Journal of the Marine Biological Association of the United Kingdom



Reproductive biology of Alvinocaris muricola (Decapoda: Caridea: Alvinocarididae) from cold seeps in the Congo Basin


Eva  Ramirez-Llodra a1c1 and Michel  Segonzac a2
a1 Institut de Ciències del Mar, CMIMA-CSIC, Psg. Marítim de la Barceloneta 37-49, 08003 Barcelona, Spain
a2 Ifremer, Centre de Brest, Laboratoire Environnement Profond-Centob, BP 70, 29280 Plouzané Cedex, France

Article author query
ramirez-llodra e   [PubMed][Google Scholar] 
segonzac m   [PubMed][Google Scholar] 

Abstract

The caridean shrimp Alvinocaris muricola has been observed forming high density populations over mussel beds on the giant pockmark cold seep site Regab in the Gulf of Guinea at 3150 m depth. Samples were collected using the ROV Victor 6000, a beam trawl and a TV grab from two sites. The specimens were sexed and measured for population structure analysis. In one sample the sex ratio was 1:1, but the other sample had a sex ratio significantly biased towards females. The maximum size of females is larger than males. A sub-sample was used for gametogenesis and fecundity analysis. The oogenesis and spermatogenesis of A. muricola is characteristic of caridean shrimps. The oogonia proliferate from the germinal epithelium and develop into previtellogenic oocytes that migrate to the growth zone. Vitellogenesis starts at 80–100 μm oocyte size and the developing oocytes are surrounded by a monolayer of accessory cells. The maximum oocyte size was 515 μm. There was no evidence of synchrony in oocyte development, with all oocyte stages present in all ovaries analysed. However, seasonal sampling would be necessary to confirm the lack of seasonality in reproduction. In males, the sperm develops in sperm sacs in the testis. As in all caridean shrimp, the broods of A. muricola are held on the pleopods P11 to P14. Total fecundity was related to female size and ranged between 1432 and 5798 embryos. Within a brood all embryos are at the same stage of development, but three different stages were identified in different females, with no clear seasonal trend. The embryos were small, with mean dimensions of 0.66×0.55 mm, suggesting planktotrophic larvae and a potential extended larval development.

(Published Online December 15 2006)
(Received April 4 2006)
(Accepted October 30 2006)


Correspondence:
c1 Corresponding author, e-mail: ezr@icm.csic.es