Spatial and Temporal Patterns in Structure of Macrobenthic Assemblages. A Three‐Year Study in the Northern Adriatic Sea in Front of the Po River Delta

Abstract

Abstract. Coastal benthic communities in soft‐bottom deposits of a restricted area were studied by seasonal sampling at nine stations. Faunal assemblages at three different depths were consistently different and exhibited a seasonal pattern of abundance and diversity. Multivariate statistical analyses suggest that each community structure is very similar during the three summer samplings; in autumn and winter many causes of disturbance can disrupt this structure, which is reconstituted the following summer. The stability of benthic communities in this physically variable environment is discussed and a “cyclic” adjustment mechanism of stability is proposed to explain the dynamics of the benthos in this area.

Effects of an artificial protection structure on the sandy shore macrofaunal community: the special case of Lido di Dante (Northern Adriatic Sea)

“…In the sheltered zone at the same depth, the Eurydice -Scolelepis association was replaced by a sizeable Spio decoratus population, a species usually dominant on estuarine fine sand sediments with low to moderate organic content (Sardá et al, 1999). Moreover, species typically present in the exposed site at 3 m, such as Cyclope neritea and Donax semistriatus (Parisi et al, 1985;Ambrogi et al, 1990), were found in sheltered site at 1 m depth (Table 6). More in general the LCS system at Lido di Dante seemed to favour the settlement of species more adapted to inhabit less stressed and enriched environments.…”

“…In the exposed locations, the macrofaunal assemblages are referable to the typical subtidal communities of the Northern Adriatic Sea, which are intrinsically poor in species and little diversified (Daelli, 1999;Ambrogi et al, 2001). During summer, these communities are dominated by Lentidium mediterraneum, and are also characterized by the presence of Donax semistriatus, Cyclope neritea, Prionospio caspersi and Spio decoratus (Parisi et al, 1985;Ambrogi et al, 1990). The most noticeable effect observed in both surveys is the increase in species number in the sheltered location behind the LCS, in contrast with the exposed zones.…”

Influence of estuarine dynamics on macrobenthos spatial variability along the southeast continental shelf of Brazil

“…An increase in the amount and quality of OM can lead to an increase in the biomass and density of the benthic organisms and also to dystrophic events, such as episodes of hypoxia or anoxia, which can cause massive reductions or elimination of the benthic fauna. Such phenomena are frequent and well documented in the northern Adriatic Sea (e.g., Ambrogi et al 1990, Crema et al 1991, Moodley et al 1998.…”

Influence of environmental factors on the dynamics of macrobenthic crustaceans on soft-bottoms of the Ebro Delta continental shelf (northwestern Mediterranean)

“…The temporal dynamics of the infaunal crustaceans matched the seasonal pattern described in the area: increased river runoff and phytoplankton blooms in spring that supply organic matter to the seabed; the establishment of a thermocline with the high water temperature in summer, causing the shortage of organic matter supply to the seabed and possibly causing anoxic conditions at the end of summer; and in autumn a renewal of the bentho-pelagic fluxes because of the increase in turbidity and decrease in water temperature caused by autumn storms (Ambrogi et al, 1990;Sardá et al, 1999;Salat et al, 2002). The PCO ordination reflects this pattern, with summer samples characterized by the difference between surface and bottom temperature and autumn samples characterized by near-bottom turbidity and temperature.…”