University of Cape Town

South Africa sits astride two of the most contrasting ocean currents in the world, creating ideal circumstances to investigate the effects of productivity on community structure and functioning. The Andrew W. Mellon Foundation has funded a research program led by George Branch on rocky-shore dynamics since 2002. There are two different geographic thrusts at work, one focused on the warm nutrient-poor waters of the east coast and the other, on the up-welled cold nutrient rich west coast.

A central focus of the west-cost studies has been unraveling the effects of wave action and upwelling against the backdrop of biological interactions. Evie Wieters is undertaking a PhD comparing community structure on Chilean and South African west-coast shores, and the effects that upwelling has on the interaction between algal growth and size composition, and mussel settlement and survival. Maya Pfaff has started a PhD concerned with larval supply and settlement and their relationship with adult stocks. Complementing this is a study on water movement and wave action that will model the effects of hydrodynamics on larval dispersal and on the abundance and distribution of particulate food sources and in situ macroalgal growth. A PhD study by Nina Steffani has already been completed on the effects of an alien mussel, Mytilus galloprovincialis, on intertidal communities, revealing that competitive effects are modulated by wave action. This has been followed by more detailed studies on mussel growth in relation to wave action and upwelling, (Barbara Xavier, MSc) and the spread and effects of Mytilus galloprovincialis on intertidal communities (Tammy Robinson, PhD). Limpets are key grazers in South Africa and reach sizes larger than those recorded anywhere else in the world. The processes allowing the maintenance of these extraordinary standing stocks have been central to the understanding of the dynamics of rocky shores in South Africa. Studies are not confined to the intertidal. Tom Peschak is undertaking a PhD on interactions among abalone, urchins and kelp in the shallow subtidal, following up on earlier work showing the importance of urchins as trappers of kelp drift. Effects of rock lobsters are also being pursued by Laura Blamey (MSc) in a study of an area that has been “invaded” by rock lobsters.

On the east coast, Kathleen Reaugh has developed a novel means of quantifying surface water movements, in a PhD that relates larval abundance to water movements and settlement. Maya Pfaff recently completed an MSc on the interactive effects of disturbance and productivity on species diversity, experimentally exploring the intermediate disturbance hypothesis. Studies are also underway on the biogeography of the coast, including intertidal, shallow and deep subtidal reefs (Sean Porter, PhD, Cloverley Lawrence, MSc). In a combination of archaeological and modern studies, Lucy Kemp (MSc) is exploring the effects of pre-historic “fish vywers” (ancient fish traps) on rocky shore communities.

A long reach from South Africa has been a study in Galapagos on the relative effects of herbivory and El Niño on intertidal rocky shores (Luis Vinueza, MSc), also funded in part by the Mellon Foundation.

Apart from these postgraduate studies, the Mellon grant supports three research assistants.

Postgraduate students supported by the Mellon Grant:

Kathleen Reaugh (Honours): A regime shift caused by increases in rock-lobster numbers at the southern end of their range. (Completed 2002)

Kathleen Reaugh (PhD): Investigation of the connectivity of rocky shore species on the northern KwaZulu-Natal coast through an integrated study of coastal oceanography, larval supply and settlement. (To be completed 2005)

Evie Wieters (PhD): Between-System Comparisons of Topographically-Driven Environmental Heterogeneity and its Affects on Rocky Intertidal Communities. (To be completed 2005)

Tammy Robinson (PhD): Biology and harvesting of Mytilus galloprovincialis. (To be completed 2004/5)

Tom Peschak (PhD): Interactions between abalone, corallines and kelp. (To be Completed 2005)

Maya Pfaff (MSc): Interactions between disturbance and nutrient input: effects on community composition. (To be completed 2004)

Maya Pfaff (PhD): Larval abundance and distribution on west-coast rocky shores. (Starting 2005)

Rabecca Rademeyer (Honours): Influence of wave action on settlement and early post-settlement survival of the mussel Mytilus galloprovincialis. (Completed: 2003).

Luiz Vinueza (MSc): Effects of El Niño, sites and grazing on the community composition of rocky shores in Galapagos. (Completed 2003)

Lucy Kemp (MSc): Influence of fish vywers on community composition, with a comparison with archaeological records of biota. (Starting 2004; to be completed 2005)

Timony Siebert (MSc): The ecological effects of bioturbation on the eelgrass Zostera capensis: community interactions and the impacts on biota of an intertidal sandflat. (Comleted 2003)

Andrea Angel (MSc): Cause of rarity and range restriction in a rare and endangered limpet, Siphonaira compressa. (Completed 2003)

Cloverley Lawrence (MSc): Surveys of deep benthic reefs off the coast of KwaZulu-Natal: identification of biotopes and conservation status. (To be completed 2005)

Sean Porter (MSc): Shallow reefs in KwaZulu-Natal: classification and determination of biotopes. (Starting 2004, completion probably 2006)

Laura Blamey (Honours): Identification of rocky-shore ‘habitats’ in relation to wave action: implications for the selection of marine protected areaas. (Completed 2003)

Nina Steffani (PhD): Interactions between an indigenous limpet, Scutellastra argenvillei, and an alien invasive mussel, Mytilus galloprovincialis: moderation by wave action. (Completed 2002)

Barbara Xavier (Diplom/MSc): Growth of the mussel Mytilus galloprovincialis in relation to upwelling. (To be completed, 2004)

Carlos Ruiz Sebastion (Honours): Influnce of an alien mussel on movement patterns of the limpet Scutellastra argenvillei. (Completed 2002)

Helen Bloomfield (Honours, University of Bangor): Abundance, habitat preferences and movement patterns of the ‘siffie’, Haliotis spadicea, in a marine protected area. (To be undertaken in 2004.)