This paper is a synthetic overview of some of the threats, risks, and integrated water management elements in freshwater ecosystems. The paper provides some discussion of human needs and water conservation issues related to freshwater systems: (1) introduction and background; (2) water basics and natural cycles; (3) freshwater roles in human cultures and civilizations; (4) water as a biosphere cornerstone; (5) climate as a hydrospheric ‘game changer’ from the perspective of freshwater; (6) human-induced stressors’ effects on freshwater ecosystem changes (pollution, habitat fragmentation, etc.); (7) freshwater ecosystems’ biological resources in the context of unsustainable exploitation/overexploitation; (8) invasive species, parasites, and diseases in freshwater systems; (9) freshwater ecosystems’ vegetation; (10) the relationship between human warfare and water. All of these issues and more create an extremely complex matrix of stressors that plays a driving role in changing freshwater ecosystems both qualitatively and quantitatively, as well as their capacity to offer sustainable products and services to human societies. Only internationally integrated policies, strategies, assessment, monitoring, management, protection, and conservation initiatives can diminish and hopefully stop the long-term deterioration of Earth’s freshwater resources and their associated secondary resources.

This paper explores the nature and timing of the Middle Stone Age/Later Stone Age transition in South Africa and considers some of the potential causes of this technological reorganisation. It uses multivariate statistical methods to re-examine two important case studies: Umhlatuzana in KwaZulu-Natal, described by Kaplan (1989), and Rose Cottage Cave in the Free State, described by Clark (1997). Consistent with these previous analyses, it concludes that the Middle Stone Age/Later Stone Age transition at the sites occurred around 28 kya, involved a pre-Robberg transitional early Later Stone Age (ELSA) industry lasting until around 20 kya, and is defined by a series of secular changes demonstrating broad continuity over time. The paper also seeks to articulate these case studies with other explanations of the MSA/LSA transition, from the perspective of technological organisation and models of forager behavioural ecology. It argues that the microlithic technology seen with the origins of the LSA was a response to increasingly risky environments created by fluctuations in climate around the Last Glacial Maximum (LGM) and rising human populations. Microlithic technology may have emerged as a strategy for adding value to tools and weapons, increasing both their effectiveness and reliability in the face of riskier environments. It is also possible that new knapping strategies seen during the LSA resulted from restricted access to preferred sources of lithic raw material and were methods of optimising the use of poorer-quality local stone.

The feeding characteristics of the nase, based on its mouth morphology and feeding behavior related to aquatic habitat substrata sediments make this fish a biological uptake vector for microplastics in freshwater ecosystems. Fibers may have limited absorption through the gastrointestinal tract therefore unlikely to be found in fish gastrointestinal tissue and muscle tissue. The presence of microplastic fibers in the gastrointestinal content is proof of how difficult it is for these fibers to become embedded in other organs. The absence of microplastic fibers in muscle tissue and gastrointestinal tissue is key information for microplastic fabrication and management in aquatic ecosystems. The majority of fish have relatively low levels of microplastics; however, a few individuals have a higher dose. This is true for all types of microplastics analyzed, with the exception of fish that had just one microplastic present in the analyzed matrix. The microplastics are not concentrated in the fish muscle tissue, gastrointestinal tissue and gastrointestinal content in relation to fish age, which may be due to their different mobility in the ecosystem, or due to the recent appearance of this type of contamination and the scale at which microplastics bioaccumulate. Such a relatively common fish species must be included in the assessment and monitoring systems of the Eurasian lotic systems. The risks involved include the transfer of the freshwater environments microplastics into human tissues via the food web of fishing species with the nase as a key basis.

Experiments in replicating facsimiles of Late Neolithic engraved slate plaques from southwestern Iberia suggest that variation related to fine-motor skills is greater between individual engravers than within the work of a single engraver. This implies that the work of different individuals producing certain classes of material culture may be distinguishable on the basis of repetitive, idiosyncratic traits. These studies also generate otherwise unobtainable information about the experience of plaque making. We examine past and present methodological attempts to differentiate unconscious, individual styles from intentional, culturally mediated styles, and discuss why in some cases it is extremely difficult to separate such variation. We explore the link between individual variation and theoretical notions of the individual, and its implications for understanding the organization, transmission, and shared expression of ancient social practices.