The development of Mazzaella capensis (J.Ag.) Fredericq in culture, in the field, and the effect of environmental factors

Bachelor Thesis


Permanent link to this Item
Journal Title
Link to Journal
Journal ISSN
Volume Title

University of Cape Town

Past research on Mazzaella species in Chile and Pacific North America concentrated on their carrageenan-producing potential and of patterns and mechanisms of gametophyte / sporophyte alternation. The South African Atlantic species, Mazzaella capensis, however has been neglected in these studies. This project sets out to investigate some basic hypotheses on the biology of M. capensis. The rate of development of M. capensis sporelings in culture was found to be faster at l8°C than at l5°C, this was thought to be related to the increased rate of reaction with increased temperature. The fact that M. capensis sporelings were able to tolerate temperatures of between 15 and l8°C is related to the biogeography of the organism and the temperature extant during their origin and dispersal. Growth rate of M. capensis sporelings was light saturated at 104.umol.m⁻² .s⁻¹ and is similar to Gigartina polycarpa and Sarcothalia stirata. Although this is a fairly high value for intertidal sporelings it is low considering the total sunlight received on a sunny day can be over 2000.umol.m⁻² .s⁻¹, other studies have shown that adult seaweeds on the midshore have generally higher light saturation values (in the range of 150 - 300.umol.m⁻².s⁻¹). In the field there are many more factors such as nutrient availability, water movement and grazing and complex interactions, such as competition for space nutrients and light with other organisms, which influence development of the crust and the plant. Each individual crust-holdfast complex and its related fronds were found to be monophasic with respect to life history stage, this is thought to be a result of coalescence of crusts formed by spores released together by one parent. Within the M. capensis population at Kommetjie there was a switch of dominance from tetrasporophytes in early winter to gametophytes in early summer, corresponding with an increase in biomass. It was concluded that the new recruits were mostly gametophytes and that their increase relative to the perennating tetrasporophytes was responsible for the switch in dominance. The coalescence of M. capensis crusts during developmental stages suggests that it is a clonal plant. It is similar to the clonal M. cornucopiae as it did not exhibit characteristics of self-thinning.