Microzooplankton grazing impact along a trophic gradient from the Atlantic Ocean to the Western Mediterranean Sea

2008/2009Nell'ambito della crociera transmediterranea facente parte del progetto V.E.C.T.O.R. è stato quantificato il flusso di carbonio che veicola attraverso le reti trofiche pelagiche tramite la predazione del microzooplancton su un ampio spettro di prede; si è inoltre verificato la selezione delle prede e quantificato la produzione secondaria. Per questa analisi è stato adottato il metodo delle diluizioni introdotto da Landry ed Hassett (1982)che ci permette di stimare sia il tasso di crescita delle prede, che quello di mortalità delle prede indotta da predazione. In concomitanza con gli esperimenti di diluizione,si è valutato la comunità dei predatori con differenti metodi di campionamento e di conservazione dei campioni nonchè, l'attività di predazione del mesozooplancton sul comparto microplanctonico nel Mar Ligure e nel Mar Tirreno. I risultati complessivi della ricerca indicano che in condizioni di estrema oligotrofia nelle quali è avvenuta la crociera nell'estate 2007, il flusso di carbonio di maggiore entità che fluisce attraverso il comparto microzooplanctonico deriva dalle biomasse dei batteri eterotrofi, che sono le uniche consistenti in tutta l'area. Nanoplancton e microfitoplancton, contribuiscono scarsamente alla dieta del microzooplancton. Dallo studio quali-quantitativo del microooplancton si evince che la rappresentazione migliore in termini di ricchezza si ottiene con maggiori volumi di campionamento (5 L, conservati in formalina al 2%) mentre, l'abbondanza più rilevante si riscontra quando i campioni (300 mL) vengono conservati in soluzione di Lugol al 2%. I campioni ottenuti dall'esperimento di diluizione (2 L, conservati in formalina al 2%) offrono nel complesso la miglior rappresentazione della comunità dei predatori. Nel Mar Ligure, il calanoide Centropages esercita il suo impatto di predazione sia sul comparto microzooplanctonico che su quello microfitoplanctonico, sebbene sia indirizzato in questo caso, unicamente alla categoria dei dinoflagellati a dimensioni maggiori e ai coccolitoforidi. Nel Mar Tirreno, il ciclopoide Corycaeus esercita la sua selezione unicamente sul comparto microzooplanctonico. Per la stazione tirrenica si registrano valori di export seppur minimi. Nel complesso, sembra che in condizioni di oligotrofia, l'energia trasferita ai livelli trofici superiori sia molto esigua.In the frame of the V.E.C.T.O.R. project, during the transmediterranean cruise, the carbon fluxes throughout the pelagic trophic webs were quantified by means of the grazing impact of microzooplankton on a wide variety of prey; The selection exerted by microzooplankton on its prey and the secondary production was also estimated. The dilution method introduced by Landry and hassett (1982) was applied to the research. The method assess both the growth of the prey and their mortality induced by grazing. Beside dilution experiments, a quali-quantitative analysis of the predators comunity treated with different fixatives and sampling techniques was performed. In the Ligurian and in the Tyrrhenian Sea, a further examination on mesozooplankton grazing on microplankton assemblages was estimated. Risults confirm that in extreme oligotrophic conditions as those occured during summer 2007, the major carbon flux fuelled through microzooplankton community derived from heterotrophic bacteria, that showed the most abundant biomasses along the sampled stations. Nano- and microphytoplankton were of minor importance in the diet of their direct grazers. From the quali-quantitative analysis of microzooplankton, the best representation in terms of species richness is obtained by means of higher sampling volumes (5 L, fixed in 2% formalin) whereas, the higher abundances were displayed for samples collected in 300 mL and conserved in Lugol's solution. Samples derived from dilution experiments (2 L fixed in 2% formalin) among all, displayed the best representation of the predators community. In the Ligurian Sea, the calanoid Centropages, exerted its grazing impact on both microzooplankton and microphytoplankton; on the latters, the selection is addressed only on dinoflagellates of bigger size and on coccolithophorids. In the Tyrrhenian Sea, the cyclopoid Corycaeus, selects all microzooplankton assemblage but aloricate ciliates. The Tyrrhenian Sea, recorded a minimum export. In oligotrophic conditions, the energy fuelled to the higher trophic levels seems to be very scarce.XXII Ciclo197

Multispectral data by the new generation of high-resolution satellite sensors for mapping phytoplankton blooms in the Mar Piccolo of Taranto (Ionian Sea, southern Italy)

