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• High abundance of Amphidomataceae in Argentinean 2015spring bloom communities at the shelf front. • 31 new Argentinean strains of Azadinium dalianense and Az. spinosum are characterized. • Majority of strains revealed a new non-toxigenic ribotype of Az. spinosum. • A single Argentinean Az. spinosum strain of a different ribotype produced only AZA-2. Azaspiracids (AZA) are the most recently discovered group of lipophilic marine biotoxins of microalgal origin, and associated with human incidents of shellfish poisoning. They are produced by a few species of Amphidomataceae, but diversity and occurrence of the small-sized dinophytes remain poorly explored for many regions of the world. In order to analyze the presence and importance of Amphidomataceae in a highly productive area of Argentinean coastal waters (El Rincón area, SW Atlantic), a scientific cruise was performed in 2015 to sample the early spring bloom. In a multi-method approach, light microscopy was combined with real-time PCR molecular detection of Amphidomataceae, with chemical analysis of AZA, and with the establishment and characterization of amphidomatacean strains. Both light microscopy and PCR revealed that Amphidomataceae were widely present in spring plankton communities along the El Rincón area. They were particularly abundant offshore at the shelf front, reaching peak densities of 2.8 × 105 cells L−1, but no AZA were detected in field samples. In total, 31 new strains were determined as Az. dalianense and Az. spinosum , respectively. All Az. dalianense were non-toxigenic and shared the same rRNA sequences. The large majority of the new Az. spinosum strains revealed for the first time the presence of a non-toxigenic ribotype of this species, which is otherwise the most important AZA producer in European waters. One of the new Az. spinosum strains, with a particular slender shape and some other morphological peculiarities, clustered with toxigenic strains of Az. spinosum from Norway and, exceptionally for the species, produced only AZA-2 but not AZA-1. Results indicate a wide diversity within Az. spinosum, both in terms of sequence data and toxin profiles, which also will affect the qualitative and quantitative performance of the specific qPCR assay for this species. Overall, the new data provide a more differentiated perspective of diversity, toxin productivity and occurrence of Amphidomataceae in a poorly explored region of the global ocean. [ABSTRACT FROM AUTHOR]

Vikebø, F. B., Korosov, A., Stenevik, E. K., Husebø, Å., and Slotte, A. 2012. Spatio-temporal overlap of hatching in Norwegian spring-spawning herring and the spring phytoplankton bloom at available spawning substrata. – ICES Journal of Marine Science, 69: .Analyses of bottom substrata demonstrated that a potential spawning area of 13 490 nautical miles2 is available for Norwegian spring-spawning (NSS) herring on the Norwegian shelf between 59 and 71°N. However, the availability of suitable substrata differed significantly on a latitudinal scale; 60% of the available spawning area was north of 67°N. However, the spatial distribution of larvae indicated that the bulk of the adult population wintering off northern Norway in the period 1998–2007 migrated farther south and upstream to spawn. This suggests benefits attributable to extra costs accompanying the spawning migration. To test whether southern spawning is beneficial with regard to overlap between herring larvae and their prey, remotely sensed chlorophyll a data from SeaWiFS were used as a proxy for the onset of phytoplankton bloom (OSB) in discrete bins along the Norwegian coast and linked to interannual variation in the observed average timing of larval hatching during the years 1998–2007. There was a delay in OSB with increasing latitude of 37 d within the spawning habitat of NSS herring. Overlap between larval hatching and OSB was clearly highest in the south, suggesting that match with prey availability may be an important factor in the selection of spawning grounds by NSS herring. [ABSTRACT FROM PUBLISHER]

