Chains A, B, C and D denote the 4 chains of the upstream-to-downstream WBIF. In Chain A, SL6b-SL5 denotes the WBIF from sampling transects SL6b to SL5; ##-SL4 denotes the WBIF from sampling transects SL6b to SL5 and then to SL4; ##-SL3 denotes the WBIF from sampling transects SL6b to SL5, SL4 and then to SL3; ##-SL2 denotes the WBIF from sampling transects SL6b to SL5, SL4, SL3 and then to SL2; ##-SL1 denotes the WBIF from sampling transects SL6b to SL5, SL4, SL3, SL2 and then to SL1 (estuary). 201904, 201906, and 201909 indicate the groups that were sampled in April, June and September 2019, respectively.