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A filamentous cyanobacterium (strain ITAC101) isolated from a Mediterranean sponge (Petrosia ficiformis) was characterized by a combined phenotypic and genetic approach. Morphological and ultrastructural observations were performed along with growth measurements and pigment characterization. The molecular phylogenetic analyses were based on the sequencing of the 16S rRNA gene. In culture conditions, strain ITAC101 is moderately halophilic and grew in the range 0.3-7.6% (w/v) salinity with the optimum at 3.6%. Cell dimensions, thylakoid arrangement and pigment composition of this cyanobacterium fit the Halomicronema genus description, and phylogenetic analyses evidenced 99.9% similarity with another strain endolithic in tropical corals. The new Halomicronema metazoicum species was established including the two cyanobacteria associated to marine animals.

Marine cyanobacteria are photosynthetic prokaryotes of significant ecological interest, living free or in association with Invertebrates. They are also considered as excellent sources of antineoplastic, antibacterial, antiviral and antifungal compounds. In this work, aqueous extracts from eight cyanobacterial strains isolated from the Mediterranean sponge Petrosia ficiformis have been investigated for their bioactive properties. Bioassays with human erythrocytes, Artemia salina nauplii, and Paracentrotus lividus gametes and embryos were performed. Some aqueous extracts exhibited citolytic effect on human erythrocytes and toxic activity against Artemia salina nauplii. Furthermore antimitotic activity was evidenced during sea urchin embryos development and disorganization of blastomeres with altered cell-cell contact was also induced. Some the isolated cyanobacterial strains, belonging to Leptolyngbya and Synechococcus genera with an high citotoxic activity, should be further investigated to better characterize their bioactive molecules. Our data confirm cyanobacteria as an interesting source of novel bioactive compounds with potential applications in pharmaceutics.

In the frame of a multidisciplinary international joint effort, supported by CIESM, phytoplankton composition, distribution and activity in summer and late autumn in the Southern Tyrrhenian Sea were investigated. The main aim of the study was to obtain a preliminary characterization of the autotrophic community structure of a poorly investigated and complex basin during two contrasting seasonal conditions (stratification vs homogeneity). On both occasions the phytoplankton biomass, as chlorophyll a, was low in the euphotic layer of water column (8.9 mg m−2 in July and 10.7 mg m−2 in December), with a clear dominance of the pico-phytoplanktonic component (64% and 76%, respectively), and a pronounced summer Deep Chlorophyll Maximum. Interestingly, primary production was higher in December (429 mg C m−2 d−1) than July (273 mg C m−2 d−1), again with a major contribution of pico-class in both seasons (90% and 52% in late autumn and summer, respectively). The dominant contribution of small size classes to the total photosynthetic efficiency and their fast carbon turnover time within the community hint at a preferential carbon pathway through the small-sized components of the food web that contrasts with the traditional views of the Tyrrhenian Sea as a typical component of the temperate Western Mediterranean Sea.

The composition of fatty acids was studied in the mussels collected in the Mar Grande of Taranto (northern Ionian Sea) during the four seasons. Micro-, nano- and picophytoplankton abundance, biomass and composition have been also evaluated. Fatty acids compositions were investigated for lipid biomarkers to establish the contribution of phytoplankton to the mussel diet. Saturated (SAFA) and monounsaturated fatty acids (MUFA) were the most abundant components, followed by polyunsaturated fatty acids (PUFA). The seasonal variations in the SAFAs, MUFAs and PUFAs were not significantly different during the whole study period (ANOVA,P

Synergistic/antagonistic effects of multiple contaminants in marine environments are almost completely unexplored. In the present study, we investigated the effects of heavy metals (Zn and Pb) and PCBs on picoplankton abundance, biomass, cell size distribution, and bacterial C production. Natural picoplankton assemblages were exposed to heavy metals (Zn or Pb), organic contaminants (PCBs, Aroclor 1260), and to a mixture of different contaminants. The results of the present study indicate that Zn addition stimulated heterotrophic growth, whereas Pb has a negative impact on heterotrophic picoplankton, particularly significant in the first 24 h. Heavy metals had no effects on the autotrophic component. The addition of Aroclor 1260 had a significant impact on abundance, biomass, and cell size of autotrophic and heterotrophic picoplankton, and reduced significantly bacterial secondary production. Three weeks after PCB treatment, heterotrophic bacteria displayed a clear resilience, both in terms of abundance and biomass, reaching values comparable to those of the controls, but not in terms of bacterial C production. Our results indicate that picoplankton can be sensitive indicators of impact determined by heavy metals and PCBs in coastal marine systems.

Culturable heterotrophic bacterial and phytoplanktonic densities were investigated at four sites in the Southern Adriatic Sea (Brindisi, S. Cataldo, Otranto and S. M. di Leuca) over an annual cycle. The main phytoplankton groups, the bacterial biodiversity, as well as the faecal contamination indicators were determined. Culturable bacterial numbers averaged 4.8 +/- 0.2 log CFU ml(-1) whereas phytoplankton numbers averaged 2.1 +/- 0.4 log cells ml(-1). Relationships between culturable bacteria, phytoplankton and the environmental factors were established. Bacterial and phytoplankton densities usually depended significantly on temperature, dissolved oxygen, phosphate and nitrite only in the S. Cataldo transect. In all the examined transects phytoplankton showed a bloom during the January-February period followed by a bacterial peak during the February-March period. Thus we can suppose that the phytoplankton winter bloom is responsible for the availabily of organic matter for bacterial populations in the following months in this oligotrophic ecosystem.

