I want to share an amazing experience with you and to start to think about some of the issues raised in thinking about deep-sea biodiversity.
Back in 2012 I was incredibly fortunate to join an artist, Michelle Atherton, on a 4-hour-long submarine dive off the coast of Roatán, Honduras. We travelled up to 2,000 feet (610 metres) below sea level into the mesopelagic zone. All of the images in this blogpost are stills taken from the artist’s video during this trip.
The submarine, Idabel, that would take us on our exciting adventure 2,000 feet into the ocean depths.
Marine ecosystems support approximately half of global primary productivity and a range of ecosystem services operating from local to global scales. It is widely acknowledged that deep-sea ecosystems are the most extensive on Earth, represent the largest reservoir of biomass, and host a large proportion of undiscovered biodiversity (Ramirez-Llodra et al. 2011; Snelgrove et al. 2014; Tyler, 2003).
As sampling techniques and underwater exploration have improved, so the identification of new deep-sea species has grown year-on-year (Levin and Dayton 2009; Miloslavich and Klein, 2009; Ausubel et al. 2010; Danovaro, Snelgrove and Tyler, 2014). There is, however, still a lack of data for the middle waters and deep-sea ecosystems.
On a cross-section of the global oceans, the spectrum from red to blue extends from many to few or no records. The records are concentrated near the shores and in shallow waters, while the largest habitat on Earth, the vast middle waters, is largely unexplored. Ausubel et al (2010)
Deep-sea megafauna have evolved a variety of adaptations to deal with the unique circumstances associated with the depths, such as: darkness, cold, high atmospheric pressure, ocean currents and unreliable food sources. This has resulted in peculiar morphological traits such as dark or red-colouration or even translucence to avoid detection; bioluminescence to attract prey often on a ‘lure’ or as a flash to serve as a warning or create confusion. The fauna are also quite often soft-bodied, small in size and sedentary or carried by the motion of the water.
Featured: Chaunax stigmaeus, the redeye gaper anglerfish; Leptostomias sp. dragon fish with bioluminescent chin barbel lure; unidentified polyp of a solitary octocoral; Dumbo octopod Grimpoteuthis sp.; squat lobster surrounded by snake stars Asteroschema sp. entwined with wire coral Cirrhipathes leutkeni; Acanthacaris caeca deep-sea lobster; bioluminescent comb jelly Mnemiopsis leidyi; Suttkus Sea Toad Chaunax suttkusi; and Bathypterois phenax tripod fish resting on the ocean floor.
With the recent discovery of Jurassic deep-sea fossils of extant families in the Austrian Alps providing evidence of colonisation of shallow waters from the deep (Thuy et al. 2014), the deep sea should be considered a biodiversity refugium.
Anthropogenic impacts such as bottom trawling and deep sea gas and oil extraction do, however, pose a significant threat to this biodiversity and ecosystem functioning (Costello et al. 2010; Baker, Ramirez-Llodra and Billet 2013; Ramirez-Llodra et al. 2011). It is imperative that an international conservation framework be agreed and implemented in order to preserve this ecosystem that we are only now beginning to explore.
References:
Ausubel, J.H., Crist, D.T., Waggoner, P.E. eds. (2010). First Census of Marine Life 2010: Highlights of a Decade of Discovery. New York, Census of Marine Life.
Baker, M., Ramirez-Llodra, E., Billett, D. (2013). Preface [in special issue: Deep-Sea Biodiversity and Life History Processes] Deep Sea Research Part II: Topical Studies in Oceanography, 92. 1-8. DOI: 10.1016/j.dsr2.2013.03.040
Costello, M., Coll, M., Danovaro, R., Halpin, P., Ojaveer, H., & Miloslavich, P. (2010). A Census of Marine Biodiversity Knowledge, Resources, and Future Challenges. PLoS ONE, 5 (8) DOI: 10.1371/journal.pone.0012110
Danovaro, R., Snelgrove, P.V., Tyler, P. (2014). Challenging the paradigms of deep-sea ecology. Trends in Ecology and Evolution. 8:465-75. DOI: 10.1016/j.tree.2014.06.002
Levin, L.A. and Dayton, P.K. (2009). Ecological theory and continental margins: where shallow meets deep. Trends in Ecology and Evolution. 24: 606-627.
Miloslavich, P. and Klein, E. (2009). The world conference on marine biodiversity: Current global trends in marine biodiversity research. Marine Biodiversity. 39(2):147-152
Ramirez-Llodra, E., Tyler, P.A., Baker, M.C., Bergstad, O.A., Clark, M.R., Escobar, E., Levin, L.A., Menot, L., Rowden, A.A., Smith, C.R., Van Dover, C.L. (2011). Man and the Last Great Wilderness: Human Impact on the Deep Sea. PLoS ONE 6(8): e22588. DOI: 10.1371/journal.pone.0022588
Thuy, B., Kiel, S. Dulai, A., Gale, A.S., Kroh, A., Lord, A.R., Numberger-Thuy, L.D., Stöhr, S., Bisshack, M. (2014). First glimpse into Lower Jurassic deep-sea biodiversity: in situ diversification and resilience against extinction. Proceedings B of The Royal Society. DOI: 10.1098/rspb.2013.2624
Ecology Field Notes 
you are so fortunate to have gone down there. I wish I could, I just get my deep sea fix by watching the live cam feed from Rob Ballard’s projects 😦
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It was an incredible experience and as my partner was the artist it was too good an opportunity to pass up.
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