NW Adriatic Sea Research Articles

Screening, classification, capacity estimation and reservoir modelling of potential CO2 geological storage sites in the NW Adriatic Sea, Italy

In Italy, the central-northern Apennines and Adriatic Sea domains have been identified as potential CO2 storage areas. Although capacity estimates have been undertaken at a regional scale, more detailed research is required to reduce uncertainty. The present study helps address this gap by conducting a detailed screening of a representative area in the north-western Adriatic Sea for suitable CCS sites, using an extensive dataset composed of both public and private seismic and borehole data. Work included selecting suitable sites based on proposed selection criteria, calculating their theoretical and effective storage capacities applying a probabilistic approach, and then performing dynamic flow modelling on one of the selected sites that is representative of fractured carbonate reservoirs. Based on the screening results, a total of 21 out of 38 structures were selected as having the required characteristics suitable for CO2 storage. As expected, the clastic rock reservoirs have the greatest potential capacity, although some fractured carbonate reservoirs did yield important volumes due to their dual porosity / permeability characteristics. Modelling of one such site highlighted the complex interplay between primary and secondary porosity / permeability on plume migration and capacity estimation. Our results highlight the need to integrate analytical calculations with dynamic simulations for more detailed, site-specific studies to improve the estimates of CO2 storage capacity.

Successful acclimation of marine diatoms Chaetoceros curvisetus/pseudocurvisetus to climate change

AbstractTwo main parameters that structure the marine ecosystem by affecting species distribution, abundance, community structure, timing of major life cycle events, and trophic state of the ecosystem are temperature and nutrient availability. Faced with climate change, eukaryotic plankton cope at multiple levels through physiological accommodation, adaptive evolution, shift in time and/or space of habitat, and/or community responses. Thirty‐two years of our phytoplankton research indicate that Chaetoceros curvisetus/pseudocurvisetus adjust to climate change more successfully than the majority of the accompanying phytoplankton taxa in the mesotrophic part of the NW Adriatic Sea, the Mediterranean. While the abundance of the entire accompanying phytoplankton community has decreased significantly since 2003 (the period of the northern Adriatic warming and oligotrophication) compared to the previous period (1986–2003), the abundance of C. curvisetus/pseudocurvisetus remained unchanged, while its contribution to the community increased significantly. Accommodation strategies include a change in the timing of high abundance and blooms in the surface layer and successful blooming in the deeper layers during warm months. Apart from the observed in situ accommodation, physiological acclimation to warming may involve changes in photosynthesis, respiration, growth, and cell biochemistry. Here, we conducted laboratory experiments with C. pseudocurvisetus to investigate how warming affects its biochemical response through the fatty acid remodeling of phospholipid classes. Long‐term field observations and short‐term laboratory experiments suggest that marine diatoms C. curvisetus/pseudocurvisetus are potential global winners with the ability to acclimate/adapt to climate change.

Integrative taxonomy of the Pseudo-nitzschia (Bacillariophyceae) populations in the NW Adriatic Sea, with a focus on a novel cryptic species in the P. delicatissima species complex

ABSTRACT Species of the genus Pseudo-nitzschia are common inhabitants of phytoplankton communities of the northern Adriatic Sea, reaching high abundances. During 2018–2019, a total of 138 cultured Pseudo-nitzschia strains were isolated from northwestern Adriatic Sea and were characterized by using both morphological (TEM) and molecular (LSU, ITS, ITS2 secondary structure) approaches. Observation of frustule ultrastructure and phylogenetic analysis resolved a total of six taxa, i.e. P. fraudulenta, P. pungens, P. calliantha, P. mannii, P. delicatissima and P. cf. arenysensis. Results of the integrative taxonomic approach clearly revealed that P. cf. arenysensis is a cryptic species within P. delicatissima species complex. Pseudo-nitzschia cf. arenysensis is closely related to P. arenysensis, which forms a subclade and a sister group in LSU and ITS phylogenies, respectively. When comparing ITS2 secondary structure of P. cf. arenysensis and P. arenysensis, 1 CBC, 1 HCBC and 2 SNPs were recognized, suggesting reproductive isolation. Domoic acid production was not detected in any of the studied strains.

