Re: Mass Stranding of Sea Hares in nthn New South Wales
January 16, 2007
From: Inger Vandyke
Concerning message #19225:
Hi there,
I am another witness of the Crescent Head sea hare stranding and returned from that location last night (14 January). All facts from the previous post were as I had witnessed also except we noticed there were some individuals that were slightly different than others in that they had white spots. This didn't appear to be size related.
Locality: Crescent Head, up to 3 m, New South Wales, Australia, On shore location, calm water conditions, 14 January 2007, Intertidal, sandy bottom. Length: smallest 20 mm largest around 240 mm. Photographer: Inger Vandyke.
I also wondered, since I am a keen diver, if the unsettled water temperatures from the last six weeks may have had something to do with this. I dive two weeks before Christmas in 23 degree C water temperature. The following week in the same location was 16 degrees. I didn't record this at Crescent Head I'm sorry.
Is there a connection between sea hare reproduction and water temperature?
Thank you for a great site. You have solved the ID query I have had for years looking at large sea hares in Nelson Bay, NSW.
Regards
Inger Vandyke
ingervandyke@hotmail.com
Inger Vandyke, 2007 (Jan 16) Re: Mass Stranding of Sea Hares in nthn New South Wales. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/19232Dear Inger,
Thanks for the photos. It's possible that water temp has something to do with it but these animals are living off shore in fairly open water so I don't think oxygen levels would have been greatly affected and the temperature in itself wouldn't have caused them much stress. I can't recall any research showing water temp triggered mating behaviour, but there are many things we don't know about these animals. All things being equal, mating seems to be triggered by the close proximity of another Sea Hare!
It's possible you had more than one species of Sea Hare but I am afraid the photos don't give me enough detail to identify them. Certainly the large Sea Hares in Nelson Bay are almost certainly Aplysia extraordinaria.
If you get a chance to take higher resolution photos I am happy to try and identify them. Your photos show their purplish ink very well.
Best wishes,
Bill Rudman
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