Marine heatwave conditions drive carryover effects in a temperate sponge microbiome and developmental performance

Abstract

Marine heatwaves are increasingly subjecting organisms to unprecedented stressful conditions, but the biological consequences of these events are still poorly understood. Here we experimentally tested the presence of carryover effects of heatwave conditions on the larval microbiome, settlers growth rate and metamorphosis duration of the temperate sponge Crella incrustans . The microbial community of adult sponges changed significantly after ten days at 21°C. There was a relative decrease in symbiotic bacteria, and an increase in stress-associated bacteria. Sponge larvae derived from control sponges were mainly characterised by a few bacterial taxa also abundant in adults, confirming the occurrence of vertical transmission. The microbial community of sponge larvae derived from heatwave-exposed sponges showed significant increase in the endosymbiotic bacteria Rubritalea marina. Settlers derived from heatwave-exposed sponges had a greater growth rate under prolonged heatwave conditions (20 days at 21°C) compared to settlers derived from control sponges exposed to the same conditions. Moreover, settler metamorphosis was significantly delayed at 21°C. These results show, for the first time, the occurrence of heatwave-induced carryover effects across life-stages in sponges and highlight the potential role of selective vertical transmission of microbes in sponge resilience to extreme thermal events.

Unveiling microbiome changes in Mediterranean octocorals during the 2022 marine heatwaves: quantifying key bacterial symbionts and potential pathogens

“…In colonies with 90% tissue loss, we observed a significant increase in bacterial diversity, which is likely attributed to the proliferation of opportunistic bacteria. The shift towards a more diverse bacterial community is a commonly observed phenomenon in heat-stressed organisms [ 20 , 82 , 87 , 90 , 91 ], including octocorals and may be a consequence of the temperature-induced changes in the bacterial growth dynamics and/or the octocoral loss of control over the microbiota [ 38 , 49 , 82 ]. Among the opportunistic bacteria, Vibrio sp.…”

Dynamics, diversity, and roles of bacterial transmission modes during the first asexual life stages of the freshwater sponge Spongilla lacustris

“…The intermediate transmission mode was initially named “leaky vertical transmission” [ 12 ], or “mixed-mode transmission” [ 13 ]. While VT was confirmed for a large diversity of sponge models [ 14 – 18 ], it appears insufficient to explain the origin of the overall bacterial community [ 8 , 19 , 20 ]. For example, larvae of eight Mediterranean sponge species shared only 17% of the bacterial ASVs with their parents, on average [ 8 ].…”