Grand Central Station

A segmented worm larva in our HG-IV sample, 
probably Prinospio cirrifera

The central station of the HAUSGARTEN observatory, HG-IV, is a very special place. I'm willing to bet it's one of the most researched points in the Arctic Ocean. Since 1999, this unassuming seafloor habitat has been the subject of long-term experiments and repeat annual sampling. Water temperature and current speed are recorded year-round by instruments on a long-term lander. We return to HG-IV over and over on every HAUSGARTEN expedition. I could rattle off a list of the common species on the seafloor at HG-IV, and I'm sure many of my colleagues could as well. It is a place that we all know very well. 

We've spent quite a bit of time at HG-IV this week. Between water sampling, sediment sampling, plankton nets, and landers, there is hardly a component of the ecosystem that we have not touched. 

The larval samples we collected at HG-IV were our best ones yet! There was much higher biodiversity, with larval brittle stars, clams, and worms all landing in our net. Even cooler, we collected some of the same species from last year. We were able to identify many of our larvae to species right away by referencing the photos on the lab wall! Plus, it's a good sanity check to have some of the same organisms show up two years in a row. That means the patterns we detected are actually consistent rather than a fluke. 

A brittle star larva, Ophiocten gracilis

Probably the most satisfying aspect of our HG-IV samples was being able to identify the brittle star larvae. Last year, Kharis had marked all brittle star larvae as a single morphotype - "Pluteus 1" - before discovering that she had actually collected 4 different species. In the lab, we had to back up and re-examine all of her specimens. We looked up papers that others had written about brittle star larvae and ended up sequencing more individuals to verify our identifications. It took a lot of time, but it appears that time has paid off! This year, I can tell the difference between brittle star larvae based on how they look - no sequencing required! The differences are subtle, but once you know what you're looking for, you can definitely tell the species apart!

We're up to specimen #60, so the larvae are accumulating on board! I'm very pleased with our larvae!