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Romero Martinez, Maria Lorena
(2022).
DOI: https://doi.org/10.21954/ou.ro.0001457a
Abstract
The intricate and complex connectivity between the benthic and planktonic habitats was studied by addressing two distinct compartments of the planktonic community and two levels (community and population) of biological organisation. The strategy of resting stage production in phyto- and zooplankton species, exemplifies one of the biological links coupling the two habitats. Therefore, the present is a written account of the occurrence, viability, and temporal genetic fingerprint of resting stages in marine diatoms, dinoflagellates and cladocerans. A unique set of tools were employed to target each research question and target group. The study of eukaryotic and protist communities was approached by using next generation sequencing of two barcode regions (V4 and V9) of the 18s rDNA. Diatom diversity and viability of resting stages was examined by High Throughput sequencing metabarcoding and by the revival of present day and past strains from dated sediment layers. The occurrence and abundance of resting eggs in marine cladocerans was investigated by sampling both the water column and the sediments, as well as depicting the demographic profiles of cladoceran populations. Main findings highlighted temporal changes in relative abundance of key eukaryotic and protists groups, temporal changes in community corresponded with changes to the environment due to industrial pollution. Viability of diatom resting stages was limited to ~ 67 years with only Chaetoceros species germinating from old layers. Species of planktonic with resting stages and benthic diatoms revealed clear temporal breaks. Interspecific patterns in occurrence and abundance of the different life stages in marine cladocerans populations resulted in contrasting contributions to the sedimentary egg bank. Penilia avirostris and Pleopis polyphemoides were the main contributors to the cladoceran egg bank.
Overall, this thesis adds a unique contribution to the understanding of the benthic-pelagic coupling terms in coastal marine habitats at short (annual) and long (~180 years) timescale.