Abstract

CASSET, María A; MOMO, Fernando R  and  GIORGI, Adonis DN. Population dynamics of two amphipod species and its relationship with the aquatic vegetation in a Luján river basin microenvironment (Argentina). Ecol. austral [online]. 2001, vol.11, n.2, pp.79-85. ISSN 1667-782X.

The dynamics of two amphipod species in a freshwater micro-environment was studied. Samples were taken monthly, during a whole year, from Las Flores stream, a Luján river tributary. Hyalella (Mesohyalella) curvispina is a herbivore and feeds mainly on phytobenthos. Hyalella (Mesohyalella) sp. is a H. (M.) curvispina predator and uses macrophytes as a refuge. Periphyton algal biomass reaches its maximum during June, the phytobenthos biomass reaches its maximum during October, and macrophyte biomass reaches its maximum between November and February. H. (M.) curvispina shows its maximum density (1267 individuals/m²) and its highest secondary production (2225 mg.m^-2.month^-1) in October coinciding with the phytobenthos' peak in biomass; its density correlates positively with phytobenthos abundance. H. (M.) sp. density (7067 individuals/m²) and secondary production (1018 mg.m^-2.month^-1) both peak in January. H. (M.) curvispina density is positively correlated with phytobenthos biomass. H. (M.) sp. density, biomass and secondary production are all positively correlated with macrophyte biomass.

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