Impact of climate change to the potential habitat distribution of three cephalopod species from offshore of Zhejiang

Cephalopods are predominantly short-lived marine organisms, and their habitats are more susceptible to the effects of climate change. Modelling and predicting the distribution of potential habitats of cephalopods and their changing habitat spatial patterns under climate change scenarios can provide an essential scientific foundation for cephalopod habitat conservation and fisheries ecosystem management in the context of climate change. The trawl survey data collected along Zhejiang offshore in the spring and autumn of 2017-2023, in conjunction with marine environmental data including sea surface temperature (SST), sea surface salinity (SSS), dissolved oxygen concentration (DO) and chlorophyll-a concentration (CHLA), collected by temperature-salt-depth instrument, were employed to simulate and predict the potential habitat distribution of Uroteuthis duvauceli, Abralia multihamata, and Sepiella maindroni in the four RCP climate scenarios in 2100 by random forest as a species distribution model. The results demonstrated that the Random Forest predictions were accurate and reliable, with an AUC exceeding 0.8 for each group and a standard deviation below 0.05. The main environmental factors affecting the habitat distribution of three cephalopod species are SST and SSS, with an average contribution rate of 0.28 in spring and 0.33 in autumn. The average contribution rate of SSS in spring is 0.32, and in autumn it is 0.29. The response curves demonstrated that the three cephalopod species exhibited varying degrees of response to changes in SST and SSS. During the spring period, the optimal habitat for cephalopods was characterised by SST ranging from 18 degrees C to 20 degrees C, and SSS exceeding 28 parts per thousand. In contrast, in autumn, S. maindroni exhibited a preference for warmer water compared to U. duvauceli and A. multihamata. The potential habitat suitability zones of cephalopods under high gas emission scenarios were found to mainly extend to the southern and northern coast of Zhejiang. Among them, the area of the high adapted zone of S. maindroni increased by 352 % in the RCP4.5 scenario, the area of the high adapted zone of U. duvauceli increased by 69 % in the RCP4.5 scenario, and the area of the high adapted zone of A. multihamata increased by 69 % in the RCP8.5 scenario. The centroid changes of the three species of cephalopods were not found to be significant in the high suitability zones of the three cephalopod species in different climatic scenarios. The present study proposes that climate change will result in alterations to the potential habitat of cephalopods offshore Zhejiang, which is a significant consideration for the future conservation and management of cephalopod fisheries.