https://vital.seals.ac.za/vital/access/manager/Index ${session.getAttribute("locale")} 5 https://vital.seals.ac.za/vital/access/manager/Repository/vital:2099 Wed 12 Oct 2022 12:49:41 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:31265 Wed 12 May 2021 23:59:58 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:31262 Wed 12 May 2021 23:25:31 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5669 Wed 12 May 2021 23:22:29 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:35885 Wed 12 May 2021 23:10:02 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:20043 Wed 12 May 2021 23:09:16 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:33238 Wed 12 May 2021 23:00:47 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:2098 Wed 12 May 2021 22:56:50 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3041 Wed 12 May 2021 22:54:15 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5722 Wed 12 May 2021 22:26:45 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:36366 Wed 12 May 2021 20:54:55 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:2557 Wed 12 May 2021 20:53:02 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5375 Wed 12 May 2021 20:36:28 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:31267 Wed 12 May 2021 20:10:44 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:2571 Wed 12 May 2021 20:09:56 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:26012 Wed 12 May 2021 20:08:02 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4837 Wed 12 May 2021 19:59:51 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4969 Wed 12 May 2021 19:45:59 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4043 Wed 12 May 2021 19:40:59 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:26013 Wed 12 May 2021 19:35:11 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3077 Wed 12 May 2021 19:10:30 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:1788 Wed 12 May 2021 18:59:55 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:33178 Wed 12 May 2021 18:57:38 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5163 Wed 12 May 2021 18:50:42 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:2236 Wed 12 May 2021 18:47:28 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:39856 Wed 12 May 2021 18:42:02 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4610 Wed 12 May 2021 18:33:31 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5457 Wed 12 May 2021 18:24:03 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4199 Wed 12 May 2021 17:56:52 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:31259 Wed 12 May 2021 17:38:02 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:1696 Wed 12 May 2021 17:33:50 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:1451 Wed 12 May 2021 17:18:35 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:663 Wed 12 May 2021 17:18:09 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:31269 Wed 12 May 2021 17:05:01 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5220 100 mm SL) exposed animals relied on shell thickness and adhesion to combat predators, while small (> 45 mm SL) sub-boulder animals and medium sized (50 - 95 mm SL) animals relied on their cryptic microhabitats and the protective spine canopies of co-resident urchins (Parechinus angulosus) for daytime protection. Populations of H. midae were discontinuously distributed along the coast, occupying small isolated reefs which offered a suitable array of microhabitats and a good food supply. They mostly inhabited shallow intertidal and subtidal reefs, but were occasionally encountered on deeper subtidal reefs at 4 - 5 meters. Mean length- and width-at-age were determined from growth rings composed of alternate conchiolin (dark) and aragonite (white) bands in the internal nacreous shell layer. Growth was described by the Special Von Bertalanffy growth equation: Lt(mm) = 176.998918 (1 - e⁻°·²⁴²⁴¹⁹⁽t ⁺ °·⁴⁹⁵⁴⁹⁴⁾) Wt(mm) = 159.705689 (1 - e⁻°·¹⁹⁵⁴³⁹⁽t ⁺ °·²¹¹⁶⁾) The ageing technique used was validated for animals from Great Fish Point and Mgwalana using independent tag-return data. The same data provided evidence that growth rates varied between animals from Great Fish Point and Bird Island. The growth data also showed that H. midae exhibited a high degree of individual variation in growth rate. Males and females exhibited similar growth rates. Exposed large animals showed a preference for red seaweeds, in particular Plocamium corallorhiza and Hypnea spicifera, while small sub-boulder cryptic animals included larger proportions of brown (Ralfsia expansa) and green (VIva spp.) algae in their diets. Exposed individuals also exhibited a higher degree of selectivity towards prey items, but in general, stomach contents reflected the most abundant seaweed types. Both drift and attached algal species were utilized by H. midae which was a nocturnal feeder. Pigments from red algae were incorporated into the shell layers giving the shells a pink or brick red colour. Haliotis midae is a dioecious broadcast spawner. Gonad Bulk Indices in combination with detailed histological examination of gonads showed that individuals were iteroparous, asynchronous spawners and that the breeding season extended from March through to October, although the peak spawning activity was between April and June. Males and females can spawn partially, totally or not at all, with atresia of residual gametes occurring after spawning. There is no resting stage, and gametogenesis is initiated directly after spawning. The structure of the ovary and testis and the process of gametogenesis is typical of haliotid species. AI: 1 sex ratio was observed from all populations studied. Sexual maturity was first attained in the 40 - 59 mm SL size class, although evidence for the smallest size at first spawning was recorded at 54.6 mm SL for females and 69 mm SL for males. Sizes at 50% sexual maturity were 72.5 mm SL (52.8 mm SW) at Great Fish Point, 72.5 mm SL (57.4 mm SW) at Mgwalana, 73.7 mm SL (51.2 mm SW) at Cape Recife, and 73.5 mm SL (53.8 mm SW) at Kelly's Beach. Haliotis midae was typically highly fecund, although a high degree of variation resulting in poor relationships between fecundity/shell length and gonad weight/shell length. The relationship between fecundity and gonad weight was linear. In the Eastern Cape, H. midae possessed a faster growth rate, smaller size at sexual maturity, smaller maximum size and lower longevity when compared to con specifics in Western Cape waters. A smaller minimum legal size of 93 mm SW is proposed for Eastern Cape animals and it is suggested that the closed season be moved to the peak spawning period between April and June. The benefit of a closed season during the spawning period is questioned, and the feasibility of closed areas as a management option for H. midae in the Eastern Cape is discussed.]]> Wed 12 May 2021 16:44:38 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:1473 Wed 12 May 2021 16:37:35 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:13472 Wed 12 May 2021 16:31:41 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3207 Wed 12 May 2021 16:15:33 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:26011 Wed 12 May 2021 16:15:30 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:39535 Wed 12 May 2021 16:09:51 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:31268 Wed 12 May 2021 15:57:28 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4048 Wed 12 May 2021 15:55:08 SAST ]]> 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https://vital.seals.ac.za/vital/access/manager/Repository/vital:4998 63% Fe. Deposits of Zimbabwe have more than 33 000 Mt of beneficiable iron-formation. The evaluation of an iron ore prospect involves many factors which must be individually assessed in order to arrive at an estimate of the probable profitability of the deposit. Many of these are geological and are inherent in the deposit itself. Other factors are inherent aspects of the environment in which the ore is formed. Although the geological character of the ore does not change, technological advances in the processing techniques may have a great effect on the cost of putting the ore into marketable form. Geochemical, geophysical and remote sensing methods would be used for regional exploration. Chip sampling and drilling are useful for detailed exploration. Purely geological exploration techniques are applicable on a prospect scale in the exploration of iron ore deposits. Regional exploration targeting should choose late Archaean greenstone belts containing oxide facies iron-formation or Early Proterozoic basins located at craton margins as they are both known to host high-grade haematite orebodies formed by supergene/hypogene enrichment. Most types of iron ore deposits in southern Africa are described and classified. An attempt is made to emphasize the major controls on mineralisation, in the hope that these may be applicable to exploration both in the southern African region and within analogous settings around the world.]]> Thu 13 May 2021 00:57:50 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3433 Thu 13 May 2021 00:03:54 SAST ]]>