ACOUSTIC SEDIMENT PROPERTIES AND THE ABUNDANCE OF BURROWING SHRIMP IN MARINE SEDIMENTS FROM REFLECTION MEASUREMENTS

摘要

The mapping of sediment properties and of the distribution of benthic invertebrates in marine sediments using traditional coring methods is extremely labor-intensive. Acoustic methods are being explored to characterize sediment properties, which, in very shallow waters, may be strongly influenced by the activity of infauna, particularly the thalassinid burrowing shrimp, thus providing indicators of their abundance and distribution. Acoustic reflection measurements were made at several sites over very shallow sediments (intertidal and subtidal) that contained either very high or very low densities of two species of burrowing shrimps (Neotrypaea or Upogebia). The acoustic signal was a chirp from 45 to 60 kHz, with significant third and fifth harmonics.