André Vosloo

Can diatom-based pollution indices be used for biomonitoring in South Africa? A case study of the Crocodile West and Marico water management area

The inclusion of diatoms into the current suite of biomonitoring tools in use in South Africa, as well as the use of European and other diatom indices in South Africa, and in particular the Crocodile and West Marico water management area, is discussed. The indices, when compared to chemical analyses, proved useful in providing an indication of the quality of the investigated waters. Several widely distributed diatom species were shown to have similar ecological tolerances in South Africa when compared to Europe. Although most of the diatoms encountered in the study were cosmopolitan, several possibly endemic species were recorded. The occurrence of endemic species, not included in existing diatom indices may lead to miscalculations of diatom indices. It is concluded that although diatom indices developed in Europe and elsewhere are useful at the present to indicate water quality, a diatom index unique to South Africa including endemic species will have to be formulated.

Animals and Environments: Resisting Schisms in Comparative Physiology and Biochemistry

The articles in this volume are a product of the enthusiasm shown by delegates to meet in a remote corner of southern Africa and to discuss comparative physiology and biochemistry in their wider interpretation and future course. This collection reflects a small but long‐standing commitment to fostering the engagement of biological research with African issues and colleagues. Comparative physiology and biochemistry are evolving, but in this we must guard against fractionation of effort and purpose. Increasingly available molecular methods are seductive in encouraging work on model species and in employing these species in place of more appropriate comparative models. Concomitantly, the comparative approach is reaching out beyond the individual organism and organism‐organism interactions to establish underlying principles at ecosystem and landscape levels. The integration of molecular methods into comparative studies will require judicious selection and use of such skills if it is to be achieved without abandoning nonmodel species. The physiological and metabolic bases of ecosystem and evolutionary approaches must be underpinned by relevant data, requiring comparative researchers to accommodate colleagues contributing this specialist knowledge. These articles report distinct symposia, prefaced by a plenary paper. While each paper is itself a review of an entire symposium, they all exhibit a common theme, that comparative physiology and biochemistry are about interactions. It is our hope that the Comparative Physiology and Biology in Africa meetings will continue to facilitate special interactions between the people who make this happen.

Gill damage, metallothionein gene expression and metal accumulation in Tilapia sparrmanii from selected field sites at Rustenburg and Potchefstroom, South Africa

Fish were collected from field sites in the mining and agricultural areas of Potchefstroom and Rustenburg, North-West Province, South Africa. Water and sediment samples from each site, together with fish muscle and gills, were analysed by Inductively Coupled Plasma Mass Spectrometry (ICP-MS) for Li, Na, Mg, Al, Ca, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Cd, Hg, Pb and U. All metal levels were within the levels set by the South African Department of Water Affairs and Forestry, except for copper, which was still within the levels set by other guidelines. Water hardness, pH, dissolved oxygen concentration and conductivity were measured at each site. Fish gills were analysed morphometrically for arithmetic mean epithelial thickness (Har) and with Reverse Transcriptase PCR for metallothionein (MT) gene expression levels. Fish liver was also analysed for MT expression. Har was found to increase with changing copper levels in gills of fish, while gill and liver MT levels corresponded to changes in sediment and gill cadmium levels, respectively. There were highly significant differences in Har between different sampling sites, while no significant differences in gill and liver MT expression were found.

Short Postspawning Recovery Time Affects Dna Integrity and Fertilization Success of South African Abalone (Haliotis midae) Oocytes

ABSTRACT Hydrogen peroxide (H2O2) is used routinely by the abalone farming industry to induce spawning of adult abalone. The aim of the current study was to quantify DNA integrity of adult hemolymph cells as well as germ cells (oocytes and sperm) with different recovery times between spawning events. In addition, fertilization success of exposed germ cells was quantified. The results indicate that spawning events separated by short recovery (2–6 wk) will not provide sufficient recovery from H2O2-induced DNA fragmentation in adult hemocytes. It is recommended that the industry should ideally allow 6–8 wk between spawning events to prevent accumulation of DNA strand breaks in adults over time and to ensure adequate fertilization success to maximize farm production.

Molecules to Migration: Pressures of Life

The highly successful Fourth International Conference in Africa for Comparative Physiology and Biochemistry (ICA‐CPB) was held in the Maasai Mara National Reserve in July 2008. The theme of the meeting was “Molecules to Migration: Pressures of Life.” To enhance the theme, the venue and timing of the meeting were chosen to coincide with the arrival of approximately 1.4 million wildebeest on their annual migration from the Serengeti National Park in Tanzania. Like the three previous ICA‐CPB meetings, the discussion topics and the resulting collection of synthesia presented here were very diverse. The articles in this special collection reflect the authors’ interest in broadening our understanding of the field of comparative physiology and biochemistry and their commitment to engaging in global research with international colleagues. These articles are brief, synthetic reviews integrating information presented at and inspired by the meeting. From seasonal migration and reproduction in birds, to cardiovascular system development in vertebrates, to strategies for hypoxia survival, papers range from specific to broad interactions. What they all have in common: they increase our understanding of how animals are affected by and respond to the pressures of life.