https://commons.ru.ac.za/vital/access/manager/Index ${session.getAttribute("locale")} 5 https://commons.ru.ac.za/vital/access/manager/Repository/vital:27823 Wed 21 Jul 2021 12:10:53 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28394 Wed 17 May 2023 16:02:37 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28146 Wed 17 May 2023 08:48:14 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28235 Wed 15 Sep 2021 14:30:53 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28200 Wed 15 Sep 2021 12:17:59 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28408 Wed 12 May 2021 23:41:05 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28148 Wed 12 May 2021 23:18:51 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:26313 Wed 12 May 2021 23:08:33 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:26616 80 %) feeding, and morning courting behaviour for this species were confirmed. However, during the summer holiday period (mid-December to mid-January) few seahorses were observed on camera, which suggests that the increase in motor boat activity and the related increase in noise had a negative effect on H. capensis feeding and courting behaviour. The marina development, and in particular the Reno mattresses, created a new habitat for this endangered species within the Knysna estuary. In addition to the protection and restoration of natural habitats in which H. capensis is found, the conservation potential of artificial structures such as Reno mattresses should be realised.]]> Wed 12 May 2021 22:34:55 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:26623 Wed 12 May 2021 20:17:12 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28325 Wed 12 May 2021 20:04:55 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28296 Wed 12 May 2021 20:04:41 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:32290 Wed 12 May 2021 19:54:45 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:26734 Wed 12 May 2021 19:34:32 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28594 Wed 12 May 2021 19:05:02 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28173 Wed 12 May 2021 19:03:16 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28535 Wed 12 May 2021 18:46:25 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28704 Wed 12 May 2021 18:01:51 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:21051 Wed 12 May 2021 17:38:32 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:26607 Wed 12 May 2021 17:33:21 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28222 Wed 12 May 2021 17:20:34 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:2084 Wed 12 May 2021 17:09:31 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:27819 Wed 12 May 2021 17:04:32 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:26617 Wed 12 May 2021 16:53:37 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28311 Wed 12 May 2021 16:51:36 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28348 Wed 12 May 2021 16:48:33 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28432 Wed 12 May 2021 16:25:10 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28059 Wed 12 May 2021 16:23:24 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28156 Wed 12 May 2021 16:21:52 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:26751 Wed 12 May 2021 16:19:00 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:21281 Wed 12 May 2021 16:15:31 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:26564 1 (indicating autochthony). In addition to the tracer and FFG analyses for examining trophic connections between land and river, the bidirectional exchange of organisms between the riparian zone and the river was assessed using floating pyramidal traps (to measure emergence) and pan traps (for infalling invertebrates) placed at different sites in the river and the biomass in each trap was determined. The exchanges were variable over space and time, with emergence peaking in summer (169 to 1402 mg m-2 day-1) and declining in winter (3 to 28 mg m-2 day-1). Similarly, infalling invertebrates increased in summer (413 to 679 mg m-2 day-1) and declined in winter (11 to 220 mg m-2 day-1). Biomass measurements are indications of quantity that ignore nutritional quality, so I determined the bidirectional flow of invertebrates using absolute concentrations of physiologically important biochemical compounds (essential and polyunsaturated fatty acids). The fluxes of emergent and infalling arthropods peaked in summer (emergence = 0.3 to 18 mg m-2 day-1 and terrestrial infall = 0.3 to 3 mg m-2 day-1) and declined in winter (emergence = 0.01 to 0.51 mg m-2 day-1 and terrestrial infall = 0.01 to 0.03 mg m-2 day-1). However, during some seasons, no significant differences in polyunsaturated fatty acid flux in either direction were observed; this finding indicated the balance of reciprocal subsidisation via reciprocal flows of animals. Factors such as air temperature and algal productivity affected the reciprocal flows between adjacent habitats, with algal productivity being positively related to emergence while air temperature was positively correlated to infalling terrestrial invertebrates. This research enhances the growing body of literature on the function of riverine systems and offers some invaluable information on the flow of energy and the role played by invertebrates in translocating nutrients from terrestrial systems to aquatic systems and vice