Millennium Institute of Oceanography (IMO), University of Concepcion, 4030000, Concepcion, Chile.
Department of Oceanography, Faculty of Natural and Oceanographic Sciences, University of Concepcion, 4030000, Concepcion, Chile.
Sci Rep. 2023 Feb 23;13(1):3158. doi: 10.1038/s41598-023-29541-9.
Predicting species distribution in the ocean has become a crucial task to assess marine ecosystem responses to ongoing climate change. In the Humboldt Current System (HCS), the endemic copepod Calanus chilensis is one of the key species bioindicator of productivity and water masses. Here we modeled the geographic distribution of Calanus chilensis for two bathymetric ranges, 0-200 and 200-400 m. For the 0-200 m layer, we used the Bayesian Additive Regression Trees (BART) method, whereas, for the 200-400 m layer, we used the Ensembles of Small Models (ESMs) method and then projected the models into two future scenarios to assess changes in geographic distribution patterns. The models were evaluated using the multi-metric approach. We identified that chlorophyll-a (0.34), Mixed Layer Depth (0.302) and salinity (0.36) explained the distribution of C. chilensis. The geographic prediction of the BART model revealed a continuous distribution from Ecuador to the southernmost area of South America for the 0-200 m depth range, whereas the ESM model indicated a discontinuous distribution with greater suitability for the coast of Chile for the 200-400 m depth range. A reduction of the distribution range of C. chilensis is projected in the future. Our study suggests that the distribution of C. chilensis is conditioned by productivity and mesoscale processes, with both processes closely related to upwelling intensity. These models serve as a tool for proposing indicators of changes in the ocean. We further propose that the species C. chilensis is a high productivity and low salinity indicator at the HCS. We recommend further examining multiple spatial and temporal scales for stronger inference.
预测海洋物种分布已经成为评估海洋生态系统对持续气候变化的响应的关键任务。在洪堡海流系统（HCS）中，特有桡足类 Calanus chilensis 是生产力和水体的关键生物指标之一。在这里，我们为两个水深范围（0-200 和 200-400 m）模拟了 Calanus chilensis 的地理分布。对于 0-200 m 层，我们使用了贝叶斯加性回归树（BART）方法，而对于 200-400 m 层，我们使用了小模型集（ESMs）方法，然后将模型投影到两个未来情景中，以评估地理分布模式的变化。使用多指标方法评估模型。我们确定叶绿素-a（0.34）、混合层深度（0.302）和盐度（0.36）解释了 C. chilensis 的分布。BART 模型的地理预测表明，在 0-200 m 水深范围内，从厄瓜多尔到南美洲最南端存在连续分布，而 ESM 模型表明，在 200-400 m 水深范围内，分布更为连续，智利沿海地区更为适宜。预计未来 C. chilensis 的分布范围将会缩小。我们的研究表明，C. chilensis 的分布受到生产力和中尺度过程的影响，这两个过程与上升流强度密切相关。这些模型可作为提出海洋变化指标的工具。我们进一步提出，C. chilensis 是 HCS 中高生产力和低盐度的指示物种。我们建议进一步研究多个时空尺度，以进行更有力的推断。
