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Number and concentration of calcium nitrate plus Kelpak® sprays for control of bitter pit in 'Braeburn5 apple fruit
Item type: Journal Article • Journal: South African Journal of Plant and Soil • Authors: M. North --- , J. Wooldridge --- ,In a spray trial to test the effects of calcium nitrate and a kelp extract (Kelpak®), fruit calcium (Ca) concentrations in ‘Braeburn’ apples peaked between 7.6 and 9.5 mg 100 g−1 fresh mass (FM) on 19 December 2000, then declined... -
The effects of kelp harvesting on its regrowth and the understorey benthic community at Danger Point, South Africa, and a new method of harvesting kelp fronds
Item type: Journal Article • Journal: South African Journal of Marine Science • Authors: G. J. Levitt R. J. Anderson C. J. T. Boothroyd F. A. KempAt Danger Point, South Africa, mariculture of the abalone Haliotis midae has led to increased demand for freshly harvested kelp Ecklonia maxima. This study estimates the biomass of E. maxima available for harvesting, investigates the effects of harvesting on the... -
Supernormal clutches in southern African Kelp Gulls Larus dominicanus vetula
Item type: Journal Article • Journal: Ostrich: Journal of African Ornithology • Authors: PeterG Ryan --- DST/NRF Centre of Excellence at the Percy FitzPatrick Institute, South Africa BruceM Dyer --- Department of Environment Affairs, South Africa A Paul Martin --- Department of Zoology, South Africa VincentL Ward --- Department of Biodiversity and Conservation Biology, South Africa PhilA Whittington --- Department of Zoology, South Africa AnthonyJ Williams --- , South AfricaThe Kelp Gull Larus dominicanus typically lays clutches of 1–3 eggs, but larger clutches have been recorded occasionally. We report that four- and five-egg clutches comprise 0.3% of clutches among the southern African subspecies L. d. vetula, with a higher... -
Populations of Surface-nesting Seabirds at Marion Island, 1994/95–2002/03
Item type: Journal Article • Journal: African Journal of Marine Science • Authors: R. J. M. Crawford J. Cooper B. M. Dyer M. D. Greyling N. T. W. Klages P. G. Ryan S. L. Petersen L. G. Underhill L. Upfold W. Wilkinson M. S. De Villiers S. Du Plessis M. Du Toit T. M. Leshoro A. B. Makhado M. S. Mason D. Merkle D. Tshingana V. L. Ward P. A. WhittingtonDuring the 1990s and early 2000s, populations of surface-nesting seabirds at Marion Island showed different trends, but for the majority of species numbers decreased. Reduced numbers of gentoo penguins Pygoscelis papua, eastern rockhopper penguins Eudyptes chrysocome filholi, Crozet shags Phalacrocorax... -
A simple method for rapid estimation of Ecklonia maxima and Laminaria pallida biomass using floating surface quadrats
Item type: Journal Article • Journal: African Journal of Marine Science • Authors: MD Rothman --- Department of Agriculture, South Africa RJ Anderson --- Department of Agriculture, South Africa JJ Bolton --- Department of Botany, South Africa CJT Boothroyd --- Department of Agriculture, South Africa FA Kemp --- Department of Agriculture, South AfricaIn South Africa two species of kelp, Ecklonia maxima and Laminaria pallida, occur in quantities sufficient for commercial use. Currently, the former species is harvested in large quantities (about 5 000 tonnes wet weight per year) as abalone feed. In... -
Temporal changes in kelp forest benthic communities following an invasion by the rock lobster Jasus lalandii
Item type: Journal Article • Journal: African Journal of Marine Science • Authors: LK Blamey --- , South Africa GM Branch --- , South Africa KE Reaugh-Flower --- , South AfricaThe rock lobster Jasus lalandii expanded its centre of distribution south-eastwards into an area known as ‘East of Cape Hangklip’ on the south-west coast of South Africa in the early 1990s. Using historical and present data, we analysed differences in... -
Assessing the ecosystem effects of the abalone Haliotis midae from its diet and foraging behaviour
Item type: Journal Article • Journal: African Journal of Marine Science • Authors: Z Zeeman --- Department of Zoology and Marine Research Institute, South Africa GM Branch --- Department of Zoology and Marine Research Institute, South Africa TP Peschak --- Department of Zoology and Marine Research Institute, South Africa D Pillay --- Department of Zoology and Marine Research Institute, South AfricaThe South African abalone Haliotis midae is commercially exploited and seriously threatened by overfishing. This not only affects the species itself but potentially the functioning of the ecosystem because of associated changes in community structure. The nature of effects that... -
Growth of market-size abalone (Haliotis midae) fed kelp (Ecklonia maxima) versus a low-protein commercial feed
Item type: Journal Article • Journal: African Journal of Aquatic Science • Authors: TL Francis GW Maneveldt J VenterThe growth of grow-out abalone fed on kelp, with c. 10 % dry weight protein content, was compared with that of those fed on 'Feed A' (a new low-protein commercial feed of c. 26 % protein), in a flow-through system... -
Further notes on age of first breeding, plumage and biometrics of kelp gulls in South Africa
