https://commons.ru.ac.za/vital/access/manager/Index en-us 5 https://commons.ru.ac.za/vital/access/manager/Repository/vital:10686 1000 per annum), inshore trawling (ca. 41 per annum), shark nets (protective gill nets) (21.6 ± 6.7 per annum) and the pelagic longline fishery (5.0 ± 4.4 per annum). In contrast, leatherbacks with a pelagic lifestyle, were mostly exposed to pelagic longline fisheries (7.8 ± 7.8 per annum). A spatial analysis of fishing activities indicated that leatherback home ranges overlapped 41percent with pelagic longline fishing activity in the SA EEZ, whereas the overlap between pelagic longliners and loggerhead home ranges was 29 percent. The quantified sources of mortality provide some explanation for the trend in the loggerhead nesting population but not the trend in the leatherback nesting population. Hatchling survivorship to adulthood was estimated to determine the viability of the two nesting populations as well as to determine whether offshore mortality was responsible for the difference in recovery of the two populations. Loggerhead hatchling survivorship to adulthood was estimated at between 2 and 10 per 1000 hatchlings, the minimum requirement for an increasing population. The adopted sophisticated model shows that leatherbacks have a survival rate of 5 to 10 per 1 000 hatchlings. However, this suggests that the population is increasing, but the leatherback population is stable. Perhaps the age to maturity of SA leatherbacks is greater than 12 years, or fisheries-related mortality affects younger age classes than initially thought. It is therefore recommended that the turtle monitoring area is extended to include other potential nesting grounds. In addition, observer or monitoring programs for commercial as well as artisanal fisheries needs to be extended throughout the SWIO to quantify sea turtle mortality. Ultimately a comprehensive multi-regional approach is required for the conservation of these highly migratory species.]]> Wed 23 Jun 2021 09:43:42 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4655 Wed 12 May 2021 23:48:25 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5660 Wed 12 May 2021 23:31:40 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5120 Wed 12 May 2021 23:30:20 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4141 Wed 12 May 2021 23:28:19 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:10164 Wed 12 May 2021 23:26:02 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4661 Wed 12 May 2021 23:13:02 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:10667 Wed 12 May 2021 23:07:05 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5272 Wed 12 May 2021 23:00:16 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4013 Wed 12 May 2021 22:54:42 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:10474 Wed 12 May 2021 22:48:57 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4026 Wed 12 May 2021 22:38:58 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:10463 Wed 12 May 2021 20:58:20 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5249 Wed 12 May 2021 20:52:43 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5383 3m) coastal shark species, widely distributed in tropical and sub-tropical Indo-Pacific waters. Despite its large size and wide distribution, very little is known about its movement behaviour throughout ontogeny. The primary aim of this thesis was to gain an understanding of the movements of sub-adult N. acutidens, in and around the St. Joseph Atoll, Republic of Seychelles, to facilitate the effective conservation of this vulnerable species. A total of 22 sharks (139 – 202 cm TL) were equipped with coded acoustic transmitters and passively monitored using moored acoustic receivers for a period of 20 month from March 2009 to October 2010. The use of passive acoustic telemetry arrays to study behavioural ecology has increased in popularity in recent years and been successfully applied to study a host of teleost and elasmobranch species in a diversity of habitats, ranging from sheltered estuaries to the offshore pelagic environment. However, the practicalities of designing an effective network of receivers to optimally monitor animal movements can be challenging. In this study the receiver array was optimised through a series of incremental steps to achieve an efficient design that allowed for the specific objectives to be addressed. The specific objectives of this study were to i) gain an understanding of the long term space use patterns and site fidelity of sub-adult N. acutidens within degree of use of the St. Joseph Atoll lagoon and surrounding habitats, and ii) investigate their short term behavioural patterns in response to natural rhythmic cycles. The important role the atoll plays in the sub-adult stage of this species was demonstrated by the very low numbers of detections outside the atoll compared to the very large numbers of detections inside the atoll. Over the course of a year the tagged sharks showed a high degree of site fidelity to the atoll, with 79 – 100% of the individuals detected during each month and 50% being detected on a near daily basis. This result provides testimony of the nursery role of the atoll and importance of these habitats in the early life history for this species. Individual area use was generally found to be restricted to the eastern part of the atoll incorporating a portion of the central deep lagoon and a nearby adjacent area of the sand flats. The movements of sub-adult N. acutidens on and off of the shallow flats surrounding the central lagoon (likely for foraging) were found to be strongly influenced by the tidal height and the diel cycle. Tagged sharks were found to utilise the flats more regularly when the tidal height was greater than 90 cm and particularly more so during the night and early morning than during daylight times. The combined results of this study expose the vulnerability of this species to rapid local depletion. Similarly, the effectiveness of spatial management measures, such as no-take marine protected areas is highlighted as an efficient tool for the future conservation of this species. In the St. Joseph Atoll in particular, the use of a multi-levelled protection approach, where the eastern portion on the atoll is completely restricted while the remaining area is utilized for non-consumptive tourism activities, could be highly effective. Future research should investigate changes in area use throughout the ontogeny of this species as well improve the understanding of the breeding site fidelity and population size of reproductive females using the St. Joseph Atoll.]]