BIOLOGY, POPULATION DYNAMICS, AND SECONDARY PRODUCTION OF TALITRUS SALTATOR (AMPHIPODA, TALITRIDAE) AT KORBA BEACH (EAST COAST OF TUNISIA)

Abstract

[The biology and population dynamics of Talitrus saltator (Montagu, 1808), a talitrid amphipod of the supralittoral zones of sandy beaches, was studied from December 2001 to December 2003 at Korba beach, Tunisia. Ovigerous females and the emergence of new cohorts were observed during the warmer months, with recruitment taking place from February-March to November. The population thus showed a seasonal pattern of reproduction, with stronger breeding during summer. The sex ratio was slightly in favour of females. Mean brood size was 11 and fecundity appeared to be positively correlated with female size. Life span was estimated at 6 to 9 months depending on the time of birth, with cohorts born at the beginning of the reproductive period tending to have shorter lives than those born later in the season. The present two-year study was consistent with previous preliminary results obtained at Zouara (Tunisia) (Marques et al., 2003), confirming Talitrus saltator as a semiannual species, with iteroparous females and a bivoltine life cycle. Growth production (P) was estimated at 0.41 g m–2 y–1 AFDW (ash free dry weight) (9.62 kJ m–2 y–1). Elimination production (E) (summation of losses) was estimated at 0.37 g m–2 y–1 AFDW (8.9 kJ m–2 y–1). The average annual biomass (B) was estimated at 0.073 g mm–2, resulting in a P/B ratio of 5.6 and an E/B ratio of 5.07., The biology and population dynamics of Talitrus saltator (Montagu, 1808), a talitrid amphipod of the supralittoral zones of sandy beaches, was studied from December 2001 to December 2003 at Korba beach, Tunisia. Ovigerous females and the emergence of new cohorts were observed during the warmer months, with recruitment taking place from February-March to November. The population thus showed a seasonal pattern of reproduction, with stronger breeding during summer. The sex ratio was slightly in favour of females. Mean brood size was 11 and fecundity appeared to be positively correlated with female size. Life span was estimated at 6 to 9 months depending on the time of birth, with cohorts born at the beginning of the reproductive period tending to have shorter lives than those born later in the season. The present two-year study was consistent with previous preliminary results obtained at Zouara (Tunisia) (Marques et al., 2003), confirming Talitrus saltator as a semiannual species, with iteroparous females and a bivoltine life cycle. Growth production (P) was estimated at 0.41 g m–2 y–1 AFDW (ash free dry weight) (9.62 kJ m–2 y–1). Elimination production (E) (summation of losses) was estimated at 0.37 g m–2 y–1 AFDW (8.9 kJ m–2 y–1). The average annual biomass (B) was estimated at 0.073 g mm–2, resulting in a P/B ratio of 5.6 and an E/B ratio of 5.07.]