The growth and autoecology of two alien invasive species: Sargassum muticum and Undaria pinnatifida spreading in the Venice Lagoon were studied monthly, during one year, in two sites of different ...depth. S. muticum was present year-round and reached its largest size (485 cm) and maximum growth (8.33 cm d−1) at the deepest station. U. pinnatifida was present only from November to May, reaching the highest size (130 cm) in March–April in the shallow station with growth peaks of 2.32 cm d−1. The growth of both species was mainly regulated by water temperature, nutrient concentration, especially nitrogen, and water turbidity. The study highlights the different ecological role already observed for the two species: U. pinnatifida prefers eutrophic areas and is not present along the sea-coastline. Its total standing crop does not exceed 0.2 ktonnes fwt for all the Venice Lagoon. Conversely, S. muticum colonizes areas with a lower eutrophication level, such as the lagoon inlets, reaching a total lagoon standing crop of 4–6 ktonnes fwt.
•Sargassum muticum and Undaria pinnatifida annual growth.•Role of environmental parameters in macroalgal growth.•Annual changes of tissue and environmental nutrient concentrations.•Venice Lagoon.
Transitional water systems (TWSs) may be threatened by various metals originating from increased agricultural, industrial activities, or urban effluents. Macroalgae are one of the biological quality ...elements used to monitor and assess the health status of TWS due to their structural and functional key role in marine ecosystems. Here, metal accumulation from the macroalgae Ulva laetevirens Areschoug (1854) and oxidative stress by lipid peroxidation (LPO) biomarker were investigated during four sampling seasons from three sampling sites (SMM: Santa Maria del Mare; PM: Porto Marghera; SG: San Giuliano) of Venice Lagoon, affected by different anthropogenic stressors. The metal pollution index (MPI) scores for U. laetevirens increased in the order SMM < PM < SG (sea inlet < industrial area < Osellino River estuary), with average values per site of 2.99, 4.37, and 6.33, respectively. The level of LPO was statistically correlated with the concentration of toxic metal(loid)s (As, Pb, Hg) measured in macroalgae, and seasonality affected both levels of LPO and metal bioaccumulation, with peak values during spring and summer. These findings highlighted the efficiency and usefulness of the oxidative stress test (LPO) on the common macroalga U. laetevirens as an early warning signal for health assessment in aquatic ecosystems.
Gracilaria vermiculophylla (Ohmi) Papenfuss, an invasive Rhodophyta recently recorded in the Po Delta lagoons (May 2008), was also found in the Venice lagoon in March 2009 and successively in ...Pialassa della Baiona (Emilia–Romagna Region) in May 2009. The species has colonized the eutrophic and confined areas of Venice by pleustophytic tangled populations (5–15 kg fwt m−2), replacing the allochthonous species whereas it is absent in the areas characterized by low nutrient availability and high water exchange. In contrast, in the Po Delta lagoons and in Pialassa della Baiona it is present everywhere, also with high water renewal, because of the eutrophication caused by the Po river and the industrial area of Ravenna. This study presents the autoecology and distribution of G. vermiculophylla in the above environments, according to their different eutrophication status, showing its relationship with physico-chemical parameters and nutrient concentrations in water column, pore-water, surface sediments and particulate matter collected by traps in a station of the Venice lagoon (Teneri) sampled monthly during one year. Furthermore, we give new information on its morphology and the high dimorphism between female and male gametophytes and tetrasporophytes.
► Species distribution in the transitional systems of the North Adriatic Sea. ► Annual biomass change in Venice Lagoon. ► Relationship with environmental parameters. ► Additional morphological information.
The benthic diatom abundance and taxonomic composition were investigated in the Venice lagoon to integrate the knowledge on the trophic food web of shallow coastal areas. Samples of surface sediment ...layer (ca. 1
cm) were collected and stored until inverted light microscope determination. One-year comparison was carried out in six sites with a monthly frequency. In summer 2003, sediment cores were also collected at 165 stations distributed throughout the whole lagoon. Abundance varied between 0.26 and 5.65
×
10
6 cells
ml
−1, whereas the Shannon diversity index ranged between 0.93 and 4.36
H′ depending on seasonal and spatial variability. The seasonal variations were not correlated with water temperature, although it varied between 6 and 29
°C, but with nutrient concentrations, sediment re-suspension and grain size. The spatial fluctuations mostly were influenced by water turbidity.
Amphora,
Cocconeis,
Navicula,
Nitzschia and
Thalassiosira were the most common genera.
Thalassiosira sp. constituted an interesting case as it was quite abundant near the mainland and was correlated with nutrient concentrations. The community structure was investigated by applying univariate and multivariate statistical analysis such as cumulative dominance curves, cluster analysis and canonical correspondence analysis.
