Functional diversity and metabolic response in benthic communities along an ocean acidification gradient.

Altered ocean chemistry caused by ocean acidification (OA) is expected to have negative repercussions at different levels of the ecological hierarchy, starting from the individual and scaling up to the community and ultimately to the ecosystem level. Understanding the effects of OA on benthic organisms is of primary importance given their relevant ecological role in maintaining marine ecosystem functioning. The use of functional traits represents an effective technique to investigate how species adapt to altered environmental conditions and can be used to predict changes in the resilience of communities faced with stresses associated with climate change. Artificial supports were deployed for 1-y along a natural pH gradient in the shallow hydrothermal systems of the Bottaro crater near Panarea (Aeolian Archipelago, southern Tyrrhenian Sea), to explore changes in functional traits and metabolic rates of benthic communities and the repercussions in terms of functional diversity. Changes in community composition due to OA were accompanied by modifications in functional diversity. Altered conditions led to higher oxygen consumption in the acidified site and the selection of species with the functional traits needed to withstand OA. Calcification rate and reproduction were found to be the traits most affected by pH variations. A reduction in a community's functional evenness could potentially reduce its resilience to further environmental or anthropogenic stressors. These findings highlight the ability of the ecosystem to respond to climate change and provide insights into the modifications that can be expected given the predicted future pCO2 scenarios. Understanding the impact of climate change on functional diversity and thus on community functioning and stability is crucial if we are to predict changes in ecosystem vulnerability, especially in a context where OA occurs in combination with other environmental changes and anthropogenic stressors.

Functional diversity of free-living nematodes in river lagoons: can biological traits analysis (BTA) integrate traditional taxonomic-based approaches as a monitoring tool?

In four Po River lagoons, functional diversity of free-living nematodes was studied according to five biological traits (feeding type, life history, tail shape, body length and shape) considered singularly and combined in a Biological Traits Analysis (BTA). With the exception of 'Body length', similar distribution patterns were obtained for the other biological traits, considered singularly or in combination. From a functional point of view, the higher number of slender c-p3 selective deposit feeders with elongated tails rendered the assemblage in Marinetta-Vallona different from those in the other waterbodies where, by contrast, the nematodes were mainly represented by c-p2 non-selective deposit feeders with clavate tails and variable body lengths and shapes. On the contrary, the spatial patterns highlighted by genera data did not perfectly overlap with those identified by the biological traits. From a taxonomic point of view, the change ascribable to the higher abundance of Terschellingia in Marinetta-Vallona was comparable to those attributable to the other dominant genera (Sabatieria and Daptonema) in the other lagoons. Only the biological traits analysis was able to indicate that the dominance of Terschellingia in Marinetta-Vallona led also to a functional change within the assemblage. According to both functional and taxonomic approaches, the nematodes seemed influenced by polybrominated diphenyl ethers (ΣPBDEs), whose concentrations in the sediments clearly exceeded their toxicity thresholds in Marinetta-Vallona, suggesting, therefore, that this group of emerging pollutants might induce a nematodes response at both taxonomic and functional level. Our findings suggest that for scarcely biodiverse assemblages, such as those of river lagoons, the BTA may not provide further information than the analysis of single traits while both these functional approaches may add relevant ecological information to traditional taxonomic-based methods, representing therefore a potential integration in the use of nematodes in monitoring actions.

Functional biodiversity of marine soft-sediment polychaetes from two Mediterranean coastal areas in relation to environmental stress.

Biological Traits Analysis (BTA) was used to identify functional features of infaunal polychaete assemblages associated with contamination in two Italian coastal areas: the harbour of Trieste (Adriatic Sea) and the Mar Piccolo of Taranto (Ionian Sea). The analysis was performed on 103 taxa, collected at four stations in each area. The two areas differed in species composition. The low diversity and the presence of stress-tolerant species in more polluted sites were not reflected in functional diversity, due to species contributing little to community functions or being functionally redundant. Sand and clay fractions were significant drivers of trait category expressions, however other environmental parameters (depth, total organic carbon and nitrogen, and Hg in sediments) influenced traits composition. Motile was the prevalent trait in environments with coarse sediments, and tube-builder were related to fine-grained ones. Motile, endobenthic and burrower were essential traits for living in contaminated sediments. Epibenthic and sessile polychaetes dominated at stations subjected to high organic loads. BTA offers an integrative approach to detect functional adaptations to contaminated sediments and multiple anthropogenic stressors.

Benthic ecosystem functioning in the severely contaminated Mar Piccolo of Taranto (Ionian Sea, Italy): focus on heterotrophic pathways.