> Wed 12 May 2021 20:28:57 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4670 Wed 12 May 2021 20:21:05 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:10717 Wed 12 May 2021 20:19:17 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:10580 Wed 12 May 2021 20:12:56 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:10654 Wed 12 May 2021 20:09:19 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:18489 0.05) in species richness and abundance across sites for soil surface-dwelling invertebrates. Bray-Curtis similarity measures in PRIMER and correspondence analysis (CA) in CANOCO showed that sampling units with alien invasive plants shared most soil surface-dwelling invertebrate species at ± 75% level of similarity. Sampling unit A from the Mix alien (MA) site shared most species with indigenous vegetation sites. Sampling units from indigenous vegetation sites shared most species at ± 65% level of similarity. Multivariate analysis using CANOCO indicated that certain site variables such litter depth influenced the distribution of soil surface-dwelling invertebrates across sites. The study provided preliminary data and information for promoting invertebrate biodiversity conservation within protected areas (Nduli and Luchaba Nature Reserves) of the KSD Local Municipality. Key words: invertebrates, indigenous vegetation, alien vegetation, Lantana camara, Acacia mearnsii, and Eucalyptus.]]> Wed 12 May 2021 19:57:38 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:10135 Wed 12 May 2021 19:42:13 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:10754 Wed 12 May 2021 19:39:30 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:3751 Wed 12 May 2021 19:31:21 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4825 Wed 12 May 2021 19:22:58 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:10443 Wed 12 May 2021 19:22:32 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:10573 Wed 12 May 2021 19:17:53 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:10661 Wed 12 May 2021 19:09:19 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4654 Wed 12 May 2021 19:01:39 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:10428 Wed 12 May 2021 18:55:46 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4752 Wed 12 May 2021 18:49:36 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5559 Wed 12 May 2021 18:44:41 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5171 Wed 12 May 2021 18:40:05 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:10343 Wed 12 May 2021 18:12:11 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:10633 Wed 12 May 2021 17:55:01 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:10318 Wed 12 May 2021 17:54:43 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4586 Wed 12 May 2021 17:23:55 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5726 Wed 12 May 2021 17:21:41 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4769 Wed 12 May 2021 17:15:16 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:10625 Wed 12 May 2021 17:14:35 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:10745 Wed 12 May 2021 17:10:07 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5893 Wed 12 May 2021 17:07:28 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4665 Wed 12 May 2021 17:05:33 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:10722 Wed 12 May 2021 16:43:18 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:10508 Wed 12 May 2021 16:32:14 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5644 Wed 12 May 2021 16:23:44 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:10629 Wed 12 May 2021 16:19:53 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5229 0.05) amount of variability (63%) was explained by a predictive model incorporating these variables as investigations were constrained by small sample sizes and aggregated catch information. Scientific survey data provided multi-species information and highlighted the high proportion of non-native fish species in Eastern Cape impoundments. Gillnet catches were influenced primarily by species composition and were less subject to fluctuations induced by environmental factors. Overall standardised gillnet CPUE was influenced by surface area, conductivity and age of impoundment. Although the model fit was not significant at the p<0.05 level, 23% of the variability in the data was explained by a predictive model incorporating these variables. The presence of species which could be effectively targeted by gillnets was hypothesised to represent the most important factor influencing catch rates. Investigation of factors influencing CPUE in impoundments dominated by Clarias gariepinus and native cyprinids indicated that warmer, younger impoundments and smaller, colder impoundments produced higher catches of C. gariepinus and native cyprinids respectively. A predictive model for C. gariepinus abundance explained a significant amount of variability (77%) in CPUE although the small sample size of impoundments suggests that predictions from this model may not be robust. CPUE of native cyprinids was influenced primarily by the presence of Labeo umbratus and constrained by small sample size of impoundments and the model did not adequately explain the variability in the data (r² = 0.31, p>0.05). These results indicate that angling catch- and scientific survey data can be useful in providing predictions of fish abundance that are biologically realistic. However, more data over a greater spatial scale would allow for more robust predictions of catch rates. This could be achieved through increased monitoring of existing resource users, the creation of a centralised database for catch records from angling competitions, and increased scientific surveys of South African impoundments conducted by a dedicated governmental function.]]