A model predicting the PSP toxic dinoflagellate Alexandrium minutum occurrence in the coastal waters of the NW Adriatic Sea

Increased anthropic pressure on the coastal zones of the Mediterranean Sea caused an enrichment in nutrients, promoting microalgal proliferation. Among those organisms, some species, such as the dinoflagellate Alexandrium minutum, can produce neurotoxins. Toxic blooms can cause serious impacts to human health, marine environment and economic maritime activities at coastal sites. A mathematical model predicting the presence of A. minutum in coastal waters of the NW Adriatic Sea was developed using a Random Forest (RF), which is a Machine Learning technique, trained with molecular data of A. minutum occurrence obtained by molecular PCR assay. The model is able to correctly predict more than 80% of the instances in the test data set. Our results showed that predictive models may play a useful role in the study of Harmful Algal Blooms (HAB).

Phytoplankton communities in the northwestern Adriatic Sea: Interdecadal variability over a 30-years period (1988–2016) and relationships with meteoclimatic drivers

Abstract In this study the interannual variability of phytoplankton over a ~30-years period in the coastal site of LTER-Senigallia transect (N Adriatic Sea) was investigated to document patterns potentially related to environmental/climatic drivers. Comparing physical and chemical data of the periods 1988–2002 and 2007–2016 periods, we showed that phytoplankton abundance and biomass and inorganic nutrient concentrations increased in the last decade, indicating that the tendency to oligotrophication due to the drop of the Po River outflow in the years 2002–2007 was reversed in the period 2007–2016. The typical P-limited conditions of the N Adriatic Sea seem to have been attenuated in the study area. P levels were not explained by the P concentrations in the Po River waters, suggesting the possible influence of other local P sources that could be related to the anomalous meteorological events (intense rainfalls) that took place in the 2007–2016 period. In the last decade, the community structure and seasonality of phytoplankton markedly changed, as highlighted by the different indicator species for each season: the blooms of Skeletonema marinoi shifted from winter to spring. A significant decrease of coccolithophores was observed particularly in winter months in the 2007–2016 period: some indicator species among the most relevant in the 1988–2002 period (such as Emiliania huxleyi in winter, and Syracosphaera pulchra in spring) have lost this role in 2007–2016. Dinoflagellate abundances decreased, except in spring when the occasional proliferation of large sized species caused biomass peaks. The phytoplankton annual cycle became irregular with sudden diatom blooms, reflecting the variability of meteorological events in recent years. It is noteworthy that in the last decade, an allochthonous species, i.e. the diatom Pseudo-nitzschia multistriata, became a regular inhabitant of the autumn phytoplankton communities of the NW Adriatic Sea.

Phylogenetic structure of bacterial assemblages co-occurring with Ostreopsis cf. ovata bloom

Extensive blooms of the toxic epiphytic/benthic dinoflagellate Ostreopsis cf. ovata are being reported with increasing frequency and spatial distribution in temperate coastal regions including the Mediterranean. These blooms are of human and environmental health concern due to the production of isobaric palytoxin and a wide range of ovatoxins by Ostreopsis cf. ovata. Bacterial-microalgal interactions are important regulators in algal bloom dynamics and potentially toxin dynamics. This study investigated the bacterial assemblages co-occurring with O. cf. ovata (OA) and from ambient seawaters (SW) during the early and peak phases of bloom development in NW Adriatic Sea. Fractions of the bacterial assemblages co-occurring with O. cf. ovata (OA) and more closely associated to the mucilage layer (LA) embedding O. cf. ovata cells were also reported.In total, 14 bacterial phyla were detected by targeted 454 pyrosequencing of the 16S rRNA gene. The dominant bacterial phyla in the OA assemblages were Proteobacteria and Bacteroidetes; while at the class level, Alphaproteobacteria were the most abundant (83 and 66%, relative abundance, early and peak bloom phases), followed by Flavobacteria (7 and 19%, early and peak phases). Actinobacteria and Cyanobacteria were of minor importance (<5% of the relative bacterial abundance each). Gammaproteobacteria showed a notably presence in OA assemblage only at the early phase of the bloom (genus Haliea, 13%). The Alphaproteobacteria were predominately composed by the genera Ruegeria, Jannaschia and Erythrobacter which represented about half of the total phylotypes’ contribution of OA at both early and peak phases of the O. cf. ovata bloom, suggesting interactions between this consortium and the microalga. Moreover, the highest contribution of Ruegeria (30% of the total phylotypes) was observed at the early phase of the bloom in LA assemblage.Microbial assemblages associated with the ambient seawaters while being also dominated by Alphaproteobacteria and Flavobacteria were partially distinct from those associated with O. cf. ovata due to the presence of genera almost not retrieved in the latter assemblages.