Item type: Journal Article • Journal: African Journal of Marine Science • Authors: PA WhittingtonAdult kelp gulls Larus dominicanus vetula were caught at the nest in the Eastern Cape region of South Africa, in October and November 2006 using a 'walk-in' trap. In all, 13 previously ringed birds were re-trapped and a known-aged colour-ringed... -
Mapping and quantifying the South African kelp resource
Item type: Journal Article • Journal: African Journal of Marine Science • Authors: RJ Anderson A Rand MD Rothman A Share JJ BoltonTwo species of kelp are exploited commercially in South Africa. Use of beach-cast Laminaria pallida is limited, although it comprises the bulk of the biomass on the northern West Coast. Ecklonia maxima dominates the southern West Coast and provides most... -
Estimates of numbers of kelp gulls and Kerguelen and Antarctic terns breeding at the Prince Edward Islands, 1996/1997–2008/2009
Item type: Journal Article • Journal: African Journal of Marine Science • Authors: PA Whittington --- , South Africa RJM Crawford --- Department of Environmental Affairs, South Africa BM Dyer --- Department of Environmental Affairs, South Africa PG Ryan --- , South AfricaBreeding numbers of Laridae and other surface-nesting seabirds have been monitored at sub-Antarctic Marion Island since 1996/1997 and counts of breeding birds were made at nearby Prince Edward Island in December 2001 and December 2008. Four species are regular breeders... -
Differential reactions to anthropogenic disturbance by two ground-nesting shorebirds
Item type: Journal Article • Journal: Ostrich: Journal of African Ornithology • Authors: Shirley Van de Voorde --- Van Hall Larenstein, The Netherlands Minke Witteveen --- Percy FitzPatrick Institute of African Ornithology, DST–NRF Centre of Excellence, South Africa Mark Brown --- School of Life Sciences, South AfricaMany ground-nesting shorebirds experience a high level of anthropogenic disturbance, often to the detriment of their breeding success. This study investigated the responses of the Near-Threatened African Black Oystercatcher Haematopus moquini (ABO) and the Least Concern Kelp Gull Larus dominicanus... -
Bald kelp: natural and harvesting-induced frond loss in the South African kelp Ecklonia maxima
Item type: Journal Article • Journal: African Journal of Marine Science • Authors: C Elston --- Department of Biological Sciences, South Africa RJ Anderson --- Department of Biological Sciences, South Africa LM Price --- Department of Biological Sciences, South AfricaEcklonia maxima dominates kelp beds on the west coast of southern Africa, and is commercially and ecologically valuable. Some plants lose all their secondary blades (fronds), leaving only the gas-filled bulb and short primary blade at the top of the... -
Colonisation of South African kelp-bed canopies by the alien mussel Mytilus galloprovincialis: extent and implications of a novel bioinvasion
Item type: Journal Article • Journal: African Journal of Marine Science • Authors: C Lindberg --- , South Africa CL Griffiths --- , South Africa RJ Anderson --- , South AfricaThe Mediterranean mussel Mytilus galloprovincialis is the most significant invasive alien marine species in South Africa and, although not normally found subtidally, has recently been observed colonising heads and stipes of the kelp species Ecklonia maxima in False Bay. We... -
Effects of biostimulants on tissue and rhizospheric acid phosphatase activity of chickpea genotypes
Item type: Journal Article • Journal: South African Journal of Plant and Soil • Authors: Rebahlotse Mapula Moloto --- , South Africa Felix D Dakora --- , South Africa Puffy Soundy --- , South Africa Sipho Thulane Maseko --- , South AfricaAlthough the application of biostimulants to soils and plants affects their phosphatase activity, this has not been shown in chickpea (Cicer arietinum L.) grown under South African conditions. In this study, chickpea genotypes were grown in silty-loam and silty-clay-loam soils... -
Prevalence, population structure and burrow morphology of the kelp-boring amphipod Sunamphitoe roberta
Item type: Journal Article • Journal: African Journal of Marine Science • Authors: MJ Wilcox --- , South Africa J Landschoff --- , South Africa CL Griffiths --- , South AfricaThe recently described amphipod Sunamphitoe roberta lives only on the kelp Ecklonia maxima, where it excavates slit-like burrows along the distal margins of thicker primary fronds. Oval chambers along the bases of these slits may represent feeding areas. As burrowing... -
Site- and habitat-dependent variations in the diversity of polychaetes associated with golden kelp Ecklonia radiata holdfasts along the southeast coast of South Africa
Item type: Journal Article • Journal: African Journal of Marine Science • Authors: N Nkohla --- Walter Sisulu University, South Africa TS Dlaza --- Walter Sisulu University, South AfricaPolychaetes are important components of the macrofaunal communities associated with golden kelp Ecklonia radiata holdfasts across different spatial scales. However, the polychaete component varies in different habitat types in response to varying environmental conditions. Here, we compared patterns of variation...