Tide-induced variations in the bacterial community, and in the physical and chemical properties of the water column of the Mondego estuary

Nicolau, Paula Bacelar; Marques, João C.; Morgado, Fernando; Pastorinho, Ramires; Nicolau, Leonor Bacelar; Azeiteiro, Ulisses

http://hdl.handle.net/10400.2/14023

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Authors

Nicolau, Paula Bacelar

Marques, João C.

Morgado, Fernando

Pastorinho, Ramires

Nicolau, Leonor Bacelar

Azeiteiro, Ulisses

Abstract(s)

The bacterioplankton is a key component of the structure and function of aquatic ecosystems. Yet, present understanding of the controls on microbial abundance and activity only highlights their complexity. In estuaries, the problem is further complicated by the high variability of environmental properties (salinity, temperature, pH, organic loading and other factors). The present study investigates the dynamics of three main metabolic groups of planktonic bacteria involved in the cycling of organic matter (aerobic heterotrophic bacteria, sulphate-reducing bacteria, and nitrate-reducing bacteria), over one tidal cycle in the estuary of the Mondego. The association of various physical, chemical and biological parameters with the composition of the bacterial community was assessed by multivariate analysis in order to identify key factors controlling the composition and tidal dynamics of the bacterial communities in the Mondego estuary. Principal component analysis (PCA) identified the sources of variability for the bacterial communities in the estuary, as being, on one hand, the different dynamics in the two stations under study (Foz and Pranto) and, on the other hand, the flood and ebb tide fluxes, by their effects in the environmental parameters.