Hello!   This is Alex.  I am a MIT/WHOI student on the biology team.  I  am interested in how well pteropods can cope with the changing ocean  chemistry. Yesterday we tested our equipment off the continental  shelf.   Spirits rose as we developed our sea legs and got salty.
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| Peter Wiebe and Mohammad Uddin look at a plot of our transect stations and notice our transition into the warm         water of the Gulf Stream. | 
The  HammerHead was the first to go in, towed by the A frame on the stern.   It has six broadband transducers to detect animals and physical water  characteristics with sound.    Off the starboard winch system, we  lowered a CTD rosette to 550 m, which sensed conductivity, temperature,  and depth, had bottles for testing the chemistry of different water          layers and a VPR (Video Plankton Recorder).  Later we will be  sending our equipment deeper, up to 3000 m, but  this will take more  time.  Then, we set up the MOCNESS (Multiple Opening  and Closing Net  and Environmental Sensing System) with its nets and cod  ends (which  condense the sample) and towed it in the top 100 m. 
  
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| Left: Bosun Clindor and  ABs Mark and Chris deploy the HammerHead Center: Gareth and marine tech  Rob discuss by the CTD rosette Right: Everybody is excited to recover  the MOCNESS. | 
We  emptied the nets...and, Eureka! Pteropods! And they were diverse, even  gymnosomes (no shell) that would gladly eat some of the others.
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| Photos  that we took  under a microscope of pteropods found in our nets from  different  genera, Top left: Peraclis has an operculum (door that can  block the  shell, unlike most other pteropods), Top right: Cavolinia, Center: Cresis, Bottom left: young Pneumodermopsis (gymnosome) still has a cilliary band for locomotion, Bottom right: adult Pneumodermopsis | 
Also,  there were small and larval fish, purple jellies, copepods that  were a  luminescent blue-purple, and some swiftly-moving amphipods.  All  in all,  it was a successful tow, and we are all looking forward to  taking more  samples.
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| Jacinta  Edebeli, Leo  Bercial, Cris Luttazi, and Amy Maas (clockwise from the  left) pick  their favorite specimens from this sample, including  pteropods! | 
 
Ahoy there! I would like to add my 'pteropod-two-cents' to your post- while you may find Limacina helicina at your furthest station to the north, you are most likely to find Limacina retroversa in the waters off the eastern seaboard! Not easy to tell the two apart, actually! We find L. helacina occasionally in Barrow Canyon in the Arctic- apparently it's the only Limacinid in Arctic waters. Happy hunting!
ReplyDeletePhil
PS: You should get some great pteropod pictures with the VPR - look to see if they're surrounded by mucous nets- we've NEVER seen any!
Nice to hear from you Phil. Like you predicted, we caught our first Limacina retroversa last night -- no doubt the first of many.
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