Advances in Biology & Earth Sciences

The Indonesian Sea is a vital pathway for connectivity between the Pacific and Indian Oceans, with the Indonesian Throughflow (ITF) playing a key role in facilitating water exchange, particularly in the Halmahera Sea (HS), Maluku Sea (MS) and Banda Sea (BS). Despite prior research, there remains a limited understanding of oceanographic parameters - such as SST, SSS, SSH, EKE, current speed, chlorophyll-a and volume transport in HS, MS and BS - and their implications for marine ecosystems from 2009 to 2020. EOF analysis reveals that SSH and SST variability is largely driven by interannual signals, with EOF 1 and EOF 2 explaining 67.85% and 23.10% of the total variance, respectively. The Hovmöller diagram shows that the strongest climate phenomena occurred in 2020, with SSH reaching 0.86 m and SST peaking at 31°C in HS. In contrast, 2010 recorded the weakest phenomena, with the lowest SSH at -0.2 m and SST at 27.5°C. The highest EKE was 0.5766 m²/s² during El Niño 1 and the lowest was 0.0961 m²/s² during La Niña 3. Volume transport in HS, MS and BS was -1.700 ± 0.987 Sv, -3.116 ± 1.691 Sv and -0.740 ± 0.423 Sv, respectively. This study, focusing on oceanographic dynamics and their ecological implications, highlights that HS is most impacted during El Niño events, while MS and BS show more moderate responses. These findings contribute to the broader understanding of climate variability in the Indo-Pacific, aligning with the journal’s focus on physical oceanography and marine ecosystems. The observed oceanographic variability also has important implications for terrestrial soil in the surrounding Molucca Islands. Variations in sea level, ocean circulation, and climate conditions associated with the Indonesian Throughflow and ENSO may influence coastal erosion, river discharge, soil erosion, and sediment delivery from adjacent watersheds to the coastal environment.