Unveiling differential thermal sensitivities in marine phytoplankton within the China Seas

In this study, we explored the realized thermal sensitivities of various phytoplankton groups in natural seawater, a crucial aspect for understanding the dynamics of marine ecosystems under climate change. Utilizing a decadal pigment dataset (2002-2015) from China Seas and employing generalized additive mixed models coupled with maximum entropy modeling, we discerned thermal sensitivity differentiations among nine phytoplankton groups, encompassing the full-size spectrum. Our findings revealed that cryptophytes were exceptionally thermally sensitive, with a strong correlation between temperature changes and biomass variance. Characterized by a preference for cooler waters, cryptophytes had a low mean temperature niche and a narrow niche breadth. Notably, they exhibited the lowest temperature tipping point, highlighting their heightened vulnerability to warming trends. These findings underscored the significance of cryptophytes, an often-overlooked group, in understanding ecosystem responses to climate shifts, and emphasized their potential role as key indicators in marine ecological studies under global warming.