Browsing by Author "Maneveldt, Gavin W."
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Item Documenting the association between a non-geniculate coralline red alga and its molluscan host(University of the Western Cape, 2010) Eager, Rosemary; Maneveldt, Gavin W.; Faculty of ScienceTo further investigate the strength of the association and the relative advantages of the association to both organisms, several manipulation experiments were set up. A cage experiment set up in the shallow subtidal zone showed that the coralline survived equally well without the winkle and did therefore not require the winkle or its empty shell for survival. A second controlled laboratory aquarium experiment was designed under both fluorescent (rich in blue light) and incandescent light (rich in red light) to ascertain whether the coralline had a preference for O. sinensis over the similar O. tigrina. This experiment was inconclusive as no recruitment was obtained under either of the light regimes. A third laboratory experiment was designed to determine whether the extra coralline weight had any possible advantage to the winkle, particularly against predation from the rock lobster Jasus lalandii. Results suggested that there were no apparent advantages to the winkle bearing the extra coralline load as adult O. sinensis bearing the coralline alga (3.7 ± 2.2 winkles 24hr-1) were equally prone to predation than those lacking the coralline (2.3 ± 1.9 winkles 24hr-1) (p = 0.184). Observations suggested instead that the convoluted nature of the coralline may indeed have promoted predation. We ultimately deduced that the high occurrence of the coralline on the shells of O. sinensis was probably due to the substantial overlap in the niches of the two organisms. This conclusion was supported by the high densities of juvenile O. sinensis combined with the high percent cover abundance of the coralline in intertidal rockpools. Understanding sexual reproduction in coralline algae as well as the life cycle of the winkle, ultimately provided insight into the postulated life cycle of this coralline-winkle association.Item The effects of anthropogenic disturbance upon African penguin colonies(University of Western Cape, 2020) Miller, Rebecca Jane; Maneveldt, Gavin W.; Pichegru, Lorien; Sherley, Richard B.; Waller, Lauren J.African penguin (Spheniscus demersus) mainland colonies are a popular tourist attraction in the Western Cape of South Africa. The African penguin population is in decline and the species is listed as endangered on the International Union for the Conservation of Nature (IUCN) Red List. This thesis aimed to investigate the impact of ecotourism upon African penguin colonies by comparing two colonies of differing levels of tourist visitation in the Western Cape in 2017. The high visitation colony is a mainland colony where ecotourism activities take place (Stony Point), and the low visitation colony is an island colony where ecotourism does not occur (Robben Island). As well as inter-colony comparisons, nests at the high visitation colony within areas of differing exposure levels were also compared.Item The effects of differences in feeding regime and of export simulations on the growth of the abalone Haliotis midae Linnaeus(University of the Western Cape, 2008) Francis, Tamson L.; Maneveldt, Gavin W.; Venter, Jonathan; Faculty of ScienceBeach-cast kelp (the most widely used feed for commercially grown South African abalone) is plentiful during winter months when periodic storms cause kelp to wash ashore. During summer, however, this resource is not always readily available and farmed abalone are often starved for short periods. The aim of this research was to assess how periodic kelp starvation influences growth of the commercially grown abalone, Haliotis midae Linnaeus.Item First report of the melobesioid alga (Corallinales, Rhodophyta) Mesophyllum incisum (Foslie) Adey in South Africa(Elsevier, 1997) Keats, Derek W.; Maneveldt, Gavin W.Mesophyllum incisum is reported and studied for the first time in South Africa. It has a th all us surface (SEM) with Leptophyturn-type epithallial cells. TetraJbisporangial conceptacles are mound-like and lack a peripheral rim but have a flattened pore plate. The rosette cells surrounding the tetrasporan gial po res are distinct from su rrounding roof cells (SEM, surface view) in be ing narrower, and sunken below the level of the surrounding pore plate. The cells of filaments bordering the tetrasporangial conceptacle pore canal differ from the othe r roof cells within the pore plate in being more elongate, narrower, and often more densely staining. Pore canal filaments also generally contain fewer cells than the surrounding filaments of the pore plate and th e pore can al is more-Dr-less parallel