https://commons.ru.ac.za/vital/access/manager/Index ${session.getAttribute("locale")} 5 https://commons.ru.ac.za/vital/access/manager/Repository/vital:5326 Wed 12 May 2021 23:04:37 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:3806 Wed 12 May 2021 23:02:43 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5699 0.05). Seventeen woody plant species were utilized on Kwandwe and 23 species were utilized on Shamwari. Grass constituted a significantly greater percentage of the diet in summer than winter (p<0.05). Elephants on Kwandwe showed a selective preference for Ozoroa mucronata, Pappea capensis and Acacia karroo; while on Shamwari, A. karroo was selected. Transects were conducted in two different vegetation types on each reserve so as to assess the impact of elephant on the vegetation and damage scores were then calculated from these data. There was no significant effect of vegetation type or elephant density on mean damage scores in Kwandwe (p>0.05). Five hundred and seventy-eight plants were assessed in the subtropical thicket vegetation type and 225 plants were assessed in the savanna-type vegetation, with more than half the trees showing low levels of damage that could not only be attributed to elephants. Mean damage was highest for Portulacaria afra and Pappea capensis in subtropical thicket and for Rhus spp. in the savanna-type vegetation. On Shamwari, 408 plants were assessed in subtropical thicket and 215 in the savanna-type vegetation, with more than 70 % of trees showing low levels of damage. There was a significant effect of plant species and elephant density on the mean damage scores in subtropical thicket, with Aloe ferox showing more damage than the other plant species (p<0.01). In the savanna-type vegetation, A. karroo was the most severely damaged. Overall, damage was greater in the thicket vegetation type compared to the more open vegetation type on both reserves.]]> Wed 12 May 2021 22:53:13 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:3048 Wed 12 May 2021 22:41:26 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4614 Wed 12 May 2021 22:27:28 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:3749 Wed 12 May 2021 20:37:38 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4773 Wed 12 May 2021 20:36:50 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4247 Wed 12 May 2021 20:16:03 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4648 Wed 12 May 2021 19:06:38 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4682 Wed 12 May 2021 19:06:17 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4841 Wed 12 May 2021 18:40:12 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5689 Wed 12 May 2021 18:35:35 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:6034 Wed 12 May 2021 18:29:52 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5473 Wed 12 May 2021 17:41:31 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4738 Wed 12 May 2021 17:38:36 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4635 Wed 12 May 2021 17:10:23 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:3774 Wed 12 May 2021 16:22:39 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4973 Thu 13 May 2021 11:24:21 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5327 Thu 13 May 2021 10:27:05 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5725 Thu 13 May 2021 08:49:43 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5498 Thu 13 May 2021 08:22:08 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5653 2 cm; chaetognaths, medusae, ctenophores and mysids), with particular emphasis on the chaetognaths Eukrohnia hamata and Sagitta gazellae, were investigated during three surveys conducted in late austral summer (April/May) of 2001, 2004 and 2005 in the Polar Frontal Zone in the vicinity of the Prince Edward Islands (46º45’S, 37º50’E), Southern Ocean. The 2001 survey formed part of the Marion Offshore Variability Ecosystem Study (MOVES II), while the 2004 and 2005 surveys formed part of the Dynamics of Eddy Impacts on Marion’s Ecosystem study (DEIMEC III and IV respectively). Macrozooplankton samples were collected using WP-2, RMT-8 and Bongo nets. Results of the hydrographic survey indicated that the region of investigation, the Polar Frontal Zone (PFZ), is an area of high mesoscale variability. During the 2004 survey the Antarctic Polar Front (APF) and the Subantarctic Front (SAF) merged to form an intense frontal feature with subsurface temperature and salinity ranging from 8.5-7.5ºC and 34.15-33.88, respectively. A cyclonic cold core eddy, believed to have been spawned from the APF, was observed during the 2005 survey. Macrozooplankton abundance and biomass ranged from 0 to 43.731 ind. m⁻³, and from 0 to 41.55 mg wwt m⁻³ respectively, during the three surveys. Among the carnivorous macrozooplankton, chaetognaths (Eukrohnia hamata and Sagitta gazellae) were most prominent, contributing up to 85% of the total biomass during all three surveys. Elevated biomass values were found near and within the frontal feature during the 2004 survey, and also along the eddy edge during the 2005 survey. However, hierarchical cluster analysis did not reveal the presence of distinct zooplankton groupings associated with the various water masses encountered during the surveys and this is probably due to the high mesoscale variability in oceanographic conditions that are characteristic of the PFZ. The total average predation impact of the selected carnivorous macrozooplankton during the 2001, 2004 and 2005 surveys accounted for 4.93 ± 6.76%, 0.55 ± 0.51% and 4.88 ± 4.45 of the mesozooplankton standing stock, respectively. S. gazellae had the highest consumption rate in all three surveys, consuming up to 800 g Dwt 1000m⁻³d⁻¹ during the study. Of the two chaetognaths, E. hamata dominated the chaetognath standing stock. The combined abundance and biomass values of E. hamata and S. gazellae ranged