Connectivity between marine reserves and exploited areas in the philopatric reef fish Chrysoblephus laticeps (Teleostei: Sparidae)

"No-take‟ Marine Protected Areas (MPAs) are successful in protecting populations of many exploited fish species, but it is often unclear whether networks of MPAs are adequately spaced to ensure connectivity among reserves, and whether spillover occurs into adjacent exploited areas. Such issues are particularly important in species with low dispersal potential, many of which exist as genetically distinct regional stocks.The roman, Chrysoblephus laticeps, is an overexploited, commercially important fishery species endemic to South Africa. Post-recruits display resident behavior and occupy small home ranges, making C. laticeps a suitable model species to investigate connectivity in marine teleosts with potentially low dispersal ability. We used multilocus data from two types of highly variable genetic markers (mitochondrial DNA control region and microsatellites) to clarify patterns of genetic connectivity and population structure in C. laticeps using samples from two MPAs and several moderately or severely exploited regions. Despite using analytical tools that are sensitive to detect even subtle genetic structure, we found that this species exists as a single, well-mixed stock throughout its core distribution. This finding lends supports to the status of MPAs as an adequate tool for managing overexploited marine teleosts. Even though adult dispersal out of MPAs is limited, the fact that the large adults in these reserves produce exponentially more offspring than their smaller counterparts in exploited areas makes MPAs a rich source of recruits. We nonetheless caution against concluding that the lack of structure identified in C. laticeps and several other southern African teleosts can be considered to be representative of marine teleosts in this region in general. Many such species are represented in more than one marine biogeographic province and may be comprised of regionally-adapted stocks that need to be managed individually

Zimbabwe's coloured gemstone endowments - A regional geological overview

Zimbabwe hosts a varied array of coloured gemstones. With the exception of emerald deposits and several world-class pegmatites, few of the gemstone occurrences have received detailed attention from the scientific or mineral exploration communities. In the present contribution we summarize the status of knowledge of the gemstone deposits and occurrences in Zimbabwe, paying particular attention to the geological settings in which they were formed. Synthesis of this regional geological approach reveals that there may be significant exploration potential for further gemstone occurrences, particularly in the extensive pegmatite fields and in Al-enriched orogenic belts that have undergone greenschist to granulite facies metamorphism. Further socio-economic and developmental initiatives will aid in optimizing the value generation from this important sub-sector

Ubiquitous Presence of Fe(II) in Aquatic Colloids and Its Association with Organic Carbon

Despite being thermodynamically less stable, small ferrous colloids (60 nm to 3 μm in diameter) remain an important component of the biogeochemical cycle at the Earth’s surface, yet their composition and structure and the reasons for their persistence are still poorly understood. Here we use X-ray-based Fe L-edge and carbon K-edge spectromicroscopy to address the speciation and organic–mineral associations of ferrous, ferric, and Fe-poor particles collected from sampling sites in both marine and freshwater environments. We show that Fe(II)-rich phases are prevalent throughout different aquatic regimes yet exhibit a high degree of chemical heterogeneity. Furthermore, we show that Fe-rich particles show strong associations with organic carbon. The observed association of Fe(II) particles with carboxamide functional groups suggests a possible microbial role in the preservation of Fe(II). These finding have significant implications for the behavior of Fe(II) colloids in oxygenated waters, and their role in different aquatic biogeochemical processes

A collaborative auto-ethnographic exploration of socially just practices by new academics in two South African higher education institutions

Challenges experienced in the higher education context require new academics to engage with issues of social justice in their pedagogical practices. This article focuses on such challenges and how these are met by the authors, who are new academics from two higher education institutions in South Africa. Using a collaborative auto-ethnographic approach to analyse and interpret practices from different disciplines and higher education institutions, critical insights into “response-able pedagogies” are highlighted. “Response-able pedagogies” may be described as those which foreground attentiveness, responsibility, curiosity and capability, are used as a lens to examine the pedagogical practices of the authors, as new academics. This lens is useful in that it illuminates ethical dimensions of how a socially just pedagogy might be enacted in disparate South African higher education contexts. Issues of language, academic literacies, resources, employability, cultural diversity, large classes, and student abilities are reflected upon in relation to new academics’ engagement with socially just pedagogies. The article is intended to be a useful resource specifically, but not exclusively for, new academics entering the field of higher education in South Africa

