Adaptive Traits in sponge holobionts under Ocean Acidification (Conference Talk)

Abstract

Ocean acidification is affecting our world’s oceans. The steadily increasing absorption of anthropogenic CO2 into the ocean is predicted to decrease seawater pH by 0.5 by year 2100. The impact on marine biochemistry is profound, resulting in a net loss of biodiversity. Benthic organisms must develop adaptive strategies to cope with this stressor. Marine sponges are often forecasted as winner taxa, which will not suffer serious decline in response to increased acidification. Yet, we lack a mechanistic understanding of how these taxa tolerate high acidity and this may not be general to all species. The holobiont concept aims at assessing the sponge host and its functional associated symbiotic microbiome as a metaorganismal unit, when evaluating health, adaptive traits and resilience to environmental challenges. Sponges can therefore be categorized into high and low microbial abundance (HMA, LMA) species, depending on microbial densities in their mesohyl matrix. The HMA status implies more stable and diverse microbial communities, a denser mesohyl and more complex aquiferous systems composed of narrower and longer water channels. LMA sponges rely on simpler aquiferous circuits, which move larger quantities of water, to supply their nutritional needs based on particulate organic matter. The increased water turn-over exposes LMA species to more external stressors, such as changes in seawater chemistry. This may imply divergent strategies to maintain homeostasis and fitness under changing conditions in both sponge groups. Here we compare the microbial composition of the HMA sponge Chondrosia reniformis and the LMA sponge Spirastrella cunctatrix collected from a natural CO2 vent area with lowered pH (≈ 7,6), and from a control site with normal pH values (≈ 8,1) off Ischia island (Italy). Untargeted metabolomics further reveal the consequences in acclimatizing to ocean acidification for metabolite production.

Jana Efremova

Doctoral Researcher

My research interests include environmental research, ecology and health.