https://vital.seals.ac.za/vital/access/manager/Index ${session.getAttribute("locale")} 5 https://vital.seals.ac.za/vital/access/manager/Repository/vital:28146 Wed 17 May 2023 08:48:14 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:28235 Wed 15 Sep 2021 14:30:53 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:28200 Wed 15 Sep 2021 12:17:59 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:28408 Wed 12 May 2021 23:41:05 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:34820 Wed 12 May 2021 23:22:26 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:28148 Wed 12 May 2021 23:18:51 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:29431 20 μg Chl-a l-1) were episodic and flow-dependent in the Gamtoos Estuary, whilst those in the Sundays Estuary were persistent and seasonal. Related to its reduced hydrodynamic variability – i.e. consistent nutrient-rich baseflows and reduced propensity for flushing events – persistent undesirable disturbances were highlighted for the Sundays Estuary, including: summer bottom-water hypoxia (< 2 mg l-1) and exceptional proliferations (> 550 μg Chl-a l-1) of two HAB species (Heterosigma akashiwo and Heterocapsa rotundata). Finally, fine-scale ecological research was undertaken in the Sundays Estuary to identify the processes – abiotic and biotic – that facilitate HABs (‘Daily’ and ‘Hourly’ studies). Findings from the ‘Daily’ study, identified inorganic nutrient availability (i.e. nitrate and phosphate) and mesohaline conditions (ca. 10) as the key bottom-up controls influencing the magnitude and duration of spring/summer phytoplankton blooms. Additionally, bottom-water hypoxia was explicitly linked to the decay of a single HAB species. During the ‘Hourly’ investigation, four known HAB-forming species were recorded at bloom concentrations. Model results indicated that variability in temperature, salinity profiles and nitrate concentrations were significant in facilitating the occurrence of HAB species. Finally, local biotic interactions (e.g. interspecies competition, diel vertical migration and mixotrophy) were recognized as key mechanisms shaping phytoplankton communities. The persistent occurrence of HABs is a new feature in South African estuaries and continued research is needed to recommend management responses. Ultimately, this research highlights the multitude of processes at work shaping phytoplankton variability in estuaries. From a broad perspective (i.e. seasonal and annual), processes such as freshwater inflow regimes, degree of anthropogenic disturbance, as well as seasonal temperature and nutrient supply patterns are the key processes. At a more refined scale (i.e. hourly and daily), local processes including salinity preferences, nutrient availability, diel light cycles and internal biotic interactions are the key drivers organising phytoplankton dynamics. Given the potentially severe ecological consequences of disrupting natural phytoplankton dynamics (e.g. HABs), an element of ‘unpredictability’ should be restored to the hydrological and chemical makeup of highly-regulated estuaries to prevent the continued exacerbation of eutrophic symptoms.]]> Wed 12 May 2021 23:00:12 SAST ]]> https://vital.seals.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://vital.seals.ac.za/vital/access/manager/Repository/vital:34794 Wed 12 May 2021 22:23:04 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:34348 Wed 12 May 2021 20:55:59 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:39437 Wed 12 May 2021 20:13:12 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:28296 Wed 12 May 2021 20:04:41 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:34792 Wed 12 May 2021 19:59:46 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:34350 Wed 12 May 2021 19:59:20 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:30785 Wed 12 May 2021 19:58:54 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:30935 Wed 12 May 2021 19:36:34 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:35667 Wed 12 May 2021 19:16:05 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:34818 Wed 12 May 2021 19:13:45 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:34823 Wed 12 May 2021 19:07:45 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:28173 Wed 12 May 2021 19:03:16 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:39193 Wed 12 May 2021 18:48:05 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:28535 Wed 12 May 2021 18:46:25 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:35969 Wed 12 May 2021 18:20:29 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:34356 Wed 12 May 2021 18:17:27 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:34283 Wed 12 May 2021 17:58:29 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:29227 Wed 12 May 2021 17:43:59 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:34316 Wed 12 May 2021 17:37:42 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:34181 Wed 12 May 2021 17:37:11 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:28222 Wed 12 May 2021 17:20:34 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:27819 Wed 12 May 2021 17:04:32 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:26617 Wed 12 May 2021 16:53:37 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:28311 Wed 12 May 2021 16:51:36 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:34339 Wed 12 May 2021 16:35:52 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:34272 Wed 12 May 2021 16:28:14 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:34354 Wed 12 May 2021 16:27:22 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:28432 Wed 12 May 2021 16:25:10 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:28059 Wed 12 May 2021 16:23:24 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:28156 Wed 12 May 2021 16:21:52 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:37027 Wed 12 May 2021 16:12:16 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:30645 Wed 12 May 2021 16:09:56 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:34320 Wed 12 May 2021 15:48:53 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:30646 