ORCID Profile
0000-0002-8192-9537
Current Organisation
NIWA - The National Institute of Water and Atmospheric Research Ltd.
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Publisher: Cold Spring Harbor Laboratory
Date: 15-09-2021
DOI: 10.1101/2021.09.12.459994
Abstract: Planktonic protists are an essential component of marine pelagic ecosystems where they mediate important trophic and biogeochemical functions. Although these functions are largely influenced by their taxonomic affiliation, the composition and spatial variability of planktonic protist communities remain poorly characterized in vast areas of the ocean. Here, we investigated the ersity of these communities in contrasting oceanographic conditions of the southwest Pacific sector (33-58°S) using DNA metabarcoding of the 18S rRNA gene. Seawater s les collected during twelve cruises (n = 482, 0-2000 m) conducted east of New Zealand were used to characterize protist communities in Subtropical (STW) and Subantarctic (SAW) water masses and the Subtropical Front (STF) that separates them. Diversity decreased with latitude and temperature but tended to be lowest in the STF. S le ordination resulting from the abundance of licon single variants (ASVs) corresponded to the different water masses. Overall, Dinophyceae (34% of standardized total number of reads) and Chlorophyta (27%) co-dominated the euphotic zone, but their relative abundance and composition at class and lower taxonomic levels varied consistently between water masses. Among Chlorophyta, several picoplanktonic algae species of the Mamiellophyceae class including Ostreococcus lucimarinus dominated in STW, while the Chloropicophyceae species Chloroparvula pacifica was most abundant in SAW. Bacillariophyta (7%), Prymnesiophyceae (5%), and Pelagophyceae (3%) classes were less abundant but showed analogous water mass specificity at class and finer taxonomic levels. Protist community composition in the STF had mixed characteristics and showed regional differences with the southern STF (50°S) having more resemblance with subantarctic communities than the STF over the Chatham Rise region (42-44°S). Below the euphotic zone, Radiolaria sequences dominated the dataset (52%) followed by Dinophyceae (27%) and other heterotrophic groups like Marine Stramenopiles and ciliates (3%). Among Radiolaria, several unidentified ASVs assigned to Spumellarida were most abundant, but showed significantly different distribution between STW and SAW highlighting the need to further investigate the taxonomy and ecology of this group. This study represents a significant step forward towards characterizing protistan communities composition in relation to major water masses and fronts in the South Pacific providing new insights about the biogeography and ecological preferences of different taxa from class to species and genotypic level. Water-mass preference of different taxa emerged at class, species and genotypic level. Mamiellophyceae green algae dominated in subtropical waters. Dinophyceae and Chloropicophyceae green algae dominated in subantarctic waters. A erse assemblage of Radiolaria dominated the mesopelagic zone. Small rather than large taxa dominated phytoplankton blooms in subtropical waters.
Publisher: American Meteorological Society
Date: 23-08-2017
Abstract: This paper investigates the mechanisms causing interannual variability of upper ocean heat content and sea surface temperature (SST) in the southwest Pacific. Using the ECCOv4 ocean reanalysis it is shown that air–sea heat flux and ocean heat transport convergence due to ocean dynamics both contribute to the variability of upper ocean temperatures around New Zealand. The ocean dynamics responsible for the ocean heat transport convergence are investigated. It is shown that SSTs are significantly correlated with the arrival of barotropic Rossby waves estimated from the South Pacific wind stress over the latitudes of New Zealand. Both Argo observations and the ECCOv4 reanalysis show deep isotherms fluctuate coherently around the country. The authors suggest that the depth of the thermocline around New Zealand adjusts to changes in the South Pacific winds, modifies the vertical advection of heat into the upper ocean, and contributes to the interannual variability of SST in the region.
Publisher: Elsevier BV
Date: 08-2022
Publisher: Frontiers Media SA
Date: 26-03-2019
Location: New Zealand
No related grants have been discovered for Denise Fernandez.