August 22, 2012 Going to the Zoo—the Copepod Zoo with Carin Ashjian
Zooplankton Project by Dr. Ashjian-
Zooplankton are small animals that live in the water and that swim so slowly that they cannot swim against the ocean currents. Zooplankton are important members of the ocean food web as they consume the very small phytoplankton (plants) that grow in the water and in turn are eaten by larger animals such as fish, jellyfish, sea birds, and even the massive bowhead whales. In the Chukchi Sea, the zooplankton usually cannot eat all of the phytoplankton so that the phytoplankton falls unconsumed to the sea floor where it feeds the high abundance of benthic animals that is typical of this region. Here on Hanna Shoal, we are interested in how many and of what type of zooplankton are found at the different locations that we are sampling and how the physical characteristics of the ocean such as currents and the source of the ocean water (Bering Sea, Arctic Basin) are associated with the types of plankton that we see. We are particularly interested in the distributions of crustacean copepods of the species Calanus glacialis and Calanus hyperboreus and of crustacean euphausiids, or krill (look like small shrimp), since these animals are important food for the bowhead whale in this area of the Arctic Ocean.
To do this, we are collecting plankton using a Bongo net. The Bongo is actually two nets that are mounted on circular frames that are joined together (looks like a Bongo drum).
After we collect the plankton, we preserve them so that we can count them using microscopes once we have the samples back in the lab at home. We are also collecting some zooplankton using a ring net.
We pick Calanus copepods from the sample using microscopes and save them for genetic analysis and to determine their RNA/DNA to see how metabolically active they are. We enjoy looking at the copepods as they are quite beautiful. One day on this trip, we saw a female copepod laying eggs. Copepods have a complex life cycle and, similar to insects, molt through a series of life stages before becoming adults. There are six naupliar and five copepodid life stages before the young copepod reaches adulthood. The largest copepod in the photograph of the “copepod family” is a stage V copepodid and is probably 4 mm long.
Final notes of the day
It is midnight and we are in the Barrow Canyon sampling at 10 locations called stations. We are transiting to station 6. The stations have been taking longer as the ship frequently has to reposition as it moves away by the current or wind. We think we will be up all night. We are suppose to do 2 more stations tomorrow and one Friday morning. We all hope that we can make all of the stations. If not, the schedule will be modified to adjust for time and maximum amount of sampling.
Special thanks to Dr. Ashjian, our special guest journal writer.
Watch this video of a sea butterfly, Clione limarina, swimming around. It was found by the zooplankton team.