oral presentations

Oral presentations (total 27)

2021

1. UK/international (online)

   The African BioGenome Project enters its Pilot Phase.

   Majewska, Roksana

   Biodiversity Genomics 2021
2. USA: Online

   The genus Achnanthes (Bacillariophyceae) as a model to investigate the nature of putatively obligate epizoic diatoms.

   Ashworth, Matt P., Frankovich, Thomas A.,  Majewska, Roksana, Lam, Daryl W., and Manning, Schonna R.

   LXXV Annual Meeting of Phycological Society of America 2021
3. I African Manatee Symposium

   Charismatic microflora: what manatee-associated diatoms tell us about their hosts.

   Majewska, Roksana

   West Africa/USA: Online 2021

2019

1. Zagreb, Croazia

   Diatom genus Poulinea as epibiont on Adriatic loggerhead sea turtles.

   Kanjer, Lucija, Filek, Klara, Matek, A.,  Majewska, Roksana, Vijver, Bart, Ashworth, Matt P., Gračan, Romana, Lazar, Bojan, and Bosak, Sunčica

   VI Croatian Botanical Symposium 2019
2. Zagreb, Croazia

   On the shoulders of giants: what epizoic diatoms are teaching us about diatom evolution.

   Ashworth, Matt P., Frankovich, Thomas A., Sullivan, Michael J.,  Majewska, Roksana, and Bosak, Sunčica

   VII European Phycological Congress 2019
3. Cedar Creek, USA

   The epizoic genus Tursiocola on sea turtles and cetaceans.

   Frankovich, Thomas A., Ashworth, Matt P.,  Majewska, Roksana, Sullivan, Michael J., Arendt, Mike, Manire, C., Pelton, C., Perrault, J., Sasso, C., Schwenter, Jeffrey, Stacy, Nicole I., Wells, R., and Wood, L.

   North American Diatom Symposium 2019
4. Cedar Creek, USA

   On the shoulders of giants: what epizoic diatoms are teaching us about diatom evolution.

   Ashworth, Matt P.

   North American Diatom Symposium 2019
5. Charleston, USA

   On swimming islands, islanders, and hitchhikers – what sea turtle diatoms tell us about their hosts.

   Majewska, Roksana, Stoppel, Danay A., Swanepoel, Carla, Nolte, Christopher, and Nel, Ronel

   XXXIX Annual Symposium on Sea Turtle Biology and Conservation 2019

2018

1. Stellenbosch, South Africa

   Hunting for a treasure at the museum: how zoological collections can contribute to epizoic diatom exploration.

   Majewska, Roksana

   The I Postdoctoral Conference of Southern Africa 2018

   Abs URL

   Aquatic animals provide unique habitats for various macro and micro organisms, including many diatoms that cope especially well with challenges posed by rapidly changing conditions related to the host’s biology and behaviour. Although exploration of previously undescribed biotic aquatic habitats has yielded many new diatom taxa, some exhibiting traits of obligate epibionts, the epizoic diatom diversity, their biogeography, as well as nature of the close relationships between the host organism and its epibionts remain poorly understood. This study takes advantage of the unique resource of well-preserved aquatic vertebrate sp ecimens (including whales, sea turtles, freshwater turtles, aquatic snakes, seabirds, sharks, and marine iguanas) provided by several natural history museums. It aims to provide baseline data ab out epizoic diatoms from both marine and freshwater habitats, generating a significant advance in epibiotic diatom research and minimizing the cost and any possible environmental fo otprint of a similarly extensive study involving fieldwork and fresh material collection. The analysis of 101 samples of b oth dried and liquid-preserved specimens collected from locations across the different ocean basins proved that zoological museum collections may indeed constitute an excellent source of unique and often very rich epizoic diatom material. However, several imp ortant limitations of such study must be considered.

2. Potchefstroom, South Africa

   Zoological museum collections – what else is there? An unexplored treasure for diatom scientists.

   Majewska, Roksana

   The VI Postdoctoral Conference 2018
3. Johannesburg, South Africa

   Charismatic microflora: recent discoveries of unique sea turtle-associated diatom communities.

   Majewska, Roksana

   XXXI Congress of the Phycological Society of Southern Africa 2018

   Abs URL

   Aquatic animals, both marine and freshwater, provide unique habitats for various macro- and microorganisms. Although diatoms have long been known to grow on aquatic vertebrates such as birds, whales, and dolphins, only recently have the first studies exploring sea turtle-associated diatoms been conducted and several new diatom taxa, including three new genera, have been described. These new taxa show traits of obligate epibionts, which means they may require a direct contact with their basibionts (i.e. the host organism) to develop and survive. Since their first discovery, sea turtle diatoms have attracted growing attention, partly due to their potential use as indicators of sea turtle behavior and health. Research here may help to bridge various gaps in general understanding of both sea turtle and diatom ecology, evolution, and biogeography. However, at present many aspects of the symbiosis-like relationship between these micro- and macro-organisms remain unaddressed and it is not yet understood what factors influence epizoic diatom composition and abundance, and what ecological role and function they have in marine ecosystems. This talk will summarize the on- going investigations and recent findings in sea turtle diatoms that may open many new avenues for future research into marine epibiosis and related areas of study.

