MRI staff members

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Gridley, Tess (Dr. )
Maree, Sarita (Dr. )
Medger, Katarina (Dr. )
Penry, Gwenith (Dr. )
Tosh, Cheryl (Dr. )

MRI staff members

Current staff members of the MRI are listed below in alphabetical order. Please click on the "More details" button to view additional information for a particular staff member e.g. recent publications.

Dr. Tess Gridley

		Investigating the vocal behaviour and population ecology of cetaceans in the Benguela Ecosystem using passive acoustic methods tessgridley@yahoo.co.uk +27-12-4202539

Research project summmary My research interest lies in animal behaviour, primarily acoustic communication in cetaceans (whales and dolphins). I am interested in understanding functional call types and the factors promoting variation in these at the individual, population and species level. This has allowed me to conduct research in several different countries, using a range of research techniques. I currently work mostly in Namibia, where I am a co-PI on the Namibian Dolphin Project. As so little is known about the cetacean community in this region, our research leads us to ask fundamental questions related to conservation status, such as population abundance, distribution and habitat use, which can feed directly into management objectives. These questions can be approached using passive acoustic methods. For example, we are using passive acoustic survey techniques to investigate the cetacean community within the Namibian Islands Marine Protected Area and its capacity to provide a refuge for coastal dolphin species such as the endemic Heaviside�s dolphin and the dusky dolphin. Other research involves investigating functional call types and vocal production in the small population of bottlenose dolphins inhabiting the Walvis Bay region. Website Links of Importance Namibian Dolphin Project

Dr. Sarita Maree

		1. The conservation of golden moles (Afrosoricida; Chrysochloridae) in South Africa smaree@zoology.up.ac.za +27-12-4203871

Research project summmary My main research interests reside in the fields of molecular systematics, phylogeography conservation and population genetics. Current research primarily focuses on golden moles (Chrysochloridae), an ancient group that resorts under Africa’s most threatened small mammals, and one of only two families of subterranean mammals endemic to the continent. Two thirds of all currently recognized golden mole species are listed in the IUCN Species Survival Commission’s Afrotheria Specialist Group assessment 2007. Golden moles tend to be restricted-range taxa, which make them vulnerable to habitat degradation and local extinction, and most of the recognized species, are only known from scattered, isolated populations. Nonetheless, the habitat of many threatened species such as Juliana’s golden mole, are being ruthlessly destroyed by human activity (urbanization, agriculture and mining). The future of golden moles is largely dependent on the concerted efforts of conservationists, developers, farmers and the public to nurture the unique habitats suitable for their survival. Superficially, many of the 21 recognised species appear identical, but it is possible that several “hidden” (cryptic) species may still be described from within the current species pool. Given that a sound taxonomic classification and an adequate understanding of the population genetics at both a regional and localized scale is fundamental for making informed management decisions relevant to the conservation of taxa, Recent Publications 2009 Bastos, A.D.S., Arnot, L.F., Jacquier, M.D., Maree, S. (2009) A host species-informative internal control for molecular assessment of African swine fever virus infection rates in the African sylvatic cycle Ornithodoros vector. Medical and Veterinary Entomology. 23 (4):399-409 Taylor, P.J., Maree, S., van Sandwyk, J., Kerbis Peterhans, J.C., Stanley, W.T., Verheyen, E., Kaliba, P., Verheyen, W., Kaleme, P., Bennett, N.C. (2009) Speciation mirrors geomorphology and palaecclimatic history in African laminate-toothed rats (Muridae; Otomyini) of the Otomys denti and O. lacustris species-complexes in the. Biological Journal of the Linnean Society. 96:913-941

Dr. Katarina Medger

		The reproductive biology of two small southern African mammals, the spiny mouse, Acomys spinosissimus (Rodentia: Muridae) and the Eastern rock elephant-shrew, Elephantulus myurus (Macroscelidea: Macroscelididae) kmedger@zoology.up.ac.za +27-12-4204872

