<p> Supplement 1: Average element concentrations (ppb) and nutrient concentrations (µg/L) in filtered (<0.45 µm) seawater collected from study sites (averages are from triplicates). Cells highlighted in yellow exceed the ANZECC trigger values for marine water and cells highlighted in green exceed the background threshold. < DL below detection limit.</p><p>Seawater Seawater total total Cu Zn As Cd Pb dissolved dissolved nitrogen phosphorus (µg/L) (µg/L) Woods Inlet 0.48±0.18 2.49±1.68 1.41±0.06 < DL < DL 178±34.0 27.2±0.76 One Fella Ck 0.40±0.25 2.33±0.24 1.37±0.10 < DL < DL 126±7.61 23.3±2.15 Channel Is 0.35±0.03 0.44±0.17 1.46±0.11 < DL < DL 171±24.9 24.9±6.06 Palmerston 0.32±0.01 1.61±0.62 1.17±0.14 < DL < DL 168±62.0 22.2±1.00 Ludmilla Ck 0.54±0.03 1.42±0.63 1.00±0.03 < DL < DL 282±55.1 8.04±1.12 Hudson Ck 0.41±0.08 0.73±0.19 1.28±0.04 < DL < DL 168±51.0 23.1±1.66 Reichardt Ck 1.48±0.85 5.20±2.16 1.60±0.19 < DL < DL 359±113 14.4±1.09 Buffalo Ck 0.34±0.04 0.56±0.03 1.96±0.10 < DL < DL 333±4.57 61.3±5.20 Detection limit 0.50 0.45 0.35 0.01 0.01 3.0 2.0 ANZECC trigger 1.3 15* ID 5.5* 4.4 250 20 values1 Background 1.05 5.64 1.62 - - 260 33 threshold Darwin Harbour2 0.15-0.52 0.13-0.50 1.00-1.59 <DL-0.03 <DL-0.04 1. Trigger values for marine waters for 95% species protection (µg/L); ID = insufficient data; * see ANZECC Water Quality Guidelines for further clarification of trigger values; 2. Munksgaard & Parry 2001; Padovan 2002; Padovan et al. 2012</p><p>Quality control The trace element concentrations obtained for seawater reference materials were within a range of 99-105% of the certified values. </p>