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Atlantic humpback dolphins (Sousa teuszii) are endemic to nearshore West African waters between Western Sahara and Angola. They are considered Vulnerable by the International Union for Conservation of Nature based on restricted geographic range, low abundance and apparent decline in recent decades. We review the human activities most likely to affect the species and consider appropriate conservation actions. Bycatch (incidental capture) in gillnets is the greatest immediate threat. Deaths from entanglement have been documented in Mauritania, Senegal, Guinea-Bissau, Guinea and the Republic of the Congo. In Namibe Province, Angola, 4.8 artisanal fishing boats and two gillnets per km were observed in some areas within 1 km of the coast and gillnets are deployed regularly inside bays used by dolphins. Other concerns include the ‘marine bushmeat’ trade, habitat loss/degradation, overfishing, marine pollution, anthropogenic sound and climate change. Conservation challenges include a paucity of scientific data on the species, and widespread human poverty within most range states, resulting in high dependence on artisanal fisheries. Recommended conservation and research priorities include: (1) distribution and abundance surveys in known and potential range states, (2) bycatch monitoring programmes, (3) education/awareness schemes, and (4) protection of core areas via reduction/elimination of nearshore gillnetting.
Evolution of long-distance communication in equids may correspond with species-specific types of social organization. To compare harem-forming species (type I) with those that do not establish permanent social units (type II), we conducted a comparative analysis of stallion long-range calls in seven species/breeds of equids: two breeds of domestic horses (archaic and modern breeds) and five wild species: Przewalski's horse, kiang, Somalian ass, Grevy's zebra, Grant's zebra). Acoustic features allowed assigning calls of stallions with 92% average classification success to the correct species. The duration of the call clearly separated horses (type I) from type II species: kiang, Somalian ass and Grevy's zebra. Accordingly to its harem social system (type I), the pattern of long-range call in Grant's zebra deviates from that of its relatives in the direction of horses. Frequency of the first dominant band that was associated with body size separated modern horses from the archaic breed and Przewalski's horse. Playback experiments confirmed that equids, especially the type II species, respond strongly to conspecific calls but also to calls of other equids.
Small carnivores are parasitized by various ectoparasites that include fleas (Siphonaptera). To date few parasite studies in South Africa, and especially the Northern Cape, have focused on fleas, while those that have are biased by small sample sizes. In an attempt to address the paucity of information fleas were collected from five small carnivore species trapped at Loxton and Kimberley in the Northern Cape Province, South Africa. The aim of the study was to contribute to current data on the flea diversity found on various small carnivore species. Small carnivores were trapped and while anesthetized the fleas were manually removed from the fur of the animals. In total 48 small carnivores were trapped of which 30 harboured fleas. Of the five flea species that were recorded the most numerous and prevalent was Echidnophaga gallinacea followed by Ctenocephalides connatus and Ctenocephalides damarensis. Fleas were more numerous and prevalent on the small-spotted cat, Felis nigripes, followed by the yellow mongoose, Cynictispenicillata. The flea community on the small carnivores consisted of fleas that prefer carnivores as principal hosts and also fleas that prefer rodents. The latter maybe acquired through predation on rodents.
The spatial dynamics and home range sizes of early juvenile white steenbras (Lithognathus lithognathus Cuvier, 1829) in the permanently open Great Fish Estuary, South Africa, were assessed using acoustic telemetry. Seven individuals (154–184 mm fork length) tagged with acoustic transmitters spent the majority of their time in the mesohaline to oligohaline regions of the estuary, between five and seven kilometres from the mouth. Mean home range size was small (97 399 ± 22 557 m2, mean ± S.D.) relative to the size of the estuary (approx. 1 360 000 m2). Mean length of the estuary used by an individual was 1707 m (± S.D. = 1663 m). The fish were highly resident within the estuary, and showed fidelity towards their site of capture.
