Nick Carne
Glass sponges grow up tough in Canada.
Studies show that unique aggregations of the deep-sea species Vazella pourtalesi off the coast of Nova Scotia have survived for decades in water that varies greatly in temperature and salinity.
And that, say researchers from Canada, Norway and Portugal, may offer positive signs about how the species will respond to future climate change.
Fisheries and Oceans Canada established the Emerald Basin and Sambro Bank Sponge Conservation Areas in 2009 to protect some of North America’s most significant concentrations of V. pourtalesi from fishing activities, but the vast majority of the population remains outside these areas.
A team led by aquatic science biologist Lindsay Beazley, from Canada’s Bedford Institute of Oceanography, set out to discover exactly how much is unprotected, and how it is faring, by modelling the presence probability and predicted range distribution along the Scotian Shelf.
The answers they came up with are about 99% and remarkably well, all things considered.
“Examination of the hydrographic conditions in Emerald Basin revealed that the V. pourtalesi sponge grounds are associated with a warmer and more saline water mass compared to the surrounding shelf,” the authors say in a paper published in the journal PLOS ONE.
“Reconstruction of historical bottom temperature and salinity in Emerald Basin revealed strong multi-decadal variability, with average bottom temperatures varying by 8 degrees Celsius. We show that this species has persisted in the face of this climatic variability, possibly indicating how it will respond to future climate change.”
Glass sponges, sometimes called Russian Hat sponges but officially known as hexactinellid sponges, have mineral skeletons composed of silica spicules – small needle-like anatomical structures. There are more than 600 species around the world, mainly found in deeper waters.
Deep-sea sponge-dominated communities have gained increasing attention in recent years from both an ecological and conservation perspective.
“Growing evidence not only suggests that these habitats are widely distributed across the deep sea globally but that they also play key functional roles, directly or indirectly, in delivering a number of ecosystem goods and services,” the authors note in their paper.
“This includes, but is not limited to, habitat-provision, biodiversity enhancement, and biogeochemical cycling.”
