Spatiotemporal dynamics of Sthenoteuthis oualaniensis habitat in the Northwest Indian Ocean under anomalous climate conditions

IntroductionSthenoteuthis oualaniensis is an economically important cephalopod species whose habitat distribution is highly sensitive to climate variability. To investigate the influence of the Indian Ocean Dipole (IOD) on the habitat dynamics of S. oualaniensis in the northwestern Indian Ocean, this study sets out to examine the long-term environmental regulation processes.MethodsThis study analyzed sea surface temperature (SST), wind speed (WS), and the Dipole Mode Index (DMI) during 1951–2023. Sea surface temperature anomalies (SSTA) and wind speed anomalies (WSA) under different IOD phases were examined, and a Habitat Suitability Index (HSI) model was developed to explore spatiotemporal variations in suitable habitats and shifts in their latitudinal centroid.ResultsThe results show that DMI exhibits significant lagged correlations with WSA and SSTA at 1 and 3 months, respectively. Environmental conditions vary markedly among different IOD phases: during positive IOD (pIOD) events, both SSTA and WSA are generally higher, whereas during negative IOD (nIOD) events, the suitable ranges of SST and WS increase significantly. HSI analysis indicates that the area of suitable habitat gradually expands from pIOD years to normal years and further to nIOD years, with high-HSI regions becoming more spatially continuous during nIOD events. In addition, a significant negative lagged correlation is detected between DMI and HSI with a lag of four months. The latitudinal centroid of suitable habitat shifts northward during pIOD events but tends to move toward lower latitudes during nIOD events.DiscussionThese findings suggest that the IOD regulates the habitat suitability and spatial distribution of S. oualaniensis by modulating sea surface temperature and wind field patterns in the northwestern Indian Ocean. This study provides new insights into the response mechanisms of squid habitats to interannual climate variability and offers a scientific basis for the sustainable management and utilization of this resource.