Thermal stress disrupts microbial symbiosis and host activity in the model sponge Ianthella basta
Year: 2026
Type: preprint
Abstract: Climate change is threatening coral reef ecosystems around the world, causing significant declines in reef organisms, including sponges. The health of sponges is intimately linked to their symbiosis with microorganisms, yet little is known about their integrated response to ocean warming. Here, we present a comprehensive view of the effect of elevated sea surface temperatures (SST) on the model sponge Ianthella basta. I. basta individuals were exposed to temperatures up to 32 °C, 2-3 °C above the mean annual maxima. Host gene expression profiles showed an initial response to heat stress after 2 days, and a decreased expression of genes involved in maintaining tissue integrity, pumping capacity, vitamin transport, and stable symbioses after 4 to 8 days. Congruently, heat stressed samples started to show tissue regression and a reduced abundance of the dominant symbionts after 4 days. A significant loss of the symbionts occurred after 8 days, together with a reduction in microbially driven nitrogen cycling and amino-acid transport and an introduction of opportunistic microbes, which could lead to nutrient imbalance and further destabilisation of the holobiont. Together, this work provides important insights into the avenues through which future SST can impact host-microbe interactions in coral reef sponges.
Institutions: Translational Research Institute, Queensland University of Technology, The University of Queensland, Australian Institute of Marine Science, University of Vienna, Helmholtz Centre for Environmental Research, James Cook University, University of Canterbury, Aalborg University, University of Tasmania
Language: English
Subfield: Ecology
Field: Environmental Science
Domain: Physical Sciences
SDG: Life below water
Open Access status: green
Funder: Austrian Science Fund
OpenAlex ID: W7218919940