https://vital.seals.ac.za/vital/access/manager/Index en-us 5 https://vital.seals.ac.za/vital/access/manager/Repository/vital:10312 Wed 12 May 2021 23:42:04 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4330 Wed 12 May 2021 23:40:38 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:10695 Wed 12 May 2021 23:33:24 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3925 Wed 12 May 2021 23:30:20 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5553 Wed 12 May 2021 23:11:12 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5133 Wed 12 May 2021 22:36:06 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3974 Wed 12 May 2021 22:34:32 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5554 Wed 12 May 2021 22:30:24 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4357 Wed 12 May 2021 22:24:41 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:6038 Wed 12 May 2021 22:18:14 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:10464 Wed 12 May 2021 20:31:02 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4332 Wed 12 May 2021 20:25:51 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5116 Wed 12 May 2021 20:05:34 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4232 Wed 12 May 2021 20:03:42 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4766 Wed 12 May 2021 19:54:53 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5709 0.05 in both cases). The Reed Cormorant (Phalacrocorax africanus) was the dominant species throughout the study, with a mean of 8.25 (SD ± 7.90) individuals per count. Mean values of the Pied Kingfisher (Ceryle rudis) and Giant Kingfisher (Megaceryle maximus) were 3.42 (SD ± 1.20) and 1.17 (SD ± 0.60) individuals per count, respectively. The remaining species revealed mean values < 0.5 individuals per count. The highest bird numbers were recorded in winter reflecting the migration of large numbers of the Reed Cormorant into the system. Breaching events were associated with a decrease in total bird numbers, which was most likely due to loss of potential foraging habitat (littoral zone) for waders resulting from reduced water levels. Monthly food consumption by all piscivorous birds revealed large temporal variability, ranging from 26.35 to 140.58 kg per month. The observed variability could be linked to mouth phase and bird numbers.]]> Wed 12 May 2021 19:41:05 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5353 Wed 12 May 2021 19:04:52 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4407 Wed 12 May 2021 19:02:51 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3950 Wed 12 May 2021 18:43:44 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:10697 Wed 12 May 2021 18:32:28 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:10696 Wed 12 May 2021 18:24:05 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3955 Wed 12 May 2021 18:14:36 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:9686 Wed 12 May 2021 17:56:42 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:10614 5 m3.s-1). Salinity gradients from 30.1 PSU at the mouth to 2.2 PSU in the upper reaches were measured in 2006 after a high flow event. However the estuary quickly reverted back to its homogenous condition within weeks after this flood. This study showed that freshwater inflow increased nutrient input to the estuary. Total oxidised nitrogen (TOxN) and soluble reactive phosphorus (SRP) concentrations were higher in August 2006, after the flood, than during the other low flow sampling sessions. TOxN decreased from a mean concentration of 21.6 μM in 2006 to 1.93 μM in February 2009. SRP decreased from 55.3 μM to 0.2 μM respectively. With the increased nutrient availability, the response in the estuary was an increase in phytoplankton biomass. After the 2006 floods the average water column chlorophyll-a was 9.0 μg l-1, while in the low freshwater inflow years it ranged from 2.1 to 4.8 μg l-1. The composition of the phytoplankton community was always dominated by flagellates and then diatoms, with higher cell numbers in the nutrient-enriched 2006 period. Although the water column nutrient data indicated that the estuary was oligotrophic, benthic microalgal biomass (11.9-16.1 μg.g-1) in the intertidal zone was comparable with nutrient rich estuaries. Benthic species indicative of polluted conditions were found (Nitzschia frustulum, Navicula gregaria, Navicula cryptotenelloides). These benthic species were found at the sites where wastewater / sewage seepage had occurred. Benthic diatom species also indicated freshwater inflow. During the high flow period in 2006 the dominant diatoms were fresh to brackish species that were strongly associated with the high concentrations of TOxN and SRP (Tryblionella constricta, Diploneis smithii, Hippodonta cf. gremainii, and Navicula species). During the freshwater limited period of 2008 and 2009 the benthic diatom species shifted to a group responding to the high salinity, ammonium and silicate concentrations. The species in this group were Nitzschia flexa, Navicula tenneloides, Diploneis elliptica, Amphora subacutiuscula and Nitzschia coarctata. Ordination results showed that the epiphytic diatom species responded to different environmental variables in the different years. Most of the species in 2008/2009 were associated with high salinity, temperature, dissolved