Follow along as NG Grantee Rhian Waller explores the surprisingly diverse corals that dwell deep in the fjords of the southern tip of South America, and discover what they can tell us about the rest of the ocean as well.
It seems like only yesterday we were embarking from Boston to southern Chile, eager to start the science, eager to see “deep-sea” corals in a habitat shallow enough that we could reach by SCUBA diving. And yet here we are, two weeks later, sitting in Santiago airport, taking stock and finishing up writing dive logs and lab notes.
The last few days of diving and sampling were a whirlwind. Bad weather and sites where corals had perished unbeknownst to us meant that coming back from Pumalin Park it was a scramble to get another site cataloged and sampled and a logger deployed.
The primary objective of this study is to find out how Desmophyllum dianthus (a cold-water, and usually deep-sea, hard coral) reproduces – vital information we just don’t know. To be able to investigate reproduction well, you need samples from different seasons in the same year. This is a luxury we deep-sea biologists rarely get because of the remoteness of deepwater sites; because it’s hard and expensive to get ship time and submersible time; and because the open-ocean environment rarely stays calm enough to work through 12 months of the year.
The Patagonian fjords however provide the almost perfect natural laboratory for such a study – they house a deep-sea species living shallow enough for researchers to sample without using expensive submersibles and robots, and protected enough within a fjord so you can sample in every season. Why and how these species (that usually live below 1500m) exist here we’re not sure, but the high and low latitude fjord systems provide a habitat similar to the deep sea: cold all year, dark, and with little competition from photosynthesizing organisms like algae.
A secondary objective is to pick three populations in different environments (two different fjords and a site close to a salmon farm), and look at how their reproduction changes in these different areas. Returning from Reñihué Fjord, I had two sites down – Liliguape, at the end of the Comau fjord, open to the Gulf of Ancud, well flushed with oceanic water; and Reñihué, further within a fjord, but a healthy population, growing tall and large. The next step was to find a site close to a salmon farm, though everywhere we’d looked, there were not enough living corals to start this part of the study (you need enough so you can sample and not impact the population by taking individuals away for analysis).
So Dan Genter, Chris Rigaud and myself began the search at a few sites close to the Huinay Scientific Field Station – easily resampled by the station’s technicians over the next year before I return. With luck we found an area quickly, deeper than we really wanted (close to 100ft), but with enough live corals to sustain the study, and close enough to a salmon farm that the corals must be bathed in run-off. With two dives our goals were accomplished: deploy the logger (measuring temperature, salinity and light), perform photographic transects, and collect specimens to send back to my laboratory.
This left us with just one day to spare, and we were lucky enough to have the station’s director, Vreni Haussermann, take us on a dive to another coral area to collect not live corals, but fossil corals for a collaboration with a geochemist friend of mine.
This was possibly one of the most beautiful dives of my life, and it was instantly apparent why the station’s scientists are preserving this site (no live corals are ever taken from this area). At 90ft depth and going back into the bedrock for over 15ft was a cave, the ceiling covered in Desmophyllum corals as far as flashlight would shine. Even a stray air bubble would be enough to knock these fragile creatures from the ceiling above. We set to work in the tall piles of fossil corals lying at the bottom of the cave, showing just how long these deep-sea creatures have been living in the fjords. An amazing site, and an amazing last dive of this expedition.
With a little sadness we returned to the station and began packing equipment and samples for the long ride home.
But I’ll be back next year – to collect the loggers and download their valuable data, to inventory the samples the assistants at the Huinay Scientific Field Station will have collected for me, and to dive once again in fields of (usually) deep-sea corals.
I would like to thank the fantastic help and assistance given to this expedition from all those at the Huinay Scientific Field Station – this expedition and valuable science could not have been done without you – Muchas Gracias!
Relive the Expedition