Identification of similar environmental areas in Tagus estuary by using multivariate analysis

摘要: Abstract An observational programme consisting of physical, chemical and biological measurements has been carried out along Tagus estuary covering 13–18 stations. The multiparameter dataset generated in two distinct winter (March 2001, February 2004) summer (July 2001 July 2003) periods are analysed this work. Principal component analysis (PCA) cluster were applied to data matrices including 10 variables (salinity, temperature, dissolved oxygen, nitrate + nitrite, ammonia, phosphate, silicate, suspended particulate matter, chlorophyll a phaeopigments) order assess the seasonality respective patterns highlight areas similar influence. In both seasons, PCA clearly separates upper stations from lower ones, on basis nutrients, productivity, salinity. application further supports clarifies seasonal spatial patterns, giving better insight into other features. summer, an increment primary productivity is evident mid-estuary region, while under extreme flow conditions accumulation material, nutrients (as silicate ammonia) phytoplankton organisms seems be favoured nearby extensive salt marshes.