Microplastics in aquatic ecosystems of Africa: A comprehensive review and meta-analysis.

Microplastic pollution is a global issue of great public concern. Africa is flagged to host some of the most polluted water bodies globally, but there is no enough information on the extent of microplastic contamination and the potential risks of microplastic pollution in African aquatic ecosystems. This meta-analysis has integrated data from published articles about microplastic pollution in African aquatic ecosystems. The data on the microplastic distribution and morphological characteristics in water, sediments and biota from African rivers, lakes, oceans and seas were extracted from 75 selected studies. Multivariate statistics were used to critically analyze the effects of sampling and detection methods, ecological risks, spatial distribution and similarity of microplastics in relation to the geographical distance between sampling sites. This study found that sampling methods have significant effect on abundance and morphological characteristics of microplastics and that African aquatic ecosystems are highly contaminated with microplastics compared to global data. The most prevalent colors were white, transparent and black, the most prevalent shapes were fibres and fragments, and the most available polymers were polypropylene (PP), polystyrene (PS) and polyethene terephthalate (PET). Microplastic polymers similarity decreased with an increase in geographical distance between sites. Risk levels of microplastics in African aquatic ecosystems were comparatively high, and more than 40 % of water and sediments showed highest level of ecological risk. This review provides recent information on the prevalence, distribution and risks of microplastics in African aquatic ecosystems.

The threat of micro/nanoplastic to aquatic plants: current knowledge, gaps, and future perspectives.

Plastics have been recognized as an emerging pollutant and have raised global concerns due to their widespread distribution in the environment and potential harm to living systems. However, research on the threat of micro/nanoplastics (MPs/NPs) to the unique group of aquatic plants is far behind, necessitating a comprehensive review to summarize current research progress and identify future research needs. This review explores the sources and distribution patterns of MPs/NPs in aquatic environments, highlighting their uptake by aquatic plants through roots and leaves, and subsequent translocation via the vascular system facilitated by the transpiration stream. Exposure to MPs/NPs elicits diverse effects on the growth, physiology, and ecological interactions of aquatic plants, with variations influenced by plastic properties, plant species, and experimental conditions. Furthermore, the presence of MPs/NPs can impact the toxicity and bioavailability of other associated toxicants to aquatic plants. This review shows critical knowledge gaps and emphasizes the need for future research to bridge the current understanding of the limitations and challenges posed by MPs/NPs in aquatic ecosystems.

Microplastics in marine invertebrates from the Red Sea Coast of Egypt: Abundance, composition, and risks.

This study marked the first exploration of microplastics in marine invertebrates in the Red Sea Coast of Egypt. 110 individuals from 11 different species, including Bivalvia, Gastropoda, Echinoidea, and Holothuroidrea, were collected near a popular tourist destination. The average concentrations of microplastics varied among species, ranging from 8.2 to 136.5 items per individual or 0.2 to 18.1 items per gram of tissue wet weight, with 100 % occurrence. Bivalves had higher concentrations per gram of tissue compared to sediment dwellers and grazers, with Brachidontes pharaonis showing the highest levels. Actinopyga crassa, a sea cucumber, displayed the highest abundance per individual due to its large size and behavior. The identified plastic polymers suggested sources associated with tourism and maritime activities. The estimated human exposure to microplastics through bivalve consumption was minimal. Further research is needed to examine microplastics contamination in the Red Sea and its potential impacts on ecosystems and human well-being.

Quantifying microplastics pollution in the Red Sea and Gulfs of Suez and Aqaba: Insights from chemical analysis and pollution load assessment.

