http://vital.seals.ac.za:8080/vital/access/manager/Index ${session.getAttribute("locale")} 5 http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:5830 Wed 12 May 2021 20:57:23 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:5828 Wed 12 May 2021 20:52:24 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:5586 Wed 12 May 2021 20:11:35 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:5611 Wed 12 May 2021 20:02:09 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:5609 Wed 12 May 2021 19:43:43 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:5606 50 km/h and were also significantly influenced by light conditions (i.e. detection success was greater when the sun was high) and the position of the roadkill on the road (i.e. smaller roadkill on verges were often missed). These results suggest that roadkill sampling was most effective between 1.5 hours after dawn and 1.5 hours before dusk and that driving at slower speeds (<50 km.h⁻ₑ) was required to detect roadkill. This protocol was implemented across three ecological seasons on a 100 km paved road and a 20 km unpaved road in the Greater Mapungubwe Transfrontier Conservation Area, Limpopo Province, South Africa. Driven daily over a 120-day period (three periods consisting each of 40 days), a total of 1,027 roadkill were recorded. These comprised 162 species from all terrestrial vertebrate groups with birds being the most commonly encountered roadkill (50% of all incidents). The high numbers of vertebrates identified as roadkill suggests that road traffic could have potentially unsustainable impacts on wildlife populations and hence the biodiversity of the area. Seventeen variables were identified as possible determinants of roadkill occurrence with season, rainfall, minimum and maximum temperature, habitat type, grass height, grass density, fence type and vehicle type significantly influencing roadkill numbers. Significantly more roadkill were detected on the paved road (9.91/100km) than on the unpaved road (1.8/100km) probably because of greater traffic volumes and the increased speed that vehicles travelled on the paved road. Warmer temperatures and increased rainfall in the preceding 24 hours also increased road mortality numbers as animals tended to become more active during these times. Interestingly, more roadkill was detected in open roadside habitats compared to dense roadside habitats on both the paved and unpaved roads and when grass on the roadside verge was of intermediate height. Open habitat possibly may provide a natural corridor for wildlife which ultimately end up on the road. Roadkill numbers increased when certain other physical barriers, such as cattle fences, were present, probably because these barriers were more penetrable than electric fencing. A series of mitigation measures are proposed to reduce the impacts of roads on wildlife in South Africa. These mitigation measures highlight the need to address the balance between the development of a country’s transport infrastructure and the conservation of its fauna. It is important that research on the impacts of roads becomes standardised to enable robust statistical comparisons which will provide a greater understanding of the potential threats to vertebrate biodiversity]]> Wed 12 May 2021 19:11:07 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:5608 Wed 12 May 2021 18:53:35 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:5610 Wed 12 May 2021 18:41:58 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:5621 Wed 12 May 2021 18:05:21 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:5607 Tue 15 Aug 2023 10:51:57 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:5587 Thu 13 May 2021 05:39:45 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:5585 Thu 13 May 2021 04:38:58 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:5583 0.05 in all cases). Numerical analyses failed to identify any effect of the sandprawn density on the macrofaunal community structure. The rate of bioturbation was, however, strongly correlated to the sand prawn density. Similarly, the microphytobenthic alga concentrations were significantly negatively correlated to the sand prawn densities ((P < 0.05). The absence of any distinct impact of the sandprawn on the macrobenthic community structure appeared to be related to their low densities in the lower reach of the estuary during the study. To better understand the role of the sandprawn as an ecosystem engineer, a caging experiment was conducted using inclusion and exclusion treatments (n= 5 for each treatment). Densities of the sandprawn in the inclusion treatments (80 ind m⁻²) were in the range of the natural densities within the estuary. The experiment was conducted over a period of 18 weeks in the lower reach of the estuary during summer. The presence of the sandprawn, C kraussi, contributed to a significant decrease in the microphytobenthic algal concentrations and the abundance and biomass of the macrofauna (P < 0.05 in all cases). The decrease in the microphytobenthic algal concentrations in the presence of the sandprawn appeared to be related to the res-suspension of the sediments (bioturbation) generated by the burrowing and feeding activities of the sandprawn. The observed decrease in macrofaunal abundances and biomass in the inclusion treatments appeared to be mediated by both the decreased food availability (mainly the microphytobenthic algae) and the burial of organisms within the sediments. Numerical analysis indicated that the sandprawn did, however, not contribute to a change in the species composition of the macrofauna. Results of the current study indicate that C.kraussi plays an important role in structuring the invertebrate community and energy flow within temporarily/open closed Kasouga Estuary.]]> Thu 13 May 2021 03:41:28 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:5588 Thu 13 May 2021 03:05:37 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:5584 0.05 in all cases). Results of the stable isotope study indicated that the mean δ¹³C of the shrimps in the lower, middle and upper reaches were -12.4 (± 1.3) ‰, -15.6 (± 0.5) ‰ and -17.5 (± 0.5) ‰, respectively. The δ¹⁵N isotopes of the shrimps in the lower reach was 11.6 (± 0.5) ‰ with middle and upper reaches having similar δ¹⁵N values, 13.5 (± 0.4) ‰ and 13.4 (± 0.4) ‰, respectively. There was no significant difference in the δ¹³C and δ¹⁵N isotope (p > 0.05) between the sexes of the shrimps. Two-way ANOVA indicated a significant difference in the δ¹³C isotope of the shrimps between the sites (p < 0.05). The difference in the δ¹³C and δ¹⁵N ratios of the shrimps suggests spatial variability in the diet of P. peringueyi within the Kariega Estuary. The diet of the shrimps in the lower reach is primarily composed of Nanozostera capensis epibionts. In the middle reach the diet of the shrimps is likely comprised of the detritus of benthic algae. In the upper reach of the estuary, P. peringueyi likely derives its carbon from a combination of epibionts, benthic algae and detritus derived from Codium.]]> Thu 13 May 2021 02:12:35 SAST ]]>