http://hdl.handle.net/11189/5116 2026-08-13T21:57:05Z 2026-08-13T21:57:05Z Anderson, RJ Rand, Andrew Rothman, MD Share, A Bolton, John. J http://hdl.handle.net/11189/5113 2020-06-04T12:01:25Z 2007-01-01T00:00:00Z

Title: Mapping and quantifying the South African kelp resource Authors: Anderson, RJ; Rand, Andrew; Rothman, MD; Share, A; Bolton, John. J Abstract: Two 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 of the material for the South African kelp industry. Harvests of E. maxima fronds for abalone feed have reached 3 000–5 000 tonnes fresh weight (t f wt) y−1, whereas beachcast material of both species (about 1 000t dry wt y−1) is collected mainly for alginate extraction. For the first time, a South African kelp inventory has been compiled using all available data for the 900km-long West Coast (Cape Agulhas to the Orange River), although a few gaps remain. Beds of E. maxima and L. pallida reaching the surface at low spring tides were mapped using one or several methods: infrared aerial photography, digital multispectral aerial imagery, Landsat satellite imagery, and physical mapping with a hand-held GPS. The data are on a GIS database. Landsat 5 TM imagery could identify the presence of kelp beds, but only infrared aerial imagery and multispectral imaging at low spring tides accurately quantified surface areas of kelp beds. Biomass of the main kelp (E. maxima) is variable in space (between 3kg f wt m−2 and 24kg f wt m−2) and time (changes of up to 50%), making estimates for management difficult. Using an average biomass value of 12kg m−2, the total biomass of surface-reaching kelp beds on the West Coast is estimated to exceed 593 000t f wt, but extensive subsurface beds remain unquantified. Results are discussed in relation to sustainable limits to harvesting, gaps in knowledge, and the improved management of kelp resources.

2007-01-01T00:00:00Z Nchu, Felix Rand, Andrew http://hdl.handle.net/11189/2043 2020-06-04T12:02:07Z 2013-01-01T00:00:00Z

Title: Rift Valley fever outbreaks: Possible implication of Hyalomma truncatum (Acari: Ixodidae) Authors: Nchu, Felix; Rand, Andrew Abstract: Rift Valley fever (RVF) is a viral zoonosis that primarily affects livestock. However, the virus can also infect humans and may even cause human fatalities. Although the vast majority of human infections result from direct or indirect contact with the blood or organs of infected animals, human infections have also resulted from the bites of infected Aedes mosquitoes. Due to the increasing importance of zoonotic diseases including RFV to global health, there is need for in-depth knowledge on the transmission of RFV viruses. We postulate that some hard ticks might be involved in the transmission of Rift Valley fever virus between animals in nature. This can partially be explained by the biology of ticks. Firstly, ticks spend long periods feeding on the host. Secondly, disease-bearing ticks may survive long periods of desiccation and an infected fully fed female tick continue to harbour RVF virus post-oviposition. Current geographical distribution of Hyalomm truncatum (Acari: Ixodidae) appears to show correlation with incidence of RVF. Future interdisciplinary research focusing on Rift Valley fever molecular epidemiology and tick chemical ecology, will certainly establish the role that H. truncatum and other ticks play in the spread of the virus in nature, and consequently contributing to the development of effective Rift Valley fever management strategies.

2013-01-01T00:00:00Z