In South Africa, fishes in headwater streams are increasingly being threatened by non-native fish invasions. These invasions originate primarily from source populations in mainstream rivers and impoundments. In the Blindekloof stream, a Swartkops River headwater tributary, the non-native Micropterus salmoides was eradicated from the stream by conservation authorities in 1989. As a result of this eradication subsequent occurrences of non-native fishes are most likely a result of upstream invasions from the mainstream Swartkops River. The Blindekloof stream therefore provided a unique opportunity to investigate whether M. salmoides would reinvade after its removal in 1989 and if the more recently introduced Clarias gariepinus and Tilapia sparrmanii would invade the Blindekloof stream. During snorkel and electrofishing surveys four non-native species were recorded (M.salmoides, M. dolomieu, T. sparrmanii, C. gariepinus). The large predators, M. salmoides, M. dolomieu and C. gariepinus were neither abundant nor widespread and T. sparrmanii was the only non-native species that had successfully established in the Blindekloof stream. Where M. salmoides and M. dolomieu were observed, all other fish species were absent. By contrast, the native species were present at all sites where C. gariepinus and T. sparrmanii were found. The Pseudobarbus afer population was predominantly limited to a 1.7 km section of the stream that was not invaded and is located above a waterfall. The limited distribution range of this Endangered species makes it particularly vulnerable to predation by non-native fishes. The results of this study indicate that these non-native fishes rapidly invaded the Blindekloof stream following their introduction into the mainstream.
Estuarine frontal systems are thought to play an important role in plankton accumulations in estuaries. However, knowledge surrounding these estuarine circulation patterns is not clear, and consensus regarding the importance of fronts has yet to be reached. A full appraisal of the plankton in frontal systems in the estuary was undertaken. Ichthyoplankton, Zooplankton and phytoplankton were collected from in and out of the frontal systems in the Kowie Estuary, using two WP2 plankton nets. Plankton was identified and abundance calculated. Various water quality parameters were also recorded in and out of the front and make up an important part of determining the physical difference between the separated water masses. Values for in and out of the frontal region were determined in order to make comparisons between the different areas. All data was tested for normality and homogeneity of variance. Differences between in and out of the frontal region were determined using ANOVA or Kruskal-Wallis tests. Multiple linear regression was used to determine the relationships between water quality variables and plankton abundances. Community analysis was also run on the data in order to determine community dynamics associated with frontal system convergence and downwelling.
Road ecology is becoming an increasingly important aspect of conservation biology. Carcasses lying on the road often confront visitors travelling to the Kgalagadi Transfrontier Park between Upington and the Twee Rivieren Rest Camp. This study investigated the species killed, the factors contributing to their deaths, and suggested solutions to curtail these mortalities. Twelve surveys to record mammal and bird road mortalities were conducted on the R360 main road between Upington and Twee Rivieren (261 km) from January to September 2007. One hundred and eighty four carcasses were recorded from 22 species, and the most common taxa killed were the bat-eared fox (n = 47) and spotted eagle owl (n = 10). The road mortality rate on the R360 road was very high, 5.44 mammals and 1.14 birds per 100 km. Birds were predominantly killed in summer. Notably more nocturnal mammals were killed than diurnal and ‘indistinct’ species. A mammal hotspot was identified along the 91 km of road that traversed the Gordonia duneveld. Since the nine roadside traffic warning signs erected on the R360 road had no measurable impact on road mortalities, it is recommend that three rumble strip sections with accompanying signage be erected in the hotspot to slow down vehicles and curtail mortalities.
Intramuscular injection of the antibiotic Oxytetracycline (OTC) has been the only method previously employed for chemically marking C. gariepinus otoliths for ageing studies. This study compared intramuscular injection, immersion, and dietary incorporation methods of administering OTC to determine the most effective technique. No differences in either growth or mortality were found between experimental groups while intramuscular injection of OTC was found to be superior to either mass immersion or dietary inclusion of OTC when marking Clarias gariepinus otoliths.
