Effect of flooding on estuarine bivalve populations near the mouth of the Hopkins River, Victoria, Australia

The densities of two common intertidal/shallow subtidal bivalves, <i>Soletellina</i> <i>alba</i> and <i>Arthritica helmsi</i>, were sampled in vegetated and unvegetated habitats of the Hopkins River estuary on three occasions during the  autumn/winter 1995.Winter flooding coincided with mass mortalities of the infaunal bivalve <i>S. alba</i>, but not <i>A. helmsi</i>. Mortalities were apparent for individuals living deeper in the sediment (≈35 cm) in vegetated and unvegetated habitats, but small <i>S. alba</i> (<1mm) were less susceptible to mortality than larger individuals (>1mm). Mortalities were similar across different habitat types and sediment depths, and at multiple sites within close proximity to the estuary mouth.<br>