Comparison of Talitrus saltator (Amphipoda, Talitridae) biology, dynamics, and secondary production in Atlantic (Portugal) and Mediterranean (Italy and Tunisia) populations

Abstract

Talitrus saltator biology, population dynamics, and reproduction were studied more or less simultaneously at three sand beaches: Lavos, on the western coast of Portugal; Collelungo, on the Italian coast of the Thyrrenian Sea; and Zouara, on the northern coast of Tunisia. The species exhibited a consistent pattern of aggregated distribution. Densities were higher at Lavos than at Collelungo and Zouara. Reproduction took place from early March to late September at Lavos and Collelungo, and from late February to early November at Zouara. The average sex ratio was favourable to males at Lavos and Collelungo, and to females at Zouara. Based on data from Lavos, the population abundance was positively correlated with temperature, while the percentage of juveniles in the population was positively correlated with temperature and sediment moisture. Adult individuals from the Atlantic population were larger than the Mediterranean ones, while newborn individuals from the Mediterranean were slightly larger than Atlantic ones. Life span was estimated at 7-11 months at Lavos, 6-9 months at Collelungo, and 6-8 months at Zouara. Cohorts born at the beginning of the reproductive period tend to have shorter lives than the ones born later in the season, with longer life spans occurring in cohorts that crossed the winter to breed in the next year. The minimum period necessary for sexual differentiation after birth was estimated at AE4 weeks at Lavos, AE3 weeks at Collelungo, and AE4.5 weeks at Zouara, for males, and AE6 weeks at Lavos, and AE5 weeks at Collelungo and Zouara, for females. The period necessary for female's sexual maturation after being born was estimated at AE10 weeks at Lavos, and AE8 weeks at Collelungo and Zouara. At the studied sites, T. saltator appeared as semiannual species, with iteroparous females appearing to produce at least two broods per year, and exhibited a bivoltine life cycle. Growth production (P) was estimated at 0.74 g m ÿ2 yr ÿ1 ashfree dry weight (AFDW; 17.7 kJ m ÿ2 yr ÿ1 ) at Lavos, 0.12 g m ÿ2 yr ÿ1 AFDW (2.8 kJ m ÿ2 yr ÿ1 ) at Collelungo, and 0.61 g m ÿ2 yr ÿ1 AFDW (14.3 kJ m ÿ2 yr ÿ1 ) at Zouara. Elimination production (E) was estimated at 1.40 g m ÿ2 yr ÿ1 AFDW (33.5 kJ m ÿ2 yr ÿ1 ) at Lavos, 0.20 g m ÿ2 yr ÿ1 AFDW (4.8 kJ m ÿ2 yr ÿ1 ) at Collelungo, and 1.11 g m ÿ2 yr ÿ1 AFDW (26.6 kJ m ÿ2 yr ÿ1 ) at Zouara. The average annual biomass ð B BÞ (standing stock) was estimated at 0.13 g m ÿ2 at Lavos, 0.014 g m ÿ2 at Collelungo, and 0.084 g m ÿ2 at Zouara, resulting in P= B B ratios of 5.7 at Lavos, 8.2 at Collelungo, and 7.3 at Zouara, and E= B B ratios of 10.8 at Lavos, 14.4 at Collelungo, and 13.1 at Zouara. The present results, combined with information from literature, revealed a geographic variation in T. saltator populations with regard to their morphological characteristics, growth rates, life spans, and life cycles.

Niche segregation amongst sympatric species at exposed sandy shores with contrasting wrack availabilities illustrated by stable isotopic analysis

“…A full characterisation of the main physical features and macrofaunal communities of both beaches is provided in Gonç alves et al (2009,2013) and Marques et al (2003).…”

“…Animals were collected by hand and were kept alive in local sand and then transported to the laboratory for stable isotopic analysis. Wrack quantity (g m −2 ) and the organic matter content in the sediment were determined according to the procedures described in Marques et al (2003). A second sub-sample was taken during neap tide from each sampling season in order to assess the natural zonation pattern of the sympatric crustaceans.…”

“…Some of the most conspicuous representative species of these beaches are the talitrid amphipods Talitrus saltator and Talorchestia brito, and the oniscoidean isopod Tylos europaeus, widely studied in the central coast of Portugal (Gonç alves et al, 2005(Gonç alves et al, , 2009(Gonç alves et al, , 2013Marques et al, 2003).…”

Importancia del subsidio de macroalgas sobre la abundancia y biología poblacional del anfípodo Orchestoidea tuberculata (Nicolet) en playas arenosas del centro sur de Chile

“…2) y ii) en las playas con mayor cantidad de macroalgas, se registraron los valores más altos de los atributos poblacionales estimados para O. tuberculata. Siguiendo el mismo razonamiento anterior, es posible asumir que el crecimiento más rápido registrado para O. tuberculata en la playa de Calfuco Norte, también sería el resultado de la mayor disponibilidad de macroalgas en esa playa comparada con la de Mehuín (ver Contreras et al 2003), una hipótesis que también ha sido propuesta por Marques et al (2003) para explicar el mayor crecimiento del anfípodo Talitrus saltator en las playas arenosas de Lavos (Portugal) y Collelungo (Italia) comparado con el crecimiento por este talítrido en la playa de Zouara (Túnez).…”

Temporal changes in macrofauna as response indicator to potential human pressures on sandy beaches

“…The animals collected were separated in the laboratory and preserved in 70% alcohol for identification. Sediment samples were collected to determine the sediment grain size, water content in the sediment and organic content in the sediment following the protocol described in Marques et al (2003).…”