•Revision of knowledge on the diversity and distribution of Mediterranean Ruppia species.•An evolutionary history of the genus Ruppia shows polyploidization and hybridization.•Ecological parameters ...have a key role in Ruppia presence and growth.•The western Mediterranean basin appears a center of Ruppia diversity.•An identification key of the Ruppia species is provided.
This paper reviews the current knowledge on the diversity, distribution and ecology of the genus Ruppia L. in the Mediterranean region. The genus Ruppia, a cosmopolitan aquatic plant complex, is generally restricted to shallow waters such as coastal lagoons and brackish habitats characterized by fine sediments and high salinity fluctuations. In these habitats Ruppia meadows play an important structural and functional role. Molecular analyses revealed the presence of 16 haplotypes in the Mediterranean region, one corresponding to Ruppia maritima L., and the others to various morphological forms of Ruppia cirrhosa (Petagna) Grande, all together referred to as the “R. cirrhosa s.l. complex”, which also includes Ruppia drepanensis Tineo. Populations of hybrid origin between R. maritima and R. cirrhosa and polyploidy have been detected.
We investigated the temporal concentration of floatable plastic particles in the Po river, the largest contributor of freshwater to the Adriatic Sea. Surface waters were sampled in 2019 with a Manta ...trawl, with almost bimonthly frequency. In total, 5063 plastic particles were collected, 80.6% of which were microplastics (<5 mm). Characterization through FT-IR spectroscopy evidenced 7 polymers, of which polyethylene, polypropylene and polystyrene accounted for 40.5%, 25.7%, and 14.9%, respectively. The highest plastic concentration was recorded in December (3.47 particles m-3; 5.89 mg m-3), while the lowest in August (0.29 ± 0.01 particles m-3; 0.22 ± 0.08 mg m-3). We estimated the annual load of floatable plastic particles carried by the Po river to be 145 tons. Plastic particle load was correlated with the hydraulic regime, and was higher in autumn and spring months.
•Concentration and composition of floatable plastics in the major Italian river was studied.•Microplastics were 80.6% of particles collected.•Plastic concentration ranged from 3.47 to 0.29 particles m-3.•The annual load of floatable plastics carried by the Po river was 145 tons.•Plastic particles load was higher in autumn and spring.
The concentrations of heavy metals (Fe, Zn, Cu, Cd, Ni, Pb, Cr, As) were determined in seven seaweeds of environmental and commercial relevance (
Ulva rigida C. Ag.,
Gracilaria gracilis (Stackhouse) ...Steentoft, L. Irvine and Farnham,
Porphyra leucosticta Thuret,
Grateloupia doryphora (Montagne) Howe.,
Undaria pinnatifida (Harv.) Suringar,
Fucus virsoides J. Agardh,
Cystoseira barbata (Good. et Wood.) Ag.) collected in four sampling sites in the lagoon of Venice, in spring and autumn 1999. Metals were extracted using hot concentrated acids in a Microwave Digestion Rotor and analysed by absorption spectrophotometry using a flame mode for Fe and Zn and a graphite furnace for Pb, Cr, Cd, Cu, Ni and As. High contamination levels, especially for Pb, were detected in
Ulva and to a lesser extent in
Gracilaria. Brown seaweeds, especially
Cystoseira was highly contaminated by As. The least contaminated genera with all metals except As were
Porphyra and
Undaria. A concentration decrease for Zn and Cd was observed from the inner parts of the central lagoon, close to the industrial district, towards the lagoon openings to the sea.
The Venice Lagoon has become increasingly affected by the introduction of allochthonous macroalgae mainly coming from the Indo-Pacific area. In consequence to the recent climate changes and ...temperature increase, such species could simply find numerous habitats suitable for their growth. One local process that contributes to water temperature changes is thermal pollution. In this study we used the DNA barcoding method to identify a new alien macroalgal species, Grateloupia yinggehaiensis Wang et Luan (Rhodophyta), found near the industrial area of Porto Marghera (Venice, Italy) hosting the Fusina thermoelectric power plant. The microclimate of this area has enabled the spread of this species native of the tropical area of the Hainan Province (China) and probably introduced in the Mediterranean Sea via shellfish transfers.
Three different strains of filamentous cyanobacteria,
Tychonema
,
Limnothrix
, and
Pseudoanabaena
, were selected among the fastest growing taxa collected in the salt marshes of Venice Lagoon and ...were grown in laboratory for growth rate determination and biochemical characterization of chlorophyll-
a
, total proteins, total carbohydrates, and exopolysaccharides. Experiments were carried out both in liquid medium and two different substrates: artificial plant protection fabric and ground indigenous shells. Cyanobacterial behavior was recorded to better understand colonization of natural and new artificial marshes.
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