versa. This study unifies the concepts of the RCC and RPM and shows that these concepts are not limited only to large rivers, but are applicable to small southern temperate rivers too. However, some tenets of the theoretical models were challenged. For example, it challenges the proposition by the RCC that the fine particulate organic matter leaked from upstream breakdown of coarse particulate organic matter is predominantly allochthonous. Additionally, this study showed that in the headwaters, the RPM underestimated the role of autochthony. Overall, the results showed that the Kowie River and its riparian area are intrinsically connected. Once we understand the mechanisms controlling connections and subsidies across ecotones, we can then start to predict the consequences of disruptions to these connections by climate change and/or land use changes. To make predictions about future perturbations to rivers and riparian zones, studies like this, which considers the form and magnitude of subsidies, are needed to provide baseline information. Algal resources (e.g. epiphyton), macrophytes, riparian plants, terrestrial organisms and aquatic organisms all contributed to aquatic and terrestrial linkages in the Kowie River; therefore, it is important to conserve the different components of these ecosystems.]]> Wed 12 May 2021 16:03:58 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:26563 50 %) in the upper to middle reaches (river), but low (< 20 %) in the lower reaches (estuary). The current investigation represents the first attempt to assess the validity of the River Continuum Concept (RCC) in a southern African temperate river. The phytoplankton and phytobenthos communities, and chl-a concentration followed a trend similar to that proposed for the river continuum concept (RCC). The middle reaches based on the phytobenthos or phytoplankton communities and chl-a concentrations which were employed as proxies for primary production, were the most productive, while the upper reaches were the least primary productive. The evaluation of organic matter contributions to the SPM and detritus along the river–estuary continuum provided a baseline assessment of the nature and sources of potential food for consumers inhabiting different locations during different times of the year. Incorporating such spatio-temporal variations in SPM and detritus into food web studies will improve our understanding of the flow of carbon through aquatic systems.]]> Wed 12 May 2021 15:56:40 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:20651 Wed 12 May 2021 15:55:35 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28139 Wed 03 May 2023 14:17:38 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28508 Wed 03 May 2023 13:07:18 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28061 Tue 15 Aug 2023 11:05:18 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28410 Thu 25 May 2023 15:03:12 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:27004 Thu 22 Jul 2021 15:41:22 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28208 Thu 18 May 2023 15:27:00 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28707 Thu 13 May 2021 16:40:45 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28357 Thu 13 May 2021 15:31:22 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:26580 99 % in selectively extracting the metalloporphyrins. The impact of the template on the affinity of recognition for NTPP was evaluated. The results showed that the NTPP adsorption capacity increased as the molar ratio of NTPP to styrene was increased from 1:1 to 3:1. The optimal ratio of template to functional monomer which yielded the best specific affinity and highest recovery (99.9 %) was 3:1. The effects of trifluoroacetic acid (TFA), dichloromethane (DCM), dimethyl sulphoxide (DMSO), pentane (PEN) on electro-spinnability of the polymer solutions and the morphological appearance of the nanofibers were investigated. The imprinted nanofibers exhibited the same selectivity specialism for both NTPP and VTPP. A remarkable stability in relation to reusability was observed when imprinted nanofibers were used, as they could be reused nine times without incurring any significant loss in removal efficiency. The results were validated by analysing a certified reference material. The imprinted sorbents were therefore found to be selective sorbents that are well suited for handling trace metals in organic media.]]> Thu 13 May 2021 09:54:20 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28540 Thu 13 May 2021 07:35:41 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:29380 20% habitat loss due to invasion). Upstream invasion by centrarchids isolated and fragmented P. afer populations into headwater refugia, while top down invasion by salmonids excluded B. trevelyani from invaded, more pristine stream reaches, by forcing the species into degraded unsuitable lower stream reaches. Predation also disrupted population processes such as adult dispersal for P. afer, and centrarchid-invaded zones acted as demographic sinks, where adults dispersing through invaded reaches were rapidly depleted. While the Mandela lineage of P. afer exhibited little within or between drainage genetic structuring, B. trevelyani was >4% divergent between drainages, and up to 2% divergent between streams within the Keiskamma River system (Chapter 7). The distribution of genetic diversity for B. trevelyani also indicated that the loss of diversity was imminent without immediate conservation interventions. This thesis has provided conclusive evidence that native fishes are vulnerable to invasion and that non-native predatory fishes have significant impacts on native fishes in Eastern Cape headwater streams. If management and conservation measures are implemented, the unwanted introduction and spread of non-native fishes may be restricted, allowing native fishes opportunities for recovery.]]