http://vital.seals.ac.za:8080/vital/access/manager/Index en-us 5 http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:49977 Wed 31 Aug 2022 16:22:50 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:49976 Wed 31 Aug 2022 15:12:45 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:56779 Wed 28 Sep 2022 10:25:53 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:56775 Wed 26 Oct 2022 10:14:32 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:50006 Wed 21 Sep 2022 19:03:08 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:50008 Wed 20 Jul 2022 12:45:32 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:46478 Wed 16 Feb 2022 14:50:52 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:46715 Wed 16 Feb 2022 13:27:47 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:56075 Wed 14 Sep 2022 14:24:22 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:56077 Wed 14 Sep 2022 14:24:19 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:56076 Wed 14 Sep 2022 14:24:14 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:56071 Wed 14 Sep 2022 14:24:13 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:50128 Wed 12 Jul 2023 19:15:47 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:46379 Wed 09 Feb 2022 13:10:34 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:46362 Wed 09 Feb 2022 11:30:13 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:59241 Wed 08 Feb 2023 10:07:28 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:64770 Wed 07 Jun 2023 08:48:12 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:54733 Wed 02 Nov 2022 14:44:56 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:47525 Wed 02 Mar 2022 11:56:22 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:46480 Wed 02 Mar 2022 11:04:31 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:51703 Wed 01 Jun 2022 10:25:52 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:49978 Tue 27 Sep 2022 18:28:50 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:56808 65%) occurred in more recent decades. Canopy cover of ~ 50% was found to be rare in each decade. This suggests that ~50% canopy cover maybe a transient, unstable state. The period with the highest rate of canopy cover increase was 2002-2013, and this increase coincided with a high mean annual rainfall 10 years prior to 2002 and a high mean annual rainfall in most years between the 20022013 period. The period between 2002 and 2013 also had the highest number of sites transitioning from lower to higher tree canopy cover classes, indicating that rainfall may have been a factor driving bush encroachment during the past several decades. An increase in canopy cover (a decrease in light transmittance) was accompanied by changes in woody species composition during thicket formation. The low canopy cover (high light transmittance) sites were dominated by Vachellia karroo and Scutia myrtina trees, while high tree cover sites had fewer V. karroo and S. myrtina trees and were rather characterised by an abundance of thicket tree species. Species proportion, NMDS and dendrogram plots indicated that sites with a light transmittance range between 50-100% had similar tree species compositions, different from sites with light transmittances <50%. An increase in tree density was strongly correlated to an increase in canopy cover (from 2019 satellite imagery), density of trees > 3m, maximum height reached by trees, diversity of trees, total canopy volume, total canopy area and leaf area index (LAI), and a decrease in light transmittance. A structural equation model (SEM) was used to explore the relationships between canopy characteristics (maximum canopy area, canopy volume, tree diversity, density of trees, density of trees >3m, individual trees and maximum canopy height), aerial canopy cover in 2019, and light transmittance. The model explained 73% of the variation in light transmittance, mostly via the direct effect of canopy characteristics. Canopy characteristics had a strong influence on both aerial cover in 2019 and directly on light transmittance, but canopy cover in 2019 had a weak influence on light transmittance. The herbaceous layer was rich and dominated by C4 grasses such as Eragrostis plana, Sporobolus fimbriatus, Themeda triandra and Digitaria eriantha) and forbs including Hibiscus aethiopicus, Helichrysum dregeanum, Helichrysum nudifolium and Gerbera viridifolia at low canopy cover sites with high light transmittance. In contrast, high tree cover sites had fewer herbaceous species in general. Grass and forb species characteristic of these sites high canopy cover sites were Panicum maximum, Loudetia flavida, Pellaea viridis and Cyperus spp. Different sites with low light transmittance (<50%) had similar herbaceous species composition. Basal cover, richness, abundance and diversity of herbaceous plants decreased significantly with an increase in tree density, density of trees >3 m, canopy volume, canopy area, canopy cover, LAI, and increased significantly with increasing light transmittance. Most grasses had their highest densities at LAI <0.5, which was estimated to correspond to ~75% light transmittance and ~38% canopy cover and then started to decline thereafter. Herbaceous species basal cover was also highest at LAI <0.5. An SEM model indicated that herbaceous diversity, basal cover and richness responded both to light availability