The benthic ecosystem functioning is a rarely applied holistic approach that integrates the main chemical and biological features of the benthic domain with the key processes responsible for the flux of energy and C through the system. For the first time, such conceptual model, with an emphasis on the heterotrophic pathways, has been applied to the sediments at four stations within one of the most polluted coastal areas in Italy: the Mar Piccolo of Taranto. The functioning of the benthic ecosystem was different according to the investigated site. Nearby the military arsenal, i.e., the main source of organic contaminants and heavy metals, the system seemed inhibited at all the investigated structural and functional levels. Slow microbial processes of C reworking together with very limited densities of benthic fauna suggested a modest transfer of C both into a solid microbial loop and to the higher trophic levels. On the other hand, the ingression of marine water through the "Navigabile" channel seemed to stimulate the organic matter degradation and, consequently, the proliferation of meiofauna and macrofauna. In the innermost part of the basin, the system functioning, to some extent, is less impacted by contaminants and more influenced by mussel farms. The organic matter produced by these bivalves fueled faster C reworking by benthic prokaryotes and enhanced the proliferation of filter feeders.

Microbial mechanisms coupling carbon and phosphorus cycles in phosphorus-limited northern Adriatic Sea.

The coastal northern Adriatic Sea receives pulsed inputs of riverine nutrients, causing phytoplankton blooms and seasonally sustained dissolved organic carbon (DOC) accumulation-hypothesized to cause episodes of massive mucilage. The underlying mechanisms regulating P and C cycles and their coupling are unclear. Extensive biogeochemical parameters, processes and community composition were measured in a 64-day mesocosms deployed off Piran, Slovenia. We followed the temporal trends of C and P fluxes in P-enriched (P+) and unenriched (P-) mesocosms. An intense diatom bloom developed then crashed; however, substantial primary production was maintained throughout, supported by tightly coupled P regeneration by bacteria and phytoplankton. Results provide novel insights on post-bloom C and P dynamics and mechanisms. 1) Post-bloom DOC accumulation to 186 µM remained elevated despite high bacterial carbon demand. Presumably, a large part of DOC accumulated due to the bacterial ectohydrolytic processing of primary productivity that adventitiously generated slow-to-degrade DOC; 2) bacteria heavily colonized post-bloom diatom aggregates, rendering them microscale hotspots of P regeneration due to locally intense bacterial ectohydrolase activities; 3) Pi turnover was rapid thus suggesting high P flux through the DOP pool (dissolved organic phosphorus) turnover; 4) Alpha- and Gamma-proteobacteria dominated the bacterial communities despite great differences of C and P pools and fluxes in both mesocosms. However, minor taxa showed dramatic changes in community compositions. Major OTUs were presumably generalists adapted to diverse productivity regimes.We suggest that variation in bacterial ectohydrolase activities on aggregates, regulating the rates of POM→DOM transition as well as dissolved polymer hydrolysis, could become a bottleneck in P regeneration. This could be another regulatory step, in addition to APase, in the microbial regulation of P cycle and the coupling between C and P cycles.

Phenotypic and genetic diversity of coexisting Listonella anguillarum, Vibrio harveyi and Vibrio chagassi recovered from skin haemorrhages of diseased sand smelt, Atherina boyeri, in the Gulf of Trieste (NE Adriatic Sea).

AIMS: This study identified and characterized coexisting Vibrios associated with haemorrhagic skin lesion bearing sand smelt fishes (Atherina boyeri) in north-eastern Adriatic Sea. METHODS AND RESULTS: Bacteria were isolated from external skin lesions of four samples, and representative morphotypes grown on thiosulfate-citrate-bile salt-sucrose agar were isolated. In total 25 isolates, presumptively assigned to Vibrio genus, were biochemically characterized and were grouped in 10 phenotypic profiles. Phenotypes were heterogeneously distributed among the diseased sand smelt analysed; only one phenotype was recovered from all the samples. Sequencing of 16S rRNA was performed to identify representatives of all phenotypes. Phylogenetic analysis using the neighbour-joining method revealed six isolates clustered within the Vibrio harveyi group, three clustered with known Vibrio chagasii strains and three clustered with Listonella anguillarum. CONCLUSIONS: Vibrios with a broad phenotypic variability were found in the external lesions of diseased A. boyeri. In total three species of Vibrio were identified: V. harveyi showed the wider phenotypical and ribotypical heterogeneity while L. anguillarum shared similar biochemical characteristics with typical strains. SIGNIFICANCE AND IMPACT OF THE STUDY: Previously unreported coexistence of potential pathogenic species colonizing diseased A. boyeri has ecological as well as epidemiological significance.

Large-scale spatial distribution of virioplankton in the Adriatic Sea: testing the trophic state control hypothesis.

