Search

The free-floating aquatic plant Utricularia australis has typically subsurface shoots and subaerial showy inflorescences. To find it growing with large populations among benthic Chara stands at 4–6 m depth in two Central Italian lakes, is a phenomenon that was never previously reported. Production of showy chasmogamous flowers at this depth makes such finding yet increasingly intriguing. Here we make quantitative-qualitative comparisons of morphological characters among subaerial and underwater flowers taken from diverse sites in Central Italy. Environmental data were used to delineate differences between superficial and underwater habitats where flowering U. australis populations were found, and to help explain these extraordinary findings. Although similar, the subaerial and underwater flowers did show some differences, the most important being the length of the floral scape. Underwater scapes were around three times longer than those emerged. This might be a typical phototropic-response or a failed attempt to get flowers above water surface for allowing entomophilous pollination, or a redundant morpho-physiological trait as a result of a recent ecological move. Underwater flowers were generally smaller, but they did have longer styles, nectar signalling was less obvious, thinner petals, mucous-coated pollen (subaerial pollen is dry and grainy). Both types of flower were sterile, producing abortive fruits. Possibility of underwater ecological conditions causing stress-induced flowering is also proposed. A lack of water movement is an important ecological requirement for U. australis growth and could explain why large populations have been found in deep water far from its typical habitat.

Phylogenetic relationships are important to explain clade evolutionary history, but they are frequently difficult to identify. Myrtaceae family has been shown as potentially good case - study to resolve several phylogenetic questions regarding its family history and evolution. The Myrtaceae (Myrtales order) contains over 5500 species within 144 genera, distributed predominantly in Southern Hemisphere. Several Myrtaceae taxa are known for their economic importance and notable representation in the humid pleotropic forests. The family includes two subfamilies, Psiloxiloideae and Myrtoideae. Interestingly, the Myrtoideae subfamily has a marked disparity in taxa number among its tribes that it has never been explained. Moreover, it includes species with different fruit type (fleshy, dry fruits) and this peculiarity has been previously considered to explain the subfamily diversification, but to no avail. A more highly comprehensive matrix of the BKMMST clade within Myrtoideae was generated and newly analysed. The results showed that considering mainly certain character state (molecular, fruit type, habitus) has been possible provided a new interpretation of family evolution. Fruit types and habitus traits were mapped and different Myrtoideae tribes were spatially and temporally compared. The conclusions represent an added important step to explain the phylogenetic relationships of this complicated family and evaluate a new evolutionary prospective.

The American duckweed Lemna minuta is invasive in freshwater habitats across much of Europe, often causing serious ecological impacts. To date, few studies have addressed how to halt its expansion. However, encouraging empirical evidence of L. minuta control by the aquatic herbivorous larvae of the insect Cataclysta lemnata is emerging. To better understand the biocontrol capacity of C. lemnata, information on overlap in the phenology and the growth conditions in nature of both species is fundamental. In this study, L. minuta and C. lemnata populations were analyzed in the field to define (i) their phenological features, (ii) the main environmental characteristics where the two species occur, and (iii) any overlap or difference in phenology and ecological requirements. The seasonal occurrence of the two species and environmental data were collected from 31 wetlands in central Italy. The two species showed a large phenological overlap and ecological similarities. Populations of L. minuta and C. lemnata were found all year long, although abundances were greater in spring and summer. Both species preferred waters that were shallow, circumneutral, with moderately high conductivity and trophic level and with low dissolved oxygen. The phenology and ecology of the two species were shown to be compatible, suggesting the insect could be released in natural sites invaded by the alien L. minuta where could act as potential biocontrol agent of it.

Utricularia australis is an aquatic rootless carnivorous plant that takes up nutrients through shoots or from trapped prey digested in its bladders. As the information on the ecology of this species is scarce, the main environmental factors which favour or limit its growth were analysed. Habitat characterization was carried out on 23 aquatic sites in Central Italy where U. australis occurred. Diverse water chemical and physical factors and aquatic plant dominants were sampled and compared to Utricularia coverage. Species response curves with respect to each analysed ecological factor were elaborated. Despite the large environmental variation among sites, U. australis did show some ecological preferences. Optimal growth of Utricularia was associated with sunny sites (~ 1500µmol photon m−2s−1) and shallow waters (< 20cm) that were warm (~ 26°C), alkaline (pH 8.3 median value), with moderate-high conductivity (700µScm−1) and with low aquatic inorganic phosphorus (< 10µgL−1) but higher nitrogen (800–1600µgL−1). Dissolved and particulate organic nutrients (mainly phosphorus) were highly important in determining U. australis ecology and its distribution. The knowing of theecological preferences ofU. australis, a plant that is becoming increasingly rare in Central Italy, could be very useful to identify and protect its habitats or to identify new potential sites and to avoid further population losses.