Contraction of their historic geographic ranges and conflicts with humans underpins declines in large carnivore populations worldwide. These declines, which characterize pastoral systems where carnivores, people and livestock live in close contact, may be paralleled by changes in carnivore behaviour. We investigated this by comparing the behaviour, demography and space-use of three lion (Panthera leo) prides in the protected Masai Mara National Reserve and the adjoining Koyiaki pastoral ranch in southwestern Kenya during 2005–2006. The mean times lions were inactive was similar between the three prides except when the ranch lions were severely disturbed and became more nocturnal and inactive. The reserve lions ate their kills on open plains and returned to them often but the ranch lions did so only inside bushes and abandoned unfinished kills during a drought in 2005. The reserve lions spent most of their time on open plains while the ranch lions did so in bushes and woodlands. Activity budgets were similar between the prides regardless of land use. Adult lions altered not so much the type but the spatial location and timing of their behaviour on the pastoral ranches relative to the reserve. We discuss the implications of these findings for lion conservation on pastoral lands.
Four lacertid lizards, Pedioplanis laticeps, P. lineo-ocellata, Meroles knoxii and Nucras tessellata, occur sympatrically on the arid plains of the Tankwa Karoo Basin in South Africa. The aim of this study was to determine whether the four species are spatially separated in terms of the microhabitat each species occupies, allowing them to occur in sympatry in this structurally simple system with a limited number of potential niches. The habitat preferences of the four species were investigated on the farm Gansfontein in the southwestern parts of the Tankwa Karoo Basin. The area was surveyed by walking transects through different habitat types and recording all active lizards. For each lizard observed, the species was identified and a photograph was taken of its microhabitat. At the end of the sampling period the microhabitats in which lizards were found were sorted into distinct types on the basis of substrate composition. During the survey, only one individual of N. tessellata was recorded, but sample sizes for the other three species were sufficiently large to provide a clear perspective of habitat segregation among the three species. The results showed that the three species are spatially separated at the study site, with P. lineo-ocellata being restricted to rocky areas, P. laticeps preferring gravel substrates and M. knoxii frequenting sandy areas. Although only anecdotal information is available, all indications are that the observed spatial separation of the three species is mainly the result of historical adaptation to the different substrate types.
Environmental parameters such as temperature and rainfall influence the biology of amphibians and are likely to similarly influence the growth and prevalence of associated pathogens. Amphibian chytrid fungus, Batrachochytrium dendrobatidis (Bd), causes an infectious disease, chytridiomycosis, in amphibians worldwide. Field studies on post-metamorphic anurans from tropical Australia have correlated increased prevalence with cool winter temperatures, but similar studies are lacking from Africa. We monitored the seasonality of amphibian chytrid in the Highveld of South Africa through microscopic examination of common river frog (Amietia angolensis) tadpoles over 12 months. Within the study area Bd was found to be widespread, but largely limited to riverine systems. The seasonal infection pattern was inconsistent with the findings of past studies, which showed that prevalence usually peaks during the cooler months of the year. This study indicates that infection levels increased during spring in the Grassland Biome, when temperatures favoured optimum thermal growth of the fungus and when streams reached minimum flow levels.
Cichlidogyrus philander was originally described from Pseudocrenilabrus philander philander in Lake Kariba, Zimbabwe. Specimens from four fish species were collected during this study over a 14-month period from the Padda Dam, Johannesburg, transported to the laboratory and killed. Following examination, only P. p. philander was found to be infected with C. philander indicating strict host specificity. Parasite intensity varied from 0 to 184 specimens per fish. Although no significant correlation between season and the infection of specimens of C. philander occurred, a maximum mean intensity of 91.6 occurred in winter. The prevalence was 100% in 10 of the 14 surveys, with no preference for host sex. Mean intensity of infection correlated positively with total length of the host and more parasites were present on fish with a higher condition factor. The distribution on the gill arches shows no significant difference between the number of parasites from gill arches on the left and right sides of fish. More parasites were present on the third and second gill arches, with the majority dorsally, on the distal ends. Water quality variables showed no correlation between prevalence, abundance or mean intensity of this parasite.
