RESUMEN

Dissimilarities in habitat use, feeding habits, life histories, and physiology can result in syntopic aquatic taxa of similar trophic position bioaccumulating trace elements in vastly different patterns. We compared bioaccumulation in a clam, Corbicula fluminea and mayfly nymph Maccaffertium modestum from a coal combustion waste contaminated stream. Collection sites differed in distance to contaminant sources, incision, floodplain activity, and sources of flood event water and organic matter. Contaminants variably accumulated in both sediment and biofilm. Bioaccumulation differed between species and sites with C. fluminea accumulating higher concentrations of Hg, Cs, Sr, Se, As, Be, and Cu, but M. modestum higher Pb and V. Stable isotope analyses suggested both spatial and taxonomic differences in resource use with greater variability and overlap between species in the more physically disturbed site. The complex but essential interactions between organismal biology, divergence in resource use, and bioaccumulation as related to stream habitat requires further studies essential to understand impacts of metal pollution on stream systems.

Asunto(s)

Corbicula/metabolismo , Insectos/metabolismo , Ríos/química , Oligoelementos/metabolismo , Contaminantes Químicos del Agua/metabolismo , Animales , Carbono/metabolismo , Isótopos de Carbono/análisis , Carbón Mineral , Corbicula/química , Ecosistema , Herbivoria , Insectos/química , Nitrógeno/metabolismo , Isótopos de Nitrógeno/análisis , Oligoelementos/análisis

RESUMEN

Bacteria in transport in streams are largely derived from other parts of the ecosystem. Here we review factors that influence transport of bacteria and their movement between habitats (such as sediment, water column, rocks, wood, and leaves) and consider the role of these movements in ecosystem processes. Bacteria enter the water column by sloughing, scouring, as a consequence of changes in morphology or hydrophobicity, or dislodgment by invertebrates and fish or other aquatic vertebrates. Transported cells (which may be planktonic or particle-associated) that colonize surfaces may establish new gene pools through cell division (vertical transfer) or genetic exchange (lateral transfer). Genetic information is also transported in streams as free or protected DNA or in bacteriophages. Movement of these vectors causes genetic information to spiral along a stream in a manner analogous to that of nutrients and organic carbon. Spiraling refers to the pattern of transport, uptake or attachment, and release of a molecule or cell. The flow of water in streams causes this cycle of attachment and release to be displaced downstream resulting in a spiral rather than a closed, stationary loop.