Hypogean or enclosed monuments are important cultural heritage sites that can suffer biodegradation. Many of the stone walls of the prestigious Domus Aurea are overwhelmed by dense biofilms and so need intervention. Room 93 was chosen as a study site with the aim to test the efficacy of phyto-derivatives as new biocides. Laboratory studies were performed comparing the effects of liquorice leaf extract (Glycyrrhiza glabra L.), lavender essential oil (Lavandula angustifolia Mill.) and a combination of both. In situ studies were also performed to test the effect of liquorice. The results were compared with those of the commonly used synthetic biocide benzalkonium chloride. The effects on the biofilms were assessed by microscopy along with chlorophyll fluorescence analysis. The phototrophs in the biofilms were identified morphologically, while the heterotrophs were identified with culture analysis and 16S gene sequencing. Results showed that the mixed solution liquorice/lavender was the most effective in inhibiting the photosynthetic activities of biofilms in the laboratory tests, while, in situ, the effect of liquorice was particularly encouraging as an efficient and low-invasive biocide. The results demonstrate a high potential biocidal efficacy of the phyto-derivatives, but also highlight the need to develop an efficient application regime.

No information exists on phototrophs growing on the stone surfaces of the Catacombs of SS. Marcellino and Pietro (the site was only recently opened to the public in 2014). Therefore, it was decided to characterise the microbial communities and to compare them with those of the other previously studied catacombs. Moreover, a new non-invasive strategy to reduce the phototrophic growth was tested. Phototrophic microorganisms were investigated under light and confocal laser scanning microscopes from samples collected non-invasively in situ. Tests were carried out to determine the effect of the application of two essential oils (from L. angustifolia and T. vulgaris) on biofilm photosynthetic activity. Laser-induced fluorescence (LIF) and reflectance measurements in the visible range have been used to evaluate respectively, any chemical modification and discolouration on a frescoed stone that may occur after the application of the essential oils. At all the concentrations of essential oils, there was a quasi-immediate, large reduction in photosynthetic activity of the biofilms. At 10% essential oil concentration, there was no detectable photosynthetic activity after 15min. At 1%, there was a need for two applications and after 5-day activity was undetectable. No effect of the essential oils on the substrate surface properties or colour modification of the fresco has been observed with the LIF prototype. Cyanobacterial typical of Roman catacombs were present in the sites investigated. Innovative and non-destructive strategies, involving the application of a combination of two essential oils, have been successfully tested and developed to prevent biodeterioration of these sites.

During the last few decades, recurrent and intense blooms of the toxic benthic dinoflagellate Ostreopsis cf. ovata have been frequently reported during summer along several sections of the Mediterranean coast. Field studies about Ostreopsis blooms highlighted the important role of hydrodynamics, water temperature and inorganic nutrients, among the other environmental parameters. However, all factors (and the interactions among them) that drive the bloom development throughout its phases are not totally understood yet. For example, the potential utilization of organic phosphorus (DOP) and its role on the Ostreopsis bloom are still unclear. The potential utilization of dissolved organic phosphorus (DOP) by the toxic dinoflagellate Ostreopsis cf. ovata within its microbial-mat community was investigated during a bloom along the Conero Riviera (N Adriatic Sea). Measurements of phosphomonoesterase (PMEase) and phosphodiesterase (PDEase) activities of the epiphytic mats (including cells and exopolymeric substances) and a range of chemico- physical parameters were performed from late summer to early autumn at Passetto station. Analyses of ambient nutrient fractions revealed very high N:P values, very low filterable reactive P (FRP) concentrations and DOP concentrations that were on average 85% of the total dissolved P. A rapid increase in PMEase and PDEase activities in the microbial community was recorded coinciding with the onset of the Ostreopsis bloom. Chromogenic staining of samples showed that activity was closely associated with the Ostreopsis cells, located both extracellularly (cell surface and within the EPS) and intracellularly (ventral cytoplasm). The increase in both phosphatases indicates that Ostreopsis-mat community can utilize a wide range of DOP types confirmed through tests in laboratory. Ostreopsis cf. ovata can utilize both phosphomonoester (D- Fructose 1,6-disphosphate, β-Glycerophosphate, α-D-Glucose 1-phosphate, Guanosine 5’-monophosphate and Phytic acid) and phosphodiester (DNA and RNA) sources to grow. The experiments also demonstrated that PMEase and PDEase were strongly influenced by water temperature, with maximum values recorded at 30-35 °C. Based on the present findings, the Ostreopsis bloom seems to be maintained thanks to some adaptations that allow it to thrive in P-limited environments where organic P is the main source of P, until water temperature is enough high to allow PMEase and PDEase activity.