> Thu 13 May 2021 07:28:56 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:26387 Thu 13 May 2021 07:27:02 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28538 Thu 13 May 2021 07:11:33 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28517 Thu 13 May 2021 07:06:25 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28089 Thu 13 May 2021 06:56:43 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28227 Thu 13 May 2021 06:06:37 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:27439 Thu 13 May 2021 06:06:15 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28546 Thu 13 May 2021 06:02:40 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:26557 30%). Little Egret fed mainly on flathead mullet throughout the year. Fatty acid analysis revealed evidence for trophic transfer of specific fatty acids from basal resources to waterbirds in the Kowie Estuary but provided little information on seasonal diet of waterbirds. Waterbirds foraging in the Kowie Estuary appeared to shift their diet to coincide with resource abundance pulses, but also displayed seasonal dietary overlap. This study highlights the role that waterbirds play in aquatic food webs. The subject requires more attention so that we can better understand all the predatory drivers on aquatic communities.]]> Thu 13 May 2021 05:42:17 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28020 Thu 13 May 2021 05:35:32 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28067 Thu 13 May 2021 05:31:56 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28522 Thu 13 May 2021 05:29:11 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:27543 Thu 13 May 2021 05:03:12 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28132 Thu 13 May 2021 04:42:41 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:27820 Thu 13 May 2021 04:39:10 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28213 Thu 13 May 2021 04:33:28 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28414 Thu 13 May 2021 04:19:37 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:27479 Thu 13 May 2021 04:15:02 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28381 Thu 13 May 2021 04:13:09 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:26740 Thu 13 May 2021 04:01:16 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28608 Thu 13 May 2021 03:49:57 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28169 Thu 13 May 2021 03:49:57 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28407 Thu 13 May 2021 03:42:47 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:30662 Thu 13 May 2021 03:37:46 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28629 Thu 13 May 2021 03:31:37 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:26583 Thu 13 May 2021 03:30:11 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:26588 Thu 13 May 2021 03:30:04 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5886 Thu 13 May 2021 03:10:59 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:21289 Thu 13 May 2021 03:07:02 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28359 Thu 13 May 2021 03:06:10 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28154 Thu 13 May 2021 02:39:01 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28396 Thu 13 May 2021 02:06:20 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:27035 Thu 13 May 2021 02:03:09 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:26565 Thu 13 May 2021 01:45:19 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:27821 Thu 13 May 2021 01:17:53 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28607 Thu 13 May 2021 01:16:43 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:26875 Thu 13 May 2021 01:03:59 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28593 Thu 13 May 2021 00:58:01 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:27798 500 km) and modelled with an ordinal logistic regression. Species, life-stage (juvenile/adult) and time- at-liberty were included as predictor variables. Model coefficients were then included in a cluster analysis, which produced two primary groupings of species (Category I and II), with two sub-groupings (Category IIa and IIb). Category I species were characterised by wide-ranging movements, greatest median recapture length and highest trophic levels. Category II species were characterised by residency, lower median recapture length and lower trophic levels. These findings have implications for fisheries management. Exploitation of resident species may lead to localised depletion, but their diffuse spatial distribution may offer some resilience. In contrast, even localised targeting of migratory species may pose a population level risk if individuals are known to aggregate. Life-cycle diversity or intra-population variability describes the existence of alternative strategies or tactics among coexisting individuals within an animal population (Chapter 5). Partial migration is a specific case