Growth and reproductive cycle of Donax trunculus L., (Mollusca: Bivalvia) off Faro, southern Portugal
Introduction
Donax trunculus is an Atlantic–Mediterranean warm-temperate species. In the Atlantic it has been recorded from Senegal to the French coast (Tebble, 1966). It inhabits the high-energy environment of exposed sandy beaches, where it forms extensive, dense beds. It is the most inshore surf clam species in Portuguese waters, occurring to 6 m depth, with higher densities between 0 and 3 m depth. It is an excellent burrower, which makes it well adapted to life in the swash zone.
Along the south coast of Portugal, D. trunculus is one of the most important commercial species exploited by an artisanal fleet. Actually a total of 60 boats are involved in this fishery. These boats vary in length from 4 to 15 m, with engines of 17–150 Hp. Unfortunately no reliable statistics concerning catches are available since fishermen were not obliged to declare their catches until 1998. However in 1997, a catch of 425 t of D. trunculus, worth PTE128 million was estimated. Despite its economic importance, its biology in this region has not hitherto been described. This study reports on the rate of growth, life span and age/size at first maturity, of a population of Donax trunculus, off Faro, southern Portugal, by way of a comparison with other populations at different geographical locations.
Section snippets
Materials and methods
Samples were collected by dredging off Faro, from December 1993 to November 1994, at approximately monthly intervals.
Growth
Fig. 1 illustrates acetate peels from sections through the shell of D. trunculus. According to Taylor et al. (1973)these shells are composed of three layers, an outer composite prismatic layer, middle crossed lamellar layer, and an inner homogeneous/complex crossed lamellar layer (Fig. 1(A)).
The growth bands in the outer layer run parallel to the growing edges of the shell, and appear as thin dark lines, with wider transparent regions, i.e. the growth increments, between (Fig. 1(B)). In some
Growth
Rapid shell growth occurred in spring and summer, when wide microgrowth increments were deposited, whilst slow growth occurred during late summer and early autumn with the deposition of narrow growth increments and the formation of a well-defined annual growth ring. Surprisingly, we did not note a period of cessation of growth through the winter months. In fact, D. trunculus renewed growth in November which then continued until the following October. This is a different pattern of seasonal
Acknowledgements
We would like to thank three anonymous referees whose suggestions greatly improved the manuscript. We also thank the staff of IPIMAR/CRIPSul for collecting the samples and the crew of NI/DONAX for their skilful handling of the boat and fishing gears. M.B. Gaspar was funded by JNICT – PROGRAMA CIÊNCIA and PRAXIS XXI.
References (24)
- et al.
Seasonal changes in tissue weight and biochemical composition for the bivalve Donax trunculus L. on the Algerian coast
J. Exp. Mar. Biol. Ecol.
(1980) - Ansell, A.D., Bodoy, A., 1979. Comparison in events in seasonal cycle for Donax vittatus and Donax trunculus. In:...
- et al.
Observations on the biology of Donax trunculus and Donax vittatus at ell d'Oléron (French Atlantic Coast)
Mar. Biol.
(1980) - et al.
Neurosecretion and gonad maturation in a population of Donax trunculus L. from Leghorn (Italy)
Bull. Zool.
(1972) Reproduction de Donax trunculus sur la côte Atlantique marrocaine
Cah. Biol. Mar.
(1990)- et al.
Contribution á l'etude des populations du genere Donax: la populations de D. trunculus L. (Mollusca, Bivalvia) de Mehdia (Maroc)
Ann. L'Inst. Océan., Paris
(1985) Croissance saisonniére du bivalve Donax trunculus (L.) en Mediterranée nordoccidentéle (France)
Malacologia
(1982)- et al.
Age and growth rate of the clam Spisula solida L., from a site off Vilamoura, south Portugal, determined from acetate replicas of shell sections
Sci. Mar.
(1995) - et al.
Reproductive cycles of the razor clam Ensis siliqua and the clam Venus striatula off Vilamoura, southern Portugal
J. Mar. Biol. Ass. UK
(1998) - et al.
Aspects de la dynamique des populations de Donax vittatus Donax trunculus et en baie de Douarnenez
Ann. L'Inst. Océan., Paris
(1980)
Recherche sur la sexualité des Mollusques Bivalves
Bull. Biol. Franco-Belgian
Aspectos de la dinamica de población de Donax trunculus (Linnaeus, 1758) (Bivalvia: Donacidae) en la rı́a de El Barquero (Lugo, NO Espana)
Invest. Pesq.
Cited by (107)
Reproductive cycle of two marine sentinel bivalve species (Donax trunculus and Scrobicularia plana) in the Agadir bay, Southern Morocco
2022, Regional Studies in Marine ScienceNear-surface ocean temperature variations across temporal scales in the coastal eastern Adriatic
2022, Continental Shelf ResearchInfluence of wind, rainfall, temperature, and primary productivity, on the biomass of the bivalves Spisula solida, Donax trunculus, Chamelea gallina and Ensis siliqua
2021, Fisheries ResearchCitation Excerpt :The species E. siliqua, in the Algarve, show an extensive inactive phase between July and October, with gametogenesis beginning in November and spawning period occurring between April and May (Gaspar and Monteiro, 1998). Thus, in all cases and considering the estimated growth equations, within one year after settlement all the individuals of bivalve species studied would have grown to a capturable size during IPMA’s bivalve surveys (Gaspar et al., 1994, 1995; 1999; 2004) (Fig. 4). Multiple linear regression was used to investigate the effect of the environmental variables on species biomass of the following year (using SAS/STAT®).
Assessment of reproductive cycle, parasitism and biological indices of the wedge clam Donax trunculus along the Taghazout coastline (on the Moroccan Atlantic Coast)
2021, Regional Studies in Marine ScienceCitation Excerpt :Also, Badino and Marchionni (1972) and Mouëza and Frenkiel-Renault (1973) found a sex ratio of 1:1 in D. trunculus. However, Gaspar et al. (1999) found that the proportion of males has increased in the D. trunculus population in Portugal and this could be explained by differential growth or mortality resulting from the spawning effort. Indeed Boussoufa et al. (2015) observed that the sex ratio in D. trunculus from Tunis Bay was in favor of males.