Journal of the Marine Biological Association of the United Kingdom

Life history and reproductive biology of the invasive amphipod Melita palmata (Amphipoda: Melitidae) in the Mar Chiquita coastal lagoon, Argentina

S.  Obenat a1c1, E.  Spivak a1 and L.  Garrido a1
a1 Universidad Nacional de Mar del Plata, Departamento de Biología, Facultad de Ciencias Exactas y Naturales, C.C., 1245, 7600 Mar del Plata Argentina

Article author query
obenat s   [PubMed][Google Scholar] 
spivak e   [PubMed][Google Scholar] 
garrido l   [PubMed][Google Scholar] 


The life history and reproductive biology of the gammaridean amphipod Melita palmata was studied in the Mar Chiquita coastal lagoon (Argentina). The animals were collected fortnightly or monthly from Ficopomatus enigmaticus reefs from December 2000 to March 2002. The population density reached a maximum of 1556.67±1560 ind/m3 (mean±SD) in March 2001, decreased dramatically after intense rainfalls in winter 2001, and had a minimum value of 141.67±27.54 ind/m3 (mean±SD) in March 2002. Size differed significantly between sexes. The maximum size of males was 11.5 mm and this was 1.4 times longer than the length of females. The average sex ratio (0.44) did not differ significantly from an expected 1:1 value. Ovigerous females were present from December to March, when the temperature was above 18°C. The body size of ovigerous females ranged from 2.9 to 6.81 mm. There was a positive correlation between the brood size and body length of ovigerous females, and the maximum number of eggs per female was ten. Recruitment took place during the whole breeding season; juveniles recruited at the beginning of the season matured at the end of the same season, those recruited late would probably reach maturity in the following season.

(Published Online December 15 2006)
(Received March 6 2006)
(Accepted September 8 2006)

c1 Corresponding author, e-mail: