13 research outputs found

    Stomach contents of some shore-caught teleosts of Natal, South Mrica

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    Stomach contents of shore-caught teleosts feeding on the Natal nearshore substratum were visually analysed for percentage composition. Commonly caught fish, namely Rhabdosargus sarta, R. holubi, Pomadasys commersonni, Trachinotus africanus and T. botla, were opportunistic omnivorous predators and fed largely on sand mussels and benthic crustacea. Less frequently caught predatory fish (15 species) fed mainly on benthic crustacea and other teleosts. The results are discussed briefly and will provide an input to a current ecosystem study on the environment in which these fish feed

    Zonation of benthic communities on the subtropical Aliwal Shoal, Durban, KwaZulu-Natal, South Africa

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    Aliwal Shoal is a subtropical, algal-dominated reef in a marine protected area located south of Durban, South Africa. The shoal has historically been heavily utilized by fishermen and SCUBA divers. In this study, a survey was undertaken to describe and zone the reef and its benthic communities in terms of topography, habitat types, species diversity, species richness and benthic cover. Data were collected using underwater photography and analysed by point intercept analysis. Three distinct benthic communities were identified using multivariate non-metric statistics. Benthic communities appeared to be influenced by topography, sediment cover and wave energy. The highest abundance of zooxanthellate hard corals and the encrusting zooxanthellate sponge, Suberites kelleri were found on the large shallow areas of the shoal. This suggested that light penetration to the elevated areas on the reef was adequate for photosynthesis and played a role in the distribution of its biota. The encrusting morphology of the sponge Suberites kelleri, and the branching morphology of the hard corals Stylophora pistillata and Pocillopora spp., appeared to be tolerant of the high-energy environment near the surface. A second community was found only on steep edges of the Shoal and was characterized by a large abundance of Polychaeta and the soft coral Eleutherobia aurea, while a third  community was found deeper on the offshore side of the shoal and consisted primarily of coralline and red foliose algae.Key words: subtropical reef, algal-dominated reef, marine protected area, Aliwal Shoal, South Africa, community structure

    Corals of the South-west Indian Ocean: VI. The Alcyonacea (Octocorallia) of Mozambique, with a discussion on soft coral

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    A list of 46 species of Alcyonacea is presented for the coral reefs of the Segundas Archipelago and northwards in Mozambique, as well as a zoogeographical record for the Bazaruto Archipelago in southern Mozambique. Among the 12 genera listed, Rhytisma, Lemnalia and Briareum were recorded on Mozambican reefs for the first time and the study yielded 27 new zoogeographical records. The survey brings the number of soft coral species listed for Mozambique to a total of 53. A latitudinal pattern in soft coral diversity along the south equatorial East African coast is presented, with 46 species recorded in Tanzania, 46 along the northern coast of Mozambique, dropping to 29 in the Bazaruto Archipelago in southern Mozambique and rising again to 38 along the KwaZulu-Natal coast in South Africa. Only Indo-Pacific genera occur in Mozambique with no intrusion of any endemic South African soft coral fauna. Species of the family Alcyoniidae have a wider latitudinal distribution on south equatorial reefs than zooxanthellate members of the families Nephtheidae and Xeniidae, both of which are confined to lower latitudes

    Ecosystem service values of sediment generation and entrapment by marginal coral reefs at Sodwana Bay, South Africa

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    Coral reefs provide a multitude of goods and services, some of which are difficult to value due to their intangible nature and the absence of markets to ascribe their relative worth. The coral reefs of Sodwana Bay on the northeast coast of South Africa provide several ecological goods and services, of which only two are considered here: namely, sediment generation and sediment entrapment. Both are deemed essential to the functioning of theSodwana Bay economy. The replacement-cost method was used to estimate the annual financial cost of sediment provided to the study area if it were replaced by dredging. Sediment generation by the coral reefs was valued at R2.6–R4.8 million, and sediment entrapment valued at R71.8–R84.6 million, totalling between R74.4 million and R89.4 million (≈5.6–5.6–6.7 million, at R13.38/US$1) per year. Keywords: beach-user questionnaire, bioclastic sediment, biodiversity, coastal sand, economic valuation, iSimangaliso Wetland Park, replacement cos

    Detection of Disease Outbreaks by the Use of Oral Manifestations

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    Oral manifestations of diseases caused by bioterrorist agents could be a potential data source for biosurveillance. This study had the objectives of determining the oral manifestations of diseases caused by bioterrorist agents, measuring the prevalence of these manifestations in emergency department reports, and constructing and evaluating a detection algorithm based on them. We developed a software application to detect oral manifestations in free text and identified positive reports over three years of data. The normal frequency in reports for oral manifestations related to anthrax (including buc-cal ulcers-sore throat) was 7.46%. The frequency for tularemia was 6.91%. For botulism and smallpox, the frequencies were 0.55% and 0.23%. We simulated outbreaks for these bioterrorism diseases and evaluated the performance of our system. The detection algorithm performed better for smallpox and botulism than for anthrax and tularemia. We found that oral manifestations can be a valuable tool for biosur-veillance

    Transkei coastal fisheries resources

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    Transkei coastal fisheries resources. Special Publication number 3

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    A survey of the invertebrate subtidal and estuarine resources on the Transkei coast was undertaken in April 1993 by the Oceanographic Research Institute in association with the University of Transkei (UNITRA). This survey examined the stocks of abalone, rock lobsters, mud crabs, oysters, subtidal mussels, and sand and mud prawns. During the latter half of 1993, the Zoology Department of UNITRA examined shellfish resources in the intertidal zone along the coast. Information on past and current levels of utilisation of all resources was collated and, where possible, survey and biological data were combined to make preliminary assessments of the potential for sustainable utilisation
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