A review of the conservation status of seasonal Nothobranchius fishes (Teleostei: Cyprinodontiformes), a genus with a high level of threat, inhabiting ephemeral wetland habitats in Africa

Abstract

Abstract The small and colourful Nothobranchius fishes inhabit ephemeral habitats in freshwater wetlands of Africa and have extreme life‐history adaptations that allow their eggs to survive the periodic drying up of the seasonal natural habitats. They are subject to high levels of threat, with 72% of the 94 assessed species falling into one of the threatened Red List categories, as a consequence of habitat degradation of seasonal wetlands. There is, therefore, a need to conserve ephemeral waters for species that rely on the seasonality of habitats. Extinction risk factors for all species of the genus were entirely reworked with IUCN Red List assessments, whereas first‐time assessments were established for species that had previously not been evaluated. These fishes complete their seasonal life cycle in ephemeral natural habitats and this makes them highly vulnerable, as such wetland habitats are often degraded owing to multiple interacting human‐induced stressors and threats, including cultivation of wetlands for agriculture, abstraction of water, expansion of urban areas and pollution load. A fine‐scale classification scheme based on habitat type was used for each site to identify ecological characteristics and the pattern of threats. The classification scheme is based on a primary subdivision of natural habitats compared with those modified by human activities, with further subdivision within the two fundamental groupings. Out of the 478 analysed habitat site observations by the authors, 46% were affected by human activities. Recommended conservation actions include: conducting surveys to better understand habitat trends and threats; establishing protected areas and effectively allocating resources to preserve wetland habitats; managing protection of the structural integrity of the habitats throughout the seasonal phases of wet and dry seasons; and raising awareness of the importance of healthy wetland systems and the value of the unique seasonal freshwater biodiversity.