The HR (High-Resolution) EO (Earth Observation) satellite systems Landsat 8 OLI and Sentinel 2 were tested for mapping the frequent phytoplankton blooms and Chl a distributions in the sea basin of the Mar Piccolo of Taranto (Ionian Sea, southern Italy), using the sea truth calibration data acquired in 2013. The data were atmospherically corrected for accounting of the aerosol load on optically complexes waters (case II). Various blue-green and additional spectral indices ratios, were then satisfyingly tested for mapping the distribution of Chl a and differently sized phytoplankton populations through PLS (Partial Least Square regression) models, regressive statistical models and bio-optical algorithms. The PLS models demonstrated higher robustness for assessing the distribution of all the phytoplankton and Chl a except for those related to sub-surface micro-phytoplankton. The distributions obtained via a bio-optical approach (OC3 algorithm and full physically based inversion) showed a general agreement with the previous ones produced by statistical methods. The reflectance signals, captured by OLI and Sentinel 2 sensors in the visible and shorter wavelengths once atmospherically corrected, were found to be useful to map the coastal variability at detailed scale of Chl a and different phytoplankton populations, in the optically complexes waters of the Mar Piccolo

Dinoflagellate resting cysts from surface sediments of the Adriatic Ports: distribution and potential spreading patterns

The ability of microalgae to preserve viable in coastal sediments as resting forms provides a reservoir of biodiversity and a useful tool to determine species spreadings. This study represents the first port baseline survey on dinoflagellate cysts, investigated in nine Adriatic ports during a cross border project. 40 dinoflagellate taxa were detected. The assemblages resulted in all ports dominated by Lingulodinium polyedra and Alexandrium minutum/affine/tamutum group. General separation to the western and eastern side of the Adriatic regarding cysts assemblage composition, partially abundance, was observed. Seven taxa were detected as non-indigenous species for the Adriatic. Two taxa are included in the list of harmful aquatic organisms, indicating the potential threat of ballast waters in the Adriatic. Potential spreading of taxa by general circulation and ballast waters, intra- and extra-Adriatic was investigated. The entering in to force of the ballast waters management regulations should enhance prospects to minimize future harmful impacts

Dinoflagellate resting cysts from surface sediments of the Adriatic Ports: Distribution and potential spreading patterns

The ability of microalgae to preserve viable in coastal sediments as resting forms provides a reservoir of biodiversity and a useful tool to determine species spreadings. This study represents the first port baseline survey on dinoflagellate cysts, investigated in nine Adriatic ports during a cross border project. 40 dinoflagellate taxa were detected. The assemblages resulted in all ports dominated by Lingulodinium polyedra and Alexandrium minutum/ affine/tamutum group. General separation to the western and eastern side of the Adriatic regarding cysts assemblage composition, partially abundance, was observed. Six taxa were detected as non-indigenous species for the Adriatic. Two taxa are included in the list of harmful aquatic organisms, indicating the potential threat of ballast waters in the Adriatic. Potential spreading of taxa by general circulation and ballast waters, intra- and extra-Adriatic was investigated. The entering in to force of the ballast waters management regulations should enhance prospects to minimize future harmful impacts

First Report of the Italian Registry on Immune-Mediated Congenital Heart Block (Lu.Ne Registry)

Objective: Neonatal Lupus (NL) is a rare syndrome caused by placental transfer of maternal anti-SSA/Ro and anti-La/SSB autoantibodies to the fetus. The rarity of this condition requires the establishment of multidisciplinary registries in order to improve our knowledge. Method: Inclusion criteria in this retrospective study were the maternal confirmed positivity for anti-SSA/Ro and/or anti-SSB/La antibodies, and the presence of II or III degree congenital heart block (CHB) in utero or neonatal period (up to 27 days after birth). Result: Eighty-nine cases of CHB were observed in 85 women with 88 pregnancies that occurred between 1969 and 2017. CHB was mostly detected in utero (84 cases, 94.2%), while five cases were observed in the neonatal period. A permanent pacemaker was implanted in 51 of 73 children born alive (69.8), whereas global mortality rate was 25.8% (23 cases): 16 in utero, five perinatal, and two during childhood. By univariate analysis, factors associated with fetal death were pleural effusion (p = 0.005, OR > 100; CI 95% 2.88->100 and hydrops (p = 0.003, OR = 14.09; CI 95% 2.01-122). Fluorinated steroids (FS) were administered in 71.4% pregnancies, and its use was not associated with better survival. Some centers treated all cases with fluorinated steroids and some centers did not treat any case. CHB was initially incomplete in 24 fetuses, and of them five cases of II degree block reverted to a lower degree block after treatments. Recurrence rate in subsequent pregnancies was 17.6% (3 out of 17). A prophylactic treatment was introduced in 10 of these 16 subsequent (58.8%) pregnancies, mostly with FS or high dose intravenous immunoglobulins. Conclusion: This is the first report from the Italian Registry of neonatal lupus/CHB. The live birth rate was nearly 80%, with nearly two thirds of the children requiring the implantation of a pacemaker. The management of fetuses diagnosed with CHB was heterogeneous across Italian Centers. The registry at present is mainly rheumatological, but involvement of pediatric cardiologists and gynecologists is planned