Publication Date:
2022-05-25
Description:
Author Posting. © The Author(s), 2009. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Deep Sea Research Part II: Topical Studies in Oceanography 56 (2009): 1835-1846, doi:10.1016/j.dsr2.2009.05.024.
Description:
Protobranch bivalve species of the family Nuculidae pass either through a planktonic
lecithotrophic larval stage or a direct non-planktonic development. Oogenesis of the three
sublittoral species examined is synchronous. Deposition of egg masses by Nucula delphinodonta
and spawning by Nucula annulata and Nucula proxima occurs only during summer months.
Among the four bathyal and abyssal species, Ennucula similis, Ennucula granulosa, Deminucula
atacellana, and Brevinucula verrilli, oogenesis is asynchronous and there is no discernable
pattern of periodicity of spawning. Absence of periodicity in reproduction in these deep-sea
species is confirmed by examination of individuals from dredge samples taken at different times
of year. The median apparent fecundity among both sublittoral and deep-sea species is directly
related to size (i.e., shell length) and age. Among the Nuculidae the median apparent fecundity is
greater among sublittoral than bathyal and abyssal species. The geographic distribution of a
species depends on its capacity to disperse. The dispersal of the planktonic lecithotrophic larvae
of the sublittoral species Nucula annulata and Nucula proxima is limited to the continental shelf
of the northwestern Atlantic by inshore bottom circulation and because these very small
planktonic larvae (〈2.5 mm) lack the capacity to move vertically upward through the water
column into the offshore currents. On the other hand, the bathyal and abyssal species having
lecithotrophic larvae have a very wide amphi-Atlantic distribution extending from 60°N to 40°S
atitude along the North and South American coasts and from 55°N to ca. 19°S from off Europe
southwards to the coast of West Africa as a consequence of dispersal by planktonic
lecithotrophic larvae along the seafloor. The amphi-Atlantic dispersal must occur stepwise
between deep-sea populations (e.g., off Greenland). Such a geographic distribution indicates a
widespread dispersal and is supported by the genetic similarity that has been described between
North American and western European populations of Deminucula atacellana.
Description:
Financial support was provided by
research grants from the National Science Foundation.
Keywords:
Oogenesis
;
Periodicity
;
Fecundity
;
Geographic distribution
Repository Name:
Woods Hole Open Access Server
Type:
Preprint
Format:
application/pdf
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