Research project summmary In mammals, the survival and growth of offspring is highly dependent on environmental conditions. It is therefore important to adjust reproduction to changing environments in order to achieve maximum reproductive success. Photoperiod controls seasonal reproduction in many mammals and is often used as a proximate factor to prematurely indicate changing environmental conditions. The general biology and moreover, the reproductive biology of many small African mammals is little known at present. The proposed study hopes to contribute towards the current understanding of the general reproductive biology and hence overall natural history of the spiny mouse, Acomys spinosissimus, and the Eastern rock elephant-shrew, Elephantulus myurus, in South Africa. The project investigates the seasonality of reproduction in the spiny mouse and the Eastern rock elephant-shrew. Furthermore, it examines the response of the spiny mouse to photoperiod changes. Students currently under co-supervision BSc (Hons) Mr. Christiaan van Niekerk Molecular prevalence and diversity of bacteria in the spiny mouse, Acomys spinosissimus. Recent Publications 2012 Junker, K., Medger, K., Lutermann, H., Bain, O. (2012) Monanema joopi m. sp. (Nematoda, Onchocercidae) from Acomys (Acomys) spinosissisum Peters, 1852 (Muridae) In South Africa, with comments on the filarial genus. Parasite. 19:331-340 Medger, K., Chimimba, C.T., Bennett, N.C. (2012) Seasonal reproduction in the eastern rock elephant-shrew: Influenced by rainfall and ambient temperature? Journal of Zoology. 288:283-293 Horak, I.G., Lutermann, H., Medger, K., Apanaskevich, D.A., Matthee, C.M. (2012) Natural hosts of the larvae of Nuttalliella sp. (N. namaqua?) (Acari: Nuttalliellidae). Onderstepoort Journal of Veterinary Research. 79:- Lutermann, H., Medger, K., Horak, I.G. (2012) Effects of life-history traits on parasitism in a monogamous mammal, the Eastern rock sengi (Elephantulus myurus). Naturwissenschaften. 99(2):103-110 Medger, K., Chimimba, C.T., Bennett, N.C. (2012) Seasonal changes in reproductive development in male spiny mice (Acomys spinosissimus) from South Africa. Mammalian Biology. 77:153-159 Medger, K., Chimimba, C.T., Bennett, N.C. (2012) Reproductive photoresponsiveness in male spiny mice from South Africa. Journal of Zoology. 286:243-249 Lutermann, H., Medger, K., Horak, I.G. (2012) Abiotic and biotic determinants of tick burdens in the eastern rock sengi (Elephantulus myurus). Medical and Veterinary Entomology. 26:255-262 Recent Presentations Here are my most recent presentations. Please feel free to download them. Should you have trouble opening any of them please contact me for assistance. Download my recent presentation *Curriculum Vitae* Here is my Curriculum Vitae. Please feel free to download it. Should you have trouble opening it please contact me for assistance. Download my Curriculum Vitae

Dr. Gwenith Penry

		Further investigations of Southern African Bryde�s whales: abundance, distribution, phylogenetics and foraging ecology. gpenry@iziko.org.za +27-21-4813854

Research project summmary The inshore Bryde�s whale Balaenoptera edeni is endemic to South African coastal waters and belongs to a guild of vertebrate predators that exploit the small pelagic fish of the Agulhas Bank. A previous abundance estimate (582 +/- 184 in 1983) indicates a small population which may currently be in decline due to changing fish availabilities, ecosystem shifts and possible competition with commercial fisheries. Obtaining a current abundance estimate is a conservation imperative. This will be achieved using mark-recapture techniques based on photo-identification and molecular (individual genotypes) data. Foraging ecology will be investigated through analysis of stable isotope signatures in the baleen of museum and recently stranded individuals and the skin of biopsy sampled individuals. Global taxonomic confusion on the number of species or populations of Bryde�s whales persists. Molecular techniques will be used to determine the phylogenetic relationships between the inshore (coastal) and offshore (SE Atlantic and Madagascan) populations of the southern African subregion. Recent Publications 2011 Penry, G.S., Cockcroft, V.G., Hammond, P.S. (2011) Seasonal fluctuations in occurrence of inshore Bryde's whales in Plettenberg Bay, South Africa, with notes on feeding and multispecies associations. African Journal of Marine Science. 33(3):403-414