Microplastics (MPs) constitute the majority of marine plastic litter. The pollution caused by MPs has been categorized as a gradual and persistent crisis, but little is known about its extent along the shores of the Red Sea, particularly on the Egyptian side. The Red Sea is a rapidly developing region and home to critical ecosystems with high levels of endemism. This study represents the first comprehensive survey investigating the extent of MP pollution along the Egyptian shores of the Red Sea, including the Gulf of Suez and Aqaba. Mean concentrations ranged from 23.3 ± 15.28 to 930.0 ± 181.9 MPs/kg DW. Out of 17 beaches surveyed, 12 had mean concentrations of <200 items/kg, indicating a low occurrence of MPs compared to the shores of the Mediterranean Coast of Egypt. The pollution load index varied from low to medium levels in most locations. Ras Mohamed, a marine protected area, showed high vulnerability to MP pollution. All the investigated particles were fragments of secondary MPs. The sources of pollution mainly come from maritime activities, including cargo shipping and intense recreational activities. Fourier Transform Infrared Spectroscopy identified four plastic polymers, with polyethylene and polypropylene being the most common. The surface morphology of plastic particles was examined using scanning electron microscopy combined with energy-dispersive X-ray spectroscopy. All the particles exhibited signs of degradation, which could generate countless plastic pieces with possible deleterious impacts. This work has highlighted the importance of conducting region-specific assessments of mismanaged plastic waste, focusing on the role of tourism and recreational navigation as contributors to plastic litter, to estimate plastic waste inputs into the waters of the Red Sea Coast of Egypt. Efforts are needed to develop strategic plans to reduce the disposal of plastic waste in the region.

Prevalence and risk assessment of microplastics in the Nile Delta estuaries: "The Plastic Nile" revisited.

Recent research is directed toward studying plastic pollution in rivers, and estuaries due to the importance of freshwater bodies in all aspects of life. The river deltas and estuaries are interesting for studying the flux of plastics into the oceans. The Nile River has been identified as a hot spot of plastic litter flux in the eastern Mediterranean basin. In addition, it was nicknamed "Plastic Nile", yet this major river is largely unexplored with a lack of field measurements and adequate surveys. The current study was based on bridging this scientific gap. Three trips were conducted, covering 30 km in the Rosetta branch and 23 km in the Damietta branch, during the high water level in summer 2021, and 10 km off the inlet of Lake Burullus, in spring 2021. Microplastics in surface water ranged from 761 ± 319 to 1718 ± 1008 MPs/m3, and from 167 ± 137 to 1630 ± 1303 MPs/kg of dry sediments. Land use/ land cover mapping using Sentinel-2 images showed several sources of pollution that contribute to plastic contamination in the study area. Thermal analysis indicated seven plastic polymers; including, PE, PP, PET, PEVA, and PTFE, using discarded plastic products as reference materials. Microplastics were composed of colored and glossy fragments of sizes <500 µm, originating from land-based sources. Pollution load, polymer risk assessment, and ecological risk indices were calculated. Based on field observations macro-plastics were retained within the extensive network of infrastructure and dam systems. 80-106 billion MPs/year were estimated to flux from the Nile estuaries into the Mediterranean Sea. The current situation urges the development of binding plans to reduce plastic waste in the Nile Delta, as well as setting environmental monitoring points along the Deltaic coast.

Microplastics contamination in commercial fish from Alexandria City, the Mediterranean Coast of Egypt.

Plastic waste is a major threat to various marine ecosystems. Due to being semi-enclosed basin with dense population, the Mediterranean Sea has been considered as a hot spot for plastic pollution. Alexandria was listed as one of the major cities contributing to plastic waste in the eastern Mediterranean basin. Accordingly, microplastics (MPs) abundance and composition were investigated in the digestive tracts of commercial fish species from two major fishing areas in Alexandria; Abu-Qir Bay and Eastern Harbor, which are affected by plastic pollution. The incidence and average densities of MPs were 91.8 ± 8.4% and 11.7 ± 9.5 items fish-1, similar to highly polluted regions in the southeastern Mediterranean Sea. The average MPs concentration was significantly higher in Sparus aurata (38.3 ± 28.4 items fish-1) than all species, except for Siganus rivulatus and Boops boops. Polyethylene and poly ethylene-vinyl acetate were the dominant polymers in the fish digestive tracts. Four types of plastic polymers were recorded in Siganus rivulatus and five in Parupeneus macronemus. The dominance of glossy fragments (sizes <500 µm) in Abu-Qir Bay indicated land-based source of pollution from domestic, agricultural, and industrial wastes. The dominance of larger plastic filaments and colored fragments in the Eastern Harbor suggested secondary MPs, originating from the fragmentation of larger plastic items of sea-based sources, such as fishing and recreational activities.