sided. Our material agrees closely with the species as reported in Australia.Item The genus Spongites (Corallinales, Rhodophyta) in South Africa(University of the Western Cape, 2019) Puckree-Padua, Courtney Ann; Maneveldt, Gavin W.; Gabrielson, Paul W.Coralline red algae (Corallinales, Hapalidiales, Sporolithales: Corallinophycidae, Rhodophyta) are widespread and common in all the world’s oceans (Adey & McIntyre 1973; Johansen 1981; Littler et al. 1985; Björk et al. 1995; Aguirre et al. 2007; Harvey & Woelkerling 2007; Littler & Littler 2013). They achieve their highest diversity in the tropics and subtropics (Björk et al. 1995; Littler & Littler 2013; Riosmena-Rodríguez et al. 2017), and within the photic zone of rocky shores (Lee 1967; Littler 1973; Adey 1978; Adey et al. 1982; Steneck 1986; Kendrick 1991; Kaehler & Williams 1996; Gattuso et al. 2006; van der Heijden & Kamenos 2015; Riosmena-Rodríguez et al. 2017) where they serve as important carbonate structures (Adey et al. 1982; Littler & Littler 1994, 1997; Vermeij et al. 2011) and habitats for a host of marine species (Foster 2001; Amado-Filho et al. 2010; Foster et al. 2013; Littler & Littler 2013; Riosmena-Rodríguez et al. 2017). Coralline algae are resilient, inhabiting extreme conditions that include: low temperatures (Adey 1970, 1973; Freiwald & Hendrich 1994; Barnes et al. 1996; Freiwald 1996; Aguirre et al. 2000; Roberts et al. 2002; Björk et al. 2005; Martone et al. 2010); limited light exposures (Adey 1970; Littler & Littler 1985; Littler et al. 1985; Liddell & Ohlhorst 1988; Dullo et al. 1990; Littler & Littler 1994; Iryu et al. 1995; Stellar and Foster 1995; Gattuso et al. 2006; Aguirre et al. 2007; Littler & Littler 2013); severe wave action (Steneck 1989; Littler & Littler 2013); intense grazing pressures (Steneck 1989; Steneck & Dethier 1994; Maneveldt & Keats 2008; Littler & Littler 2013), highly fluctuating salinities (Harlin et al. 1985; Barry & Woelkerling 1995; Barnes et al. 1996; Wilson et al. 2004); including occurring in freshwater (Žuljevic et al. 2016), and constant sand scouring (Littler & Littler 1984; D’Antonio 1986; Kendrick 1991; Chamberlain 1993; Dethier 1994).Item A global revision of the nongeniculate coralling algal genere Porolithon Foslie (defunct) and Hydrolithon Foslie (Corallinales, Rhodophyta)(University of the Western Cape, 2005) Maneveldt, Gavin W.; Keats, Derek; Weitz, Frans; Faculty of ScienceThe purpose of this thesis was to provide a revision and characterization of the species of nongeniculate coralline algae previously ascribed to the now defunct genus Porolithon; to provide a modern account of selected taxa from the genus Hydrolithon and descriptions of taxa found to conform the generic delimitation of Hydrolithon and to use a phenetic cluster analysis to determine the taxonomic relationships between the various taxa ascribed to the genera Polorithon and Hydrolithon.Item Growth of juvenile abalone under aquaculture conditions(University of the Western Cape, 2006) Dlaza, Thembinkozi Steven; Maneveldt, Gavin W.; Viljoen, Cecelia; Venta, Jonathan; Faculty of ScienceThe aim of this research was, first to test the suitability of different seaweeds and formulated feeds as food for post-weaning juvenile South African abalone and secondly, to test the effects of basket design on the growth of grow-out juvenile abalone in both flow-through and re-circulation systems.Item Investigating factors that influence the breeding success of the endangered African penguin (Spheniscus demersus) at a mainland and island colony in the Western Cape, South Africa(University of Western Cape, 2022) Hugo, Corlie; Maneveldt, Gavin W.Since the 1950s the global seabird population have declined by 70% and today some penguin species are amongst the most threatened seabirds in the world. The African penguin (Spheniscus demersus) population experienced a sharp decline in the twenty first century, which led to the species being listed as endangered in 2010. African penguins are facing a range of threats including limited food resources, habitat degradation, pollution from oil spills and predation. This study aims to compare the breeding success and chick condition of African penguins at Stony Point and Dyer Island. The study contributes to the analysis of long-term monitoring of demographic data, identified in the Biodiversity Management Plan for the African penguin. The study took place at two penguin colonies in the Western Cape of South Africa.Item Rhodolith bed discovered off the south African coast(MDPI, 2020) Maneveldt, Gavin W.; Adams, Luther A.; Green, Andrew N.Rhodolith beds have not previously been recorded in South Africa. A multidisciplinary research effort used remote sampling tools to survey the historically unexplored