> Wed 12 May 2021 16:19:14 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5766 1700m) sites within the Sneeuberg Mountain Complex (SMC) from June 2009 to May 2010. I also tested the effectiveness of five different bait types for measuring small mammal diversity (i.e. number of individuals caught, species richness, Shannon diversity index and Simpson index of diversity). Out of a total of 423 captures, 292 individuals of 12 small mammal species (one shrew, one elephant shrew and 10 rodents) were recorded over 5280 trap nights. The species richness and diversity of small mammals captured at the three sites were similar and this homogeneity was probably related to the regional processes (e.g. climate and latitude) that govern species richness and diversity. The most effective bait type in terms of capture success, species richness and diversity measurements was peanut butter and oats. In addition, the use of richness estimators revealed that peanut butter and oats was the most effective bait for sampling the species richness of small mammals. The effectiveness of peanut butter and oats was related to this bait having a more attractive scent, when compared to the other bait types. Future studies should focus on researching the range of local and regional processes that drive small mammal diversity at high altitudes in South Africa. I also recommend the use of more than one bait type when planning to survey small mammal communities.]]> Wed 12 May 2021 16:13:06 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:10635 Wed 12 May 2021 15:49:34 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:10632 Wed 12 May 2021 15:44:27 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:41186 Wed 12 May 2021 14:40:49 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:10710 Thu 13 May 2021 08:16:34 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:10394 Thu 13 May 2021 08:12:30 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:10758 Thu 13 May 2021 08:12:21 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:10511 Thu 13 May 2021 07:43:59 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4021 Thu 13 May 2021 07:22:37 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:10543 Thu 13 May 2021 07:18:17 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5693 Thu 13 May 2021 07:16:52 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5767 Thu 13 May 2021 07:13:47 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4024 Thu 13 May 2021 07:08:45 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:3867 Thu 13 May 2021 07:08:36 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4129 Thu 13 May 2021 06:49:28 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:9703 Thu 13 May 2021 06:47:31 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:10622 Thu 13 May 2021 06:46:42 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:29514 Thu 13 May 2021 06:41:14 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5170 Thu 13 May 2021 06:36:24 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:10631 Thu 13 May 2021 06:19:00 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5476 Thu 13 May 2021 06:18:50 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:10546 Vmax was noted for the thermally stressed unit. This feature in the I-V curve may be attributed to the breakdown of the Ge subcell in the CTJ cell. Based on the results obtained from the two experimental HCPV modules, recommendations for an optimal HCPV module were made.]]> Thu 13 May 2021 06:06:50 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:10316 125 μg/ml. These results suggest that the extract may be selective for specific cell types. Bio-assay guided fractionation of the S. ellipticum ethanolic extract yielded two active fractions; chloroform and ethyl acetate. Two compounds isolated from the chloroform extract were screened against the three cancer cell lines and found to be inactive. Three compounds were isolated from the ethyl acetate fraction and revealed IC50 values < 62.5 and < 31 μg/ml against MCF-7. Unfortunately these two compounds soon lost activity before any further work could be done on them and work was continued with the crude extract.]]> Thu 13 May 2021 05:53:54 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5573 Thu 13 May 2021 05:44:28 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:10366 Thu 13 May 2021 05:24:19 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5104 Thu 13 May 2021 05:24:07 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:10417 Thu 13 May 2021 04:41:08 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5916 2.5 % TFA) and exhibited intermediate omnivory (intermediate levels of 20:1n-11 and 20:1n-9, intermediate 18:1n-9/18:1n-7 ratios at ~1.3, less enriched δ¹⁵N values at ~7.9 ‰; zooplankton contribution of 10-15 % of the diet). The more depleted nitrogen signatures in the mussels relative to the barnacles and polychaetes possibly illustrated a stronger preference for autotrophic food. Polychaetes mainly consumed plant food sources (i.e. microalgae, macroalgae and detritus; high levels of i-18:0, 18:1n-9, 18:4n-3 and 20:5n-3) and displayed little omnivory (low levels of 20:1n-11 and 20:1n-9, low 18:1n-9/18:1n-7 ratios at ~0.4, intermediate δ¹⁵N values at ~9.1 ‰; zooplankton contribution of <10 % of the diet). The barnacles, mussels and polychaetes are all suspension-feeders, originally presumed to consume the same food sources. The variations observed among the species, therefore, may result from differences in the proportional contributions of the various food sources to their diets as well as distinctions in metabolism. The distinct changes in the fatty acid and stable isotope signatures in all three filter-feeders in the Kariega and Great Fish regions are likely influenced by the diversity in regional vegetation and hydrology in the different systems, combined with interspecific differences in resource partitioning among the species.]]