Response of siliceous marine organisms to Permian-Triassic climate
crisis based on new findings from central Spitsbergen, Svalbard
Abstract
Siliceous marine ecosystems play a critical role in climate regulation
and the severe impact of the Permian-Triassic mass extinction on
silica-secreting animals may have contributed to a sustained greenhouse
climate during the Early Triassic, via decreased export of organic
carbon burial and increased reverse weathering rates. Yet, our
understanding of siliceous marine organisms during this critical
interval is poor, and whilst radiolarians experienced the strongest
diversity loss in their evolutionary history and perhaps also the
greatest population decline of silica-secreting organisms, only a small
number of Griesbachian localites that record siliceous organisms are
known. Here, we report newly discovered latest Changhsingian to early
Griesbachian (Clarkina meishanensis - Hindeodus parvus Zone)
radiolarians and siliceous sponge spicules from Svalbard. This fauna
documents the survival of a low-diversity radiolarian assemblage
alongside stem-group hexactinellid sponges. This is, therefore, the
first described account of post-extinction silica-secreting organisms
from the Permian/Triassic boundary, a shallow marine shelf environment,
and a mid-northern palaeolatitudinal setting. Our new data suggest that
latitudinal diversity gradients for silica-secreting organisms following
the mass extinction were significantly altered, and that silica
productivity was restricted to high latitude and deep water thermal
refugia. This also suggests that the export of organic carbon to the
deep ocean and reverse weathering rates were not as severely impacted at
non-equatorial latitudes.