4. Johannesburg, South Africa

   Epi- and endophytic diatoms associated with two South African kelp species: Ecklonia maxima (Osbeck) Papenfuss and Laminaria pallida Greville ex. J. Agardh.

   Mayombo, Ntambwe Albert Serge,  Majewska, Roksana, and Smit, Albertus J.

   XXXI Congress of the Phycological Society of Southern Africa 2018

   URL
5. Berlin, Germany

   A forgotten treasure: how zoological museum collections can contribute to epizoic diatom research.

   Majewska, Roksana, Tessier, Stéphanie, Scheinberg, L., Robinson, Nathan J., Lazo-Wasem, Eric A., Rojas, Lourdes, Pinou, Theodora, Zyskowski, K., Vijver, Bart, Hamilton, Paul, and Poulin, Michael

   XXV International Diatom Symposium 2018

   Abs URL

   Aquatic animals, both marine and freshwater, provide unique habitats for various macro- and microorganisms, including many diatoms that seem to cope especially well with challenges posed by rapidly changing conditions related to the host’s biology and behaviour. Although exploration of previously undescribed biotic marine habitats has yielded many new diatom taxa, some exhibiting traits of obligate epibionts (Holmes & al. 1993, Wetzel & al. 2012, Majewska & al. 2015), the nature of the close relationships between the host organism and its epibionts remains poorly understood. This study takes advantage of the unique resource of well-preserved aquatic vertebrate specimens (including whales, sea turtles, freshwater turtles, aquatic snakes, seabirds, and marine iguanas) provided by the Canadian Museum of Nature, the Yale Peabody Museum of Natural History, and the California Academy of Sciences. It aims to provide baseline data about epizoic diatoms from both marine and freshwater habitats, generating an advance in epibiotic diatom research and minimizing the cost and any possible environmental footprint of a similarly extensive study involving fieldwork and fresh material collection. Selected samples of both dried and liquid-preserved specimens of aquatic animals collected from locations across the different ocean basins were analysed for their associated diatom communities. Whenever possible, a few cm2 tissue sample was digested with acids to extract the diatom valves. In several cases, to avoid the destruction of the especially valuable animal tissue, samples were placed in separate beakers with distilled water and sonicated for ca. 30 minutes. Subsequently, the water with detached diatoms was collected, while the animal samples were air-dried and returned to the collection manager. Cleaned diatom frustules were examined using both light and scanning electron microscopy. Altogether 100+ samples were processed. The analysis proved that although zoological museum collections may indeed constitute an excellent source of unique and often very rich epizoic diatom material, several important limitations of such study must be considered. The advantages and disadvantages of the research approach will be critically assessed and discussed.

6. Berlin, Germany

   Revision and cladistic analysis of the genus Anorthoneis.

   Pennesi, Chiara,  Majewska, Roksana, Sterrenburg, Frithjof a. S., Totti, Cecilia, Romagnoli, T., and De Stefano, Mario

   XXV International Diatom Symposium 2018

2017

1. Potchefstroom, South Africa

   Hitchhiking on sea turtles: biodiversity and ecology of newly discovered epizoic diatoms.

   Majewska, Roksana

   V Postdoctoral Conference 2017
2. Prague, Czech Republic

   Labellicula lecohuiana, a new epizoic diatom species living on green turtles in Costa Rica.

   Majewska, Roksana, and Vijver, Bart

   XI Central European Diatom Meeting 2017
3. Prague, Czech Republic

   Green turtles (Chelonia mydas) from distant habitats share several poorly known epibiotic diatom taxa.

   Majewska, Roksana, Vijver, Bart, Nasrolahi, Ali, Ehsanpour, Maryam, Afkhami, Majid, and De Stefano, Mario

   XI Central European Diatom Meeting 2017

2016

1. Ravenna, Italy

   Revision and cladistic analysis of the genus Anorthoneis (Bacillariophyceae), including the description of a new species.

   Pennesi, Chiara,  Majewska, Roksana, Sterrenburg, Frithjof a. S., Totti, Cecilia Maria, Romagnoli, T., and De Stefano, Mario

   Gruppo di Lavoro per l’Algologia, Riunione Scientifica Annuale 2016
2. Quebec, Canada

   A comparison of epizoic diatom communities on green turtle (Chelonia mydas) from two remote localities.

   Majewska, Roksana, Vijver, Bart, Nasrolahi, Ali, Afkhami, Majid, Bolaños, Federico, Iamunno, Franco, and De Stefano, Mario

   XXIV International Diatom Symposium 2016
3. Lodz-Strykow, Poland

   Critical evaluation of an intercalibration exercise in diatom-based monitoring in Poland.

   Zgrundo, Aleksandra,  Majewska, Roksana, and Kelly, Martin

   XXXV International Conference of the Polish Phycological Society 2016
4. Budapest, Hungary

   Diatoms on sea turtles: recent findings and their implications.

   Majewska, Roksana, Vijver, Bart, Bolaños, Federico, Nasrolahi, Ali, Afkhami, Majid, and De Stefano, Mario

   X Central European Diatom Meeting 2016

2012

1. Ischia, Italy

   Diatoms associated with rhodophytes from Terra Nova Bay (Ross Sea, Antarctica).

   Majewska, Roksana, Gambi, Maria Cristina, Totti, Cecilia Maria, and De Stefano, Mario

   Gruppo di Lavoro per l’Algologia, Riunione Scientifica Annuale 2012