Delimitation of Ecotone is an important reference for ecosystem conservation, however, the assessment of marine ecotone from ecological point is a gap. The Yellow River Estuary (YRE) serves as both spawning and feeding grounds for numerous economically significant organisms. Delineating the boundary of YRE and assessing the boundary change have great importance on maintaining its ecosystem health. This study attempts to apply moving split-window (MSW) to determine marine boundary in YRE. Level-2 remote sensing satellite data spanning from 2012 to 2020, sourced from the Geostationary Ocean Color Imager (GOCI), were utilized. Chlorophyll a (Chla), Chromophoric Dissolved Organic Matter (CDOM), and Total Suspended Solids (TSS) were employed as variables, with Squared Euclidean Distance (SED) serving as the determinant for identifying the marine ecological ecotone within the Yellow Estuary and its adjacent waters. Results indicate the following: 1) SED values exhibit distinct peaks and valleys, facilitating the accurate identification of marine ecotones via MSW; 2) Evident ecotones are observable in both the gate and coastal regions; 3) The influence range of TSS on the gate spans between 10 km and 14 km. In synthesis, the ensuing conclusions are drawn: MSW proves to be a reliable method for quantitatively determining ecotones in marine environments. Furthermore, MSW introduces a novel approach to the delineation of marine ecotones.

Marine Ecosystem; Ecotone Zone; Moving Split-Window; Boundary Definition; River Estuary; Satellite Data Analysis