Abstract
Freshwater amphipods of the genus Hyalella have a great importance in aquatic ecosystems due to their role in matter and energy cycling and its utilization as bioindicators of environmental health. The aim of this work was to analyze relevant population parameters of Hyalellapampeana, such as population density and structure, individual body size, sex ratio, fecundity and recruitment, and to study the possible relation of these parameters to variations in environmental variables. Samples were taken monthly during a one-year period (2006) at three small ponds in the Natural Reserve Island of Martín García, Argentina. The inland aquatic environments showed distinctive physicochemical characteristics, mainly related to pH and conductivity values. Amphipod population density varied among sites and throughout the year, with population peaks during spring, positively correlating with pH values. The operational sex ratio of the total population was almost equal to 1 male: 1 female, displaying seasonal variation. Mean fecundity and mean size of ovigerous females were higher during winter and early spring months than in summer months. The presence of ovigerous females and juveniles in all months indicated that reproduction is continuous during the year for Hyalella, in its natural environment.
Highlights
Amphipods inhabit a wide variety of aquatic environments and have a great ecological importance, since they facilitate the matter and energy transference from inferior levels of the Biological SciencesAn Acad Bras Cienc (2019) 91(1)MARÍA FLORENCIA COLLA and INÉS I
Mean water temperature ranged between 12.3 °C in winter and 26 °C in summer, while pH values were close to neutrality at sites 1 and 2, and slightly acidic at site 3
Among the variables analyzed in the aquatic environment, pH was an important factor affecting amphipod density
Summary
Amphipods inhabit a wide variety of aquatic environments and have a great ecological importance, since they facilitate the matter and energy transference from inferior levels of the Biological SciencesAn Acad Bras Cienc (2019) 91(1)MARÍA FLORENCIA COLLA and INÉS I. Most studies in amphipod populations classically focus on Hyalella azteca Saussure 1858, a widely distributed species in aquatic ecosystems of North America, and analyze the population density and its temporal fluctuations, age and size, sex proportion, reproduction and recruitment periods (Lindeman and Momot 1983, Edwards and Cowel 1992, Wen 1992, 1993, Moore and Farrar 1996). The evaluation of these population parameters is of crucial importance since they allow to obtain information about the biology of a species, the stability of the population in a given habitat, its adaptability, reproductive success and persistence (probability of leaving offspring for prolonged periods), among others (Odum and Warrett 2005). Few studies deal with other Hyalella species, like H. pampeana Cavalieri 1968 (Lopretto 1982, 1983), and H. pseudoazteca González and Watling 2003 (Giusto and Ferrari 2008, Carusela et al 2009)
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