Coccolithophores (Haptophyte) living in the North Atlantic (50 - 30ºN): results from the AMT28

• Autor(a) principal: Pinto, Catarina Nascimento
• Data de Publicação: 2022
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10773/36967
• topic: Coccolithophore; North Atlantic Ocean; Subtropical gyre; Atlantic Meridional Transect; Holococcolithophore; Ecology; Biogeography

Coccolithophore communities living in the North Atlantic Ocean during the autumn of 2018 presented a distinct meridional pattern, divided into three assemblages, corresponding to unique environmental conditions. In the higher latitudes of the North Atlantic Drift Province, coccolithophore communities presented low diversity and high cell concentrations, being dominated by the r-selected species Emiliania huxleyi, while the communities of the southern latitudes at the North Atlantic Subtropical Gyral Province and the North Atlantic Tropical Gyral Province, presented an inverse pattern, with high diversity and lower cell concentrations. The vertical distribution of the communities throughout the studied transect showed the increasing stratification of the water column and the gradual alteration of the environmental parameters from north to south: while in the higher latitudes, coccolithophore cells were mostly biased to the surface waters, in the southern latitudes coccolithophores occurred distributed more evenly throughout the water column, presenting distinct communities at the surface and greater depths, with the surface communities being dominated by K-selected taxa such as Umbilicosphaera spp. and Discosphaera tubifera, and the deep-photic assemblages dominated by Florisphaera profunda, Gladiolithus flabellatus and Algirosphaera robusta. The results of this study show that coccolithophore communities in the studied region are influenced by several biotic and abiotic factors (i.e., nutrient concentrations, light availability, temperature, salinity, competition with other phytoplankton groups) as well as ocean circulation and that communities of the northern latitudes and the sub-euphotic zone of the southern latitudes show evidence of light-limited growth, while the communities living in the upper euphotic zone of the southern latitudes present evidence of nutrient-limited growth. Furthermore, it was also possible to identify the unique ecological preference of holococcolithophores for warm, oligotrophic environments, characteristic of the upper-euphotic zone of the subtropical gyre, further evidencing that the presence of the haploid stage of coccolithophores can provide an ecological advantage for this group in those resource-limited environments.