from 0 to 43.73 ind. m⁻³ and from 0 to 41.551 mg wwt m⁻³ respectively, during the three surveys. Inter-annual variability in the chaetognath densities was apparent. Highest abundances and biomasses tended to be associated with specific water masses, confirming the existence of a relationship between zooplankton community structure and hydrographic conditions. Generally, about 90% of the chaetognaths contained no food in their guts. S. gazellae consumed a wider variety of prey. Oil droplets occurred in the guts of ≈ 51% of E. hamata. Cannibalism was low in both species, but greater in S. gazellae than E. hamata. During the three surveys, the feeding rate values of E. hamata and S. gazellae went up to 0.48 and 2.099 prey d⁻¹ respectively. S. gazellae also had a greater predation impact on the mesozooplankton standing stock than E. hamata. The mean predation impact of the chaetognaths combined was 0.31 ± 0.291%, 0.52 ± 0.28% and 0.53 ± 0.56% of the mesozooplankton standing stock during the 2001, 2004 and 2005 surveys, respectively. During all three surveys, the majority of individuals (≈ 76%) of the chaetognaths were at stage I maturity, suggesting that during the time of study the chaetognaths were not reproducing. In both species a significant difference (log-linear analysis, p < 0.05) in maturities between the years investigated was observed. In general, there were no differences in lengths and maturities between the different water masses encountered during the surveys. The lengths of E. hamata and S. gazellae ranged from 5 to 24 mm and from 9.4 to 63.6 mm, respectively.]]> Thu 13 May 2021 08:13:35 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:3776 Thu 13 May 2021 08:08:56 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5735 Thu 13 May 2021 07:03:09 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5696 0.05 in all cases). A key feature of the two investigations was the virtual absence of juveniles (total length < 15 mm) among the amphipod population, supporting the suggestion that they exhibit strong seasonal patterns in reproduction. Gut content analysis during both years indicated that for both the male and female amphipods’, copepods were the most prevalent prey species found in stomachs, followed by chaetognaths and pteropods. Results of electivity studies indicate that T. gaudichaudii is an opportunistic predator, generally feeding on the most abundant mesozooplankton prey. Results of in vitro incubations indicated that the total daily feeding rate of T. gaudichaudii during 2004 ranged from 11.45 to 20.90 ind. m⁻³ d⁻¹, which corresponds to between 0.12 and 1.64% of the total mesozooplankton standing stock. In 2005, the feeding rate ranged between 0.1 and 1.73% of the total mesozooplankton standing stock. The low predation impact of T. gaudichaudii during this study can be related to their low abundances and high interannual variability throughout the region of investigation.]]> Thu 13 May 2021 06:57:14 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5144 Thu 13 May 2021 06:54:06 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5417 Thu 13 May 2021 06:30:47 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5759 Thu 13 May 2021 05:42:09 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4852 Thu 13 May 2021 05:23:10 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5283 Thu 13 May 2021 05:04:25 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4644 Thu 13 May 2021 03:41:44 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4442 Thu 13 May 2021 03:40:58 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:3782 Thu 13 May 2021 02:53:47 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4589 Thu 13 May 2021 02:46:25 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:3975 Thu 13 May 2021 02:27:58 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5577 Thu 13 May 2021 02:03:18 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4638 Thu 13 May 2021 01:57:48 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4641 Thu 13 May 2021 01:29:05 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4364 Thu 13 May 2021 01:03:21 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5287 Thu 13 May 2021 00:37:05 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5304 450 mm TL) occupied larger home ranges (mean size = 218 435 m²) with numerous core areas. The home ranges of small and large spotted grunter overlapped considerably yielding evidence of two high use areas, situated 1.2 km and 7 km from the mouth of the Great Fish Estuary. Tagged spotted grunter were located in a wide range of salinity, turbidity and temperature, but were found to avoid temperatures below 16 ºC. The daily change in environmental variables (salinity, temperature and turbidity) had a significant effect on the change in fish position in the estuary (p < 0.0001; R² = 0.38). The distribution of tagged spotted grunter, particularly the larger individuals, in the Great Fish Estuary was influenced by the tidal phase (p < 0.05); they moved upriver on the incoming tide and downriver on the outgoing tide. This study provides an understanding of the movement patterns of spotted grunter in the estuary and between the estuarine and marine environments. Consequently, it provides information that will assist in the design of a management plan to promote sustainability of this important fishery species. The techniques used and developed in this study also have direct application for further studies on other important estuarinedependent fishery species.]]> Thu 13 May 2021 00:10:25 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5745 Mon 30 Aug 2021 14:30:22 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4592 Mon 06 May 2024 05:32:22 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4815 Fri 27 Aug 2021 09:43:48 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4131 Fri 10 Dec 2021 08:54:22 SAST ]]>