Remarks on the morphology and distribution of some rare centric diatoms in southern Brazilian continental shelf and slope waters

• Published in: Brazilian Journal of Oceanography
• Main Authors: Garcia, Marinês, Odebrecht, Clarisse
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2012
• Subjects: Brazil; Biogeography; New records; Asterolampraceae; Azpeitia; Brasil; Biogeografia; Novos registros; Sob’; South Atlantic Ocean
• Online Access: http://repositorio.furg.br/handle/1/6478; https://doi.org/10.1590/S1679-87592012000400002

This paper provides information on the morphology and occurrence of extant diatoms of the family Asterolampraceae and Azpeitia species of the southernmost Brazilian continental shelf and slope waters in the Southwestern Atlantic Ocean (28 - 34°S), under the influence of Tropical, Subtropical, Subantarctic Waters, terrestrial discharges from La Plata River and Lagoa dos Patos lagoon. Plankton was sampled (20 µm net; vertical hauls) at the same 27 stations in winter 2005 and summer 2007. Among Asterolampraceae, Asteromphalus flabellatus was the most frequent species (57% of samples) observed mainly in winter samples (92%) in Subtropical Shelf Water but also under the influence of La Plata River plume (salinity <35). Lower frequencies were observed for Asterolampra marylandica, Asteromphalus elegans, Asteromphalus heptactis and Spatangidium arachne. Four species of Azpeitia were observed: A. barronii and A. neocrenulata for the first time in the South Atlantic Ocean while A. africana and A. nodulifer had already been registered in equatorial and southern areas of Brazil. All Azpeitia species were rare (19%) in offshore samples (100-200 m depth. Remarks on the morphology based on light and scanning electron microcopy observations are provided along with their distribution in the study area. O trabalho apresenta informações morfológicas e sobre a ocorrência de diatomáceas atuais da família Asterolampraceae e de espécies de Azpeitia encontradas na plataforma continental e talude do extremo sul do Brasil no Oceano Atlântico Sul (28 - 34°S), sob influência de Águas Tropical, Subtropical e Subantártica, bem como do aporte terrestre do Rio La Plata e da Lagoa dos Patos. O plâncton foi amostrado (rede de 20 µm; arrastos verticais) em 27 estações de coleta no inverno de 2005 e verão de 2007. Entre as Asterolampraceae, Asteromphalus flabellatus foi a espécie mais freqüente (57% das amostras), principalmente nas amostras de inverno (92%) em água Subtropical de Plataforma, mas também sob influência da pluma do Rio La ...