Data/hora: 09/06/2024 04:15:54

Provedor de dados: | 20
País: | Belgium

Título:

Estructura de la comunidad del fitoplancton en el área de El Rincón, Mar Argentino (febrero 2011)

Phytoplankton community structure in the El Rincón area, Argentine Sea (February 2011)

Autores: | Negri, R.M.; Silva, R.I.; Segura, V.; Cucchi Colleoni, A.D.
Data: | 2014-06-09
Ano: | 2013
Palavras-chave: | Phytoplankton; Nannoplankton; Community composition; Size; Chlorophylls.
Resumo: | The El Rincón area in the Argentine continental shelf (coastal sector between 39º S-41º S) is known as one of the main breeding areas of the Argentine anchovy (Engraulis anchoita) Northern stock. However, there is scarce information regarding the structure of the primary producers, base of the pelagic food webs. The aim of this study was to identify the different phytoplanktonic communities in a coastal section in the area (depth lower than 60 m) during February 2011. Mean surface chlorophyll a concentration was 0.72 mg m-3, with the highest value in the innermost station (E34: 1.84 mg m-3) and the lowest in the mid section (E31: 0.24 mg m-3). In depth, similar concentrations were registered, except for the deepest station where the maximum value was reached on the thermocline (E29 32 m: 7.33 mg m-3). In general, the chlorophyll fraction lower than 5 um represented over 60% of the total concentration, with the exception of the thermocline of the deepest station (E29) where only 15% was registered. In coincidence with chlorophyll distribution, the ultraphytoplankton was the main fraction in surficial waters in the whole section. However, qualitative differences among the sampling stations were found. The major components were Synechococcus, picophytoeukaryotes, flagellates forms of Prymnesiophyceae, Chrysophyceae and Cryptophyceae (10&lt;sup&gt;5&lt;/sup&gt; - 10&lt;sup&gt;7&lt;/sup&gt; cells l&lt;sup&gt;-1&lt;/sup&gt;) and the cocolithophorid Gephyrocapsa oceanica (1.2 x 10&lt;sup&gt;6&lt;/sup&gt; - cells l&lt;sup&gt;-1&lt;/sup&gt;) in the innermost station. As regards the largest fractions, on the surface of that last station the nanoplanktonic diatom Thalassionema nitzschoides (1.2 x 10&lt;sup&gt;5&lt;/sup&gt; cells l&lt;sup&gt;-1&lt;/sup&gt;) prevailed and on the thermocline of the deepest a bloom of microplanktonic dinoflagellate Neoceratium horridum (63 x 10&lt;sup&gt;3&lt;/sup&gt;-  cells l&lt;sup&gt;-1&lt;/sup&gt;) was verified. Results show that, in spite of the scarce variation in chlorophyll concentration, the size structure and composition of the phytoplankton community were notably different among stations. It is worth noting the impact N. horridum bloom may have on the pelagic food webs. The dinoflagellate, not very palatable for copepods, may cause the decrease of grazing pressure thus triggering massive population growth that could produce hypoxia events.
Tipo: | Journal Contribution
Idioma: | Espanhol

Identificador:

Revista de Investigación y Desarrollo Pesquero, 23, p. 7-22

0325-6375

http://hdl.handle.net/1834/5491

Fonte: | http://creativecommons.org/licenses/by-nc/3.0/