Plankton communities of the South Atlantic anticyclonic gyre

Abstract

Observations from hydrographic surveys are used to describe the density current flowing through the Dardanelles strait into the Marmara Sea. Aegean water plunges below the surface and flows into the Marmara Sea. This flow joins into the Marmara Sea as a negatively buoyant plume and sinks through the deeper parts. Seasonal variation in the incoming water density results in the observing mainly two different forms of the density current in this area. These two forms are boundary currents and intrusion. Boundary currents were observed as a dense bottom current during the winter when the inflowing water density attains to annual maxima and as an overflow during the autumn when the inflowing water density drops to annual minimum. Intrusion form of the density current was observed during the summer. RésuméDes observations de campagnes hydrographiques permettent de décrire le courant de densité traversant le détroit des Dardanelles vers la mer de Marmara. Les eaux égéennes plongent et se répandent dans la mer de Marmara. Ce flux constitue, en mer de Marmara, une « plume » à flottabilité négative qui plonge vers les zones les plus profondes. Une variation saisonnière de la densité de l'eau entrante conduit à deux types de circulation dans cette zone. Ces deux formes sont des courants de bordure et une intrusion. Les courants de bordure constituent un courant de fond dense durant l'hiver, quand la densité de l'eau entrante atteint son maximum annuel, et comme un surcourant en automne, quand la densité de l'eau entrante s'abaisse à sa valeur minimale. Des formes d'intrusion du courant de densité sont observées en été.

Zooplankton Spatial and Temporal Distribution in a Tropical Oceanic Area off West Africa

“…observations), we evidenced some differences, consistent with the temporal hydrological and/or biological variability previously evidenced in the oligotrophic tropical regions (Vinogradov, 1997;Finenko et al, 2003;Piontkovski et al, 2003b) and in the Atlantic equatorial zones (Voituriez et al, 1982;. Interestingly, instability wave effects observed in the Pacific Zhang et al, 1995) tended to show similar pattern for zooplankton biomass, composition and distribution as those evidenced in the tropical PICOLO area.…”

A multivariate approach to large‐scale variation in marine planktonic copepod diversity and its environmental correlates

“…The latitudinal distribution of modeled copepod diversity reflected the high diversity values already reported around 20-30uN globally (Rombouts et al 2009) and in the South Atlantic anticyclonic gyre (Piontkovski et al 2003). High diversity in oligotrophic regions has been related to a complex network of biological interactions (McGowan and Walker 1985;Piontkovski et al 2003). Low food resource availability for copepods in oligotrophic regions could result in competition for resources and hence, if species are to coexist in a community, efficient division of resources would be essential.…”

A global seasonal surface ocean climatology of phytoplankton types based on CHEMTAX analysis of HPLC pigments

“…This is inferred from the CYANO-4 and CYANO-2 abundances dominating provinces in cluster 4 (Fig. 6), and is corroborated by flow cytometry and gene sequencing of cyanobacterial genera along the same transects from which the HPLC climatology derive (Zubkov et al, 2000;Piontkovski et al, 2003;Zwirglmaier et al, 2008). Thus, a description of community structure at the basin scale seems sufficient for open ocean picoplanktonic regimes where the predominant circulation patterns, thus the mixed layer, are governed mainly by geostrophy (Bouman et al, 2011).…”