Biodiversity trends of the meiofaunal and foraminiferal assemblages of Lake Varano (southern Italy)

Meiofaunal Dynamics and Heterogeneity along Salinity and Trophic Gradients in a Mediterranean Transitional System

“…Regarding the meiofaunal richness, our data can be compared only with a few studies because the complete list of meiofaunal taxa is rarely reported. However, an overall high number of richness (i.e., 16 taxa) was recorded in the present study showing levels higher than those documented from both Mediterranean and European transitional water bodies [17][18][19]22,58,59]. Nematodes were the dominant taxon as frequently reported in lagoon systems worldwide [2,17,22,60,61].…”

“…This is likely related to their capacity to colonize the fine (suboxic or anoxic) sediments that generally characterize lagoons [19]. As reported in literature, the second most abundant group is represented by copepods [14,22,58,59]. Copepods are one of the most sensitive taxa to oxygen limitation and therefore they are confined to the oxic sediments [20,48], but they seem to take advantage of the high abundance of the microphytobenthos occurring in lagoon sediments and that are a primary food source for numerous copepod species [24].…”

“…Salinity gradient is one of the primary factors that influence meiofauna in transitional environments [8,18] along with the oxygen availability that seems to influence all the meiofaunal taxa and not only the oxygen sensitive ones such as copepods (see above references). The quantity and quality of the organic matter (OM, Chl-a, and phaeopigments) and Wc, which is an indirect indication of the grain size of the substrates, were also important for the meiofaunal distribution as suggested by many authors [8,17,22] and contributed mostly to the separation between the other two sites (i.e., C1 and C2). Instead, temperature did not show a relevant contribution to the ordination of the meiofauna.…”

“…Instead, the high degree of confinement and consequent trophic load existing at site C2 was marked by a higher presence of Halacaroidea and Ostracoda. Ostracoda are generally recognized as sensitive taxon to environmental perturbations, but adaptive behaviors to numerous natural and anthropogenic environmental (e.g., organic load and trace element contamination) changes have been documented in several species [22,24,63]. In that site, there was also the only record of Pycnogonida that is generally recognized as a marine taxon.…”

“…Among them, the largest amount of information on meiofaunal spatial pattern is available for the upper Adriatic Sea, including the Venice lagoon [14][15][16][17][18][19][20]. Meiofaunal diversity and assemblage structure are also well-documented in the southern part of the Adriatic Sea, including the Lesina and Varano lagoons [6,8,17,[21][22][23]. Instead, meiofaunal studies in transitional environments along the Tyrrhenian coast, with the exception of the Stagnone of Marsala (Western Sicily), are largely lacking [17,24].…”