Andrea Sfriso

Seasonal variation and yield of sulfated polysaccharides in seaweeds from the Venice Lagoon

Abstract Three red seaweeds from the Venice Lagoon: Gracilaria gracilis, Gracilaria vermiculophylla, Gracilariopsis longissima and the green seaweed Ulva rigida were investigated to determine the yields and the annual fluctuation of sulfated polysaccharides (SP) for biotechnological applications. The Gracilariaceae and U. rigida were investigated and evaluated taking into account various environmental parameters of the water column and surface sediments. The annual production of SP was the highest for G. longissima (13.2 tons dw ha−1 year−1), followed by G. vermiculophylla (11.4 tons dw ha−1 year−1) and G. gracilis (7.4 tons dw ha−1 year−1), whereas U. rigida showed the lowest production (2.7 tons dw ha−1 year−1). High nutrient availability, turbidity and phytoplankton blooms inhibited the production of SP in the red seaweeds especially in summer. The SP produced by Gracilariaceae in March and April, at water temperatures ranging between 13°C and 17°C, accounted for more than half of the total annual production. In contrast, U. rigida produced the highest quantity of SP (ulvan) in June with temperatures >25°C.

Spatial distribution, bioaccumulation profiles and risk for consumption of edible bivalves: a comparison among razor clam, Manila clam and cockles in the Venice Lagoon

Despite their ecological and economical relevance, a lack of data is still occurring about the distribution, abundance, bioaccumulation and risks for consumption of some edible bivalves. The present study has been carried out in the Venice Lagoon taking into account three bivalve species to investigate i) the possible relationship among the biological features-distribution, abundance and bioaccumulation patterns- of razor clams (Solen marginatus Pulteney, 1799), Manila clams (Ruditapes philippinarum Adams and Reeve, 1850) and lagoon cockles (Cerastoderma glaucum Poiret, 1789) and the hydrological features, namely sediment physico-chemical characteristics and contamination; ii) their specific role as bioindicators of inorganic contamination; iii) the possible risks for human health associated with the consumption of these edible bivalves. Results showed that species distribution and abundance, especially for razor clams, was mainly influenced by environmental conditions and sediment granulometric composition, above metal(loid) contamination. The contamination patterns were different among species, as Manila clam generally showed higher bioaccumulation values for most of the metal(loid)s, whilst lagoon cockles preferentially accumulated Ni. Eventually, a serious concern exists for the human consumption, for all species and investigated sites regarding As. This study will raise attention on the effects of bioaccumulation of inorganic pollutants by edible bivalves and risks for consumers safety, especially concerning razor clams and cockles, for which a critical lack of data on metal(loid) bioaccumulation occurs from the Northern Adriatic Sea.

Phycoerythrin productivity and diversity from five red macroalgae

Five red algae, Agardhiella subulata, Gracilariopsis longissima, Gracilaria vermiculophylla, Polysiphonia morrowii, and Pyropia elongata were sampled in winter for the extraction of phycoerythrin. The extracted phycoerythrin molecules were compared with the commercial phycoerythrin to determine the intrinsic fluorescence characteristics of the single pigments. An improved selective method for phycoerythrin extraction was set up for routinary investigation. The use of the mortar and pestle method for tissue homogenization with a freeze-thawing cycle allowed a simple and complete homogenization of the red algae. The extraction of phycoerythrin with diluted EDTA solutions (1xa0mM) at pHxa09 enabled a selective and easy extraction of the pigment with 95–98% extraction efficiency. The way pH affected the phycoerythrin, phycocyanin, and allophycocyanin selective extraction was also evaluated. The 3D fingerprint of each pigment was recorded, and a comparison of different phycoerythrin spectra was performed by fluorescence spectroscopy highlighting differences in A. subulata and P. morrowii phycoerythrins in comparison with commercial standards purified from Pyropia. The productivity and the advantages of phycoerythrin that was extracted from unattached red algal species are discussed.

Rediscovery of a Forgotten Mediterranean Chaetomorpha Species in the Venice Lagoon (North Adriatic Sea): Chaetomorpha stricta Schiffner (Cladophorales, Chlorophyta)

Abstract n On the basis of bibliographical, morphological and molecular studies (SSU rDNA), the reinstatement of species rank for Chaetomorpha stricta Schiffner, a poorly known Mediterranean endemic species described in the early 20th century, is proposed. Previously reduced to a posterior heterotypic synonym of C. linum (O.F. Müller) Kützing, C. stricta clearly differs from the latter by its small, light green, free-living filaments entangled in dense masses, the cells 0.5 to 1.6 (rarely 2) times as long as broad, with cell walls lamellate and broad up to 75–90 μm thick, and by molecular data. Chaetomorpha stricta was rediscovered, in May 2011, in oligotrophic clear waters of a closed fishing pond in the Valle Cavallino (northern basin of the Venice Lagoon). A critical review of Chaetomorpha taxa reported in the Mediterranean Sea and a taxonomic key to the Mediterranean taxa currently accepted are presented.

Biochemical characterization of some cyanobacterial strains from salt marshes of the Venice Lagoon

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.