In order to identify seasonal and/or spatial patterns in the environmental data, the data were log(x + 1) transformed and principle component analyses (PCA) performed on the whole dataset. The range, average and standard error of the hydrological and biological data for the twelve months period are listed in Table 1. Over the twelve months of the study, the
YSI profiles for temperature and salinity did not exhibit any vertical changes along the water column, suggesting that the water column was well mixed. This was reflected in the hydrological and biological data as there RG7204 in vivo was no significant difference between the surface and bottom samples. In addition, there was no difference between the temperature, salinity, nutrients and the biological parameters measured at the ADP intake pipe (S1) and outfall (S2–S5). In order to summarise the weight of each environmental parameter in setting the environmental conditions of the study, a PCA was applied. The PCA revealed clear clustering along the primary (PC1) and secondary (PC2) axes, explaining a total of 57.4% of the variance observed during the survey period (Figure 2). The first principal component (PC1: 41.3% of variance) was related to temperature, wind speed/direction
and phosphorus content, while the second principal component (PC2: 16.1% of variance) GNE-0877 was related to salinity, silicate and nitrogen. The main environmental drivers of the temporal variability of the Gulf therefore seem to be temperature, wind speed/direction
and phosphorus levels. However, PS-341 ic50 the variability observed during autumn and winter months is driven by changing levels of salinity, nitrogen and silica. The water temperature exhibited a clear australseasonal pattern with a maximum of 22°C in January (summer) and a minimum of 13 °C in July (winter; Figure 3). Salinity did not show any clear seasonal pattern, with an average [± standard error (SE)] of 37.17 (±0.03) PSU (Figure 3). Currents along the Adelaide metropolitan coastline generally flow parallel to the shore, but are seasonally influenced by a variety of factors, including wind direction, temperature and salinity gradients (Pattiaratchi et al. 2006). In particular, the north-south (NS) wind direction showed a seasonal pattern, with upwelling-favourable conditions prevailing in summer and autumn and downwelling-favourable conditions prevailing in winter (Figure 3). All nutrients (i.e. nitrogen, phosphorus and silicate) exhibited a seasonal cycle with lower concentrations during summer (Figure 3). During spring and summer, ammonium was the most abundant source of nitrogen, while nitrate and nitrite were the prevalent source of nitrogen during autumn and winter (data not shown).