Climate change winner in the deep sea? Predicting the impacts of climate change on the distribution of the glass sponge Vazella pourtalesii

Shallow-water sponges are often cited as being ‘climate change winners’ due to their resiliency against climate change effects compared to other benthic taxa. However, little is known of the impacts of climate change on deep-water sponges. The deep-water glass sponge Vazella pourtalesii is distributed off eastern North America, forming dense sponge grounds with enhanced biodiversity on the Scotian Shelf off Nova Scotia, Canada. While the strong natural environmental variability that characterizes these sponge grounds suggests this species is resilient to a changing environment, its physiological limitations remain unknown, and the impact of more persistent anthropogenic climate change on its distribution has never been assessed. We used Random Forest and generalized additive models to project the distribution of V. pourtalesii in the northwest Atlantic using environmental conditions simulated under moderate and worst-case CO2 emission scenarios. Under future (2046–2065) climate change, the suitable habitat of V. pourtalesii will increase up to 4 times its present-day size and shift into deeper waters and higher latitudes, particularly in its northern range where ocean warming will serve to improve the habitat surrounding this originally sub-tropical species. However, not all areas projected as suitable habitat in the future will realistically be populated, and the reduced likelihood of occurrence in its core habitat on the Scotian Shelf suggests that the existing Vazella sponge grounds may be negatively impacted. An effective monitoring programme will require tracking changes in the density and distribution of V. pourtalesii at the margins between core habitat and where losses and gains were projected. Here we provide the environmental and response data used in the analyses as well as the predicted distribution models (present and future) produced from these data.浅水海绵常被视作“气候变化赢家”，因其相较于其他底栖生物类群（benthic taxa），对气候变化影响具备更强的恢复力。然而，目前学界对气候变化对深水海绵的影响仍知之甚少。深水玻璃海绵（glass sponge）Vazella pourtalesii分布于北美东部海域，在加拿大新斯科舍省（Nova Scotia）外的斯科舍陆架（Scotian Shelf）形成了具有更高生物多样性的密集海绵礁群。尽管这些海绵礁群所处环境具有强烈的自然环境变异性，暗示该物种对变化的环境具备恢复力，但其生理限制仍未明确，且长期人为气候变化对其分布的影响从未被评估过。本研究采用随机森林（Random Forest）与广义加性模型（generalized additive models），基于中等及最坏情形二氧化碳排放情景（CO2 emission scenarios）下模拟的环境条件，对西北大西洋海域Vazella pourtalesii的分布进行预测。在未来（2046–2065年）气候变化情景下，Vazella pourtalesii的适宜栖息地面积将增至当前的4倍，并向更深海域与更高纬度转移，尤其是在其北部分布范围——海洋变暖将改善这一原本属于亚热带物种的栖息环境。但并非所有未来预测的适宜栖息地都能实际被该物种占据，而斯科舍陆架核心栖息地的适宜性下降表明，现有的Vazella pourtalesii海绵礁群可能会受到负面影响。有效的监测计划需要追踪Vazella pourtalesii在核心栖息地与预测的分布变化区域之间的边缘地带的密度与分布变化。本文提供了本研究分析中使用的环境与响应数据，以及基于这些数据生成的当前及未来情景下的预测分布模型。