Search

Major threats to South African estuaries include freshwater flow alterations, urbanisation, habitat transformation, deteriorating water quality, increased biological invasions and resource over-exploitation. Although South African estuary restoration is in its infancy, important lessons have been learnt through past efforts undertaken in some of the most impacted systems. This review presents case studies focused on hydrological and physical restoration actions, while recognizing the need to implement urgent remedial measures to restore the populations of targeted estuary-associated marine fish species. Common interventions designed to arrest declining estuary health include artificial management of estuary mouths and the use of artificial structures to restore tidal action and remediate erosion damage. Limited natural habitat restoration actions have been conducted on the subcontinent. Fortunately, estuaries are resilient ecosystems and can recover fairly rapidly if appropriate restoration interventions are successfully applied. Restoration needs to be co-ordinated through a national strategy which is currently not in place. It is particularly important to address the root cause of deterioration through active restoration and/ or rehabilitation measures rather than only managing symptoms. The implementation of existing and future conservation legislation regarding the exploitation of natural resources within estuaries needs to be prioritised, so that over-exploited angling and subsistence fish species populations can recover.

Mercury behavior upon resuspension of sediments from two impacted areas of Guanabara Bay was evaluated to assess worst-case methylmercury (MeHg) responses, under dark experimental conditions. Total mercury (THg) and MeHg concentrations were determined along 24 hours experiments of sediment resuspension in the bay water. Fine-grained Meriti River estuary (MR) sediments had 8-times higher MeHg initial concentrations than sandy Rio the Janeiro Harbor (RJH) sediments (3.4 ± 0.29 vs. 0.41 ± 0.1 ng g− 1, respectively).THg contents were uncorrelated with resuspension time, while correlations of resuspension time with MeHg (r2 = 0.66) and %MeHg in relation to THg (r2 = 0.75) were observed only for RJH sediments. These findings correspond to a 2.8-times MeHg concentration increase (ΔMeHg = 0.75 ng g− 1) and 4.4-times increase in %MeHg (Δ%MeHg = 1.0%) for station RJH.This suggests that assessments of MeHg spatial-temporal variability can be limited if concentration changes due to sediment resuspension are not considered.

In this study, we analyze similarities and differences in 957 students’ perceptions of the history of human rights in six countries: England, India, New Zealand, South Africa, Sweden and the United States of America. This is investigated through the lens of the intended, implemented and achieved curricula. Our aim is to better understand what historical events students perceive as central in the history of human rights in different countries and how this may relate to education about, through and for human rights across borders. While the findings indicate a global culture of human rights, we identify several challenges in the teaching and learning of universal human rights in history education. In some instances, notions of nationalism and exceptionalism in society and history culture pose great challenges to the teaching and learning of human rights. In others, a strong focus on the global world have complicated the identification of human rights issues in the local context. Our findings also highlight the neglect of certain historical narratives, most notably the history of indigenous and minority groups. These findings are significant to researchers, teachers and decision-makers interested in furthering human rights and international understanding through education.

Made available in DSpace on 2019-12-05T18:15:21Z (GMT). No. of bitstreams: 1 Metalsandarsenic.pdf: 1576037 bytes, checksum: 3eb80eeafb6a1e29406adcf4bb682e9c (MD5) Previous issue date: 2019 DOI: 10.1080/10807039.2018.1529552