Channels
Index
The lagoon channels are waterways of varying depth that cross the lagoon, allowing connections between the islands and enabling navigation. Some of them are natural, shaped by tidal action, while others were excavated by humans to facilitate naval and commercial traffic. The channels regulate tidal flow and ensure the exchange of water between different lagoon areas.
The edges of the channels, known as “gengive” (literally “gums”), consist of compact sediments formed by the deposition of material transported by currents. They play a crucial role in the morphological stability of the channels, as they limit sediment dispersion and help maintain the depth of the riverbed. Moreover, they provide a distinctive habitat for benthic organisms and for certain fish species that find both shelter and nourishment there. The water column of the lagoon channels is a dynamic environment influenced by several factors, among which tides are particularly significant. Water quality in the channels varies depending on proximity to the inlets, freshwater inputs from rivers, the presence of pollutants from human activities, and water residence times (exchange rates). In some stretches, water circulation is more intense, which favours nutrient mixing and oxygenation.
Along the channel banks, hard substrates can be found, mostly of anthropogenic origin, such as remains of submerged structures, mooring posts, and stone embankments. These features provide a habitat for numerous species of sessile invertebrates, such as sponges, annelids, and bivalves. Hard formations also support the colonisation of algae and other benthic life forms, contributing to the ecological diversity of the lagoon environment.
The development of the maritime-port sector during the twentieth century brought about profound changes in the network of navigable channels and in the overall morphological structure of the Lagoon. It contributed to erosion processes, particularly in shallow areas and intertidal environments, and to a net loss of sediments. The subsequent accumulation of sedimentary material on the channel beds makes dredging necessary to maintain navigability, although such operations can in turn affect the ecosystem. Sustainable management of the channel network is one of the main challenges for safeguarding the Venetian Lagoon.