of life-cycle diversity where coexisting groups exhibit either resident or migratory (wide-ranging) behaviour within a single population. Mark- recapture data collected under the auspices of the ORICFTP were used to investigate the occurrence and nature of life-cycle diversity in the movement behaviour of five non- diadromous fish species around the coastline of southern Africa. Among the five species were three teleosts (Category I and IIa) and two elasmobranchs (Category I). A fish was considered to have remained resident if recaptured within 0-5 km after 365 days at liberty. A fish was considered to have undertaken a wide-ranging movement if recaptured more than 50 km away from the release site in 365 days or less. A total of 1848 individuals from the five study species were recaptured during the study, of which 73% of the observations were classified as being resident. Binomial logistic regression confirmed that species, life-stage (juvenile/adult) and ecoregion were significant (p < 0.001) predictors of the probability of wide-ranging behaviour. A Gaussian model confirmed that species and ecoregion were also significant (p < 0.001) predictors of direction and distance of wide-ranging movement. However, the direction and distance of wide-ranging movements in juveniles did not differ significantly (p > 0.05) to that of adults. The median growth rate was mostly greater in wide- ranging individuals; however, this was only statistically significant (p < 0.05) in two cases. These findings provide unequivocal evidence of life-cycle diversity in five fish species, with vastly different life-histories. This ecological phenomenon may provide species resilience at the population level and needs to be considered in fisheries management initiatives. The movement of fishes is a fundamental aspect to consider when designing fishery management regimes. Unfortunately, traditional management strategies have often disregarded movement behaviour to the detriment of fish populations (Chapter 6). As a case study, the management of Lichia amia (Category I: wide-ranging) was evaluated in the context of its movement behaviour. Long-term catch-per-unit-effort (CPUE) datasets were examined for three South African recreational fishery sectors. The CPUE was standardised using generalized linear models (delta-Gamma/hurdle approach) to reduce the effect of factors other than abundance. Factors that were available for this purpose were year, month and locality/zone. Year was included in every model as the primary objective was to detect trends in abundance over time. Although standardised CPUE for all sectors showed an overall long-term decline, there was considerable variability in trends between the different recreational sectors and between datasets. Contrasting trends between competitive shore angling and general shore angling datasets were ascribed to hyperstability in competitive CPUE data. Hyperstability in this case was mostly influenced by rapidly improving technology, techniques and communication networks amongst competitive anglers. Month and locality were significant factors explaining the probability of catching L. amia. This suggests that the predictable aggregatory behaviour of this species could further compound the observed CPUE hyperstability. Although the CPUE responded positively for six years after implementation of the first minimum size and bag limits, and for one year after the decommercialisation of the species, these regulations and their amendments failed to arrest a long-term decline in the CPUE despite the ample evidence for hyperstability. It is clear from this case study that the predictable nature of wide-ranging behaviour in L. amia has made the population vulnerable to exploitation. This has led to the demise in the population, which could have been worse if not for the occurrence of intra-population variability in its movement behaviour, which may provide some measure of resilience.]]> Thu 13 May 2021 00:49:53 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28513 Thu 13 May 2021 00:18:31 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4492 Thu 13 May 2021 00:06:57 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:27830 Thu 13 May 2021 00:01:37 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28307 Thu 11 Apr 2024 19:25:38 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:27998 Thu 06 Apr 2023 13:57:50 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28149 Thu 04 May 2023 08:33:57 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:26877 Thu 01 Jun 2023 11:15:19 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28596 Thu 01 Feb 2024 09:56:38 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:27442 Thu 01 Feb 2024 09:48:57 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28062 Mon 22 May 2023 14:58:54 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28065 Mon 05 Jun 2023 15:41:21 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28305 Fri 23 Jul 2021 12:53:04 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28141 Fri 23 Jul 2021 12:25:01 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28228 Fri 17 Sep 2021 14:51:46 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28043 Fri 17 Sep 2021 11:42:47 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28323 Fri 07 Jul 2023 06:57:12 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:26897 Fri 06 Aug 2021 09:57:38 SAST ]]>