> Thu 13 May 2021 04:32:19 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4748 Thu 13 May 2021 04:27:01 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:10517 Thu 13 May 2021 04:19:00 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:10383 Thu 13 May 2021 04:14:47 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:10547 Thu 13 May 2021 04:10:41 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5636 Thu 13 May 2021 03:50:03 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:3870 Thu 13 May 2021 03:35:30 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:10721 150 percent) in the high density nesting beaches compared to the low density nesting beaches within and among seasons however further investigations are required. Artificial light (range: 0.045–0.5 lux) is an active deterrent of female emergences while ambient light, even under extreme conditions such as lightning during electric storms (up to 8.2 lux), appears to have no observable influence on the spatial or temporal distributions of emergences. Social facilitation appears unlikely as a primary nest site selection factor for loggerheads. It may however, play a minor secondary role to preferred areas or hotspots. Sea-finding in post-nesting female loggerheads appears to be driven exclusively by visual cues such as the light horizon, with minimal to no influence from other cues (the sound of the breakers, slope or smell of the ocean) which solidify the visual system’s use in sea-finding. This research on the nest site selection of loggerheads and the sensory systems involved in this process has added valuable information to the limited pool of knowledge already present and has created a solid framework on which further investigations can be based. Future work in this field should focus on integrating a suite of sensory stimuli and cues to receive a greater understanding of the sensory systems used in nest site selection.]]> Thu 13 May 2021 03:34:54 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:9711 Thu 13 May 2021 03:30:52 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:10691 Thu 13 May 2021 03:17:16 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5724 Thu 13 May 2021 03:05:16 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5141 Thu 13 May 2021 02:50:03 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:10718 Thu 13 May 2021 02:44:26 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5297 Thu 13 May 2021 02:27:38 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:10545 Thu 13 May 2021 02:25:24 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4005 Thu 13 May 2021 02:15:53 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5308 Thu 13 May 2021 02:15:19 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:10421 Thu 13 May 2021 02:11:29 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5661 Thu 13 May 2021 02:02:37 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4851 Thu 13 May 2021 01:25:00 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:9648 Thu 13 May 2021 01:20:52 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4334 Thu 13 May 2021 01:17:13 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5956 Thu 13 May 2021 01:08:12 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:10561 Thu 13 May 2021 01:07:12 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:10623 6 mg l-1) were maintained throughout the water column mainly by wind and tidal action. However, stratification increased towards the deeper, channel-like middle and upper reaches of the estuary, followed by a significant reduction in bottom DO concentrations and development of hypoxia and anoxia. Bottom water hypoxia commonly occurs in microtidal estuaries due to the limited influence of mixing forces, mainly by wind and tidal action. The Goukamma Estuary is a channel-like microtidal estuary where stratification effectively limited oxygenation of the bottom water which resulted in frequent occurrence of bottom water hypoxia. During June 2010 when the highest local rainfall (75 mm) was recorded for the region, salinity and DO data showed that this amount of rainfall was insignificant as it did not replenish the water column of oxygen. Only the surface 0.5 m layer was fresh and oxygenated while below this, the water column was completely hypoxic. In an unimpacted state, the Goukamma Estuary is a blackwater system and is expected to be nutrient poor; however, farming activities in the catchment have resulted in elevated nutrient concentrations. This study showed that significantly higher nutrient concentrations were measured in the middle and upper reaches of the estuary, adjacent to cattle farms situated in the floodplain of these reaches. Nutrient concentrations represented mesotrophic (dissolved inorganic nitrogen [DIN] > 500 μg l-1) to eutrophic conditions (dissolved inorganic phosphorus [DIP] > 25 μg l-1). Nutrient input stimulated phytoplankton to attain a significantly high biomass, ranging between 0.3 – 112 μg l-1 (~ 7.7 ± 1.3 μg l-1; n = 128) and 0.8 – 289 μg l-1 (~ 21.1 ± 4.4 μg l-1; n = 80) during the open and closed states, respectively. High organic loads are associated with high oxygen demands which consequently result in hypoxia following decomposition. Exacerbated by natural salinity stratification which effectively limits oxygenation of the water column, unnaturally high nutrient concentrations and coinciding organic loads place the estuary at particular risk of degradation. This study captured key patterns and processes by quantifying salinity, oxygen and nutrient concentrations in addition to biological indicators (phytoplankton biomass and community composition). Considering possible budget constraints, it is recommended that monthly salinity and oxygen concentrations should be monitored as well as seasonal nutrient concentrations. It is also recommended that riparian buffer zones should be established in the middle and upper reaches of the estuary, as these vegetation buffers have been well documented to contribute to nutrient attenuation and improved water quality from agricultural run-off.]]> Thu 13 May 2021 01:05:57 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4025 Thu 13 May 2021 00:34:02 SAST ]]>