Fig 1.
Description of the study sites in the NRE.
Appearance after intrusion of different amounts of seawater before opening the NRE (A: Sky view; C: Cross-section view) and after intrusion of 9,300,000 tons (third opening of the NRE) of seawater (B: Sky view; D: Cross-section view). The amount of salt is represented by colours ranging from blue (0) to red (greater than 9.5).
Fig 2.
NGS datasets recovered from stomach contents of E. erythropterus in the NRE.
A taxonomic phylogenetic tree of prey items identified from fish stomach contents was constructed, with bar graphs showing the operational taxonomic unit (OTU) count per phylum or order. Silhouettes represent the prey organism types; when a food source appeared both before and after the NRE opening, its silhouette was placed outside the circular bar. Red and blue colors represent prey items found after and before NRE opening, respectively.
Table 1.
Comparison of water quality parameters in the surface water before and after Nakdong River Estuary (NRE) opening. DO: dissolved oxygen; TN: total nitrogen; TP: total phosphorus.
Table 2.
Comparison of ecological indices of potential prey communities for E. erythropterus in the NRE before and after barrage opening. RA: Relative Abundance; ind.: number of individuals.
Fig 3.
The results of self-organising map (SOM) clustering.
(A) U-matrix clustering and dendrogram showing dissimilarity of the cells on the map plane. The patterning results for proportion of OTU numbers per phylum or order parameters (B) before and (C) after the NRE opening. Colour scale is related to distances between map units. Black colours represent large distances and white colours represent small distances. The diagonal red line separates the two main clusters (before and after NRE opening) identified by the SOM analysis.
Table 3.
Descriptive statistics and estimated parameters of length-weight relationships (w = aLb) for E. erythropterus before and after opening the NRE.
Fig 4.
Length distribution and condition factors K of E. erythropterus (A) before and (B) after the NRE opening.
Before, 205 individuals; After, 104 individuals.; A statistical significance of the t-test (P < 0.05) performed to deduce if there is significant difference between condition factors K before and after opening the NRE; Solid line: median; Dash line: mean; * P < 0.01.
Fig 5.
Form factor of E. erythropterus (A) and standardized form factor a3.0 (B) before and after opening the NRE.
Before, 205 individuals; After, 104 individuals. Range of form factor for body shape categories: Elongated (0.00775–0.00906), Eel-like (0.00099–0.00165). Error bars represent standard deviation.
Fig 6.
Distribution of zooplankton abundance by depth (A) before and (B) after and phytoplankton abundance by depth (C) before and (D) after the opening of the NRE.
Sampling period: before NRE opening (10 May 2022); after NRE opening (23 May 2022).