The sessile benthic community patterns on hard bottoms in response to continental vs. marine influence in northern Adriatic lagoons

Abstract

Many studies in marine coastal lagoons have focused on the marine-to-terrestrial gradient as a main source of variation for the structure of assemblages. In this paper, the magnitude of differences among locations arranged along the marine-to-terrestrial gradient of the western lagoon of Orbetello (Grosseto, Italy) was contrasted with the amount of spatial variability occurring among sets of locations that were not positioned along this axis. We propose that if the most important processes influencing assemblages were those associated with the external-internal gradient of the lagoon, as usually supposed, then assemblages should differ more among these locations than among any other locations. To test the above proposition, four locations arranged along the two major axes of the lagoon were established in November 2000. Each location was sampled three times (

Porifera and Bryozoa on artificial hard bottoms in the Venice Lagoon: Spatial distribution and temporal changes in the northern basin

“…Despite only being represented by relatively small colonies, their (1978/83, Occhipinti-Ambrogi 19851988/89, OcchipintiAmbrogi 19911993/94 and 1996/97, Occhipinti-Ambrogi 2000b2001, present study presence can be interpreted as one of the results of an ongoing marinization process of the Venice Lagoon, also suggested by other authors (Day et al 1999;Carbognin & Tosi 2002;Sconfietti et al 2003). The invasion process, in addition to the increased marine characteristics of the Venice ecosystem, might have caused unfavourable conditions for some native species, typical of lagoon environments, that have been progressively replaced by opportunistic marine species.…”

“…As regards the hardbottom zoobenthos, a trend of homogenization of the community structure, with loss of peculiar species associations, was reported for the whole macrobenthic community (Sconfietti et al 2003).…”

“…Natural hard substrates are not present in this lagoon, although some artificial ones were considered for sampling, namely wooden piles (bricole), that have been 'naturalized' by their being permanently immersed in the lagoon waters over a long time and colonized by a complex benthic community (Occhipinti-Ambrogi et al 1988;Sconfietti et al 2003). We considered 11 stations in the northern basin of the lagoon (Figure 1), whose circulation is mainly driven by sea flow from the Lido Mouth (Solidoro et al 2004).…”

“…In the confined coastal environments of the Mediterranean Sea, animal benthic assemblages usually considered as characteristic of hard bottoms may be widely represented, constituting a very important component of the zoobenthic communities (Corriero 1984;Nonnis Marzano et al 2002, 2003a, 2003bSconfietti et al 2003). This is strictly dependent on the availability of artificial hard substrates (Corriero 1984;Sconfietti 1989) but also on the occurrence of biogenic concretions (Bianchi & Morri 1996;Nonnis Marzano et al 2002).…”

Anthropogenic disturbance and spatial heterogeneity of macrobenthic invertebrate assemblages in coastal lagoons: the study case of Pialassa Baiona (northern Adriatic Sea)

“…Land-seaward gradient and the associated salinity gradient and confinement degree are widely recognised as the leading natural factors in structuring the macrobenthic invertebrate assemblages in coastal lagoons and estuaries (Guélorget and Perthuisot 1992;Sacchi and OcchipintiAmbrogi 1992;Barnes 1994;Attrill 2002;Attrill and Rundle 2002;Gray et al 2002;Sconfietti et al 2003;Rossi et al 2006;Gamito 2008). Nevertheless, models based on salinity as the main variable affecting patterns of distribution and abundance of benthic organisms at the scale of hundreds of meters within coastal lagoons, like the 'paralic domain' (Guélorget and Perthuisot 1992), were demonstrated to be over-simplistic (De Biasi et al 2003).…”