Abstract
Even though Glycymeris longior is a clam widely distributed in the SW Atlantic Ocean, little is known about its biology and life history. The present study assessed the periodicity of the internal growth increments of G. longior using thin shell sections. Each internal growth increment was composed of two alternating bands: a translucent band (light-coloured when viewed with transmitted light) and an opaque band (dark-coloured). Annual formation for each pair of bands was demonstrated. The formation of the annual growth increments was synchronous among individuals. Growth was determined from live clams collected at El Sótano, Argentine Sea (age range = 29 to 69 years). According to the growth model, G. longior grows fast during the first 5 years of life and then growth becomes slower in later years; individuals reached 50% and 90% of maximum size at 5 and 13 years of age, respectively. High variability was found in shell height for the first 10 years: differences up to 5–7 mm among individuals were registered for the first 2 years of age, and up to 11 mm between the ages of 3 and 9 years. The growth performance index phi-prime (φ′) and the index of growth performance (P) of G. longior were compared with those of other Glycymeris species. Our results indicate that G. longior is a slow-growing species with a long lifespan (maximum longevity = 69 years).
Highlights
Bivalve shells show periodic deposition in the form of regular external growth rings or internal banding; information about the life history of the individual and the environment in which it lived is preserved in the shells [1]
The genus has been studied given its commercial importance: G. glycymeris is industrially exploited in the NE Atlantic; G. nummaria and G. pilosa support artisanal exploitation at Mediterranean Sea [8]; a small-scale but expanding G. grayana fishery operates in New South Wales, Australia [9]
We assessed the periodicity of the internal growth increments in thin sections of shell
Summary
Bivalve shells show periodic deposition in the form of regular external growth rings or internal banding; information about the life history of the individual and the environment in which it lived is preserved in the shells [1]. The shell is deposited in temporal cycles that can be daily, seasonal and/or annual [2]. The assessment of such temporal frequencies is a required step in ageing methods [3, 4]. Over an annual growth cycle, an annual growth increment delimited by a growth line is deposited in the shell [2]. The genus has been studied given its commercial importance: G. glycymeris is industrially exploited in the NE Atlantic (annual catches varied from 3000 to 7000 t for the period 1999–2009, [7]); G. nummaria and G. pilosa support artisanal exploitation at Mediterranean Sea [8]; a small-scale but expanding G. grayana fishery operates in New South Wales, Australia [9].
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