Seasonal dynamics and long-term trend of hypoxia in the coastal zone of Emilia Romagna (NW Adriatic Sea, Italy)

Long-term series of meteorological, hydrological and oceanographic data were compared with hypoxia occurrence, in order to define characteristics and trends of this phenomenon in the Emilia Romagna Coastal Zone (ERCZ) in 1977–2008. During this period, hypoxia was recorded at all sampling stations, up to 20km offshore. In winter, spring and late autumn, hypoxia appearance was matched to significant positive anomalies of air and surface seawater temperatures (up to +3.6°C), whereas this effect was less pronounced in August–October. Hypoxia generally occurred with scarce precipitation (0–2dm3m2d−1) and low wind velocity (0–2ms−1), suggesting the importance of stable meteo-marine conditions for the onset of this phenomenon. Nevertheless, wind direction emerged as an indicator of hydrodynamic seasonal changes in the area and is thus a hypoxia regulator. In winter, spring and autumn, hypoxia was favored by large increases of biomass induced by river freshets. In contrast, summer hypoxia occurred during periods of low runoff, suggesting that pronounced stratification and weak circulation of coastal waters were more important in this season.Since the 1990s, a shift from widespread summer hypoxia to local hypoxia irregularly distributed across the year has occurred. This process was concomitant to long-term increases of air temperature (+0.14°Cyr−1), wind speed (+0.03ms−1yr−1) and salinity (+0.09yr−1), and decreases of Po River flow (−0.54km3yr−1), oxygen saturation (−0.2%yr−1) and PO43− (−0.004μmolPL−1yr−1) and NH4+ (−0.04μmolNL−1yr−1) concentrations in surface coastal waters. Despite that several of these changes suggest an ERCZ trophic level positive reduction, similar to that reported for the N Adriatic, the concomitant climate warming might further exacerbate hypoxia in particularly shallow shelf locations. Therefore, in order to avoid hypoxia development a further mitigation of anthropogenic pressure is still needed in the area.

Mass Mortality Events in the NW Adriatic Sea: Phase Shift from Slow- to Fast-Growing Organisms.

Massive outbreaks are increasing all over the world, which are likely related to climate change. The North Adriatic Sea, a sub-basin of the Mediterranean Sea, is a shallow semi-closed sea receiving high nutrients inputs from important rivers. These inputs sustain the highest productive basin of the Mediterranean Sea. Moreover, this area shows a high number of endemisms probably due to the high diversity of environmental conditions and the conspicuous food availability. Here, we documented two massive mortalities (2009 and 2011) and the pattern of recovery of the affected biocoenoses in the next two years. Results show an impressive and fast shift of the benthic assemblage from a biocoenosis mainly composed of slow-growing and long-lived species to a biocoenosis dominated by fast-growing and short-lived species. The sponge Chondrosia reniformis, one of the key species of this assemblage, which had never been involved in previous massive mortality events in the Mediterranean Sea, reduced its coverage by 70%, and only few small specimens survived. All the damaged sponges, together with many associated organisms, were detached by rough-sea conditions, leaving large bare areas on the rocky wall. Almost three years after the disease, the survived specimens of C. reniformis did not increase significantly in size, while the bare areas were colonized by fast-growing species such as stoloniferans, hydrozoans, mussels, algae, serpulids and bryozoans. Cnidarians were more resilient than massive sponges since they quickly recovered in less than one month. In the study area, the last two outbreaks caused a reduction in the filtration efficiency of the local benthic assemblage by over 60%. The analysis of the times series of wave heights and temperature revealed that the conditions in summer 2011 were not so extreme as to justify severe mass mortality, suggesting the occurrence of other factors which triggered the disease. The long-term observations of a benthic assemblage in the NW Adriatic Sea allowed us to monitor its dynamics before, during and after the mortality event. The N Adriatic Sea responds quickly to climatic anomalies and other environmental stresses because of the reduced dimension of the basin. The long-term consequences of frequent mass mortality episodes in this area could promote the shift from biocoenoses dominated by slow-growing and long-lived species to assemblages dominated by plastic and short life cycle species.