and to the structure of the woody vegetation directly (R2 = 0.53). While the effect of light transmittance on herbaceous communities was strong (0.41), there was little difference between the effect of light transmittance and canopy characteristics (-0.35) on herbaceous communities. Two possible threshold points, relating to two types of transitions in vegetation structure, could be deduced from this study. The first threshold occurred at canopy cover ~ 40% (LAI < ~ 0.5, light transmittance ~ 75%), at which point many of the common herbaceous species, including the dominant C4 grasses, began to decline in abundance while the composition remained characteristic of the savanna state. A canopy cover of less than ~ 40% at a site provides a suitable state for a high abundance of grass and forb species which help maintain an open system by facilitating fires. The second threshold marked a compositional shift between savanna and closed-canopy vegetation states. Savanna species (trees, grasses and forbs) dominated at high light transmittances (>50%) and were significantly reduced at low light transmittances (< 50%), indicating a possible species composition threshold at ~50% light transmittance at which a savanna state switches to a thicket (LAI ~ 1 and canopy cover ~70%). This point indicated the point where there was a significant difference in both tree and herbaceous plant compositions, with a marked reduction in the occurrence of C4 grasses at light transmittance <50%. Fire is supressed when the C4 grass layer is lost, and further thicket encroachment will take place causing complete canopy closure. Land managers in this system should start becoming concerned about a reduction in grass biomass when canopy cover reaches about 40% and would have to reduce tree cover before the threshold of 50% light transmittance (70% canopy cover from aerial photos) is reached to maintain a savanna system.]]> Tue 27 Sep 2022 11:00:55 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:46309 Tue 24 May 2022 13:48:37 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:72234 Tue 23 Apr 2024 20:07:54 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:49975 Tue 19 Jul 2022 09:14:51 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:65849 Tue 18 Jul 2023 16:30:19 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:46617 Tue 15 Feb 2022 14:58:47 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:46619 Tue 15 Feb 2022 12:03:49 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:46609 Tue 15 Feb 2022 10:32:47 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:56782 Tue 11 Oct 2022 09:36:40 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:64141 Tue 09 May 2023 07:45:36 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:58230 Tue 08 Nov 2022 11:49:33 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:46303 Tue 08 Feb 2022 12:45:34 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:46252 Tue 08 Feb 2022 11:52:42 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:46026 Tue 01 Feb 2022 13:06:45 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:46021 RhMo-AA/Al2O3 (73%) > RhMo-CA/Al2O3 (72%) > RhMo-EDTA/Al2O3 (68%). This could be that the addition of chelating ligand complexed both metallic species retarding sulfidation of both metals, hence lowering the HDS activity. Studies show that it is possible for the citric acid to complex with both promoter and an active metal (Mo), and this might result in the formation of molybdenum dimers, trimers and tetramers which are difficult to sulfide. XPS analysis showed that unchelated catalyst have more MoS2 phases of 63%, hence higher dispersion than the chelated catalyst, this could be the reason for high activity in RhMo/Al2O3 (88%) catalyst.]]> Tue 01 Feb 2022 12:45:40 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:45984 Tue 01 Feb 2022 12:10:53 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:46016 Tue 01 Feb 2022 12:01:32 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:57012 Thu 29 Sep 2022 16:29:41 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:56823 Thu 29 Sep 2022 15:26:40 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:61084 Thu 26 Jan 2023 15:14:24 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:69918 Thu 21 Dec 2023 16:08:45 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:50172 Thu 21 Apr 2022 17:46:55 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:46306 Thu 20 Oct 2022 12:38:48 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:48509 Thu 17 Mar 2022 15:41:06 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:48502 Thu 17 Mar 2022 15:39:10 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:48481 Thu 17 Mar 2022 15:37:21 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:48519 Thu 17 Mar 2022 15:11:43 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:48469 Thu 17 Mar 2022 08:55:57 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:46769 Thu 17 Feb 2022 11:07:48 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:65375 Thu 11 Jan 2024 18:15:11 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:46311 Thu 10 Feb 2022 18:49:33 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:46312 Thu 10 Feb 2022 11:07:35 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:70510 Thu 07 Mar 2024 09:43:59 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:49979 Thu 06 