I am a British PhD student based at the Australia National University, Australia and the British Antarctic Survey, UK. My research focuses on the distribution and diversity of sponges, and the biogeography of sponges and species associated with sponges, such as fish, crustaceans and annelids, in the Antarctic, sub-Antarctic and deep-sea environments.
Sponges are an abundant and highly diverse group of sessile, colonial animals that live on all ocean seabeds, from the shallow inter-tidal to the deepest seafloors.
Despite the Southern Ocean being ice-covered for many months a year, more than 400 species of sponge (and likely hundreds more yet to be found) inhabit these cold, seasonally productive waters.
My research has found that Southern Ocean sponges are fairly endemic, with at least half of all species only found there. Long-term isolation of seabed life in the Southern Ocean and evolution in a cold environment, have likely generated this unique situation. Despite this isolation, sponges from South America, South Africa, New Zealand, and the surrounding deep-sea, can inhabit the edges and deeper depths of the Southern Ocean. Strong oceanic currents, long-distance dispersal of sponge larvae, and species that have broad depth tolerances, are believed to enable these wide distributions and help create very unusual, diverse sponge communities.
Antarctic seabed shelf biomass (mass of life) is believed to be amongst the highest in the world, after tropical coral reefs. Sponges are classed as ‘ecosystem engineers’ as they create and maintain heterogeneous and complex three-dimensional habitats for many other marine animals, such as sea lilies, brittle-stars, sea spiders, crustaceans and fish. The relationships that these animals have with sponges are varied, complex, and often not completely known, however, we do know that they often utilise sponges to protect their eggs, raise their young, shelter from prey, build their homes in the outer-sponge body, consume the sponge tissue, and feed more effectively in the water column. My current research will review these relationships, assess if there are spatial aspects to these relationships, and utilise species traits (characteristics), to gain a better understanding of the role of sponges on the Southern Ocean seafloor now and how this could change in the future.
If you would like to contact me, here is how:
Personal website: https://sites.google.com/view/racheldowney/home
Project website: www.asccc.co.uk
Twitter: @rachel_marine and @asccc_news
My publications include:
Goodwin, C., J. Berman, Rachel V. Downey, & K. Hendry. (2017). “Carnivorous sponges (Porifera, Demospongiae, Poecilosclerida, Cladorhizidae) from the Drake Passage (Southern Ocean) with a description of eight new species and a review of the family Cladorhizidae in the Southern Ocean.” Invertebrate Systematics, 31(1): 37-64 https://doi.org/10.1071/IS16020
Morley, S.A., J. Berman, D.K.A. Barnes, C. de Juan Carbonell, Rachel V. Downey, & S.L. Peck. (2016). “Extreme Phenotypic Plasticity in Metabolic Physiology of Antarctic Demosponges.” Frontiers in Ecology and Evolution. https://doi.org/10.3389/fevo.2015.00157
Downey, Rachel.V., H.J. Griffiths, K. Linse, & D. Janussen. (2012). “Diversity and Distribution Patterns in High Southern Latitude Sponges.” PLoSONE 7(7): e41672. https://doi.org/10.1371/journal.pone.0041672
Downey, Rachel and Claire Christian. 2018. “Secrets of Our Ocean Planet: The Not-So-Simple Sea Sponge.” National Geographic: Secrets of Our Ocean Planet, 23 April.
Downey, Rachel and Claire Christian. 2018. “Secrets of Our Ocean Planet: Sponges as Civil Engineers and Pharmacists.” National Geographic: Secrets of Our Ocean Planet, 24 April. https://blog.nationalgeographic.org/2018/04/24/secrets-of-our-ocean-planet-sponges-as-civil-engineers-and-pharmacists/
Downey, Rachel and Claire Christian. 2018. “Secrets of Our Ocean Planet: Saving Sponges to Keep Marine Ecosystems Healthy.” National Geographic: Secrets of Our Ocean Planet, 25 April. https://blog.nationalgeographic.org/2018/04/25/secrets-of-our-ocean-planet-saving-sponges-to-keep-marine-ecosystems-healthy/