Seasonal change of multifrequency backscatter in three Baltic Sea habitats

This study investigated the seasonality of acoustic backscatter intensities, exploring three habitats in southwestern Baltic Sea: 1) a mussel-covered reef, 2) coarse sand and gravel, 3) seagrass meadows. Backscatter information different, partly calibrated frequencies (200, 400, 550, 700 kHz) was collected seasons (May, August, October). The data were supported by point samples video profiles for grain size benthic community analysis. Angular response curves helped to quantify seasonal different frequencies. multifrequency multiseasonal maps distinguish reveal variable differences backscatter, but not all changes can be recognized data. high-backscatter reef shows little frequency independent. ecologically valuable gravel areas show small-scale alterations sediment composition morphology, mainly caused local hydrodynamics. Higher found best suited identify gravel. Seagrass meadows is dominated growth blades, increasing compared bare sand. use multiple beneficial as low sensitive shallow subsurface features such rhizomes, while higher highlights related coarser sediment.