In my previous All Creatures entry I introduced you to two local stars – seastars that is-  in the waters around Palmer Station.   As members of the phylum Echinodermata, sea stars have a large and diverse extended family, as the opening image reflects. 

A five-armed purple sea star rests along a similarly colored short spined urchin partially covered in algae; below the pair stretching across the image a brownish sea cucumber and below a longer, less densely spined pencil urchin

water samplingIf you’ve read Addie’s latest post, then you know that the experiment is now officially underway! Read on to find out more about the water chemistry we do each day and why.

white bucket of seawater with green and red plants with the white tubular mixing tankNow that we have the experiment started, as Hannah discusses in her most recent post, we’re done sorting amphipods and have moved onto doing seawater chemistry. Every morning we test six water samples from randomly selected buckets to give us more precise measures of the conditions than a pH probe by itself can provide. Each of us has our own job that we take care of, which for me is running titrations to calculate the alkalinity of the water (a measure of the sample’s ability to buffer added acids and resist changes to pH). Meanwhile, Jami is running the spectrophotometer to determine pH, and Hannah is measuring the pH of all 24 tanks with the handheld probe to make sure the ones we aren’t testing that day are still at the right level.

Dive tender Addie approaching dive put in spot with divers Chuck and Maggie. Photo by Kari NelsonAs you’ve read in other posts, we wear a lot of stuff when diving. A lot of heavy stuff. We have to get everything into the boat on station and onto us at the dive site. Then we need help getting it back into the boat at the end of the dive, and everything has to get back out of the boat on return station to make diving possible overall. That doesn’t happen without a lot of help and hard work by the dive tenders.

White rectangular plastic tub filled with red amphipods no bigger than a pinkie fingernail floats in shallow water aquaria as the amphipods are counted into opaque jars nestled in a black thick foamed tray; of ice, two small sheets of white plastic, one with a yellow pencil, is nearby to record the numbers transferred
In the last several weeks, our team has discussed several of the tasks that needed to be completed before we could start our experiment: diving to collect samples, removing amphipods from algae, and sorting different amphipod species. These may seem like simple tasks, but we struggled to complete them this season.