Dr. Cheryl Tosh

		Satellite-linked identification and analysis of the foraging areas of Southern Elephant Seals Mirounga leonina at Marion and King George Islands catosh@zoology.up.ac.za +27-12-4204283

Research project summmary Marine habitats are characterized by dynamic variables that are continuously changing in relation to large-scale oceanographic processes. Sea-surface temperatures, chlorophyll concentrations and sea-surface height anomalies all influence elephant seal movements, although the degree to which these effects are observed differ between individuals. Movements vary between juvenile and adult elephant seals from Marion Island. Juveniles display more predictable behaviour and are dependant upon the interaction between the Antarctic Circumpolar Current (ACC) and the Andre Bain fracture zone (ABFZ) to form eddies characterized by variable sea-surface height anomalies which can either have warm cores (waters from north of the Sub-Antarctic front) or cold cores (waters from south of the Antarctic Polar front). The relative positions of these frontal zones may influence the interaction between the ACC and the ABFZ, either enhancing or restricting the formation of eddies and altering the available foraging areas for elephant seals from Marion Island. Adult southern elephant seals display sexual differences in terms of foraging behaviour. Adult female southern elephant seals are more predictable in their movements. Post-breeding foraging trips are similar to those displayed by juvenile southern elephant seals, and are possibly limited by restricted foraging times. Post-moulting foraging trips are longer in duration and distance travelled. Females tend to travel towards the Antarctic Recent Publications 2013 Tosh, C.A., Bester, M.N. (2013) High in the food chain - seals in the Southern Ocean. Quest. 9(1):50-53 de Bruyn, P.J.N., Tosh, C.A., Terauds, A. (2013) Killer whale ecotypes: is there a global model? Biological Reviews. 88:62-80 2012 Tosh, C.A., Steyn, J., Bornemann, H., van den Hoff, J., Stewart, B.S., Plotz, J., Bester, M.N. (2012) Marine habitats of juvenile southern elephant seals from Marion Island. Aquatic Biology. 17:71-79 McIntyre, T., Ansorge, I.J., Bornemann, H., Pl�tz, J., Tosh, C.A., Bester, M.N. (2012) Elephant seal foraging dives do indeed track prey distribution, but temperature influences the distribution of prey: Reply to Boersch-Supan et al. (2012). Marine Ecology Progress Series. 461:299-303 McIntyre, T., Bornemann, H., Pl�tz, J., Tosh, C.A., Bester, M.N. (2012) Deep divers in even deeper seas: habitat use of male southern elephant seals from Marion Island. Antarctic Science. 24(6):561-570 James, B., McIntyre, T., Tosh, C.A., Bornemann, H., Plotz, J., Bester, M.N. (2012) Inter-population differences in diving behaviour of adult male southern elephant seals (Mirounga leonina). Polar Biology. 35:1759-1766 2011 Bester, M.N., de Bruyn, P.J.N., Oosthuizen, W.C., Tosh, C.A., McIntyre, T., Reisinger, R.R., Postma, M., van der Merwe, D.S., Wege, M. (2011) The Marine Mammal Programme at the Prince Edward Islands: 38 years of research. African Journal of Marine Science. 33(3):511-521 Oosthuizen, W.C., Bester, M.N., Tosh, C.A., Guinet, C., Besson, D., de Bruyn, P.J.N. (2011) Dispersal and dispersion of southern elephant seals in the Kerguelen province, Southern Ocean. Antarctic Science. 23(6):567-577 McIntyre, T., Ansorge, I.J., Bornemann, H., Pl�tz, J., Tosh, C.A., Bester, M.N. (2011) Elephant seal dive behaviour is influenced by ocean temperature: implications for climate change impacts on an ocean predator. Marine Ecology Progress Series. 