The stability of tidal flats in Venice Lagoon - the results of in situ measurements using two benthic, annular flumes

Seabed properties in Venice Lagoon were examined in situ in two multidisciplinary field campaigns. The purpose of this study was to understand the mechanisms controlling the stability of bed types. Two benthic annular flumes (Sea Carousel and Mini Flume) were deployed simultaneously from a floating pontoon at 24 sites during summer (1998), which were considered representative of the range in bed/habitat types. As well, bottom sampling and coring, water-column monitoring and benthic habitat analyses were carried out. All but three sites were on cohesive sediments. Bed types included bare shelly mudflats and regions colonised by the seagrasses Cymodocea nodosa and Zostera noltii, by filamentous cyanobacteria, and by patches of the macrophytes Ulva rigida and Chaetomorpha sp. A subset (13) of these sites was visited during the subsequent winter to evaluate seasonal changes. Six of the sites were intertidal, the remainder were in the sublittoral zone.