Reproductive ecology of Epizoanthus arenaceus (Delle Chiaje, 1823) (Cnidaria: Anthozoa) from the North Adriatic Sea

The North Adriatic Sea is a shallow basin characterized by peculiar trophic and hydrologic conditions affecting the composition, species abundance and seasonal cycles of the benthic assemblages. Due to high productivity rates comparable to those of the north seas, here the benthic organisms reach sizes or densities significantly higher than the same species observed in other Mediterranean localities and show wider periods of reproduction. Concerning the dynamics of zoanthids, there are very few studies about these Mediterranean species, and this research is the first on the abundance and reproduction of Epizoanthus arenaceus. The zoanthid from shallow waters of the NW Adriatic Sea has a maximum abundance of 25,000polypsm−2 (about 40gCm−2). E. arenaceus shows a growth phase during winter and a regression period from summer to autumn coinciding with gametogenesis. During summer, the decreases in current intensity and prey concentration combined with the increase in the reproductive effort may cause shrinkage and fission/fragmentation of the colonies. On the contrary, the maturation and release of gametes are positively correlated with the temperature trend. A temporal and spatial separation of the production of male and female gametes was observed, leading us to hypothesize that temperature could affect sex determination.The comparison of patterns in abundance and reproduction at 3–4m and 6–7m shows that the shallower colonies seem to be more sensitive to extreme values of temperature. The NW sector of the Adriatic Sea, vulnerable to severe anthropogenic pressure and subject to frequent thermal anomalies, is particularly prone to the mortality episodes of benthic organisms. For these reasons, the study of the dynamics of invertebrates from this area is crucial to forecast the effects of environmental changes in the entire Mediterranean basin.

Dynamics and sources of organic carbon in suspended particulate matter and sediments in Pialassa Baiona lagoon (NW Adriatic Sea, Italy)

Organic carbon (OC), total nitrogen (TN) and stable carbon isotopic signature (δ13C) of suspended particulate matter and of surface sediments were investigated to assess temporal dynamics and relative contribution of autochthonous and allochthonous OC sources in the coastal eutrophic Pialassa Baiona lagoon. Water sampling for particulate organic carbon (POC), total nitrogen (PTN), nutrients and chlorophyll a (Chl a) concentrations, and bacterial abundance was carried out over a year. Seasonal changes of δ13CPOC signature and C/N ratio discriminated two main areas within the lagoon: the partially preserved northern-central area and the southernmost impacted area. Except for the southernmost impacted area, δ13CPOC (mean value: 22.11‰) showed the highest depleted values in winter and the most enriched in summer following phytoplankton seasonal development as also suggested by changes in C/N ratios, and by the significant correlations found between Chl a and POC, and δ13CPOC. Moreover, the two areas showed different timing and isotopic signature of phytoplankton blooms (e.g. Chl a 23.22 and 29.27 μg L−1, and δ13CPOC −19.15 and −30.70‰, June and March, in the northern-central and southern area, respectively). The summer bloom in the northern-central area was also associated with high bacterial abundances (up to 7.30 × 109 cells L−1), suggesting the establishment of a strong structured microbial food loop and organic matter recycling.Surface sediments from the southern impacted area showed significant higher values in OC and TN contents (3.05 and 1.44%), and significant depleted δ13C signal (−23.03‰) when compared to the control area (1.09 and 0.16%, −19.40‰); whereas no differences were found in C/N ratios (8.1 and 8.2, in northern-central and southern impacted area, respectively).Elemental and isotopic composition data showed a strong coupling between POC and surface sediments. The relative contribution of three different sources (marine, estuarine, terrestrial) to POC and surface sediments were estimated using a mixing model, which predicted a predominant fraction of marine phytoplankton in POC during spring-summer and in surface sediments from the northern-central area. Conversely, dominant allochthonous sources were predicted for POC in winter months and in impacted area sediments. δ13C values of surface sediment reflected an isotopic overprint of refractory terrestrial-derived (allochthonous) organic carbon agreeing with urban/industrial wastewaters origin.