continental shelf off the Eastern Cape coast of South Africa. A rhodolith bed, bearing both living and dead non-geniculate coralline red algae, was discovered in the 30-65 m depth range off the Kei River mouth in the newly proclaimed Amathole Offshore Marine Protected Area. Some of the rhodolith forming coralline algal specimens were identified as belonging to at least three genera based on their morphology and anatomy, namely, Lithophyllum, Lithothamnion and a non-descript genus. Rhodolith mean mass and diameter were 44.85 g ± 34.22 g and 41.28 mm ± 10.67 mm (N = 13), respectively. Remotely operated vehicle (ROV) imagery revealed a suite of epibenthic red macroalgae associated with the rhodolith bed. Taxonomy, vertical structure and distribution of rhodoliths in South Africa require further investigation.Item The role of grazers and basal sustrate cover in the control of intertidal algal distribution(University of the Western Cape, 2006) Madikiza, Liwalam Onwabile; Maneveldt, Gavin W.; Faculty of ScienceThis study investigated the role of grazing as a possible cause for the upper limit of distribution of algae on a typical South African south coast.Item The roles of intertidal marine gastropod shells as secondary substrate for macroalgae(University of the Western Cape, 2014) Padua, Courtney Ann; Maneveldt, Gavin W.Primary space within the marine benthos is by far the most limited resource for which all sessile organisms must compete. It only ever becomes available when the organisms occupying it dies or are forced to leave the area. It has long been established that herbivorous molluscs play an important role in freeing up space on rocky intertidal shores. However, their grazing activities, although freeing up space. often result in diminished species diversity because most intertidal algae and invertebrates are either consumed or displaced. The exploitation of microhabitats (secondary space) therefore becomes important under such scenarios and is known to increase the biodiversity of a particular area. Ironically, mollusc shells are knom1 to provide such microhabitats as they increase the available surface area for the settlement of a variety of epizoic organisms. While the international literature abounds with examples of the importance of mollusc shells as secondary substrata, virtually nothing is known of these associations within a South African context. Surveys were conducted on five more or less equidistant intertidal rocky shore communities (Kalk Bay. Rooiels, Sandbaai, Pearly Beach, Stinkbaai) within the South African western biogeographic transition zone. At all sites, invertebrate densities and biomass, and algal and lichen percent cover abundance were sampled along transect lines running more or less parallel to the shoreline from mean highwater spring (MHWS) tide mark to mean low water spring (MLWS) tide mark.Item Systematics of the non-geniculate coralline red algae from the South African south coast(University of the Western Cape, 2015) Van der Merwe, Elizabeth; Maneveldt, Gavin W.; Channing, AlanThe aim of this study was to document the intertidal and shallow subtidal species of non-geniculate coralline red algae from the South Africa south coast. The main emphasis of the study are encompassed in four research chapters and one concluding chapter focusing on: 1) the documentation of the non-geniculate coralline red algae occurring along the South Africa south coast; 2) revisiting the Leptophytum-Phymatolithon complex in order to resolve the taxonomic status of species previously ascribed to the genus Leptophytum from South African; 3) starting to prepare modern monographic accounts of the higher taxa; and 4) the production of updated keys to all the currently recognised taxa of non-geniculate coralline algae for South Africa. Although nowhere near complete, here we present our findings and report on the current biodiversity status of the non-geniculate coralline red algae after a further four years of extensive sampling.Item Testing the suitability of local seaweeds and formulated feed as a food source for abalone (Haliotis midae Linnaeus) in an Integrated Land-based Aquaculture System(University of the Western Cape, 2008) Naidoo, Krishnaveni; Maneveldt, Gavin W.; Ruck, Kevin; Dept. of Biodiversity and Conservation Biology; Faculty of ScienceThe direct methanol fuel cell or DMFC is emerging as a promising alternative energy source for many applications. Developed and developing countries, through research, are fast seeking a cheap and stable supply of energy for an ever-increasing number of energyconsuming portable devices. The research focus is to have DMFCs meet this need at an affordable cost is problematic. There are means and ways of making this a reality as the DMFC is found to be complementary