**5.1 Methods applied in continental slope of the Campos Basin (SE, Brazil)**

In the Oceanprof project, 41 surface sediment samples were collected by using a box corer, along transects ranging from 750 to 1950 m of water depth on the continental slope (**Figure 5**), in the austral winter of 2003. The core top (0–2 cm interval) sediment sampled in each site was used to understand the living and dead benthic foraminifera distribution patterns and ecological preferences. For this purpose, identification and quantitative foraminifera analysis were performed using the 63 μm size fraction. The variables considered for the statistical analysis included percentages of sand and mud, calcium carbonate and total organic carbon contents in the sediment, and total phosphate in the water (see details in [73]).

In the same project (Oceanprof), 20 surface sediment samples were chosen along 1050 and 1950 m depth (**Figure 5**). In this case, only living (rose Bengal stained) benthic foraminifera were analyzed in combined samples collected in four different slices of the cores (0–2, 2–5, 5–10, and 10–15 cm) to understand the distribution patterns and their ecology. In this study, the variables considered for statistical analysis included the sand and mud contents, particulate organic matter flux to the sea floor, bottom water dissolved oxygen concentrations, calcium carbonate, total organic carbon, total nitrogen, and total lipid contents in the sediment (see details in [75]).

 In the Habitats project, an ecological study of living (rose Bengal stained) benthic foraminifera was performed in samples collected with a box corer, on the continental slope, Plateau of São Paulo, and canyons, during two campaigns (austral winter of 2008 and summer of 2009). The stations followed nine transects from 400 to 3000 m deep (**Figure 5**). In the Grussaí and Almirante Câmara canyons, the stations were located in four isobaths (400, 700, 1000, and 1300 m deep) and the obtained data were compared with adjacent transects on the open slope (**Figure 5**). Changes in the density, diversity, and composition of benthic foraminifera were analyzed in response to environmental factors (i.e., sand and mud contents, calcium carbonate, total organic carbon and chlorophyll-*a* concentrations, and phytopigment concentrations in the sediment) (see details in [76]).

### **5.2 Results obtained in continental slope of the Campos Basin and discussion**

 The middle slope is characterized by the dominance of different species of the genus *Bolivina, Cassidulina laevigata*, and *Globocassidulina subglobosa*. The occurrence of these species in association with *Cibicidoides kullenbergi, Epistominella exigua*, and *Uvigerina proboscidea* seems to be related to seasonal organic matter fluxes, relatively oxic bottom waters, strong bottom currents, and sandy sediments. The lower slope is inhabited by a microfauna with different characteristics, preferentially composed of epifaunal or shallow infaunal deposit feeding species (e.g., *Bolivina* spp., *Eponides weddellensis,* and *Lenticulina cultrata*) and suspension feeders that are adapted to oligotrophic conditions and high dissolved oxygen levels in the bottom waters, for example, *Rhabdammina* spp., *Rhizammina* sp. [73].

Yamashita et al. [75] concluded that besides the sediment grain size, the vertical flux of particulate organic matter seems to be the main factor controlling the spatial distribution of benthic foraminifera species in the slope of Campos Basin. The middle slope (1050 m of water depth) was characterized by relatively high

foraminiferal density and a predominance of phytodetritus-feeding foraminifera such as *Epistominella exigua* and *Globocassidulina subglobosa*. The occurrence of these species seems to reflect the Brazil Current System (BCS). The abovementioned currents are associated with the relatively high vertical flux of particulate organic matter and the prevalence of sandy sediments, respectively. The lower slope (between 1350 and 1950 m of water depth) was marked by low foraminiferal density and assemblages composed of *Bolivina* spp. and *Brizalina* spp., with low particulate organic matter flux values, muddy sediments, and more refractory organic matter. The distribution of this group seems to be related to episodic fluxes of food particles to the seafloor, which are influenced by the BCS at the surface and are deposited under low deep current activity (Intermediate Western Boundary Current; [75]).

According to Sousa et al. [76], the availability and quality of the food, the energy state (stability) at the benthic/pelagic boundary, and the grain size of the substrate seem to be the most important environmental factors determining the distribution pattern of the benthic foraminiferal assemblages in the Campos Basin slope. The highest values of density, diversity, and richness, as well as the predominance of hyaline calcareous foraminifera and infaunal species, reflect a higher contribution of food received continuously in the shallower stations (400 m depth). At 700–1000 m of water depth, the density of foraminifera decreased and there was a larger presence of opportunistic species, possibly reflecting the pulse of phytodetritus. The considerable increase in the agglutinated foraminifera, the continuous decrease in the density of foraminifera, and also decrease in the values of the Benthic Foraminifera High Productivity Index (BFHP [61]) as depth increases indicate typical oligotrophic conditions in this sector of the Campos Basin (lower slope and São Paulo Plateau).

The comparison of density and species composition data in the austral winter of 2008 and austral summer of 2009 periods allows us to infer that during the winter, the food input was higher. The values of density and biomass of living benthic foraminifera allow us to suggest that the Almirante Câmara canyon is a greater entrapment site of organic matter between 400 and 1000 m isobaths in comparison to the open areas at the same isobaths [76].

Even though the stations analyzed were the same or spatially very close to each other, the response of benthic foraminifera of the Campos Basin seems to be slightly different due to the seasonality. Because of these dissimilar times, the local hydrodynamics can change and, consequently, variations can occur in the particulate organic matter flux, and quantity and quality of the organic matter on the sea floor [73, 75, 76]. The benthic foraminifera and the geochemical results of these projects showed that, despite the intense oil exploration and production activities in the Campos Basin by PETROBRAS, these specific study areas (**Figure 5**) did not suffer anthropic impact in terms of pollutants [77].