Wed 12 May 2021 15:48:23 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:40506 Wed 12 May 2021 15:06:30 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:28139 Wed 03 May 2023 14:17:38 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:28508 Wed 03 May 2023 13:07:18 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:28061 Tue 15 Aug 2023 11:05:18 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:28410 Thu 25 May 2023 15:03:12 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:27004 Thu 22 Jul 2021 15:41:22 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:28208 Thu 18 May 2023 15:27:00 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:35609 Thu 13 May 2021 16:46:00 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:29228 Thu 13 May 2021 08:14:39 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:32853 Thu 13 May 2021 07:27:44 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:28517 Thu 13 May 2021 07:06:25 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:28089 Thu 13 May 2021 06:56:43 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:34346 Thu 13 May 2021 06:19:12 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:34333 Thu 13 May 2021 06:15:19 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:28227 Thu 13 May 2021 06:06:37 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:34814 0.05). The study revealed that the most prevalent transborder trading activities like smuggling of used tyres, small firearms and fairly used clothes had negative influence on students’ academic performance. Based on these findings, discussions were focused on the involvement of students in trans-border trading activities and the location of schools, amongst others, which has no significant influence on students’ academic performance. However, it was recommended that schools should not be located near border areas in future.]]> Thu 13 May 2021 06:02:17 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:28020 Thu 13 May 2021 05:35:32 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:28067 Thu 13 May 2021 05:31:56 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:31347 Thu 13 May 2021 05:31:19 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:30905 Thu 13 May 2021 05:30:53 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:34813 Thu 13 May 2021 05:24:20 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:34355 Thu 13 May 2021 04:47:10 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:28132 Thu 13 May 2021 04:42:41 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:27820 Thu 13 May 2021 04:39:10 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:28414 Thu 13 May 2021 04:19:37 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:28381 Thu 13 May 2021 04:13:09 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:34812 Thu 13 May 2021 03:57:17 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:32838 Thu 13 May 2021 03:55:05 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:28169 Thu 13 May 2021 03:49:57 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:33447 Thu 13 May 2021 03:47:57 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:28407 Thu 13 May 2021 03:42:47 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:34810 Thu 13 May 2021 03:16:11 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:28359 Thu 13 May 2021 03:06:10 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:34302 Thu 13 May 2021 03:00:25 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:34269 Thu 13 May 2021 02:40:39 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:28154 Thu 13 May 2021 02:39:01 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:30934 Thu 13 May 2021 02:22:08 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:30565 Thu 13 May 2021 02:09:40 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:28396 Thu 13 May 2021 02:06:20 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:29817 m-toluidine > o-toluidine) and the cresols (p-cresol > m-cresol > o-cresol). Each guest mixture was selected based on data from experiments using either the industrial significance of its separation or because the mixture would add to the knowledge base of the host compound’s preferences and selectivities. In a separate study, TETROL and its derivative, (–)-(2R,3R)-2,3-dimethoxy-1,1,4,4- tetraphenylbutane-1,4-diol (DMT), were also allowed to compete for the inclusion of the guest cyclohexanone, where TETROL demonstrated superior ability. This host, in addition, showed potential for the separation of cis- and trans- 2-methylcyclohexanol.]]> Thu 13 May 2021 01:55:11 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:27821 Thu 13 May 2021 01:17:53 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:26875 Thu 13 May 2021 01:03:59 SAST ]]> https://vital.seals.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://vital.seals.ac.za/vital/access/manager/Repository/vital:35825 Thu 13 May 2021 00:45:59 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:34175 Thu 13 May 2021 00:45:22 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:28513 Thu 13 May 2021 00:18:31 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:28307 Thu 11 Apr 2024 19:25:38 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:27998 Thu 06 Apr 2023 13:57:50 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:28149 Thu 04 May 2023 08:33:57 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:26877 Thu 01 Jun 2023 11:15:19 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:28062 Mon 22 May 2023 14:58:54 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:28065 Mon 05 Jun 2023 15:41:21 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:28305 Fri 23 Jul 2021 12:53:04 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:28141 Fri 23 Jul 2021 12:25:01 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:28228 Fri 17 Sep 2021 14:51:46 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:28043 Fri 17 Sep 2021 11:42:47 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:28323 Fri 07 Jul 2023 06:57:12 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:26897 Fri 06 Aug 2021 09:57:38 SAST ]]>