441:257-272 de Bruyn, P.J.N., Tosh, C.A., Bester, M.N., Cameron, E.Z., McIntyre, T., Wilkinson, I.S. (2011) Sex at sea: alternative mating system in an extremely polygynous mammal. Animal Behaviour. 82:445-451 McIntyre, T., Bornemann, H., Pl�tz, J., Tosh, C.A., Bester, M.N. (2011) Water column use and forage strategies of female southern elephant seals from Marion Island. Marine Biology. 158:2125-2139 Reisinger, R.R., de Bruyn, P.J.N., Tosh, C.A., Oosthuizen, W.C., Mufanadzo, N.T., Bester, M.N. (2011) Prey and seasonal abundance of killer whales at sub-Antarctic Marion Island. African Journal of Marine Science. 33(1):99-105 2010 de Bruyn, P.J.N., Cameron, E.Z., Tosh, C.A., Oosthuizen, W.C., Reisinger, R.R., Mufanadzo, N.T., Phalanndwa, M.V., Postma, M., Wege, M., van der Merwe, D.S., Bester, M.N. (2010) Prevalence of allosuckling behaviour in Subantarctic fur seal pups. Mammalian Biology. 75:555-560 McIntyre, T., Tosh, C.A., Pl�tz, J., Bornemann, H., Bester, M.N. (2010) Segregation in a sexually dimorphic mammal: a mixed-effects modelling analysis of diving behaviour in southern elephant seals. Marine Ecology Progress Series. 412:293-304 McIntyre, T., de Bruyn, P.J.N., Ansorge, I.J., Bester, M.N., Bornemann, H., Plotz, J., Tosh, C.A. (2010) A lifetime at depth: vertical distribution of southern elephant seals in the water column. Polar Biology. 33(8):1037-1048 2009 de Bruyn, P.J.N., Tosh, C.A., Oosthuizen, W.H., Bester, M.N., Arnould, J.P.Y. (2009) Bathymetry and frontal system interactions influence seasonal foraging movements of lactating subantarctic fur seals from Marion Island. Marine Ecology-Progress Series. 394:263-276 Tosh, C.A., Bornemann, H., Ramdohr, S., Schroder, M., Martin, T., Carlini, A., Plotz, J., Bester, M.N. (2009) Adult male southern elephant seals from King George Island utilize the Weddell Sea. Antarctic Science. 21(2):113-121 2008 de Bruyn, P.J.N., Bastos, A.D.S., Eadie, C., Tosh, C.A., Bester, M.N. (2008) Mass mortality of adult male subantarctic fur seals: are alien mice the culprits? PLoS One. 3(11):- de Bruyn, P.J.N., Tosh, C.A., Oosthuizen, W.C., Phalanndwa, M.V., Bester, M.N. (2008) Temporary marking of unweaned southern elephant seal (Mirounga leonina* L.) pups.* South African Journal of Wildlife Research. 38(2):133-137 de Bruyn, P.J.N., Tosh, C.A., Bester, M.N. (2008) Sexual harassment of a king penguin by an Antarctic fur seal. Journal of Ethology. 26:295-297 2007 Lombard, A.T., Reyers, B., Schonegevel, L.Y., Cooper, J., Smith-Adao, L.B., Nel, D.C., Froneman, P.W., Ansorge, I.J., Bester, M.N., Tosh, C.A., Strauss, T., Akkers, T., Gon, O., Leslie, R.W., Chown, S.L. (2007) Conserving pattern and process in the Southern Ocean: designing a Marine Protected Area for the Prince Edward Islands. Antarctic Science. 19(1):39 -54 de Bruyn, P.J.N., Cooper, J., Bester, M.N., Tosh, C.A. (2007) The importance of land-based prey for sympatrically breeding giant petrels at sub-Antarctic Marion Island. Antarctic Science. 19(1):25-30 de Bruyn, P.J.N., Pistorius, P.A., Tosh, C.A., Bester, M.N. (2007) Leucistic Antarctic fur seal at Marion Island. Polar Biology. 30(10):1355-1358 Website Links of Importance Recent Presentations Here are my most recent presentations. Please feel free to download them. Should you have trouble opening any of them please contact me for assistance. Download my recent presentation