Thirteen of South Africa's national parks contain aquatic systems which support 63 indigenous and 11 alien freshwater fishes. Indigenous fishes include 43 species of the Zambezian faunal group (70% of the national total), eight Karroid (47%), five Cape (31%) and seven species of Marine origin (79%). Six represented Zambezian species, two Marine origin, and all of the Cape and Karroid species are endemic to South Africa. Only three threatened species naturally occur within national parks (Serranochromis meridianus, Barbus andrewi, Pseudobarbus afer) all of which are classified as Endangered. Two extralimital IUCN threatened species (Chetia brevis and Oreochromis macrochir) have been introduced. At least three of the five lineages of Galaxias zebratus and two of the four lineages of Pseudobarbus afer occur within national parks in the Cape region. Many fish populations within national parks remain threatened, particularly by hydraulic alterations, impoundment, and predation by alien fishes. There are few aquatic systems within national parks where one or more of these threats are not prominent, and these collectively support only half of the freshwater fish species occurring in all national parks. Proposed management actions include determination and implementation of Environmental Flow Reserves in stressed systems, management of existing alien fish populations and prevention of new establishments, and regular assessments of fish communities.
P.K. Kaleme, J.M. Bates, H.K. Belesi, R.C.K. Bowie, M. Gambalemoke, J. Kerbis-Peterhans, J. Michaux, J.M. Mwanga, B.R. Ndara, P.J. Taylor, B. Jansen van Vuuren
The threat posed by biological invasions is well established. An important consideration in preventing the spread of invasives and also subsequent introductions lies in understanding introduction pathways. The Democratic Republic of the Congo (DRC) houses a large percentage of the world's biodiversity, yet no national strategy exists to deal with the growing number of invasive alien species. Amongst these are the house mouse and ship and Norwegian rats. By comparing our result to published data, we show that species were possibly introduced into the DRC via two routes. The first is via the western seaport at Kinshasa where specimens of M. m.domesticus and R. rattus on the western and northwestern side of the DRC show ties with European haplotypes. The second is via the east where specimens of R. rattus appear linked to Arab and southeast Asian haplotypes. Future work should consider more comprehensive sampling throughout the DRC to more accurately investigate the occurrence of invasive species throughout the country as well as extend sampling to other African countries.
It has been proposed that melanism in cordylids evolved in response to a single climatic event and that melanistic populations of Karusasaurus polyzonus are relictual. This study investigates the genetic relationships of melanistic and non-melanistic populations of K. polyzonus along the west coast of South Africa. Thirty-five specimens of K. polyzonus were collected from three ‘melanistic’ and eight ‘non-melanistic’ sample localities. Partial sequence data were derived for two mitochondrial DNA loci (16S rRNA and nicotinamide adenine dinucleotide dehydrogenase component 2 (ND2)) and analysed using maximum parsimony, maximum likelihood and Bayesian inference. In addition, a haplotype network was constructed using TCS and an analysis of molecular variance (AMOVA) was conducted. The derived topologies were highly congruent and showed that melanistic and non-melanistic populations were interdigitated on all tree topologies and a number of haplotypes were shared between melanistic and non-melanistic specimens. These results suggest that melanistic populations of K. polyzonus are ecotypes, not relics.
Two species of Cubitermes coexist in the grassy Loudetia Savanna of Bondoé, in the Central African Republic, namely C. sankurensis (Wasmann, 1911) and C. ugandensis (Fuller, 1923) Despite the obvious size difference between individuals their nests have the same general shape but there are significant, though small, differences in height, diameter, number of caps, surface and volume. The closest correlations between these five parameters can be seen between the surface and the volume of the nests. The regressions between these two parameters are identical for both species; the addition of a first cap decreases the volume/surface ratio but a second or third cap does not alter this ratio further. Three apparent age classes have been attributed to the nests based on their external appearance: recent, eroded, and dilapidated. The great density (1297 nests/ha) and abundance of the nests that are dilapidated but still occupied by a declining population clearly suggests that the pressure from predation is weak. This study suggests that the environmental conditions are more influential than the species in shaping the mounds and tentative population dynamics of the termite mounds of Bondoé are outlined.