Picoeukaryotes (protists <3 μm) form an important component of Arctic marine ecosystems, although knowledge of their diversity and ecosystem functioning is limited. In this study, the molecular diversity and autotrophic biomass contribution of picoeukaryotes from January to June 2009 in two Arctic fjords at Svalbard were examined using 18S environmental cloning and size-fractioned chlorophyll a measurements. A total of 62 putative picoeukaryotic phylotypes were recovered from 337 positive clones. Putative picoeukaryotic autotrophs were mostly limited to one species: Micromonas pusilla, while the putative heterotrophic picoeukaryote assemblage was more diverse and dominated by uncultured marine stramenopiles (MAST) and marine alveolate groups. One MAST-1A phylotype was the only phylotype to be found in all clone libraries. The diversity of picoeukaryotes in general showed an inverse relationship with total autotrophic biomass, suggesting that the conditions dominating during the peak of the spring bloom may have a negative impact on picoeukaryote diversity. Picoplankton could contribute more than half of total autotrophic biomass before and after the spring bloom and benefited from an early onset of the growth season, whereas larger cells dominated the bloom itself. [ABSTRACT FROM AUTHOR]

The marine ecosystem in Kongsfjorden (79°N), a glacial fjord in Svalbard, is to a large extent well known with regard to hydrography, mesozooplankton and higher trophic levels. Research on primary production and lower trophic levels is still scare and especially investigations from winter and spring periods. The spring bloom dynamics in Kongsfjorden were investigated in 2002. The development in nutrient conditions, phytoplankton, protozoans and primary production were followed from 15 April until 22 May. The winter/spring in 2002 was categorized as a cold year with sea ice cover and water masses dominated by local winter-cooled water. The spring bloom started around 18 April and lasted until the middle of May. The bloom probably peaked in late April, but break-up of sea ice made it impossible to sample frequently in this period. Diatoms dominated the phytoplankton assemblage. We estimated the total primary production during the spring bloom in 2002 to range 27-35 g C m. There was a mismatch situation between the mesozooplankton and the phytoplankton spring bloom in 2002. [ABSTRACT FROM AUTHOR]

Abstract: During a circumnavigation of the Svalbard archipelago in May 2006, simultaneous marine environmental (meteorology, heat flux, ocean turbulence, irradiance) and biological (phytoplankton and zooplankton biomass/species) data were sampled at selected stations. The zooplankton data were supplemented by high-resolution, high-speed VPR sampling down to 100m depth at most stations. We were able to sample different phases of the phytoplankton spring bloom in Arctic as well as in Atlantic waters, and the stations represented different situations with respect to irradiance, turbulence and water-column stability. Phytoplankton growth and depth distribution were physically controlled, while zooplankton distributions were affected by biological parameters and turbulence. Development of the zooplankton followed the phytoplankton bloom phase, which was progressing in a direction from west to east in the waters north of Svalbard, and southwards in the Barents Sea. Our results also showed that the zooplankton did not avoid Phaeocystis pouchetii colonies, which have earlier been described as toxic. Despite an early retreat of the ice this year there was no apparent mismatch between the phytoplankton bloom and the dominant mesozooplankton, Calanus spp. [Copyright &y& Elsevier]

Chlorophyll a, meteorology and hydrography were sampled during a 3 year period in Altafjord and Porsangerfjord. The analysis demonstrated a decoupling between spring bloom progression and the classical 'Sverdrup' regulators, i.e. there was no correlation between spring bloom biomass and critical depth, mixed or station depth and irradiance. The only significant correlation was linear between bloom magnitude and day length. We also observed significant correlations between log chlorophyll a and critical depth, irradiance and heat flux. From early March to mid-May, day length increases from 7 to 24 h in the area, whereas daily integrated irradiance increases ca. 14 times. Then, if blooms have not yet triggered early in April, water turbidity will remain low and critical depth will deepen rapidly, causing blooms to start after this date, i.e. irradiance will become the main forcing function if initial stocks are present. Another characteristic feature in the area is that spring bloom concentrations are low and that production is more spread out throughout the growth season, contrary to what is common further south (spring bloom, summer recession and autumn bloom). [ABSTRACT FROM AUTHOR]