Distribution of benthic invertebrate biomass and secondary production in relation to floodplain connectivity in a large river system (Paraná River, Argentina).

ZILLI, FLORENCIA LUCILA

INTERNATIONAL REVIEW OF HYDROBIOLOGY

WILEY-V C H VERLAG GMBH

Lugar: Weinheim; Año: 2013 p. 284 - 293

1434-2944

An investigation of benthic invertebrates was conducted in the Paraná River (Argentina)floodplain to assess patterns of biomass and production in relation to lateral river connectivity.Environmental and invertebrate samples were collected monthly from April 2005 toMarch 2006 at sites with different lateral surface-connection. The investigated invertebrateassemblages were characterized by high biomass and high production. The key factordetermining the benthic assemblages was river connectivity and indirectly, substratecharacteristics, water transparency, and depth. With increasing river connectivity, biomassand production of oligochaetes, native bivalves, and dipterans decreased, whereas bothvariables increased for non-native bivalves, gastropods and ephemeropterans. Benthicassemblages of most of sites had an average similarity in the composition of about 50% alongthe study period, but the number of taxa contributing to the overall similarity was lower at siteslocated at long distance from the main channel than at sites located next to it. Potentialproduction was high compared to literature data, which underscores the importance ofpreserving floodplain areas and maintaining natural lateral connectivity. High habitatpatchiness mediated by lateral-surface connectivity appeared to promote benthic resourcesdiversity, which in turn controls productivity of this floodplain-river system.