Palytoxin and an Ostreopsis Toxin Extract Increase the Levels of mRNAs Encoding Inflammation-Related Proteins in Human Macrophages via p38 MAPK and NF-κB

BackgroundPalytoxin and, likely, its analogues produced by the dinoflagellate genus Ostreopsis, represent a class of non-proteinaceous compounds displaying high toxicity in animals. Owing to the wide distribution and the poisonous effects of these toxins in humans, their chemistry and mechanism of action have generated a growing scientific interest. Depending on the exposure route, palytoxin and its Ostreopsis analogues may cause several adverse effects on human health, including acute inflammatory reactions which seem more typical of cutaneous and inhalation contact. These observations have led us to hypothesize that these toxins may activate pro-inflammatory signalling cascades.Methodology and Principal FindingsHere we demonstrate that palytoxin and a semi-purified Ostreopsis cf. ovata toxin extract obtained from a cultured strain isolated in the NW Adriatic Sea and containing a putative palytoxin and all the ovatoxins so far known – including the recently identified ovatoxin-f – significantly increase the levels of mRNAs encoding inflammation-related proteins in immune cells, i.e. monocyte-derived human macrophages, as assessed by Real-Time PCR analysis. Western immunoblot and electrophoretic mobility shift assays revealed that nuclear transcription factor -κB (NF-κB) is activated in cells exposed to toxins in coincidence with reduced levels of the inhibitory protein IκB-α. Moreover, Mitogen-Activated Protein Kinases (MAPK) were phosphorylated in response to palytoxin, as also reported by others, and to the Ostreopsis toxin extract, as shown here for the first time. By using specific chemical inhibitors, the involvement of NF-κB and p38 MAPK in the toxin-induced transcription and accumulation of Cycloxigenase-2, Tumor Necrosis Factor-α, and Interleukin-8 transcripts has been demonstrated.Conclusions and SignificanceThe identification of specific molecular targets of palytoxin and its Ostreopsis analogues, besides contributing to expand the still limited knowledge of the intracellular signalling cascades affected by these toxins, may have important implications in setting up focused pharmacological interventions, replacing currently used symptomatic treatments.

Ecology ofOstreopsiscf.ovataBlooms in the Northwestern Adriatic Sea

The ecology of Ostreopsis cf. ovata blooms was investigated to evaluate the role of environmental factors (temperature, hydrodynamism, nutrient concentrations, depth and substratum) on the bloom dynamics. This paper reports the present knowledge on O. cf. ovata blooms along the Conero Riviera (NW Adriatic Sea), on the basis of samplings carried out from 2006 to 2010. The annual maximum of benthic cell abundance was always observed in late-summer, reaching the order of magnitude of 106 cells g-1 fw (corresponding to 107 cells g-1 dw and 104 cells cm-2) on macrophyte samples. Comparing the mean abundances settled on seaweeds with those growing on hard substrata, significantly higher abundances were observed on the latter. Hydrodynamism plays a major role in Ostreopsis blooms, as significantly higher abundances were observed in sheltered sites compared with exposed ones. The abundances of O. cf. ovata showed a marked decrease with depth. Temperature and nutrients do not seem to play an important effect on the O. cf. ovata blooms. High levels of ovatoxins were recorded in natural samples; episodes of death of both benthic invertebrates (limpets, sea urchins and mussels) and macroalgae were commonly observed during O. cf. ovata blooms.

Acid-labile sulfides in shallow marine bottom sediments: A review of the impact on ecosystems in the Azov Sea, the NE Black Sea shelf and NW Adriatic lagoons

Abstract Acid-labile sulfides (LS) increase in bottom sediments at sites in the Azov Sea, at the NE Black Sea shelf and in the coastal lagoons of NW Adriatic Sea experiencing direct impacts of anthropogenic pollution. Fresh anthropogenic organic matter stimulates the bacterial sulfate reduction and here the rate of the LS production overcomes their loss during the oxidation and pyritization. This results in the expansion of reduced sediment layer up to the bottom surface. The LS concentration in the reduced sediments varies between 300 and 2000 mg S l−1 of wet silt depending on the size of pollution loading and on the rate of sedimentation. In the oxidized sediments away from the direct pollution impact, the LS concentration did not exceed 100–150 mg S l−1. Being a strong cytochrome toxin, the LS adversely affect the coastal ecosystems. The concentrations over 600 mg S l−1 result in quasi total benthic mortality whereas >300–400 mg S l−1 depletes the benthic faunal abundance and taxonomic diversity. Accumulation of the LS in sediments also induces nocturnal hypoxia and stimulates domination of toxic cyanobacteria in the pelagic phytocenoses.

