Spatial and seasonal distribution the groups of microzooplankton in the Campos Basin in five bodies of water, from surface to bathypelagial

Author(s)

Tulia Isabel Martinez Aguilar

• Document type: Master's Dissertation
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Instituto Oceanográfico (IO/DIDC)
• Defense date: 2013-02-08

Examining board members

Rubens Mendes Lopes; Luciano Felicio Fernandes; André Carrara Morandini

• Advisor: Rubens Mendes Lopes

Abstract

The composition and the distribution of numerical abundance and biomass of microzooplankton groups were sutudied in the Campos Basin located southeastern Brazil, between Victoria (20.5°S) and Frio Cape (24°S). Microzooplankton samples were collected with horizontal hauls using a Multinet (64 ?m) in five depth layers (surface up to 2300m bathypelagial zone) and in two seasonal periods: Period one (P1) May, April - 2009 and Period two (P2) August, September - 2009 (HABITATS CENPES / PETROBRAS). The total abundance ranged from 1 to 57 Org/m³ during the P1 and from 80 to 207 Org/m³ during the P2. Total biomass ranged from 2x10-5 to 2 mg/m³ during the P1, and from 6x10-6 to 5 mg/m³ during the P2. Most frequent taxonomic groups (> 50% relative frequency) in P1 were Radiolaria, Tintinnina, Foraminifera, Copepod nauplii, Cyclopoida, Calanoida, Gastropoda, Pteropoda, and Bivalvia. In P2, the most frequent taxonomic groups were Acantharia, Radiolaria, Tintinnina, Foraminifera, Copepod nauplii, Cyclopoida, Calanoida, Harpacticoida, Gastropoda, Bivalvia, and Polychaeta. Copepod nauplii dominated the surface samples, with 65% of relative abundance during both periods; Radiolaria, Tintinnina and Foraminifera dominated the deep water samples. There were differences in the abundance and biomass in response to environmental, spatial and seasonal variationsn the Tropical Water (TW-1 m) and in the South Central Atlantic Water (SCAW-250 m), These variations may related tothe rise of nutrient-rich deep waters of the SCAW to the euphotic zone, which leads to the increase of the productivity and the increase of the primary production in neritic areas, linking it to the frequent occurrence of cyclonic vortices associated with Brazil Current. In the deepest layers Antarctic Intermediate Water (AAIW-800 m), Upper Circumpolar Water (UCW-1200 m) and North Atlantic Deep Water (NADW-2300 m) it was noted a horizontal homogeneity of the microzooplankton associated with thermohaline stability. However, it is noteworthy that the high values of Radiolaria in deep water could be conditioned by the physical and chemical characteristics of the UCW. It was possible to conclude thatthe abundance and biomass of microzooplankton were higher in the surface layer and SCAW, f due to climatic fluctuations of temperature and salinity.. The temperature was the variable that most influenced the concentrations of organisms; in contrast, the low salinity fluctuations in the Campos Basin had no significant influence on the groups of microzooplankton. The data from AAIW, UCW, and NADW obtained in this work are fundamental for the understanding of the mesopelagical and bathypelagical zones in the Brazilian oceanic waters. Finally the FlowCAM used for semi-automatic analysis of samples was a useful tool for counting and obtaining information about the morphometric microzooplankton. (AU)

• FAPESP's process: 10/04780-2 - Aplication of semi-automathic analises methodology(FlowCAM) in the study of zooplanctonic comunity , in an area of Marine Perforation, Basin of Campos-RJ
• Grantee: Tulia Isabel Martinez Aguilar
• Support Opportunities: Scholarships in Brazil - Master