Abstract

Geologic and biological data from box cores, gravity cores, and bottom photographs across the modern coastal upwelling system of central California reveal that biogeochemical activity increases along the edges of the oxygen-minimum zone (OMZ; <0.5 ml/1 O2). Macrofauna and benthic foraminifers, as well as relative concentrations of calcium carbonate, glauconite, and fecal pellets, all display edge effects. The major controls appear to be a combination of dissolved oxygen concentration of near-bottom waters, bottom currents, and possibly bacterially mediated nutrient recycling, as well as food supplies. OMZ edge effects should be recognizable in the rock record and may prove to be powerful paleoenvironmental/paleoecological indicators.

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