Contribution of Richard A. Vollenweider toward understanding eutrophication of the coastal Adriatic Sea

The main scope of the work of R. A. Vollenweider in Italy, that is to say his principal scientific merit, was to critically examine the cause-effect relationships related to the manifestations of the eutrophication phenomenon. These relationships were observed in the NW Adriatic Sea over more than 20 years, along the Emilia Romagna coast, an area strongly affected by Po river inputs, the principal Italian river (Vollenweider et al., 1992). In particular, he stressed the need to examine the integrated system, and to consider both scientific and socio-economic issues as interrelated. Accordingly, coastal waters and their catchment areas with related nutrient loads represent the total system, of which the natural, anthropogenic and socio-economic components are the respective subsystems. In more practical terms, he suggested nutrient load assessment based on the different sources of N and P, to prepare an inventory of all these sources according to types and quantity released, and in terms of pathways of transfer and input-output fluxes. In this way it was finally possible to reach a first realistic evaluation of N and P mass balance across the various productive compartments.

A simplified approach to evaluate sedimentary organic matter fluxes and accumulation on the NW Adriatic Shelf (Italy)

Total organic carbon (TOC) and total nitrogen (TN) concentrations and fluxes were estimated in surface sediments of a shelf area in the NW Adriatic Sea (Italy), together with lithology and 210Pb contents at 18 stations during four cruises (1996–1998) carried out offshore of the Po River delta. Mass accumulation rates (MAR) were ∼0.1–0.8 g cm−2 yr−1 and surface concentrations of TOC and TN were within the range of 0.5–1.4 and 0.08–0.19% of dry weight, respectively. Their spatial variability showed a direct correlation with the inputs of suspended matter from the Po River. A simplified approach to calculate average TOC and TN yearly fluxes to surface sediments over the whole area was adopted by subdividing the study area into three zones, selected on the basis of the grain size distributions and of the influence of the Po River discharge, in order to take into account major differences of sedimentological regimes on the shelf. The values of TOC (×103 tC yr−1) and TN (×103 tN yr−1) fluxes for these areas were, respectively, 17.9 and 2.4 near the delta, 45.2 and 6.5 for the intermediate area, and 9.5 and 1.5 for the offshore area.

Aggregate indicators in coastal policy making: potentials of the Trophic Index TRIX for sustainable considerations of eutrophication

AbstractSustainable development is one of the key concepts in coastal management, and indicators are widely considered to be suitable communicative and easy‐to‐use tools in providing environmental information for management. However, the applicability of aggregate indicators still needs examination and discussion. In this study the Trophic Index TRIX was applied in the northern Baltic Sea, an environment different from where it has been elaborated (the NW Adriatic Sea). The results of TRIX were in accordance with the general classification scheme of Finnish coastal waters. The results indicate that TRIX, like other aggregate indicators, is site dependent and needs to be calibrated to the conditions of the area in question. TRIX can provide useful information for decision‐making, but needs to be linked with other sources of information to draw a broader picture that is needed in adaptive management of coastal waters. Copyright © 2008 John Wiley &amp; Sons, Ltd and ERP Environment.

Biochemical composition and early diagenesis of organic matter in coastal sediments of the NW Adriatic Sea influenced by riverine inputs

River inputs influence trophodynamic and biogeochemical processes of adjacent continental shelves. In order to provide new insights on the influence of continental inputs on the benthic trophic state and early diagenesis of sediment organic matter we collected surface sediments in the NW Adriatic Sea at three stations located at increasing distance from the Po River. Sediment samples were collected in four periods characterized by different river outflows and analysed for chloropigment content (chlorophyll-a and phaeopygments), protein, carbohydrate and lipid concentrations, prokaryote abundance and aminopeptidase activity. Sediments of the NW Adriatic Sea displayed high organic loads, tightly coupled with the outflow dynamics of the Po River. A major flooding event was responsible of an enhanced accumulation of organic material on the sea bottom. The resulting increased nutrient load in the sediment impaired organic matter degradation processes. The results of the present study suggest that the enhanced trophic state of marine coastal sediments subjected to riverine inputs are related not only to the increased nutrient inputs, but that they may be amplified by impaired degradation processes.

