Comparison of the biology, dynamics, and secondary production of Talorchestia brito (Amphipoda, Talitridae) in Atlantic (Portugal) and Mediterranean (Tunisia) populations

Abstract

The biology, population dynamics, and production of Talorchestia brito were studied at two sandy beaches located on the Atlantic (Portugal) and on the Mediterranean (Tunisia) coasts, respectively. The seasonal variation in abundance and the overall densities were similar in both populations. Reproduction occurred from February to September in the Atlantic, and from March to early November in the Mediterranean. The sex ratio was male biased in the Atlantic, and female biased in the Mediterranean. Based on data from the Atlantic population, both abundance and the proportion of reproductive females were positively correlated with temperature, while the proportion of juveniles in the population was positively correlated with temperature and sediment moisture. On average, individuals from the Atlantic were larger than the ones from the Mediterranean. Life span was estimated at six to nine months in the Atlantic, and five to eight months in the Mediterranean. Talorchestia brito was shown to be a semiannual species, with iteroparous females producing two broods per year, and exhibited a bivoltine life cycle. The minimum age required for males' and females' sexual differentiation and for female sexual maturation was shorter in the Mediterranean. Growth production (P) was estimated at 0.19 g m ÿ2 y ÿ1 ash free dry weight (AFDW; 4.3 kJ m ÿ2 y ÿ1) in the Atlantic population, and 0.217 g m ÿ2 y ÿ1 AFDW (4.9 kJ m ÿ2 y ÿ1) in the Mediterranean one. Elimination production (E) was estimated at 0.35 g m ÿ2 y ÿ1 AFDW (7.9 kJ m ÿ2 y ÿ1) in the Atlantic, and 0.28 g m ÿ2 y ÿ1 AFDW (6.3 kJ m ÿ2 y ÿ1) in the Mediterranean. The average annual biomass (B B) (standing stock) was estimated at 0.032 g m ÿ2 in the Atlantic beach, and 0.029 g m ÿ2 in the Mediterranean one, resulting, respectively, in P= B B ratios of 5.9 and 7.5 and E= B B ratios of 10.8 and 9.6. Like other talitrids, T. brito exhibited geographic variation in morphometrical characteristics, sex ratio, growth rates, life span, and reproduction period, with the Atlantic population presenting a slower life history.

Impact of Environmental Factors on Zonation, Abundance, and Other Biological Parameters of Two Tunisian Populations of Talitrus Saltator (Amphipoda, Talitridae)

“…This correlation is in accordance with our expectations in the sense that recruitment took place with temperature increase, leading to density increase. These results are similar to those of Marques et al (2003) and Gonçalves et al (2003) for two Atlantic populations of Talitrus saltator and Talorchestia brito, respectively. As for Zouaraa, no correlation between density and environmental factors was found, mainly perhaps because of the important decrease of the population, which does not allow statistical analysis.…”

“…When assessing the effect of environmental factors on these parameters at Zouaraa, only the percentage of juveniles was positively correlated with temperature, thus controlling breeding activity, and also with sediment moisture. These results confirm those of Marques et al (2003) and Gonçalves et al (2003) for Talorchestia brito, and indicate a more important sensitivity of talitrid juveniles to dehydration (shown by their correlation with sediment moisture), which induces higher concentrations closer to the high water mark (Morrit, 1987). A correlation between juvenile percentage and temperature was also established for the population at Korba.…”

Population dynamics of a freshwater amphipod from South America (Crustacea, Amphipoda, Hyalellidae)

“…These types of distribution have already been observed for other species of Hyalella, such as H. pleocuta, H. castroi (Castiglioni and Bond-Buckup, 2008b) and H. azteca (Saussure, 1858) (Pickard and Benke, 1996). For other amphipods, bimodal distribution also appears to be common as, for example, in Corophium multisetosum Stock, 1952(Cunha et al, 2000, Echinogammarus longisetosus Pinkster, 1973 (Guerao, 2003), Talorchestia brito Stebbing, 1891 (Gonçalves et al, 2003) and Gammarus chevreuxi Seston, 1913 (Subida et al, 2005).…”

Temporal variation in the shore amphipod community in the supralittoral zone of Bizerte Lagoon (northern Tunisia)

“…comm.). Gonçalves et al (2003), demonstrated that cohorts born in the beginning of the reproductive period, i.e., in late winter (Quiaios) and spring (Quiaios and Zouaraa), reproduced in the same season, exhibiting shorter life spans and most probably not surviving the winter.…”