BIOLOGICAL INVASIONS IN MARINE SYSTEMS
One of the oldest invasive species occurring on the coast of South Africa is the mediterranean/ blue mussel (Mytilus galloprovincialis). The spread of invasive species have beneficial aspects such as habitat provision; however, they can also adversely affect the invaded environments by causing significant ecological and environmental change. M. galloprovincialis is an ecosystem engineering species, which has considerably and rapidly altered the structure of rocky shore communities by interacting (e.g., competition for habitat) with other native species (i.e., the brown mussel [Perna perna] and the black mussel [Chloromytilus meridionalis]).
However, despite its high rate of spread, there are a couple of stressors that potentially hinder the spread and population sizes of this species. Some of these include high levels of endolithic infestations which lead to slower growth rates or high mortality. It is hypothesised that these effects may be exacerbated especially at their range edge, where they are likely to experience sub‑optimal conditions. For this project, we tested and evaluated these assumptions on the blue mussel population. |
The project was led by Dr Kevin Ma and the main aims were to assess (1) if the rate of spread of M. galloprovincialis decreased or halted as the species approached a biogeographic boundary; (2) if the rate of spread increased immediately or shortly after breaching a biogeographic boundary; (3) if any along-shore spatial structure in its abundance can be detected at biogeographic scales; and (4) if populations at the margins of the range are dissimilar to populations nearer to the centre of the range in terms of abundance, size-frequencies, degree of endolithic infestation and whether the severity of endolithic infestation and the level of epibiosis will increase for range edge populations approaching a biogeographic barrier due to underlying abiotic stressors present at or near such a barrier.
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FOOD SECURITY AND SUSTAINABILITY:
Understanding seaweed-pathogen interactions
Understanding seaweed-pathogen interactions
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I was one of the 30 students who got the opportunity to attend the 4th International Summer School in Marine Biology hosted by the University of Namibia in conjunction with the Daniel Jouvance Foundation and Sorbonne University.
The School exposed students to the current issues affecting marine biology in Southern Africa. We had the opportunity to learn about the latest techniques used in Marine biotechnology, Bio-informatics, Genomics, Post-genomics, Marine bio-resources and Blue biotechnology. Of deep interest to me were lectures that covered “Algal-pathogen relationships and impact on the productivity of marine ecosystems.” |
Seaweed farming is believed to be one of the fastest-growing aquaculture sectors with significant benefits to many livelihoods. However, over the past few years an increasing threat to seaweed productivity has been realised due to pests and diseases. Although substantial work is being done in other parts of the world, very little work is available for the coastline of southern Africa. Further, because seaweeds are primary producers at the base of the food web, any factors that negatively affect/ slow down their productivity will have detrimental consequences along the marine food web system. It is therefore, one of my research interests to understand (i) the epiphytes, pathogens and subsequently diseases affecting seaweeds (ii) and how these potentially affect ecosystem productivity.
Examples of epiphytes and possibly orange lethal disease on coralline seaweed. Images captured from records stored at The Bolus Herbarium at University of Cape Town, South Africa
MARINE SPECIES RECORDS:
Patterns across ecoregions of the South African coastline
Patterns across ecoregions of the South African coastline
Understanding the causes driving species distribution is a major challenge of modern biogeography. The account of which taxa occurs where and the relation between patterns of distribution of organisms and physical or biological factors are usually the first steps towards this goal. In this project, we address the former and provide a checklist of marine micro- and macro-invertebrate species observed at ten sites from South Africa’s intertidal habitat i.e., the Delagoa, Natal, Cape, Agulhas, Southwest, and Namaqua ecoregions. The list for each site combines records from field observations and specimen collected between 2018 and 2022.