Population dynamics and secondary production of Donax trunculus (Mollusca, Bivalvia) in the Gulf of Annaba (Northeast Algeria)

Abstract

The population dynamics and secondary production of the wedge clam Donax trunculus were studied in the Gulf of Annaba (Northeast Algeria) monthly for one year at a site close to the Annaba port and the Seybouse river, affected by industrial and agricultural pollution (Sidi Salem), and at a site more distant from major pollution sources, but exploited by fishery (Echatt). The number of individuals (N) was lower at Sidi Salem (36–148 ind m-2) than at Echatt (63–272 ind m-2) in most sampling dates, while the biomass was more variable from one date to another, with no consistent pattern of differences between sites. The condition index (CI), although slightly higher at Sidi Salem than at Echatt, showed at both sites a major increase in March/April, June/July and October, reflecting two main periods of gonads development and increase in the level of stored reserves at the end of the reproductive period. Consistently, the recruitment of D. trunculus ran from April to October with a major peak of abundance in spring and a minor one in early fall. The maximum age of D. trunculus was 3 years and the growth rate was highest in the first year. Annual somatic production (P) was lower at Sidi Salem (0.773 g AFDM m-2 yr-1) than at Echatt (1.262 g AFDM m-2 yr-1), possibly reflecting a lower mean annual biomass at Sidi Salem (1.642 AFDM m-2) than at Echatt (3.046 AFDM m-2), while the annual P/B ratio was similar between the two sites (i.e. 0.471 and 0.414 yr-1, respectively). Lower N and P at Sidi Salem compared to Echatt are consistent with the proximity of Sidi Salem to the industrial port of Annaba and low hydrodynamic conditions which may favor the accumulation of pollutants, such as hydrocarbons. On the other hand, moderate secondary production of D. trunculus at Echatt compared to other Mediterranean sites may be due to excessive harvesting. We suggest that the low secondary production described in this study should be taken into account for the development of sustainable strategies of clam exploitation in the Gulf of Annaba. In particular, effort should be made to reduce land-based pollution and to regulate the collection of D. trunculus according to the life cycle and production potential of this species.

Morphometric Aspects and Growth Parameters of the Wedge Clam (Donax trunculus) of the Black Sea, Turkey

“…The highest growth rate in length was found in 5-10 mm length group. Neuberger-Cywiak et al, (1990) found similar results and reported the highest growth rate at the first 2.5 months, and Hafsaoui et al, (2016) reported the highest growth rate within the first year. Individuals within the length group 25-30 mm constitutes 20.75 % of overall samples.…”

“…There are various studies conducted on wedge clam from the Atlantic Ocean (Bayed & Guillou, 1985;Bayed, 1991Bayed, , 1998Guillou & Bayed, 1991) and from the Mediterrranean Sea (Mouëza, 1972;Mouëza & Chessel, 1976;Ansell & Bodoy, 1979;Neuberger-Cywiak et al, 1990;Deval, 2009;Hafsaoui et al, 2016).…”

Population dynamics of blood clams Tegillarca granosa in Kendari Bay, Southeast Sulawesi, Indonesia

“…The size classifications of blood clams in Kendari Bay were less diverse compared to those of other species in other estuaries, such as Cerastoderma edule (Callaway et al 2013), Darina solenoides (Lizarralde et al 2018), each consisting of 4 age groups, as well as beach clams, namely Donax trunculus (Hafsaoui et al 2016) and Circenita callipyga with 3 and 3-4 age groups, respectively (Bagher et al 2007). However, the group composition obtained had little difference from the Pokea clams exploited in the Pohara River and Lasolo River, each having 2 and 3 size categories (Bahtiar et al 2018).…”

Habitat Preferences of PokeA (Batissa violacea var. celebensis von Martens, 1897) Basic on Substrat Characterisation in Pohara River Southeast Sulawesi

“…Kepadatan kerang pokea selama penelitian di Sungai Pohara Kepadatan pokea di Sungai Pohara yang ditemukan berada pada kondisi yang relatif sama dengan kerang yang sama di Sungai Lasolo (Bahtiar et al, 2018), dan beberapa kepadatan jenis kerang lainnya seperti: Cerastoderma edule (Callaway et al, 2013), Mesodesma mactroides Hermann et al, 2010), Anomalocardia brasiliana (Rodrigues et al, 2013). Namun kepadatan kerang pokea jauh lebih tinggi dibandingkan bivalvia lainnya seperti: Donax trunculus (Hafsaoui et al, 2016), Anomalocardia brasiliana (Mattos & Cardoso 2012;, tetapi jauh lebih rendah pada spesies yang invasif seperti: Dreissena polymorpha (Kobak, 2005) Anomalocardia brasiliana (Corte et al, 2015)…”