Connectivity and ecological networks : Technical Information Note 01/2016

This Information Note introduces connectivity and ecological networks within the context of landscape planning, design and management and should assist discussions members typically hold with professional ecologists

The nature of the CO2-concentrating mechanisms in a marine diatom, Thalassiosira pseudonana

• Diatoms are widespread in aquatic ecosystems where they may be limited by the supply of inorganic carbon. Their carbon dioxide concentrating mechanisms (CCM) involving transporters and carbonic anhydrases (CAs) are well known, but the contribution of a biochemical CCM involving C4 metabolism is contentious. • The CCM(s) present in the marine centric diatom, Thalassiosira pseudonana, was studied in cells exposed to high or low concentrations of CO2, using a range of approaches. • At low CO2, cells possessed a CCM based on active uptake of CO2 (70% contribution) and bicarbonate, while at high CO2, cells were restricted to CO2. CA was highly and rapidly activated on transfer to low CO2 and played a key role because inhibition of external CA produced uptake kinetics similar to cells grown at high CO2. • The activities of PEP carboxylase (PEPCase) and the PEP regenerating enzyme, pyruvate phosphate dikinase (PPDK), were lower in cells grown at low than at high CO2. The ratios of PEPCase and PPDK to ribulose bisphosphate carboxylase were substantially lower than one even at low CO2. • Our data suggest that the kinetic properties of this species results from a biophysical CCM and not from C4 type metabolism

Stakeholder perspectives on the value and challenges of private rhinoceros ownership in South Africa

The value of private sector rhinoceros conservation in South Africa is a topic of much debate, often fueled by controversies surrounding trade in rhinoceros horn. We used semi-structured interviews (n = 16) to assess perceptions of private rhinoceros owners and other stakeholders regarding the value of the industry and its challenges. All stakeholders attested to the conservation value of privately-owned rhinoceroses and identified poaching as the main challenge. Most of the private owners identified the lack of legal international horn trade as driving the escalation in poaching, whereas other stakeholders perceived a wider range of contributing factors. The rhinoceros owners mostly favored international trade in rhinoceros horn, whereas non-governmental organization representatives were broadly opposed. Other stakeholders noted both positive and negative outcomes. Our results suggest greater collaboration between private sector stakeholders and government agencies will be essential for consensus around future management policies, especially concerning divisive options such as trade