Sampling, isolating and identifying microplastics ingested by fish and invertebrates

Microplastic debris (<5 mm) is a prolific environmental pollutant, found worldwide in marine, freshwater and terrestrial ecosystems. Interactions between biota and microplastics are prevalent, and there is growing evidence that microplastics can incite significant health effects in exposed organisms. To date, the methods used to quantify such interactions have varied greatly between studies. Here, we critically review methods for sampling, isolating and identifying microplastics ingested by environmentally and laboratory exposed fish and invertebrates. We aim to draw attention to the strengths and weaknesses of the suite of published microplastic extraction and enumeration techniques. Firstly, we highlight the risk of microplastic losses and accumulation during biotic sampling and storage, and suggest protocols for mitigating contamination in the field and laboratory. We evaluate a suite of methods for extracting microplastics ingested by biota, including dissection, depuration, digestion and density separation. Lastly, we consider the applicability of visual identification and chemical analyses in categorising microplastics. We discuss the urgent need for the standardisation of protocols to promote consistency in data collection and analysis. Harmonized methods will allow for more accurate assessment of the impacts and risks microplastics pose to biota and increase comparability between studies

Historical archaeology of the 19th century caravan trade in north-eastern Tanzania: a zooarchaeological perspective

This zooarchaeological study examined animal economies practiced by local communities against the context of the expansion of the caravan trade in eastern Africa during the nineteenth century. Specific objectives were to establish whether: a) animal economies in areas crossed by caravan trade routes were transformed as a result of expanding trade and the demand for supplies; b) new herd management strategies were adopted by local communities to ensure production of surpluses for exchange; and c) the expansion of this trade caused subsistence stress for local communities. The study area is the Lower Pangani River Basin, north-eastern Tanzania. The three studied riparian island settlements of Ngombezi, Old Korogwe and Kwa Sigi are mentioned in the nineteenth-century European accounts as caravan halts in the Lower Pangani. These were identified through archaeological survey and oral interviews - using the nineteenth-century accounts as a guide to their likely locations. Excavation exposed evidence for human settlements dating to the late seventeenth or early eighteenth centuries AD, and materials recovered include over 30,000 pieces of animal bone, 39,000 potsherds, 4,020 local and imported beads, metal objects, worked bones, remains of flintlock muskets and coins. The analysis of the faunal remains indicates that domestic livestock, a wide range of wild animals, and locally caught fish, were all being consumed at these settlements. The proportion of wild fauna in the assemblage suggests their significant contribution to the diet. At Ngombezi where the longest dated sequence was revealed, such a consumption pattern of mixing domestic and wild resources is not significantly different from that of the pre-nineteenth-century levels, suggesting that the integration of these settlements into the caravan trade network had limited effects on food procurement strategies and consumption patterns. There is a general lack of evidence that young animals were slaughtered, which would be indicative of consumption pressure on domestic stock, as the majority of domestic stock was slaughtered after reaching maturity age - over 3 years for cattle and over 2 years for sheep and goat. These major findings contradict arguments made by historians that the caravan trade had a transformative effect on communities lying along the main trade routes in the region, though additional research at other sites is needed to strengthen this argument

Building a Ngalawa Double-Outrigger Logboat in Bagamoyo, Tanzania: A Craftsman at his Work

This is the author accepted manuscript. The final version is available from Routledge via the DOI in this recordThis article documents master logboat-builder Alalae Mohamed’s construction of a ngalawa fishing vessel in Bagamoyo, Tanzania. The ngalawa is an extended logboat with double outrigger and lateen sail used by low-income, artisanal fishers. It is the most common marine vessel type of the East African coast. This article follows the construction process from Alalae’s selection and the felling of the tree(s) to the launching of the vessel. It outlines the tools and materials used, details the sequence he followed, and presents his choices and considerations made along the way. It is accompanied by a documentary film recording the construction process, a 3D digital model of the vessel and detailed construction drawings.Arts and Humanities Research Council (AHRC)Gerda Henkel Foundatio