Figure 1.
Map showing the location of surveyed estuaries along the coastline of New South Wales (NSW; Australia).
Table 1.
Physical and chemical attributes and mean values of sediment characteristics (mean ± SE, n = 6 for median grain size, sorting and silt/clay content, n = 12 for organic matter [OM] content) for the 16 estuaries surveyed.
Figure 2.
PCA (Principal component analysis) of the 11 environmental variables, excluding longitude, listed in Table 1 (transformed and normalised).
Dots represent sites within estuaries. Vectors show the two-dimensional (PC1 and PC2) correlation structure among the environmental variables (% of variance explained = 52.4). Abbreviations: catch a = catchment area, disturb a = % of disturbed area of the catchment, est a = estuary area, flushing t = flushing time, lat = latitude, MGS = median sediment grain size, sorting = sediment sorting, OM = sediment organic matter, silt/clay = % sediment silt/clay content, TN flux = flux of total nitrogen, TN ratio = ratio of total nitrogen loading pre-European settlement to present.
Figure 3.
dbRDA plots representing the reduced model of spatial variation in macrofaunal community structure and its relationship to a) environmental variables and b) the abundance of key taxa significantly correlated with db-RDA axes (multiple correlation >0.30).
Points omitted in plot b for clarity. See Fig. 2 for abbreviations.
Table 2.
Results of multivariate multiple regression analyses (distLM) using data from: (a) all estuaries, (b) estuaries with a median sediment grain size of <250 µm and (c) estuaries with a median grain size of >250 µm.
Table 3.
Pearson’s correlation coefficients of significant (pperm <0.05, DistLM routine) correlations between the abundances of macrofaunal taxa that were most correlated to abiotic data and individual predictor environmental variables for (a) all estuaries, (b) estuaries with a median sediment grain size of <250 µm and (c) estuaries with a median grain size of >250 µm.
Figure 4.
dbRDA plots representing the reduced model of spatial variation in the macrofaunal community structure of estuaries with a median sediment grain size of <250 µm (a, b) and estuaries with a median grain size of >250 µm (c, d).
Macrofaunal communities are related to environmental variables (a, c) and taxa significantly correlated with db-RDA axes (b, d) (multiple correlation >0.30). Points omitted in plot b and d for clarity. See Figure 2 for abbreviations.