Reviewing evidence of marine ecosystem change off South Africa

Recent changes have been observed in South African marine ecosystems. The main pressures on these ecosystems are fishing, climate change, pollution, ocean acidification and mining. The best long-term datasets are for trends in fishing pressures but there are many gaps, especially for non-commercial species. Fishing pressures have varied over time, depending on the species being caught. Little information exists for trends in other anthropogenic pressures. Field observations of environmental variables are limited in time and space. Remotely sensed satellite data have improved spatial and temporal coverage but the time-series are still too short to distinguish long-term trends from interannual and decadal variability. There are indications of recent cooling on the West and South coasts and warming on the East Coast over a period of 20 - 30 years. Oxygen concentrations on the West Coast have decreased over this period. Observed changes in offshore marine communities include southward and eastward changes in species distributions, changes in abundance of species, and probable alterations in foodweb dynamics. Causes of observed changes are difficult to attribute. Full understanding of marine ecosystem change requires ongoing and effective data collection, management and archiving, and coordination in carrying out ecosystem research.DHE

A rest potential study of impurity (As, Au, Ni and Co) bearing synthetic pyrite in alkaline flotation conditions

Pyrite is an important mineralogical component of most sulphide ore deposit classes, where it commonly forms part of the gangue mineralogy, but may also represent an important ore mineral (i.e., auriferous pyrite). Effective and efficient separation of pyrite is thus a crucial step during most ore processing operations, and this is in part influenced by the pyrite mineral chemistry. Here, electrochemical measurements were used to study the reactivity of a series of well-characterised synthetic trace-element substituted pyrite samples under alkaline conditions relevant to industrial flotation. The presence of metals and metalloid impurities (As, Au, Co, and Ni) in pyrite were tested using rest potential measurements to infer oxidation and associated hydrophobicity. In the absence of any collector phases, pure- and Ni-substituted pyrite have the highest rest potential, followed by Co-substituted pyrite and couple-substituted (Co + Au) pyrite, whilst As-substituted pyrite has the lowest measured rest potential. Importantly, the degree of oxidation at the mineral surface correlates linearly with the concentration of each of the substituents, with the largest effect observed when As is the substituent. These results correspond to the semiconducting properties and noble character of each pyrite sample, with n-type pyrite (Au-, Co- and Ni-substituted) associated with noble character and high rest potential, whereas p-type As-substituted pyrite associated with least noble character and lowest rest potential. With the addition of a potassium amyl xanthate collector, the mineral chemistry further had an impact on the probability of dixanthogen formation. Increased substituent concentration in the pyrite lattice decreased the probability of dixanthogen formation, except in a sample where high Au (and moderate Co) was incorporated. These results highlight the importance of developing improved understanding of the impacts of substitution mechanisms on the surface reactivity and flotability of pyrite. Such an understanding will form the foundation for further improved (and engineered) approaches towards reagent design and mixture. This will serve to optimise separation of both gangue and valuable pyrite by using fundamental knowledge to target specific collector bands and flotation domains. © 2023 The AuthorsMinistry of Education and Science of the Russian Federation, Minobrnauka; Universiteit Stellenbosch, US; DSI-NRF Centre of Excellence for Integrated Mineral and Energy Resource Analysis, CIMERA; Institute of Experimental Mineralogy, Russian Academy of Sciences, IEM, RAS: NSh-2394.2022.1.5The authors are grateful to the DSI-NRF Centre of Excellence for Integrated Mineral and Energy Resource Analysis (CIMERA) for providing funding for this research. Special thanks to the Russian Academy of Science's Institute of Experimental Mineralogy for facilitating this collaboration and assisting with the synthesis of the pyrite crystals used in this study. In addition, Dr. Chareev acknowledges the state financial support of the leading scientific schools of the Russian Federation No. NSh-2394.2022.1.5 and the research funding from the Ministry of Science and Higher Education of the Russian Federation (Ural Federal University Program of Development within the Priority-2030 Program) that helped establish the experimental lab used to generate synthetic samples for this study. The authors would also like to express their gratitude to the colleagues at Stellenbosch University's Central Analytical Facilities (CAF) for their excellent assistance with the SEM and LA-ICP-MS evaluations. Thanks to Remy Bucher at Ithemba Labs for his help with the XRD analysis of our samples. Additionally, the authors would like to thank the editor and reviewers for reading and evaluating our manuscript

Identification of stomach contents from a Shepherd's beaked whale Tasmacetus shepherdi stranded on Tristan da Cunha, South Atlantic

