Environmental features and macrozoobenthic communities of climatic microniches in salt marshes of the Venice Lagoon

Aquatic vegetation, once died, is converted into detritus that drift in the water. In coastal habitats, seagrass and algal detritus is frequentely stranded on the shore by waves and wind action; in the Venice Lagoon, this detritus can be stranded on the salt marshes. These vegetation wracks can offer to the organisms food, shelter and habitat, since salt marshes, and in general marsh bare soil is subjected to extreme and variable environmental conditions. These dead vegetation wracks can be preferred by organism to live and feed for their environmental characteristics acting as thermal and humidity microniches. Due to these features, these microniches are important to study to underline environmental parameters but also the faunal communities present, for conservation perspective, since these microhabitat are part of salt marshes ecosystem, and in a future perspective can increase organisms protection against climate change providing more livable environmental conditions, under a global change threat of temperature rising and heat waves. The goal of this thesis is the study of these microniches in natural saltmarshes of the Venice Lagoon, in particular seagrass, algal wracks and marsh plant meadows, compared to bare salt marsh soil kept as a control. The work described here is focused on sampling physical characteristics of wracks, especially humidity, temperature and granulometry. Together with the sampling of environmental variables, the work has focused on the taxonomic identification and quantification of macro-invertebrates living inside the wracks, to be compared to macrozoobenthos of the bare soil and marsh plant meadows, to study any difference in terms of fauna between these microniches. The selected study site was a salt marsh in the southern Lagoon of Venice, Ca’ Manzo, investigated in spring-summer 2024.