Size of first sexual maturity in Brachidontes rodriguezii (d?Orbigny, 1846) from the southwestern Atlantic Ocean

MARÍA EUGENIA TORROGLOSA; MARIEL OJEDA; HENRIQUE KNACK DE ALMEIDA; JULIANA GIMÉNEZ

Pellston, Michigan

Congreso; 81st annual meeting of the American Malacological Society; 2015

American Malacological Society

The mussel Brachidontes rodriguezii (d´Orbigny, 1846) is the most abundant speciesof rocky shores intertidal at Buenos Aires cost. The intertidal community complexity isrelated to the presence and developed of this mussel. The temporal and spacevariation of the community structure depend on physical (e.g. temperature,salinity and wave exposition) and biological factors (e.g. reproductive cycleand growth). Reproductive aspects as gametogenesis, spawning events and size atmaturity provide valuable information about the biology of species and changes through time and space. The objective of this study was to estimate thesize at first maturity of B. rodrigueziiat artificial hard substrate. A histological determination was done during twoconsecutive reproductive events at summer 2012 and 2013. A total of 335specimens between 3 to 25 mmof total length were studied. Sexualmaturity was related to gonadal activity. Two categories of immature stageswere described: undetermined (without gonadal development) and determined (withearlier gonadal development) where the gonad was restricted to the dorsalregion of the visceral mass. Meanwhile gonad of mature males and females wascompletely developed in both lobes of the mantle and the visceral mass. At 4 mm shell length, oogenesisand spermatogenesis were observed. Minimum sizes at maturity were 6.99 mm for females and 6 mm for males. The size offirst maturity for the population, defined as the shell length at which the 50%of the population reach the gonadal maturity was 8.30 mm for both sexes.