Base Line Study of Nematodes from a Patagonian Salt Marsh

VIRGINIA LO RUSSO; CATALINA TERESA PASTOR

Recife

Conferencia; Thirteenth International Meiofauna Conference; 2007

Universidade Federal de Pernambuco (UFPE)

Free-living marine nematodes are abundant and diverse in the coastal benthos, especially in salt marsh or estuaries areas. Salt marshes are environments where marine and land features conjugate producing areas with rich productivity and high biodiversity. In Argentina little is known about nematodes in salt marshes. The aim of this research was to study the biodiversity and vertical distribution of the Nematoda community in a salt marsh of the Fuerte San José beach (Patagonia, Argentina) during two seasons of the year (summer and winter). Three samples were collected each season with a Plexiglas corer (2.9 cm inner diameter) along a parallel line to the salt marsh edge. Each sample was dividing in 10 sub-samples of 1 cm of thickness each. Separation of sediment was done using the decantation method. Then samples were sieved (mesh=500 and 50 µm) and Nematoda were quantified and mounted in glycerine. Individuals were identified at taxonomic level of genera. Abundance, distribution and diversity in Nematoda were different between seasons. The total average density found in summer was 9470 ind x 10 cm-2. The first centimetre (the closer to the surface) presented the peak of abundance. Abundance diminished with depth. During winter the scenario was inverse. The total average density was 291 ind x 10 cm-2. Summer presented higher values than winter. There also was a great difference in the genera found during each season. During summer, Paramonohystera was the most abundant taxa in the oxic zone, Oncholaimellus in the RPD layer and Theristus in the anoxic zone. On the contrary, during winter Paraethmolaimus, Cobbia and Odontophora were dominant in the three zones.