Oct 2022 18:43:15 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:46022 Thu 03 Feb 2022 13:55:30 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:46123 Thu 03 Feb 2022 10:31:48 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:69919 Sun 21 Jan 2024 14:16:49 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:70248 Sun 03 Dec 2023 19:12:04 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:70223 Sun 03 Dec 2023 18:51:33 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:49972 Sun 02 Jul 2023 12:24:22 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:45722 Sat 22 Jan 2022 12:11:10 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:45720 Sat 22 Jan 2022 11:08:19 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:45714 Sat 22 Jan 2022 10:36:51 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:49974 Sat 16 Apr 2022 19:38:39 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:70522 Sat 09 Dec 2023 19:39:22 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:54394 Sat 06 Aug 2022 19:25:38 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:71953 Sat 06 Apr 2024 12:11:21 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:47656 Sat 05 Mar 2022 12:11:37 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:70259 Mon 29 Jan 2024 11:42:58 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:56783 Mon 26 Sep 2022 09:58:04 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:57239 Mon 24 Oct 2022 16:23:01 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:57729 Mon 24 Oct 2022 10:52:53 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:70309 Mon 22 Apr 2024 19:39:16 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:70220 Mon 18 Dec 2023 12:52:38 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:46577 Mon 14 Feb 2022 15:26:49 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:50129 Mon 10 Oct 2022 08:54:24 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:49988 20 μg Chl-a l-1) that result in instances of bottom water oxygen depletion (< 4 mg/l). During the present study in the Sundays Estuary, low oxygen waters were recorded in the middle reaches (Site S5) mostly during summer (four months of low DO conditions). In the Swartkops Estuary, low dissolved oxygen was recorded in the upper reaches during spring. The lowest dissolved oxygen concentration recorded was 0.5 mg/l and 2.4 mg/l in the bottom waters of the Sundays and Swartkops estuaries, respectively. Selected dominant species were only absent from areas where dissolved oxygen was < 1 mg/l and present in the adjacent sites (for example Site S4, and S3) where DO was higher mostly during January 2019. As such, the low dissolved oxygen concentrations recorded in the Swartkops Estuary did not have a noticeable impact on fish distribution, although the total abundance of species did show a slight decline when dissolved oxygen was < 3 mg/l. This study demonstrates the importance of concurrently examining estuarine and nearshore marine habitats in order to identify ecologically important habitats, which has important implications for the development of effective management strategies for coastal fish populations, particularly in the light of anthropogenic change. In addition, in order to identify nursery hotspots it is crucial to correctly identify all the species occupying these areas. As such, this study confirms the importance of also using DNA barcoding for fish identification, particularly for the early life history stages of cryptic species (e.g. Argyrosomus inodorus and Argyrosomus japonicus).]]> Mon 10 Oct 2022 08:22:49 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:51737 Mon 06 Jun 2022 10:23:08 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:56834 Fri 30 Sep 2022 11:21:50 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:45688 Fri 28 Jan 2022 11:06:50 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:45682 Fri 28 Jan 2022 09:32:18 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:50003 Fri 22 Jul 2022 11:49:37 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:46381 Fri 18 Mar 2022 09:40:13 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:46880 Fri 18 Feb 2022 14:42:37 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:46877 Fri 18 Feb 2022 11:49:53 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:46866 Fri 18 Feb 2022 10:40:32 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:70300 Fri 16 Feb 2024 17:40:04 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:53641 Fri 14 Oct 2022 15:47:43 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:46487 Fri 11 Feb 2022 17:56:31 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:45630 Fri 07 Jan 2022 10:29:50 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:47660 Fri 04 Mar 2022 12:00:30 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:46217 Fri 04 Feb 2022 15:52:06 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:46206 Fri 04 Feb 2022 15:09:11 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:46195 Fri 04 Feb 2022 14:44:48 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:46181 Fri 04 Feb 2022 11:43:28 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:46174 Fri 04 Feb 2022 10:43:00 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:46171 Fri 04 Feb 2022 10:00:24 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:46166 Fri 04 Feb 2022 09:28:23 SAST ]]>