At 23:45 25-7-2008, you wrote:
>>While running a little submersible camera in Akutan Bay (about 54.13^N,
>165.82^W, in the eastern Aleutian Islands) last month for a harbor study, my
>colleagues and I came across some impressive fields of what I suspect is a
>tubiculous polychaete. I am not a marine biologist, and have only a passing
>(if admiring) acquaintance with Polychaeta.
>>I've attached several screen-shots from the digitized video. The resolution
>is extremely poor, but we could see beds (sometimes very dense, sometimes
>sparse) of dark brownish tubes, about 1 cm in diameter and extending maybe
>10-20 cm from the seafloor. The tubes seemed to be semi-rigid but resilient,
>and there is a hint of a small pale-to-reddish tuft emerging from the top.
>We viewed the masses of tubes over hundreds of meters of transect, in waters
>roughly 25 to 8 meters deep, but don't have a real idea over how wide an area
>the field covered. Unfortunately, we didn't have a dredge with us, and
>couldn't grab a sample.
>>Questions: Are these polychaetes we're looking at here? Assuming these are
>polychaetes, is it possible to say anything about the taxonomy of these
>fellows (even just down to order or family) based on the gross information
>available in the photos (size, living habit, etc.)? They resemble a blurry
>photograph I've found of a wad of Alaskan polychaetes brought up in a dredge,
>identified as 'Sabella sp.'. I had assumed such tubiculous polychaetes were
>primarily infaunal (based on the few illustrations I'd seen), and not
>extending so far above the sediment as seen in the photos and video.
>>>Thanks much for any guidance or insight you might be able to provide,
>>Chris Floyd
>Environmental Resources
>US Army Corps of Engineers
>Anchorage, Alaska
Dear Chris,
Don't know if you already had reactions upon your question. Anyhow, I
am a specialist in calcareous tubeworms, family Serpulidae. Even
though these can form fields of the size like figured by you, the
individual size of the serpulid builders is less than what you
figure, and the structure of the reefs is more compact, not as open
as your fields. Moreover, serpulids build rigid calcareous tubes.
Your tubes remind me of the family Sabellidae. Not all of them are
"infaunal", many are epifaunal. Must say that I never have seen such
large aggregations of this family, but I have mainly worked in
tropical waters. The "tufts" in your photographs are too blurred
unfortunately, and not the nice radiolar crowns typical for
sabellids, but that may be due to the screenshot quality. Have a
feeling that Bush (1905) photographed Alaskan sabellids of your
indicated size (Bush, K.J., 1905.- Tubicolous annelids of the tribes
Sabellides and Serpulides from the Pacific Ocean. Harriman Alaska
Exp. 12, 1904 [publ.1905]: 169-355, pl.21-44. )
Maybe one of my sabellid colleagues can give a better guess.
wormly
dr. Harry A. ten Hove
Zoological Museum
University of Amsterdam
Mauritskade 57
P.O.B. 94766, 1090 GT Amsterdam
the Netherlands
H.A.tenHove from uva.nl
