不同印度洋偶极子模态下西南印度洋深海散射层生物热点栖息地分布

Potential habitat distribution on hotspots of deep scattering layer in the southwestern Indian Ocean under different Indian Ocean dipole modes

摘要:

目的 为了探究不同印度洋偶极子模态 (IOD)下西南印度洋深海散射层 (DSL)生物热点栖息地分布。方法 研究选取2012年10月—2020年7月的西南印度洋海域声学调查数据，利用热点分析方法和最大熵模型，分析不同IOD模态下DSL生物热点栖息地的变动规律。结果 不同IOD模态的最大熵模型精度均大于0.9，模型预测效果较好，其中溶解氧是对栖息地分布贡献率最高的因子，平均贡献率为50.88%。DSL热点适宜栖息地的重心主要在西北-东南方向移动，第1个IOD冷相位时期热点适宜栖息地重心变动最为明显。DSL热点的适宜栖息地分布在30°~45°S与11和22 °C等温线之间。结论 不同IOD模态下DSL热点受溶解氧等变化的影响，其适宜栖息地变动明显，最大熵模型可以较好地预测DSL热点栖息地的分布。本研究可为阐明DSL中渔业资源的空间分布和变动规律提供新的参考。

Abstract:

The deep scattering layer (DSL) is crucial for marine ecosystems and oceanographic studies. It consists of dense aggregations of organisms such as zooplankton and micronekton, which form a key link in the food web, transferring energy from primary producers to higher trophic levels. Understanding the DSL is essential for assessing ecosystem health, global biogeochemical cycles, and the effects of climate change on ocean dynamics. Based on the acoustic data from October 2012 to July 2020 in the southwestern Indian Ocean, hotspot analysis and maximum entropy model were used to study the potential habitats’ distribution on hotspots of deep scattering layers under different IODs. The results showed that the maximum entropy model had a good performance with the accuracy of the model was more significant than 0.9. Dissolved oxygen had the highest contribution rate to habitat distribution, and the average contribution rate was 50.88%. The gravity centre of DSL hotspot habitats mainly moved in the northwest to southeast direction, and the most significant changes were observed during the first cold phase of IOD. DSL hotspot habitat was distributed between 30 °-45 ° S and 11-22 °C isotherms, which indicated a specific latitude correlation. This research showed that the suitable habitat changes on DSL hotspots were influenced by dissolved oxygen. The maximum entropy model could effectively predict the distribution of DSL hotspots' habitats. This study can provide new references for elucidating the spatial distribution and resource variation patterns of DSL.