Characterization and distribution of plastic particles along Alexandria beaches, Mediterranean Coast of Egypt, using microscopy and thermal analysis techniques.

Microplastics (MPs) contamination has become a global concern with potential impacts on the marine environment. Alexandria is the second-largest city in Egypt and a significant contributor of plastic litter inputs into the Eastern Mediterranean Sea. The current study provides an in-depth analysis of the plastic particles accumulated along Alexandria beaches. Types, composition, and potential sources of MPs were investigated using microscopy and thermal analysis. A mean value of 389.1 ± 285.9 items kg-1 dry weight was detected in the shore sediments similar to other records from the Eastern Mediterranean region. An average of 457.4 ± 281.8 items m-3 was recorded in the surface water, which was the highest recorded MPs density in onshore waters of the Mediterranean region. Thermogravimetric analysis (TGA) showed that plastics made up 0.5% - 72% of the materials extracted from the sediment samples, and 0.58% - 20.6% from the water samples. Differential scanning calorimetry (DSC) identified ten semi-crystalline polymers. Low-density polyethylene (LDPE) and polyethylene vinyl acetate (PEVA) were the common polymers. The single-use plastic bags and detergents were the land-based sources of marine plastic litter. The sea-based sources included antifouling paints, maintenance of ships, and abandoned fishing gears. Proper management plans of domestic waste input, polluter-pay strategy, and education programs aiming at the Fishermen and how plastic pollution would impact their livelihood are urgently needed.

Thermal analysis and enhanced visual technique for assessment of microplastics in fish from an Urban Harbor, Mediterranean Coast of Egypt.

Enhanced visual counting technique coupled with combustion analysis and differential scanning calorimetry (DSC) was applied to assess microplastics (MPs) contamination in fish digestive tracts from Eastern Harbor, Egypt, to provide a simple and economic method for MPs assessment. This was the first study in Egypt to quantify MPs in fish. Plastic particles were detected in all fish samples, represented by seven thermoplastic polymers. The average number of MPs was at its highest level in Siganus rivulatus, Diplodus sargus, and Sardinella aurita (7527, 3593, and 1450MPs fish-1, resp.) and the lowest in Sphyraena viridensis and Atherina boyeri (46 and 28MPs fish-1, respectively). The average weight of MPs as measured by combustion ranged from 302mg kg-1 in S. rivulatus to 2mg kg-1 in Terapon puta.

Identification of marine microplastics in Eastern Harbor, Mediterranean Coast of Egypt, using differential scanning calorimetry.

Microplastic pollution has gained significant attention, and there are growing concerns about its potential effects on aquatic environments. The lack of proper solid waste management in Egypt has resulted in the accumulation of plastic litter and its deposition in waterways. However, no attempts have been made to identify or assess marine plastic litter in Egypt. We provide, for the first time, a precise, simple, and cost-effective method to identify microplastics in Eastern Harbor by using differential scanning calorimetry (DSC). This screening revealed the presence of ten polymers in seawater and shoreline sediments. Most of the extracted microplastics are secondary microplastics, as they appear to be remnants of larger plastic fragments.

Genetic analysis of the Linnaean Ulva lactuca (Ulvales, Chlorophyta) holotype and related type specimens reveals name misapplications, unexpected origins, and new synonymies.

Current usage of the name Ulva lactuca, the generitype of Ulva, remains uncertain. Genetic analyses were performed on the U. lactuca Linnaean holotype, the U. fasciata epitype, the U. fenestrata holotype, the U. lobata lectotype, and the U. stipitata lectotype. The U. lactuca holotype is nearly identical in rbcL sequence to the epitype of U. fasciata, a warm temperate to tropical species, rather than the cold temperate species to which the name U. lactuca has generally been applied. We hypothesize that the holotype specimen of U. lactuca came from the Indo-Pacific rather than northern Europe. Our analyses indicate that U. fasciata and U. lobata are heterotypic synonyms of U. lactuca. Ulva fenestrata is the earliest name for northern hemisphere, cold temperate Atlantic and Pacific species, with U. stipitata a junior synonym. DNA sequencing of type specimens provides an unequivocal method for applying names to Ulva species.