Brazil-Malvinas confluence: effects of environmental variability on phytoplankton community structure


Contact
rafael.goncalves.araujo [ at ] awi.de

Abstract

This study investigates the relationships between the spring phytoplankton community and environmental factors in the Brazil-Malvinas confluence region. Phytoplankton community composition was determined by the high performance liquid chromatography/CHEMTAX approach, complemented with microscopic examination. Abiotic factors included temperature, salinity, dissolved inorganic macronutrients (ammonium, nitrite, nitrate, phosphate and silicate), water column stability and upper mixed layer depth (UMLD). These environmental variables were reasonably informative to explain the variability of the phytoplankton communities (44% of variation explained). Cluster and canonical correspondence analyses allowed discrimination of four zones (coastal, Sub-Antarctic, tropical and intermediate zones), also identifiable in the T–S diagrams and in the nutrient spatial distribution patterns. The presence of nutrient-rich Sub-Antarctic waters was a major oceanographic feature, associated with diatoms and dinoflagellates. However, in the Sub-Antarctic zone, biomass was particularly low, probably as a result of grazing pressure, as suggested by chemical and biological indicators. In contrast, in oligotrophic tropical waters, phytoplankton was mainly composed by small nanoflagellates and cyanobacteria. A large intermediate zone was also dominated by nanoflagellates, mainly Phaeocystis antarctica, probably favored by strong water column stability. The coastal zone exhibited fairly similar conditions to those in the intermediate zone, but with deeper UMLD, a favorable condition for diatom growth. These results emphasize the importance of the properties of water masses and also biological processes such as grazing in structuring phytoplankton communities in the region.



Item Type
Article
Authors
Divisions
Primary Division
Programs
Primary Topic
Research Networks
IPY
Peer revision
ISI/Scopus peer-reviewed
Publication Status
Published
Eprint ID
34422
DOI 10.1093/plankt/fbs013

Cite as
Goncalves Araujo, R. , De Souza, M. S. , Mendes, C. R. B. , Tavano, V. M. , Pollery, R. C. and Garcia, C. A. E. (2012): Brazil-Malvinas confluence: effects of environmental variability on phytoplankton community structure , Journal of Plankton Research, 34 (5), pp. 399-415 . doi: 10.1093/plankt/fbs013


Download
[img]
Preview
PDF
Goncalves-Araujo_etal_2013_JPR.pdf

Download (642kB) | Preview
Cite this document as:

Share


Citation

Research Platforms
N/A

Campaigns


Actions
Edit Item Edit Item