Martina de Freitas Prazeres
Phone: +31 (0)717519329
Room number: Vondellaan t04.00.20
In coral reefs, major ecosystem builders enhance their calcification rates by housing algal symbionts. However, species that rely on algal endosymbiosis for survival usually respond negatively to ocean warming, and coral reefs are increasingly threatened by shifts in the world's climate. Levels of genetic diversity within populations of both hosts and symbionts, how these holobionts are distributed in space, and their dispersal capacity are important elements in their responses to climate change. However, the interpretation of biogeographical and evolutionary patterns of morphologically defined species has been challenged by the discovery of intraspecific genetic diversity, often linked with distinct biogeography and ecological adaptation of the host.
My research focuses on reef-dwelling large benthic Foraminifera (LBF) as model organisms to capture the mechanisms of evolutionary responses to climate change, such as adaptation and shifts in distribution range. Specifically, I am interested in investigating the genotypic diversity within widespread morpho-species, and understanding how genotypes are distributed among biogeographical regions and shift their distribution ranges; and the role of prokaryotic and eukaryotic associations in facilitating the colonisation of new habitats.
LBF are crucial marine calcifiers that rely on algal symbiosis for growth and calcification. Morpho-species of LBF host an array of algal types, and a diverse microbial community. Fossil records show that during past events of ocean warming their biogeographic range expanded significantly, dominating shallow carbonate platforms over reef-building corals. It is speculated that the capacity of LBF to host algal types other than the dinoflagellate genus Symbiodinium, which is associated with corals, have conferred LBF the capacity to withstand episodes of warming in the geologic past. Additionally, LBF have short-life spans (3-12 months), and can acquire different types of symbionts at each generational turnover that are more suited to the local environmental conditions. These characteristics make LBF ideal model organisms to study the ecological and evolutionary responses of holobiont systems to climate change.
Keywordsocean warming, cryptic diversity, microbiome, molecular phylogeography, large benthic foraminifera, symbiosis
Current research topics
Assess intraspecific genotypic diversity and structure within populations
Intraspecific genetic variation provides the basis for any evolutionary change, and is thus the most fundamental level of biodiversity. Study the presence of cryptic diversity and phylogeography of species that have been previously described utilising morphological characteristics. Cryptic speciation tends to be prevalent in unicellular organisms, such as protists, and genetic differences are not necessarily accompanied by the development of morphologically divergent traits. The presence of cryptic diversity might shed light on biogeography and distribution boundaries of eukaryotic and prokaryotic communities, and abiotic factors that drives host-microbiome specialisation.
Importance of eukaryotic and prokaryotic microbiome associated with LBF across broad geographical scales
Flexibility in host-microbiome association can be advantageous when environmental conditions change, as hosts that are flexible can acquire different associates, more suited to the prevailing conditions. Recent molecular studies showed that LBF can host an extraordinary diversity of eukaryotic and prokaryotic associates, which may facilitate their colonisation of a wide range of habitats. As observed for corals, and other Symbiodinium-bearing LBF, thermal tolerance can be strongly influenced by the identity of obligated symbionts. However, organisms that host Symbiodinium as endosymbionts are more sensitive to increases in sea-surface temperature than diatom-bearers. Additionally, the association of LBF with a range of different prokaryotes over a broad geographical scale would greatly contribute to host distribution and survival across different habitats. The presence of a variable microbial community that is responsive to biotic and abiotic process across spatial and temporal scales could be responsible for their adaptive capacity. The potential for the recombination of different partners, and natural selection of host populations, associating with more tolerant associates may serve to create communities of holobionts suited to changed environmental conditions, and may assist species to acclimate and adapt to ongoing climate change.
CoursesAvailable student projects
Prazeres M, Ainsworth T, Roberts TE, Pandolfi JM, Leggat W. 2017. Symbiosis and microbiome flexibility in calcifying benthic foraminifera of the Great Barrier Reef. Microbiome5:38.
Prazeres M, Roberts TE, Pandolfi JM. 2017. Variation in sensitivity of large benthic Foraminifera to the combined effects of ocean warming and local impacts. Scientific Reports7:45227.
Prazeres M, Roberts TE, Pandolfi JM. 2017. Shifts in species abundance of large benthic foraminifera Amphistegina: possible effects of Tropical Cyclone Ita. Coral Reefs36:305-309.
Schmidt C, Morard R, Prazeres M, Herut B, Kucera M. 2016. Retention of high thermal tolerance in the invasive foraminifera Amphistegina lobifera from the Eastern Mediterranean and the Gulf of Aqaba. Marine Biology 163:228.
Prazeres M & Pandolfi JM. 2016. Effects of elevated temperature on the shell density of the large benthic foraminifera Amphistegina lobifera. Journal of Eukaryotic Microbiology 63:786-793.
Prazeres M, Uthicke S, Pandolfi JM. 2016. Changing light levels induce photo-oxidative stress and alterations in shell density of Amphistegina lobifera (Foraminifera). Marine Ecology Progress Series 549:69-78.
PrazeresM, Uthicke S, Pandolfi JM. 2016. Influence of local habitat on the physiological responses of large benthic foraminifera to temperature and nutrient stress. Scientific Reports 6:21936.
Prazeres M, Uthicke S, Pandolfi JM. 2015 Ocean acidification induces biochemical and morphological changes in the calcification process of large benthic foraminifera. Proceedings of the Royal Society B – Biological Sciences 282: 20142782.
Abujamara LD, Prazeres MF, Borges VD, Bianchini A. 2014 Influence of copper pre-exposure on biochemical responses of the sea anemone Bunodosoma cangicum to changes in oxygen availability. Comparative Biochemistry and Physiology Part C - Toxicology & Pharmacology 162:34-42.
Prazeres MF, Martins SE, Bianchini A. 2012 Assessment of water quality in coastal waters of Fernando de Noronha, Brazil: Biomarker analyses in Amphistegina lessonii. Journal of Foraminiferal Research 42:56-65.
Prazeres MF, Martins SE, Bianchini A. 2011 Biomarkers response to Zinc exposure in the symbiont-bearing foraminifer Amphistegina lessonii (Amphisteginidae, Foraminifera). Journal of Experimental Marine Biology and Ecology 407:116-121.
Barbosa CF, Prazeres MF, Ferreira BP, Sicoli JCS. 2009 Foraminiferal assemblage and Reef Check census in coral reef health and monitoring of East Brazilian margin. Marine Micropaleontology 73:62-69.