Shepherd’s beaked whale Tasmacetus shepherdi is one of the most poorly known cetaceans, whose diet has created some speculation given that its dentition differs greatly from that of most other beaked whales that are primarily teuthophagous. The few stomachs examined previously have given seemingly conflicting dietary information. In this paper the stomach contents of a freshly stranded adult female on Tristan da Cunha have been examined through identification of trace elements and genetic analysis of soft parts. At least 13 cephalopod and 8 fish species were identified from beaks and otoliths respectively, but only undigested fish remains were present in the stomach and identified genetically as Beryx splendens. Reconstituted masses totaled 8809 g for cephalopods and 17,554 g for fish, with four species (Histioteuthis atlantica, Taningia danae, Ommastrephes bartrami and Pholidoteuthis ‘A’) comprising 78.6% of the cephalopods and one species (B. splendens) comprising 87.4% of the fish eaten. It is concluded that Tasmacetus may alternately exploit fish and cephalopods, depending on the time of day and access to seamount or continental slope areas.P.B.B. and M.J.S. acknowledge support from the National Research Foundation, South Africa, and S.v.d.H. thanks the Stellenbosch University Discretionary Fund for financial assistance.http://journals.cambridge.org/action/displayJournal?jid=mbi2015-09-30am201

Determination of nutrient salts by automatic methods both in seawater and brackish water: the phosphate blank

9 páginas, 2 tablas, 2 figurasThe main inconvenience in determining nutrients in seawater by automatic methods is simply solved: the preparation of a suitable blank which corrects the effect of the refractive index change on the recorded signal. Two procedures are proposed, one physical (a simple equation to estimate the effect) and the other chemical (removal of the dissolved phosphorus with ferric hydroxide).Support for this work came from CICYT (MAR88-0245 project) and Conselleria de Pesca de la Xunta de GaliciaPeer reviewe

Molecular ecology meets systematic conservation planning

Integrative and proactive conservation approaches are critical to the long-term persistence of biodiversity. Molecular data can provide important information on evolutionary processes necessary for conserving multiple levels of biodiversity (genes, populations, species, and ecosystems). However, molecular data are rarely used to guide spatial conservation decision-making. Here, we bridge the fields of molecular ecology (ME) and systematic conservation planning (SCP) (the ‘why’) to build a foundation for the inclusion of molecular data into spatial conservation planning tools (the ‘how’), and provide a practical guide for implementing this integrative approach for both conservation planners and molecular ecologists. The proposed framework enhances interdisciplinary capacity, which is crucial to achieving the ambitious global conservation goals envisioned for the next decade.Environment and Climate Change Canada (ECCC); Nature Conservancy of Canada; NERC Wallacea Programme Strategic Grant; an individual research contract by Fundação para a Ciência e Tecnologia; the National Research Foundation; a European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement.https://www.cell.com/trends/ecology-evolution/homeam2023BiochemistryGeneticsMicrobiology and Plant Patholog

Distribution and Phylogeny of EFL and EF-1α in Euglenozoa Suggest Ancestral Co-Occurrence Followed by Differential Loss

BACKGROUND: The eukaryotic elongation factor EF-1alpha (also known as EF1A) catalyzes aminoacyl-tRNA binding by the ribosome during translation. Homologs of this essential protein occur in all domains of life, and it was previously thought to be ubiquitous in eukaryotes. Recently, however, a number of eukaryotes were found to lack EF-1alpha and instead encode a related protein called EFL (for EF-Like). EFL-encoding organisms are scattered widely across the tree of eukaryotes, and all have close relatives that encode EF-1alpha. This intriguingly complex distribution has been attributed to multiple lateral transfers because EFL's near mutual exclusivity with EF-1alpha makes an extended period of co-occurrence seem unlikely. However, differential loss may play a role in EFL evolution, and this possibility has been less widely discussed. METHODOLOGY/PRINCIPAL FINDINGS: We have undertaken an EST- and PCR-based survey to determine the distribution of these two proteins in a previously under-sampled group, the Euglenozoa. EF-1alpha was found to be widespread and monophyletic, suggesting it is ancestral in this group. EFL was found in some species belonging to each of the three euglenozoan lineages, diplonemids, kinetoplastids, and euglenids. CONCLUSIONS/SIGNIFICANCE: Interestingly, the kinetoplastid EFL sequences are specifically related despite the fact that the lineages in which they are found are not sisters to one another, suggesting that EFL and EF-1alpha co-occurred in an early ancestor of kinetoplastids. This represents the strongest phylogenetic evidence to date that differential loss has contributed to the complex distribution of EFL and EF-1alpha