In the 1950s, the field of ecology incorporated the gradient paradigm, which demonstrated that the structure and functionality of ecosystems are governed by spatial gradients of environmental conditions. The southern coast of Africa is home to one of the most dramatic environmental gradients in the world, largely governed by the confluence of two oceans in this region, but also by the influence of two opposing currents (the cold Benguela Current and the warm Agulhas Current). Therefore, within a relatively small region, one can range from ecosystems dominated by coral reefs (typical of tropical waters) on the southeast coast to ecosystems dominated by kelp (typical of cold waters) on the southwest coast. This makes the coasts surrounding present-day South Africa a unique natural laboratory in the world for studying the effects of environmental gradients on ecosystems.
One of the factors that most negatively impacts the world’s ecosystems is biological invasions (non-native species transported intentionally or unintentionally to new regions where they can have significant ecological and economic impacts). Recently, much progress has been made in the ecological understanding of biological invasions, but very little is known about the population dynamics of these biological invasions over time and space.
This project aims to study biological invasions over time and across environmental gradients along the South African coast. The South African coast contains a large number of marine protected areas and is frequented by a large number of vessels (directly or indirectly responsible for the transport of non-native species) each year. This study will be conducted by analyzing environmental DNA (eDNA) preserved in sediments from well-preserved estuarine areas. These areas are key points for the introduction of non-native marine species that are abundant and well-characterized along the coasts where this study will be conducted. eDNA research focuses on the detection of DNA found in ecosystems (e.g., in water or sediment) that can be isolated and sequenced (via metabarcoding). eDNA detection provides us with information on all the species found in the sampled ecosystem, from enormous whales to tiny bacteria. This approach is innovative (it has only recently been used for the detection of metazoans or animals) and revolutionary as it provides us with a resolution for estimating biodiversity patterns never seen before. The CEAB research group is a national leader in the study of eDNA in marine coastal environments.
