambique Channel (0.6–2.5 km) were lower than at the other two locations, and showed a near-bottom maximum. The data suggest that advection of surface waters down to a depth of about 1 km is an important mechanism of contaminant transport into the deep ocean.

Estuaries are important nursery areas for many species and these habitats are often affected by anthropogenic activities. We investigate possible negative effects of pesticides and metals on penaeid shrimps in Maputo Bay, Mozambique. Shrimps and water samples were collected in three estuaries and one coastal area for biomarker and chemical analysis. Acetylcholinesterase (AChE) and glutathione-S transferase activities were analysed as biomarkers for pollutants. 37 different pesticides were analysed in water samples and shrimp muscle tissue was analysed for 10 metals. Risk assessment showed that the environmental thresholds were exceeded for several herbicides in three of four of the assessed nursery areas. Lower AChE activities were detected in shrimps captured close to an agriculture area and this location had the lowest shrimp densities. Metal analysis in shrimp showed low levels. Despite localized effects, results highlight the need to improve the regulation of pollutants in the Espírito Santo estuary in Maputo bay.

Liquid natural gas (LNG) exploration has started off the coast of northern Mozambique, in the Rovuma Basin, East Africa. In advance of gas production, we collected in 2018 over 100 samples of surface sediments from 40 locations in the pristine and exploration areas at water depths of 5–2000 m. We have determined the levels of hydrocarbons (total hydrocarbon contents (THC) and 49 individual PAHs), heavy metals, arsenic, grain size and total organic carbon. While sediment composition varied strongly from coarse sediment to high mud contents (<63 μm), background levels of hydrocarbons and metals were found in most samples. We found anthropogenic contamination at one site in Pemba harbor. We observed no petroleum-related contamination, including the Palma area with numerous exploration wells. Elevated concentrations of barium and THC at some locations in this area are attributed to drilling activities but are not considered to be of environmental concern.

Little is known about the dynamics of particulate inorganic and organic matter in brackish water controlled by tidal prism and seasonal river discharges in Macuse estuary, on central Mozambique coast, southern Africa. This manuscript illustrates seasonal variation of biogeochemical flow dynamics in a tropical estuarine system in Zambézia province. The data were collected at 42 stations, including tidal current measurements with an Acoustic Doppler Current Profiler, tidal elevation with a tidal-gauge and nitrate, silicate (SiO2), dissolved oxygen and chlorophyll-a with a photometer device system and tidal currents with multisensory instrument device (Current, Temperature and Depth device). These field data helped to calibrate a twelve months simulation of a 3D Computational Aquatic Ecosystem Dynamics Model (3D CAEDM) in 2014. The results emphasize a tidal elevation of 4-m height that generated tidal currents of 120 cm/s. They combination with seasonal runoff of ~500 m3/s from Namacurra River and averaged bathymetry morphology of 10-m depth, led on to the seasonal concentration flux of dissolved oxygen, nitrate, SiO2 and chlorophyll-a during the ebbing and flooding. In addition, the river discharges were found to be the main source of nitrate and SiO2, while the tidal prism led on the hydrological flow of the brackish-waters during the rainy season with maximum salinity anomaly of 16%. Besides the data obtained, the 3D model matches in reproducing the biogeochemical data flow have considerable potential possess of a valuable information in long- and short-term and large- and small-scale that may allow policy-makers to determine political decisions for bio-conservation, sustainability and coastal management.

Recent studies have revealed significant impact of anthropogenic aerosols to both climate and human health. Even though significant efforts have been made across the globe, studies related to aerosols over Southeast Africa remain scanty, hence causing high uncertainty in predicting and understanding the impacts of these aerosols. The present study therefore analyzed long-term spatial and temporal distribution of aerosol optical depth at 550 nanometer wavelength (AOD₅₅₀) over the entire Southeast Africa. Relatively low AOD₅₅₀ has been detected over the region in comparison to highly polluted regions across the globe. The highest annual average (>0.2) was observed over Lake Malawi, Zambezi valley, and the coastal areas of Central Mozambique while low annual values were recorded over northeast of Mozambique, and the eastern areas of Zimbabwe. In terms of seasonality, AOD₅₅₀ was observed to be high (>0.3) during the dry months of September-October-November (SON) while being low (<0.1) during March-April-May (MAM) and June-July-August (JJA) in most areas. The seasonality of AOD₅₅₀ was observed to be highly influenced by changes in seasonal biomass burning and seasonal atmospheric circulation. Statistical analyses revealed an insignificant change of AOD₅₅₀ between 2002 and 2020 in most areas of the study domain. Regional open burning of biomass like bush fires and burning of crop residues during the dry months are the main sources of aerosol concentration. Therefore, the present study advocates the regulation and institutionalization of proactive and strategic mechanisms that curtail open burning activities within the region.

Indicators are substances that change color as the pH of the medium. Many of these substances are dyes of synthetic origin. The mulala plant (Euclea natalensis), which roots are commonly used by rural communities for their oral hygiene, and roseira (Hibiscus rosa-sinensis), an ornamental plant, are abundant in Mozambique. Currently, synthetic acid-base indicators are most commonly used but have environmental implications and, on the other hand, are expensive products, so the demand for natural indicators started. This study investigated the applicability of aqueous extracts of H. rosa-sinensis and E. natalensis as acid-base indicators. Ground on this work, the extracts can be used as acid-base indicators. On the basis of the absorption spectroscopy in both the UV-Vis region and previous studies, it was possible to preliminarily pinpoint anthocyanins and naphthoquinones as responsible for the shifting of colors depending on the pH range of aqueous extracts of H. rosa-sinensis and E. natalensis. These natural indicators are easily accessible, inexpensive, easy to extract, environmentally safe, and locally available.