Nine decades of research on Zostera capensis: from foundational science to conservation and resilience

Cape dwarf eelgrass Zostera capensis is the most abundant seagrass in South Africa, with some isolated populations occurring along the East African coastline. Providing numerous ecosystem services that support biodiversity and human wellbeing, it is endangered throughout its distribution. As such, the long-term persistence of Z. capensis is uncertain and novel approaches are required to reverse declines and the loss of associated critical ecosystem functions. Central to this is the need to build on existing scientific knowledge, so that habitat requirements, responses to future global change pressures and the functional significance of Z. capensis from a socio-ecological perspective can be better understood. In this comprehensive review, we summarise 8 key topics from 197 studies published between 1933 and 2023 and present a timely overview of research conducted on Z. capensis. Some of the earliest research that focussed on foundational knowledge included geographical distribution and aspects of seagrass ecology and physiology. In the last 3 decades, the breadth and diversity of research increased to encompass themes particularly relevant to ecological value and conservation, including emerging approaches such as conservation genomics, restoration and assessing the value of seagrass meadows in the context of blue carbon. This review also identifies critical gaps in our understanding of Z. capensis, including the impact of pollutants and sea level rise on seagrass persistence, novel techniques for mapping seagrass meadows, the interaction of microbiomes and seagrass health, alternative sources for upscaling seagrass restoration, increasing management and conservation efforts and engaging with people's perceptions on the value of seagrass meadows.