Extreme Phenotypic Plasticity in Metabolic Physiology of Antarctic Demosponges

Abstract

Seasonal measurements of the metabolic physiology of four Antarctic demosponges and their associated assemblages, maintained in a flow through aquarium facility, demonstrated one of the largest differences in seasonal strategies between species and their associated sponge communities. The sponge oxygen consumption measured here exhibited both the lowest and highest seasonal changes for any Antarctic species; metabolic rates varied from a 25% decrease to a 5.8 fold increase from winter to summer, a range which was greater than all 17 Antarctic marine species (encompassing eight phyla) previously investigated and amongst the highest recorded for any marine environment. The differences in nitrogen excretion, metabolic substrate utilization and tissue composition between species were, overall, greater than seasonal changes. The largest seasonal difference in tissue composition was an increase in CHN (Carbon, Hydrogen, and Nitrogen) content in Homaxinella balfourensis, a pioneer species in ice-scour regions, which changed growth form to a twig-like morph in winter. The considerable flexibility in seasonal and metabolic physiology across the Demospongiae likely enables these species to respond to rapid environmental change such as ice-scour, reductions in sea ice cover and ice-shelf collapse in the Polar Regions, shifting the paradigm that polar sponges always live "life in the slow lane." Great phenotypic plasticity in physiology has been linked to differences in symbiotic community composition, and this is likely to be a key factor in the global success of sponges in all marine environments and their dominant role in many climax communities.

Characterization of a thaumarchaeal symbiont that drives incomplete nitrification in the tropical spongeIanthella basta

“…), but also appears to be a common substrate for group I.1a Thaumarchaeota residing in marine sponges. In this context it is also interesting to note that some sponges excrete urea (Morley et al ., ). In contrast to Nitrososphaera gargensis (Palatinszky et al ., ), Ca .…”

Changes in Genome-Wide Methylation and Gene Expression in Response to Future pCO2 Extremes in the Antarctic Pteropod Limacina helicina antarctica

“…Many Antarctic ectotherms have classically been considered to be specialized to an invariable environment, subsequently lacking phenotypic and physiological plasticity necessary for acclimatizing to environmental shifts on par with future climate change (Peck et al, 2004(Peck et al, , 2010(Peck et al, , 2014Beers and Jayasundara, 2015). A growing body of work is beginning to demonstrate, however, that physiological plasticity is retained and sufficient for metabolic recovery under a warmer and/or more acidic ocean in at least some Antarctic ectotherms (Seebacher et al, 2005;Peck et al, 2010;Enzor and Place, 2014;Reed and Thatje, 2015;Huth and Place, 2016a,b;Morley et al, 2016;Enzor et al, 2017;Davis et al, 2018;Hawkins et al, 2018). The responsiveness of DNA methylation in L. helicina antarctica to variation in pCO 2 may be linked to this species' environmental experience in situ.…”

Characterization of a thaumarchaeal symbiont that drives incomplete nitrification in the tropical spongeIanthella basta

“…Furthermore, urease subunit gene transcripts from CCThau were found in the metatranscriptomes from C. concentrica (Moitinho-Silva et al, 2017a). Thus, it seems likely 205 that urea is not only used by marine AOA in Arctic waters (Alonso-Sáez et al, 2012), but is also a common substrate for group I.1a Thaumarchaeota residing in marine sponges and likely represents an important adaptation to life within their hosts that might be excreting urea (Morley et al, 2016).…”