Little is known concerning environmental factors that may control the distribution of virioplankton on large spatial scales. In previous studies workers reported high viral levels in eutrophic systems and suggested that the trophic state is a possible driving force controlling the spatial distribution of viruses. In order to test this hypothesis, we determined the distribution of viral abundance and bacterial abundance and the virus-to-bacterium ratio in a wide area covering the entire Adriatic basin (Mediterranean Sea). To gather additional information on factors controlling viral distribution on a large scale, functional microbial parameters (exoenzymatic activities, bacterial production and turnover) were related to trophic gradients. At large spatial scales, viral distribution was independent of autotrophic biomass and all other environmental parameters. We concluded that in contrast to what was previously hypothesized, changing trophic conditions do not directly affect virioplankton distribution. Since virus distribution was coupled with bacterial turnover times, our results suggest that viral abundance depends on bacterial activity and on host cell abundance.

Chrysaora hysoscella in the Gulf of Trieste: presence, evolution and cutaneous toxicity in man.

In the past few years important changes in the occurrence of scyphomedusae have been observed in the North Adriatic Sea and in particular in the Gulf of Trieste, often reaching alarming proportions. Spring coastal blooms of C. hysoscella were observed in 1989. Until 1989, this jellyfish was considered to be innocuous but the data presented show its cutaneous toxicity in man.

[Dermatotoxicity of the Adriatic jellyfish]. / Dermotossicità da meduse del mare Adriatico.

We have tested the dermatotoxicity of some purified nematocysts preparations of Aurelia aurita, Chrysaora hysoscella, Rhizostoma pulmo, in 25 volunteers by means of scratch-patch test. Our results show the validity of the method used for nematocyst purification. The few skin reactions obtained confirm the low dermototoxicity of the jellyfish studied.

[Dermatotoxicity caused by Chrysaora hysoscella. Presentation of a case]. / Dermotossicità da Chrysaora hysoscella. Presentazione di un caso.

Chrysaora hysoscella L. rarely occurs in coastal waters of the Adriatic sea and is usually considered an innocuous jellyfish. In June 1989, P.D.N., a 29 year old healthy female, biologist at the Marine Biology Laboratory of Trieste, treated some samples of Chrysaora hysoscella captured that day. She took the animals from the transport tanks and cut the tentacles and oral arms from their bell. About ten minutes later she felt itching and burning of her hands, especially the right one. Twenty minutes later erythematous and slightly edematous lesions appeared on her fingers. These lesions spontaneously disappeared in about 2 hours. We decided to test Chrysaora hysoscella dermotoxicity on healthy volunteers by cutting a Chrysaora hysoscella tentacle and placing it on a gauze soaked in a solution of 3% NaCl and applying then to the volar side of the right wrist for one minute. Both volunteers presented itching and burning within forty seconds of contact. Three minutes later erythematous and vesicular lesions appeared on the sting site. To the best of our knowledge this is the second reported but first documented report of the dermotoxic effect of Chrysaora hysoscella. We underline that the absence of other previous reports may be due to both the relative rarity of this jellyfish and to the fact that people often confuses Chrysaora hysoscella with other more common jellyfish.

Anti-inflammatory and peripheral analgesic activity of esculetin in vivo.

Esculetin determined a reduction in oedema and granulocyte infiltration in the Croton oil ear test in vivo. The drug was able to inhibit Acethylcholine-writhing test and showed a LD50 of 1450 mg/kg i.p. and greater than 2000 mg/kg by mouth. In our experimental conditions, esculetin has an anti-inflammatory and analgesic effect.

Anti-inflammatory activity of Echinacea angustifolia fractions separated on the basis of molecular weight.

Five fractions of an aqueous extract obtained from the roots of Echinacea angustifolia were separated on the basis of molecular weight. The topical anti-inflammatory activity of the fractions has been evaluated in mice using the Croton oil ear test. The fraction with a molecular weight between 30,000 and 100,000 was the most active in inhibiting the oedema; it also reduced the infiltration of inflammatory cells. The activity of this fraction was comparable with that of a raw polysaccharidic extract obtained from E. angustifolia roots by differential solubility. The high-molecular weight polysaccharides are therefore proposed as the anti-inflammatory principles of the plant.

Anti-inflammatory activity of a polysaccharidic fraction of Echinacea angustifolia.

The anti-inflammatory activity of a polysaccharidic fraction (EPF) obtained from Echinacea angustifolia roots has been examined using the carrageenan paw oedema and the croton oil ear test. EPF (0.5 mg kg-1 i.v.) almost inhibited the carrageenan-induced oedema over 8 h and furthermore, EPF, topically applied, inhibited mouse ear oedema induced by croton oil. EPF also reduced the leukocytic infiltration of the croton oil dermatitis, evaluated both as peroxidase activity and histologically. After topical application EPF appears to be slightly inferior in potency to indomethacin. The results suggest that the anti-inflammatory activity of E. angustifolia resides in its polysaccharidic content.