**6. Conclusion**

 This work presents results of living foraminifera used to analyze these meiofaunal organism responses to different types of environmental disturbance in different transitional and marine settings: a semienclosed coastal lagoon (Aveiro Lagoon), an estuarine system (São Sebastião Channel), a continental shelf (Campos Basin), and continental slope environments (Campos Basin). Each area has different particularities, conditioning the type of living foraminifera associations that inhabit them, being the first two areas highly anthropized.

 The dynamics of tidal currents, in interaction with the configuration of channels and local topography, generates different sedimentary facies in the Aveiro Lagoon, influencing the abundance of living benthic foraminifera. Salinity is a key factor

#### *Response of Benthic Foraminifera to Environmental Variability: Importance of Benthic… DOI: http://dx.doi.org/10.5772/intechopen.81658*

 for governing the structure (diversity) of foraminifera assemblages, as well as the concentrations of PTE, whereas the sensitive species ("marine species") avoid the inner lagoonal environments. Species such as *H. germanica*, *A. tepida*, *T. inflata*, and *C. excavatum* increase their frequencies in the most confined places and are impacted by high concentrations of PTE.

 In São Sebastião Channel, the sediments near the "Dutos e Terminais Centro Sul" (DTCS) of PETROBRAS were enriched by As, Cu, and Ni, with concentrations exceeding TEL; these levels are associated with adverse biological effects. Comparatively, foraminiferal parameters (density and diversity) at the DTCS were lower than those observed in neighboring areas, even near the Araçá submarine outfall less than 3 km away. These findings lead us to conclude that wastewater treatment in DTCS is not effective in removing some chemical elements from petrochemical waste liquid. Moreover, it may negatively impact benthic fauna around the DTCS.

The distribution pattern of the living foraminiferal assemblages in the continental shelf of the Campos Basin changes depending on the bathymetry, sediment characteristics, and the supply of organic matter. The abundance of benthic foraminifera populations is strongly enlarged by the seasonal supply of phytobenthos and phytoplankton. The application of the ABC curves method in foraminiferal assemblages is a promising alternative to evaluate the environmental conditions and to access specific areas over time, and thus, they can be applied in environmental monitoring studies.

The benthic foraminifera species that occur in the deep marine system of the Southwestern Atlantic (continental slope of the Campos Basin) are mainly controlled by local hydrodynamics, which mainly controls changes in the particulate organic matter flux, quantity, and quality of the organic matter in the seafloor. It should be also considered that these parameters are affected by seasonality.

The data presented here show the importance of understanding the ecology of the benthic foraminifera species for environmental assessment of the ecosystems, and therefore for the establishment of biomonitoring procedures.