to secondary batteries when used as a trickle charger, full charger, or in some other hybrid fuel cell combination. The core functioning component is a catalyst containing MEA, where when pure platinum is used, carbon monoxide is the thermodynamic sink and poisons by preventing further reactions at catalytic sites decreasing the life span of the catalyst if the CO is not removed. Research has shown that the bi-functional mechanism of a platinum-ruthenium catalyst is best because methanol dehydrogenates best on platinum and water dehydrogenation is best facilitated on ruthenium. It is also evident that the addition of other metals to that of PtRu/C can make the catalyst more effective and increase the life span even further. In addition to this, my research has attempted to reduce catalyst cost for DMFCs by developing a low-cost manufacturing technique for catalysts, identify potential non-noble metal catalytic systems and develop a basic process to combine various non-noblel, less expensive metallic systems to form binary, ternary and quaternary catalysts. The initial research focused on the identification of a suitable Pt/C preparation method, and characterization of the resulting catalysts by electrochemical methods (including voltammetry), elemental analysis (by EDS), and morphological characterization (by TEM). Once the preparation method for Pt/C had been established, binary (Pt–M/C), ternary (Pt–M1M2 /C) and quaternary (Pt–M1M2M3 /C) catalysts were prepared by modifying the initial Pt/C preparation method. These multi-metallic catalysts primarily function in preventing CO poisoning and allowing MeOH oxidation at the anode. To determine the effectiveness of the in-house multi-metallic catalysts the catalysts were then compared to the commercially available bench mark JM commercially available catalyst. Cyclic voltammetric and chronoamperommetric analysis revealed that the in-house catalysts electrochemical catalytic activity were similair to that of the commercially available catalysts. The Fuel application testing revealed similair trends to that of the EC activity at 0,5V (Ag/AgCl) test results, with the quaternary catalyst proving to be the most active anode catalyst producing the highest power density. The quaternary catalysts proved to be superior with its increased mass activity and high surface area (80% of the catalytic particles < 3nm).Item Toward best management practices for the growth of the abalone Haliotis midae Linnaeus on a commercial South African abalone farm(University of the Western Cape, 2008) Van der Merwe, Elizabeth; Maneveldt, Gavin W.; Venter, Jonathan; Faculty of ScienceItem Using Ulva (Chlorophyta) for the production of biomethane and mitigation against coastal acidification(University of the Western Cape, 2016) Amosu, Albert Oluwatobi; Maneveldt, Gavin W.; Roberson-Andersson, Deborah V.; Bolton, John J.In South Africa the green macroalga Ulva armoricana is the main species of macroalgae cultured. The species is currently the largest aquaculture (2884.61 tonnes) product by weight with a corresponding capacity for biogas (CH₄) production. We have shown that biotransformation of U. armoricana to Liquefied Petroleum Gas (LPG) is viable and economically feasible as a clean fuel. pH toxicity tests showed that U. armoricana can be used as a health index, under potentially increased CO₂ concentrations that can occur in IMTA carbon sequestration. We have shown sporulation to be the morphological response to environmental stress, which is indicative of chlorophyll degradation and a reduction in the photosynthetic activity of the alga. With the exception of Cadmium (Cd), the physico-chemical values obtained and the dissolved nutrient/heavy metals uptake by the alga all fell within the FAO/WHO permissible standards. Our Cd values therefore negate the use of these macroalgae for human consumption. We have also shown that U. armoricana can be used in eco-monitoring by playing a significant role in wastewater filtration and bioaccumulation. Nutrient utilization and proximate composition results show that African mud catfish (Clarias gariepinus) grow well on a protein-enriched Ulva diet, suggesting that enriched Ulva has the potential to be a successful fish feed. This thesis suggests among others, that South Africa could take advantage by being the first African country to propose specific standards for edible macroalgae as its successful research innovations and development provides a template for other African countries to further their aquaculture sectors. Additional benefits (bioremediation, ocean de-acidification through the capture of atmospheric and dissolved CO₂ during growth to assist in climate change mitigation) from Ulva farming activities bode well for the aquaculture industry.