oxygen, ammonium and silicate concentrations while the response was towards TOxN and SRP in 2006. The dominant species were Cocconeis placentula v euglyphyta in 2006; Nitzschia frustulum in 2008; and Synedra spp in 2009. The average biomass of the epiphytes was significantly lower in May 2008 than in both August 2006 and February 2009; 88.0 + 17.7 mg.m-2, 1.7 + 0.8 mg.m-2, and 61.8 + 14.4 mg.m-2 respectively. GIS mapping of past and present aerial photographs showed that submerged macrophyte (Zostera capensis) cover in 1966 and 1973 was less than that mapped for 2004. Salt marsh also increased its cover over time, from 86.9 ha in 1966 to 126 ha in 2004, colonizing what were bare sandy areas. Long-term monitoring of the health of the Bushmans Estuary should focus on salinity (as an indicator of inflow or deprivation of freshwater), benthic diatom identification and macrophyte distribution and composition (for the detection of pollution input), and bathymetric surveys (for shallowing of the estuary due to sedimentation).]]> Wed 12 May 2021 17:53:52 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4190 Wed 12 May 2021 17:53:35 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4743 Wed 12 May 2021 17:38:48 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:10565 Wed 12 May 2021 17:35:15 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4839 Wed 12 May 2021 17:22:14 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4744 Wed 12 May 2021 17:10:05 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5303 Wed 12 May 2021 17:09:45 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:10694 Wed 12 May 2021 17:08:02 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4961 Wed 12 May 2021 16:29:16 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5125 Wed 12 May 2021 16:15:59 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:10311 Wed 12 May 2021 15:44:28 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5324 Thu 29 Sep 2022 14:19:13 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4643 Thu 13 May 2021 14:53:46 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:10309 Thu 13 May 2021 10:44:30 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4652 Thu 13 May 2021 08:52:16 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4217 Thu 13 May 2021 08:49:26 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5578 Thu 13 May 2021 08:05:05 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:10462 Thu 13 May 2021 07:20:59 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5370 0.001) and A. gilli between Rondegat and Noordhoeks rivers (x₂ = 34.74, d.f. = 4, p > 0.001). The Spearman's rank correlation test showed no shifts in the diet of A. barnardi from Noordhoeks River and A. gilli from Rondegat River with a change in size and season (p>O.OS). However, there was a shift in the diet of A. gilli from the Noordhoeks River which could suggest a distinct patchiness of benthic macroinvertebrates between the riffle feeding areas used by juveniles and other biotopes used by adults. The occurrence, in stomach contents, of other prey items from a wide variety of taxa and the presence of allochthonous material from the terrestrial environment could suggest an opportunistic feeding guild for both Austroglanis species. The life-history traits of A. gilli and A. barnardi, which are charaterized by slow growth, long life span and low relative fecundity, indicate that both species are relatively precocial and K-selected. The population of a precocial species is relatively stable and if population numbers were to be greatly reduced, they would require a long time to rebuild. An urgent conservation intervention is therefore recommended for Austroglanis spp. so as to maintain the diversity of populations within these species. The creation of protected river reserves and raising public conservation awareness may minimise activities that result in altered river hydrology and the destruction of complex benthic habitats.]]> Thu 13 May 2021 07:20:05 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:10377 Thu 13 May 2021 07:15:25 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4413 [M(2-OH-oVANPN)Xn] + HnX MX₂ + 2-OH-oVANPN (2:1) -> [Mn(2-OH-oVANPN)OH] + H₂X₂ MX₂ + (o-vanillin : diaminopropanol) (1:1) -> [M(1:1)X₂] MX₂ + (o-vanillin : diaminopropanol) (1:1) -> [M₃(1:1)X₄] M = Cu(II), Co(II) or Co(III); X = Cl; n = 1, 2. Their structural features have been deduced from their elemental analytical data, IR spectral data, and electronic spectral data. With the exception of {Cu₃(C₁₁H₁₄N₂O₃)(Cl)₄(H₂O)₆}(A4), the Cu(II) complexes were monomeric with 2-OH-oVANPN acting as a tetradentate ligand. A binuclear Co(II) complex, [Co₂(C₁₉H₁₉N₂O₅)(OH)] (B1), was synthesised and the rest of the Co(II) and Co(III) complexes were monomeric with chloride ions coordinating to the metal centre in some cases. Electronic data suggest that the cobalt(II) complexes have octahedral geometries and the copper(II) complexes have square planar structures – Co(III) is likely to be octahedral. Thermal analyses, which included the copper-block-method for determining sublimation temperatures, revealed that some copper(II) and cobalt(II) complexes are hygroscopic and sublime at 200 °C and below. DSC analyses of the Cu(II) complexes gave exotherms around 