Coastal waters monitoring data: frequency distributions of the principal water quality variables

Examining the results of the Italian national programme of marine coastal monitoring, the old problem has arisen about the choice of the most appropriate procedures and methods to validate data and screen preliminary data. Therefore, statistical distributions of water quality parameters have been taken into consideration, in order to assign appropriate frequency distributions to all the routinely measured variables. Each sample distribution has been analysed and defined by a probability density function (p.d.f.), by means of a powerful method of data analysis (Johnson 1949) that allows for the computation of statistical parameters of a wide variety of non-normal distributions. The resulting Johnson distributions are then classified depending on four fundamental categories of frequency distributions: normal, log-normal, bounded and unbounded. Theoretical aspects of the method are explained and discussed in an adequate way, so as to allow for practical applications. The shape and nature of these curves require further consideration, in order to understand the behaviour of water quality variables and to make comparison among different coastal zones. To this end, two coastal systems were considered in this work: the Emilia-Romagna coastal area of the NW Adriatic Sea and the Tuscany littoral of the Northern Tyrrhenian Sea. There are notable advantages to the adopted approach. First it offers the possibility to overcome severe constraints requested by the normality assumption, and avoids the troublesome search for the most appropriate transformation function (i.e. for ensuring normality). Second, it avoids searching for other kinds of theoretical distributions that are appropriate for the data. In our approach, the density functions are opportunely integrated, in such a way that, for whatever value assumed by a given variable, the corresponding expected percentage point value under the respective frequency curve, can be calculated, and vice versa. We believe that the Johnson method, although tested with coastal monitoring data, can be usefully adopted whenever we have to analyse environmental data and try to understand how an aquatic system works (e.g. large lakes). In the Appendix specific details about the Johnson classification criterion are reported and highlight the case of bimodal distributions. Finally, an example of data analysis is provided, by using the R (V. 2.11) software, with both graphical and numerical outputs.

Potentially harmful microalgal distribution in an area of the NW Adriatic coastline: Sampling procedure and correlations with environmental factors

In this study, the trend of potentially Harmful Algal (HA) taxa (genera and species), was analysed along a coastal area of the NW Adriatic Sea on a monthly scale. The study included the use of a phytoplankton net for sample collection. The investigation was carried out in four sampling stations characterised by different ecological features. The composition of potentially HA phytoplankton taxa and their succession were related to the environmental factors. The potentially HA group abundance accounted for 8% of all the phytoplankton taxa considered. Multivariate analyses of environmental factors suggested that potentially HA taxa are sensitive to phosphate content: potential DSP-YTX (Diarrhetic Shellfish Poisoning-Yessotoxin) producers were positively correlated with P content ( p = 0.023), while potential ASP (Amnesic Shellfish Poisoning) producers were negatively correlated with P content ( p = 0.006). Phosphorus could be considered to be the limiting factor for phytoplankton taxa density in the NW Adriatic Sea. There was a highly positive correlation between the occurrences of potentially HA taxa and low values of salinity ( p = 0.001 for potential producers of ASP, p = 0.029 for potential DSP-YTX producers). The counting of potential HA dinoflagellates in net samples represented a more accurate estimation of potential HA abundances in the water column making it possible to concentrate a greater number of potential HA dinoflagellate cells by net sampling along the entire water column rather than by sampling only at the surface as in routine monitoring procedures.

Differential diagnosis of Perkinsus species by polymerase chain reaction-restriction fragment length polymorphism assay

Perkinsosis is an infection of marine molluscs caused by the protistan parasites of the genus Perkinsus, which has been classified by the OIE as a disease that warrants notification. In the present study, we have applied a molecular genetic approach to develop an optional method for the specific identification of Perkinsus species. A species-specific polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay of the rRNA ITS region was developed to identify and distinguish among Perkinsus species. A taxonomic key was established that allows successful identification of Perkinsus species using a single restriction enzyme (Rsa I) to discriminate P. chesapeaki and P. marinus or by a combination of two endonucleases (Rsa I plus Hinf I) to discriminate P. olseni and P. mediterraneus. In order to validate the RFLP assay, the PCR products were cloned and sequenced, and its phylogenetic affinity was determined. Phylogenetic analysis confirmed the specific identification carried out by RFLPs. Herein is the first report of P. olseni in Manila clams from the NW Adriatic Sea (Italy), which we identified by employing this method. The PCR-RFLP assay herein described may be useful to provide accurate, rapid and inexpensive identification of Perkinsus species, and may aid in ongoing epizooetiological studies and diseases control programmes.