In the Southern Adriatic Sea (Italian coasts) bacterial and diatom diversity was studied over an annual cycle and the relationships between these two microbial components were analyzed. As regards the culturable heterotrophic bacteria, Aeromonas was the predominant genus among the Gram-negative bacteria. The presence of Enterobacteriaceae, Cytophaga, Pseudomonas, Acinetobacterand Photobacteriumwas also remarkable. Flexibacter, Moraxella, Chromobacterium, Flavobacteriumand Vibriowere present at less than 5%. Of the 92 diatom species determined, 16 were the most abundant representing the 96% of this phytoplankton group. The results obtained demonstrated that several bacterial genera were significantly related to the most abundant and representative diatoms ( Chaetocerosspp., Pseudo-nitzschia pseudodelicatissimaand Rhizosoleniaspp.).

Species of Dinophysis Ehrenberg sensu lato were collected opportunistically along the southern Adriatic coasts (Apulia, Italy) during a survey of phytoplankton community structure and dynamics carried out from 1995 to 1997. Most previous reports of Dinophysis spp. in the Adriatic Sea concentrated on northern populations, with few data available on phytoplankton inhabiting the southern coastal areas. Thus, the present study is the first on Dinophysis sensu lato species composition and spatio-temporal distribution in these essentially oligotrophic waters. Twelve Dinophysis species were identified; some of which can be assigned to the genus Phalacroma. Dinophysis sacculus, D. fortii, D. caudata, Phalacroma rotundatum and P. mitra are potentially producers of diarrhetic shellfish poisoning. Seasonal changes in Dinophysis and Phalacroma populations are presented, as well as their relationships with hydrographic and biotic factors. These dinoflagellates were associated with mixing conditions, low water temperatures and high nutrient inputs. Furthermore, the statistical analysis evidenced significant correlations of Dinophysis species to chlorophyll a and phytoplankton. Ecological implications arising from the data are discussed. (C) 2001 Elsevier Science Ltd. All rights reserved.

The seasonal composition of phytoplankton communities was investigated in a Mediter- ranean brackish area (Varano lagoon). Twelve stations were sampled monthly from March 1997 to February 1998. Numbers of prokaryotic and eukaryotic picophytoplankton cells were estimated by epifluorescence microscopy, while larger phytoplankton (nano and micro fractions) were enumerated by the Utermohl settling technique. Picophytoplankton densities ranged from 0.7 to 448.6 cells 3 10 6 l -1 . Nano- and microphytoplankton abundances varied between 0.2 and 7.9 cells 3 10 6 l -1 . The picoplankton fraction was represented mainly by cyanobacteria and the Utermohl fraction by nano- sized phytoflagellates (56.2%) and diatoms (20.1%). The phytoflagellates had a greater abundance over time while diatoms reached the highest densities in summer and fall. In Varano lagoon, phyto- plankton development is related to 'nitrogen-poor' waters and to phosphorus availability. Suspen- sion-feeding bivalves (Mytilus galloprovincialis) are sufficiently abundant to filter a volume equivalent to the volume of Varano lagoon at least once daily. These observations suggest that grazing exerts an important influence on phytoplankton dynamics, mainly on the micro fraction, and that diatoms seem to play an important role in the food web dynamics of this coastal fishery.

Monitoring cruises were carried out on four coastal transects of the Southern Adriatic Sea over two years to investigate the effects of the hydrodynamic regime on environmental factors and phytoplankton species composition and succession. The concentration of nutrient salts is usually low except for the winter months. Biomass levels (in terms of chlorophyll a) proved to be very low, with values ranging between 0.05 and 1.25 mg Chla L-1. Phytoplankton densities showed specific oligotrophic water values and varied in a wide range from 9 • 103 to 2.9 • 106 cells L-1; the maxima values were reached in January-February mainly because of a bloom of the diatom Skeletonema costatum. Diatoms were present throughout the year and represented the majority of the population (44.3%) together with phytoflagellates (39.6%), while dinoflagellates and coccolithophorids reached, respectively, 10.3% and 5.8%. During the year, diatoms were dominant with high cell densities in winter time, while phytoflagellates had a larger distribution over time and reached the highest values in spring and summer. Species diversity values were typical of temperate coastal areas (H’ = 2.79 ± 0.73). The type of circulation determined the distribution of thermohaline characteristics, abundance and biomass, as well as species composition and succession of phytoplankton in time. However, no great spatial variations were observed.

Mar Piccolo of Taranto is an estuarine basin heavily exploited for commercial mussel (Mytilus galloprovincialis L.) farming. The historical renown of the Taranto mussels has suffered over the last decade following policy decisions to expand the mussel farms and to relocate a portion of the urban sewage to an outfall outside of Mar Piccolo. The resulting decline in mussel quality and the quandary of how to restore stability to Taranto mussel production became the focal issue for our application of the systems approach framework (SAF). We simulated the ecological, economic, and social interactions that affect mussel production. Stakeholders and mussel farmers contributed by participating in meetings during the entire exercise. Our simulation analysis provided them with a means for understanding the effects of policy scenarios on the system. We present three aspects from our initial results that demonstrate the value of the SAF, as: (1) an operational model to monitor and better research the status of the ecosystem, (2) a management tool to evaluate sustainable mussel farming strategies, and (3) an opportunity for improved communication with and engagement of stakeholders, policy, and the public. The application has also raised important questions about how the food chain is controlled, what could be changed to stabilize the ecosystem to a higher level of productivity, and what role the public and policy could play in promoting sustainable development.