WATER CHEMISTRY AND NUTRIENTS OF THE BAH´IA BLANCA ESTUARY

FREIJE, R.H.; SPETTER, C.V.; MARCOVECCHIO, J.H.; POPOVICH, C.; BOTTE, S.; NEGRIN, V.; ARIAS, A.H.; DELUCCHI, F.; ASTEASUAIN, R.

Perspectives on Integrated Coastal Zona Management in South America

IST Press

Lugar: Lisboa; Año: 2008; p. 243 - 256

Different characteristics of the estuarine environments (i.e. geo-morphological, hydrographical, climatic or chemical ones) strongly condition the biodiversity development within those systems (Harrison 2004). So, the range of values of the different involved parameters (temperature, salinity, pH, dissolved oxygen, inorganic nutrients, organic matter, etc) as well as their corresponding seasonality or unexpected variations would directly determine the scenario where the whole biological processes will occur also including populations movement along different spatial gradients due to physiological problems (Laprise and Dodson 1994). In addition the distribution and availability of non-conservative constituents such as oxygen, nutrients or organic carbon fully condition the productivity ability of the system, and consequently its potential transference of energy to higher trophic levels (Cantoni et al. 2003, Rydberg et al. 2006). Bah´ýa Blanca estuary has been the object of a large amount of environmental studies along the last 30 years, including most of the above mentioned scientific disciplines. So, a large time-series database on physicochemical parameters has been developed at the inner part of the estuary (Pto.Cuatreros and Pto.Ing.White; Figure 1) which allows to bring a better image of the condition and functioning outline of this area. It is a very useful tool to diagnose the environmental condition of the system considering that the mentioned inner zone of the estuary includes not only the discharges of the main rivers from the region but also the largest anthropic activities such as cities, industries and harbours location, with their consequent impacts on the estuary. In addition, information has also been recorded through cruises developed along the Main Navigation Channel, as well as many coastal studies on the tidal flats at Villa del Mar, Puerto Galv ´an and Puerto Cuatreros (Fig. 1). The main goal of the present chapter is to summarize the available information on the physicochemical condition of Bah´ýa Blanca estuary, including the corresponding range of values of the considered parameters (temperature, salinity, turbidity, dissolved oxygen, inorganic nutrients (DIN, Dissolved Inorganic Nitrogen; DIP, Dissolved Inorganic Phosphorous and DSi, Dissolved Silicates), particulated organic matter and photosynthetic pigments (Chlorophyll a and phaeopigments), and to identify seasonal variations, as well as the influence of external sources to the estuarine balance.