300 °C for complexes K[Cu(C₁₉H₂₀N₂O₅)(OH)]·2H₂O (A1) and [Cu(C₁₁H15N₂O₃)(Cl)₂]·2H₂O (A2) and above 400 °C for [Cu(C₁₁H₁₆N₂O₃)(Cl)₂] (A3) and {Cu₃(C₁₁H₁₄N₂O₃)(Cl)₄(H₂O)₆} (A4). Antioxidant studies were carried out against the 2,2-diphenyl-1-picrylhydrazyl radical (DPPH·). The cobalt(II) complex, [Co₂(C₁₉H₁₉N₂O₅)(OH)] (B1), which was synthesized in the presence of KOH, had no antioxidant activity, whilst the other cobalt(II) complexes, [Co(C₁₇H₁₇N₂O₅(Cl))]·1½H₂O (B2), [Co(C₁₉H₂₂N₂O₅) (Cl)₂]·5½H₂O (B3) and [Co(C₁₉H₂₂N₂O₅)(Cl)₂]·5½H₂O (B4), which were synthesised in the absence of KOH, demonstrated antioxidant activity. The latter complexes are candidates for cancer cell line testing, while [Cu(C₁₁H₁₆N₂O₃)(Cl)₂] (A3), {Cu₃(C₁₁H₁₄N₂O₃)(Cl)₄(H₂O)₆} (A4), [Co(C₁₉H₂₁N₂O₅)(Cl)₂ ]·5H₂O (C2) and [Co(C₁₉H₂₀N₂O₅)(Cl)]·3H₂O (C3) may show anticancer activity through possible hydrolysis products. Most of the complexes synthesized displayed antimicrobial activity against Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Aspergillus niger and Candida albicans. The results indicated that complexes [Cu(C₁₁H₁₆N₂O₃)(Cl)₂](A3), [Co(C₁₉H₂₂N₂O₅)(Cl)₂]·5½H₂O (B3) and [Co(C₁₉H₂₁N₂O₅)(Cl)₂ ]·5H₂O (C2) are active against the Gram-negative Ps. aeruginosa and that the ligand, 2-OH-oVANPN, did not have any activity. The same trend was observed with 2-OH-oVANPN, {Cu₃(C₁₁H₁₄N₂O₃)(Cl)4(H₂O)₆} (A4) and [Co(C₁₉H₂₀N₂O₅)(Cl)]·3H₂O (C3) against the Gram-positive S. aureus. As for activity against E. coli and C. albicans, some complexes showed more activity than the ligand. There is an observed trend here that the metal complexes are more active (toxic) than the corresponding ligand, which is in agreement with Tweedy’s chelation theory.]]> Thu 13 May 2021 07:08:10 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3959 Thu 13 May 2021 07:01:49 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5793 Thu 13 May 2021 06:54:20 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:10660 Thu 13 May 2021 06:31:36 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5677 Thu 13 May 2021 06:30:18 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5723 Thu 13 May 2021 06:19:17 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:10373 Thu 13 May 2021 06:16:09 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:10618 Thu 13 May 2021 06:11:35 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5768 500 μm) was investigated in the warm temperate, permanently open Kariega Estuary situated along the south-eastern coastline of South Africa. Spatial and seasonal patterns in the hyperbenthic community structure were assessed monthly at six stations along the length of the estuary over a period of twelve months. Data were collected using a modified hyperbenthic sledge, comprising two super-imposed nets. Physico-chemical data indicate the presence of a constant reverse salinity gradient, with highest salinities measured in the upper reaches and lowest at the mouth of the estuary. Strong seasonal patterns in temperature, dissolved oxygen and total chlorophyll-a (chl-a) concentrations were evident. Total average hyperbenthic densities ranged between 0.04 and 166 ind.m-3 in the lower net and between 0.12 and 225 ind.m-3 in the upper net. Hyperbenthic biomass values ranged between 0.02 and 11.9 mg.dry weight.m-3 in the lower net and between 0.02 and 17.4 mg.dry weight.m-3 in the upper net. A spatial and temporal pattern in total densities was detected with an increase in abundance over the period of September to October 2008 particularly in the middle reaches (Stations 3 and 4). Both the lower and upper nets were numerically dominated by decapods (mainly brachyuran crab zoeae) with the exception of June and July 2008 when mysids (mainly Mesopodopsis wooldridgei) dominated, making up 72.4 ± 58.14% of the total abundance in the lower net. A redundancy analysis (RDA) indicated that 99.2% of the variance in the hyperbenthic community structure could be explained by the first two canonical axes. Axis one, which accounted for 96.8% of the total variation detected in the ordination plot was highly correlated with sedimentary organic content and to a lesser extent the chl-a concentration within the Kariega Estuary. The correlations with the second canonical axis (2.4%) were less obvious, however, salinity and seston concentration were weakly correlated with this axis. Diel variability in the hyperbenthic community structure was assessed during March 2009. Samples were collected during the day and night (n = 6 for each period) using sampling gear described above. Total average hyperbenthic densities during the day (497.9 ± 254.1 ind.m-3) were significantly higher than night-time estimates (129.9 ± 38.5 ind.m-3; p<0.05). There were no significant differences in the average dayand night-time estimates of hyperbenthic biomass (p>0.05). A hierarchical cluster analysis identified two significantly distinct groupings, designated the day and night samples. Results from the SIMPER procedure indicated that the high densities of crab zoeae recorded during the day-time accounted for the majority of the dissimilarity between the day and night groupings (44.7%). In addition, it is apparent that several benthic species, especially from the cumacean and isopod orders, were absent from the hyperbenthos during the day-time and emerged into the water column at night.]]