Free-tailed bats (Molossidae) are widely distributed in Africa and exhibit considerable reproductive flexibility. The Egyptian free-tailed bat, Tadarida aegyptiaca, is one of the most widespread of the molossids and is therefore an excellent model to study the variation in reproduction through latitudinal changes. Bats were collected during 2008 and 2009 from Pretoria (25°S), South Africa. In males, spermatogenesis was already underway in January (summer) and spermatozoa were first noted in the epididymis during May (late autumn), where they are stored until the end of September. From September, the testes showed little spermatogenic activity and possibly remained quiescent until early summer. In females, follicular development started prior to January with large Graafian follicles present in June. Ovulation, copulation and subsequent fertilization occurred in late August (spring). When compared to the same species from a low temperate latitude (33°S) it is apparent that spermatogenesis and follicular development were initiated earlier in the year at 25°S. We propose that the seasonal monoestry displayed by T. aegyptiaca at 25°S may be the norm throughout their distributional range and that a latitudinal difference of just eight degrees could influence the timing of events in the reproductive cycle of a free-tailed bat.
Pans are isolated, shallow depressions that are endorheic in nature. Because of the natural hydrological functioning of pans, these systems are usually restricted to arid regions and complete desiccation occurs seasonally. In the eastern provinces of South Africa many pans are perennial in nature often remaining inundated for several years. A study of the aquatic invertebrate community structure of selected perennial pans indicated that when these systems undergo complete desiccation, the communities are comparable to the communities of ephemeral ecosystems. During these periods the community displays normal succession patterns with branchiopod crustacean dominating the community structure a few weeks after inundation. These perennial ecosystems are comparable to similar habitats around the world but are under increasing threat due to an increase in mining and agricultural activities within the study area.
The Wilderness Lakes System incorporates a RAMSAR listed wetland. Previous ichthyological surveys reported three invasive freshwater fishes; Oreochromis mossambicus (Mozambique tilapia), Gambusia affinis (mosquitofish) and Micropterus salmoides (largemouth bass) from this system. To assess the status of these alien fishes, the fish assemblages in the lakes system were sampled with seine nets and fyke nets in 2009 and 2010. A total of 87 893 fish comprising 16 species were caught. In addition to confirming the persistence of O. mossambicus and G. affinis in the system, the current study also reports the presence of a new invader, Cyprinus carpio (common carp). M. salmoides were absent from 2009 and 2010 samples. Key words: freshwater fish, invasive alien fishes, estuary, RAMSAR site, diversity.
A vagrant adult male Subantarctic fur seal Arctocephalus tropicalis was seen and photographed on the beach in Mayumba National Park in the Gabonese Republic. This is the northern most sighting on record for the species. The likely source of the vagrant is the population at Gough Island, South Atlantic.
Opportunistic shore-based sightings of southern right whales Eubalaena australis for Marion Island (46°54′S, 37°45′E) were documented at five different times between 1974 and 2009. Whales were sighted between May and September and exclusively on the eastern lee side of the Island. Notwithstanding some observer biases over this time frame, the species appears to be an infrequent visitor to the inshore marine environment of Marion Island.
The aardwolf, Proteles cristata, is a highly specialized myrmecophagous carnivore that feeds almost exclusively on termites of the genus Trinervitermes. Here we report data from an ongoing analysis of aardwolf diet, where we documented remains of sun spiders and scorpions in aardwolf scats. Although the prevalence of these items was low, with sun spiders recorded in nine and scorpion remains in one of 246 scats, our observations suggest that aardwolves opportunistically feed on larger prey than previously thought. However, our observations do not suggest that aardwolves utilized these large prey items as alternatives to their main food resource during periods of food scarcity. Therefore, we suggest that the adaptive advantages of such opportunism may be small, but that the observed behavioural plasticity could be advantageous under specific environmental conditions and therefore is maintained as a behavioural trait.
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