The Lago di Varano: Hydrologic Characteristics and Sediment Composition

Abstract

The Lago di Varano is situated on the north side of the Gargano National Park (southeast Italy) and covers a surface area of about 65 km 2 . It communicates with the Adriatic Sea through two artificial canals (Foce Capoiale and Foce Varano) located at the two ends of a long and narrow coastal dune. This work presents preliminary results of four seasonal surveys (1999±2000) carried out to measure chemical and physical parameters of the water column (temperature, salinity, dissolved oxygen and pH) and to analyse a number of biogeochemical characteristics of surface sediments (organic matter, total phosphorus, total nitrogen and total Hg, As, Pb, Cd, Cr, Cu and Ni content). Water analysis indicated poor exchange between the coastal pond and the open sea, limited to autumn and winter. Surface sediments were rich in organic matter, whose distribution was influenced by chemical-physical and hydrodynamic variations in the water column. At the sediment level, the highest values of Cd were found in the central zone of the basin, while the highest Cr values were measured in the central and southeastern areas. With the exception of Cd and Pb, the metal content did not indicate anthropogenic pollution, in particular when compared with the Venice Lagoon and the Central Adriatic Sea. ProblemAmong natural ecosystems, a high level of primary and secondary production distinguishes coastal environments and explains their considerable economic importance. They are characterised by a series of gradients, largely induced by hydrodynamics (Carrada, 1988), and they play an important role in filtering dissolved and particulate substances coming from the inland. In such coastal ecosystems, much of the allochthonous P.S

The influence of invasive jellyfish blooms on the aquatic microbiome in a coastal lagoon (Varano, SE Italy) detected by an Illumina-based deep sequencing strategy

“…Nonetheless, in spite of strong seasonal fluctuations of most environmental variables (as typical of confined coastal habitats), the Varano lagoon is apparently a relatively homogeneous basin from spatial, hydrological, and geomorphological standpoints. Previous studies on the water column, sediments, and biological features (organic matter, Chl-a, phyto-and zooplankton compositions) did not show significant differences across the lagoon and, specifically, between the two areas (high-jellyfish vs low-jellyfish) (Caroppo 2000;Spagnoli et al 2002;Specchiulli et al 2008), which are marked by a comparable level of confinement (e.g. in terms of relative distance from the open sea).…”

“…1) and two artificial channels (foce Capojale, NW; foce Varano, NE) regulate lagoon-sea water exchanges (Specchiulli et al 2008), facilitating the hydrodynamic balance of sea water masses at reduced salinity (25-29 ppt) through tidal and wind forces. Prevailing N-NE winds make these exchanges much more effective in autumn and winter (Spagnoli et al 2002), with the main sea water inflow through the NW channel. Due to the small tidal excursion and reduced exchange with the adjacent coastal area, water residence time is very long (about 1.5 years; Specchiulli et al 2008).…”

The nematode assemblage of a coastal lagoon (Lake Varano, southern Italy): ecology and biodiversity patterns

“…As shown by the PCA, the positive correlation between silt and the PLI is noteworthy. Spagnoli et al (2002) and Fabbrocini et al (2010) have already evidenced a correlation between trace elements and the fine sediment in Lake Varano. This greatly depends on the adsorptive properties of clay and silt particles, and supports the notion that grain size is also important in influencing pollutant accumulation in sediment (Bernardello et al 2006).…”

“…65 km 2 with an average water depth of ca. 4 m (Spagnoli et al 2002). The lake is connected to the Adriatic Sea via two artificial channels (Capoiale and Varano) that are located at the two ends of a coastal dune (Fig.…”

Avaliação das condições ambientais da lagoa de Varano, no sul da Itália

“…É impossível estabelecer se a presença do cromo está associada com um agente antropogênico 34 , mas em relação ao chumbo existem algumas fontes que poderiam ter determinado o acúmulo na matriz sedimentária. Especificatamente, parece que isto ocorre além da contribuição típica das fontes mais tradicionais, ou seja, aquela derivada do peso das redes constituído deste elemento, que se deposita sobre o fundo.…”