> Thu 13 May 2021 05:37:41 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4294 Thu 13 May 2021 04:10:37 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:10459 Thu 13 May 2021 04:00:48 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:10693 Thu 13 May 2021 04:00:03 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5321 Thu 13 May 2021 03:56:56 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5119 Thu 13 May 2021 03:46:30 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3775 Thu 13 May 2021 03:40:13 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4601 Thu 13 May 2021 03:06:32 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5652 Thu 13 May 2021 02:19:05 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:10692 Thu 13 May 2021 02:08:07 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:10685 Thu 13 May 2021 02:06:31 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5108 Thu 13 May 2021 01:54:35 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:10612 1.57 m amsl) and high salinity (30 - 42 ppt) in the TOCE. Principle Components Analysis showed that high water level and reduced sediments were the most significant environmental factors affecting macrophyte phenology. Macrophyte phenology in the POE was primarily driven by temperature, sediment redox potential and salinity. The saline high water level and reduced sediment significantly reduced macrophyte cover in all habitats in the TOCE. Macrophytes in the POE maintained high cover abundance due to seasonal re-growth compared to the TOCE where cover declined over the sampling period due to the high water level. Subsequent to water level dropping by as little as 11 - 20 cm in the TOCE, the intertidal species Sarcocornia tegetaria and Salicornia meyeriana completed their life-cycles and produced viable seeds within four and three months of germinating respectively. In contrast, the Sarcocornia hybrid and S. meyeriana in the POE took longer to complete their life-cycles, namely seven and nine months respectively, while S. tegataria did not germinate in situ but reproduced vegetatively despite producing seed. In the TOCE, the submerged species Ruppia cirrhosa and Chara vulgaris completed their life-cycles within five and three months and produced a maximum of 26 242 and 196 998 seeds m-2 respectively. Due to high water level and prolonged inundation, the reproductive periods were shorter for the intertidal and reed and sedge species in the TOCE compared to the POE. Seed output during the two reproduction periods varied between the two estuaries. Sarcocornia decumbens and S. tegetaria produced a substantially higher number of seeds in the TOCE compared to the POE, namely 0 - 102 847 versus 20 661 - 48 576 seeds m-²; and 7 001 - 45 542 versus 1 587 – 16 958 seeds m-² respectively. Seed output in the TOCE was significantly higher in S. tegetaria during the second reproduction period despite the significantly lower plant cover, which may be a function of the stressful environment in the TOCE. Seed production of S. meyeriana was significantly higher in the POE compared to the TOCE, with 264 224 - 640 292 compared with 24 050 - 27 643 seeds m-², due to higher plant cover in the POE. The research suggests that macrophyte phenology in the TOCE was significantly influenced by mouth condition. Further, macrophytes were able to demonstrate considerable phenotypic plasticity in response to changing and unfavourable environmental conditions. These data can be used in mouth management plans and freshwater requirement studies in TOCEs to ensure that macrophytes can complete their life-cycles and produce viable seeds for the safeguarding of habitat persistence and ecological processes. In impacted estuaries where artificial mouth opening is practised and the macrophytes have been severely degraded or extirpated, management should ensure that the intertidal and supratidal habitats are not inundated during peak flowering and seed production periods i.e. late spring to early autumn (November to March).]]> Thu 13 May 2021 01:41:40 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3861 Thu 13 May 2021 01:38:35 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:10424 Thu 13 May 2021 01:20:08 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3854 Thu 13 May 2021 01:17:10 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5319 Thu 13 May 2021 01:15:49 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:9688 Thu 13 May 2021 01:14:34 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:10610 Thu 13 May 2021 01:11:09 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:10682 Thu 13 May 2021 00:48:48 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:9664 Thu 13 May 2021 00:37:42 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:10699 1 kg). By excluding small rodents from the analysis, prey preference could be estimated for other species and prey size categories. Small- and medium-sized mammals were significantly preferred, whereas large mammals were significantly avoided by the Cape leopard.]]> Thu 13 May 2021 00:37:40 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5123 Thu 13 May 2021 00:23:27 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5114 Thu 13 May 2021 00:18:45 SAST ]]>