Hirudíneos asociados a hidrófitas en la laguna Los Patos, Buenos Aires, Argentina

Abstract

El objetivo de este trabajo es identificar los hirudíneos hallados en la Laguna Los Patos, Partido de Ensenada, Provincia de Buenos Aires (34° 49’ S y 57° 57’ W) y analizar las variaciones estacionales de sus poblaciones teniendo en cuenta: densidad media, riqueza específica, dominancia y frecuencia. Se identificaron doce especies de hirudíneos: Helobdella triserialis, H. lineara, H. hyalina, H. adiastola, H. diploides, H. duplicara, H. striata, H. simplex, H. michaelseni, Haementeria eicchorniae, Batracobdella gemmata (Glossiphoniidae) y Orchibdellapampeana (Cyclobdellidae). Helobdella triserialis, H. lineata, H. adiastola, H. diploides y O. pampeana fueron especies dominantes y constantes mientras que H. duplicata, H. striata, H. simplex, H. michaelseni, Haementeria eicchorniae y Batracobdella gemmata fueron ocasionales. Helobdella triserialis y H. hyalina fueron las especies con la densidad media más elevada, registrándose su presencia durante las cuatro estaciones del año. Helobdella duplicata, H. striata, H. simplex, H. michaelseni, Haementeria eicchorniae y Batracobdella gemmata resultaron las especies con densidad media mas baja y fueron halladas durante la primavera, verano y otoño. La riqueza específica mayor de hirudíneos estuvo asociada a Hydrocotyle ranunculoides (Umbelliferae) donde se recolectaron diez especies, mientras que la menor correspondió a Azolla filiculoides donde se hallaron cinco.

Leeches associated to Hydrophyta in laguna Los Patos, Buenos Aires, Argentina. The most important environmental factors influencing the number and kind of leeches in a given habitat are: food’s availability, nature of the substrate, depth, water movements, size and nature of the water body, hardness, ph and water temperature, disolved oxygen, siltation, turbidity, and water salinity. Leeches are usually less abundant at greater depths primarily because of the lack of vegetation, suitable substrates, and food. The main objective of this work is to identify the leeches associated to aquatic plants in Laguna Los Patos and to analyse seasonal population variations considering mean density, species richness, dominance, and frequency. Quantitative samples were taken monthly, from June 2000 to April 2002. Temperature, ph, conductivity, and dissolved oxygen were measured. Twelve species were found: Helobdella triserialis, H. lineata, H. hyalina, H. adiastola, H. diploides, H. duplicatei, H. striata, H. simplex, H. michaelseni, Haementeria eicchorniae, Batracobdella gemmata, and Orchibdella pampeana (Cyclobdellidae). Helobdella triserialis, H. lineata, H. adiastola, H. diploides, and O. pampeana were dominant and constant whereas H. duplicata, H. striata, H. simplex, H. michaelseni, Haementeria eicchorniae, and Batracobdella gemmata were occasional. Helobdella triserialis and H. hyalina exhibited the higher mean density and occurred around all year. Helobdella duplicata, H. striata, H. simplex, H. michaelseni, Haementeria eicchorniae, and Batracobdella gemmata were scarce, being recorded in spring, summer and autumn. Hydrocotyle ranunculoides housed the highest species richness (ten species) while the lowest species richness was observed in Azollafiliculoides (five species).