Subaerial green algae are exposed to extreme hydration stress, yet cells need to remain fully hydrated and ultrastructurally intact in order to function physiologically. To compound the problems of dehydration, there is also an increased possibility of photochemical damage from high levels of irradiance. Algae can retain their chlorophyll viability during desiccation, but under high light these pigments can continue to absorb damaging radiation even though the chemical reactions of photosynthesis are stalled. Cells need effective protective mechanisms to allow harmless dissipation of this excess excitation energy. Species of the genus Trentepohlia are known to produce significant quantities of the photo-protective compounds and suppress photosynthesis during periods of desiccation, with rates of photosynthesis associated with diurnal changes in relative humidity (T. odorata) and full, rapid recovery of photosynthesis upon rewetting cells following extended periods of desiccation of 40 days (T. umbrina). Studies of the desiccation tolerance of Trentepohlia have been conducted ex situ and restricted to samples taken from single environments, yet, ecological ranges of some species, e.g. T. umbrina, can be quite wide and so in situ investigations of such species would be highly informative regarding stress tolerance. The study site, the Grassi Hospital, Ostia, is very particular as it has multiple sites with extensive growths of T. umbrina on substrates with multiple aspects and a wide range of light intensity and associated environmental conditions. Four sites were chosen that ranged from highly exposed to highly shaded. For each site, the environmental conditions were characterised and biofilm samples for chlorophyll a and b and total carotenoids were taken. Photosynthetic parameters were measured in situ with a mini-PAM. Diurnal environmental conditions that would normally inhibit photosynthesis occurred at each site. Pigment analysis of the biofilms showed a high variability (chl a and b, CV 70%; carotenoids, CV 40%) with higher concentrations in biofilms associated with the higher light exposure. The ratio of total carotenoids and total chlorophyll was lowest at the shaded site (3:1) compared the sites receiving direct light (mean 12.5:1). Estimations of biomass showed that the lowest biomass occurred at the exposed site and the highest in the shaded site. A 3 to 6-fold increase in the yields of photosynthesis following re-hydration of biofilms was identified at all sites. The results showed that T. umbrina could physiologically adapt to diverse solar irradiation exposure and dehydration. All biofilms suffered diurnal desiccation yet maintained chlorophyll viability allowing T. umbrina to be photosynthetically active during the briefest window when conditions are met for photosynthesis. Adjusting pigment content to adapt environmental stress allows T. umbrina to maximise its rate of photosynthesis before inhibitory levels of light and relative humidity are reached throughout the day. The diverse biomass levels at each site suggest that growth is restricted, but the survival capacity of T. umbrina allows for slow colonisation of highly hostile substrates.

La Polledrara di Cecanibbio is a Pleistocene fossiliferous deposit near Rome (Italy) where large quantities of bones, belonging mainly to elephants, have been discovered and ‘musealized’ under an enclosing structure. The prevailing environmental conditions inside the museum and the exposition in situ of the fossilized remains have resulted in the development of phototrophic biofilms on the bones and the nearby sediments. Samples of bones and sediment were investigated with different microscopy techniques (light, confocal laser scanning, scanning electron and petrographic microscopes) that allowed the identification of the cyanobacterium Leptolyngbya sp. as the almost entirely dominant organism of the biofilms. The present study identifies for the first time endolithic activity of this cyanobacterium on exposed fossilized bones. There was some indication that this species was euendolithic but this remains to be elucidated. The development of these phototrophic biofilms greatly reduces the aesthetic value of the site and evidence suggests that they may cause extensive structural damage to the bones, threatening the scientific and cultural assets of one of the richest fossiliferous deposits in Italy. This study on the biodeterioration of fossil remains gives useful insights for the conservation of this spectacular site.

The study raises a number of practical matters for management. The failure of water management organizations, including those in the UK and Ireland, to include organic phosphate in surveys is a hindrance to interpreting the wider literature. This means that general surveys on diatoms already made on rivers of some European countries are of limited use for understanding the ecology of Didymosphenia. The following are possible approaches to controlling nuisance growths. 1. Catchment management should aim to minimize changes likely to enhance the organic phosphate concentration of the water. Possible factors which might do so include deforestation and soil disturbance, especially on peaty or other organic-rich soils, and deliberate release to the river of liquids or other materials with a high organic content. 2. Understanding of the distribution of the diatom within the catchment is needed to avoid the risk of repeat re-inoculation from upstream. 3. As it seems likely that Didymosphenia (and perhaps other stalked diatoms) compete(s) for organic P more effectively than most non-stalked diatoms, enhancing inorganic:organic P should favour non-stalked diatoms. This should be done in early spring at the time when Didymosphenia is just starting to form stalks. Once the colonies have started to form, it is probably be too late to achieve much success in that particular year. It might be necessary to continue phosphate addition for several months each year. The site chosen for phosphate addition should be towards the upper end of the distribution range within the river, though it may be impractical to include small tributaries. Experimental studies are needed to establish the ratio of phosphate forms needed for non-stalked diatoms to outcompete Didymosphenia, but inorganic P would probably need to be well in excess of organic P. Phosphate addition would be most effective, if the inflow were matched to the river flow. 4. It might be possible to enhance the competitive success of algae less dependent on organic phosphate by using agents selectively inhibitory to PMEase and PDEase. For instance, Durrieu et al. (2003) showed that the heavy metals Cr, Ni, Cu, Zn, Cd, Hg and Pb were all highly inhibitory to Chlorella vulgaris surface PMEase activity. However, the present authors would discourage such an approach, because of the wider implications for the ecosystem. In addition, upland streams with elevated Zn and Cd are often dominated by metal-tolerant strains of other organic phosphate-utilizing algae (Whitton et al., 2005), so Didymosphenia might also evolve strains tolerant to these and perhaps other metals. The authors suggest that the increases in Didymosphenia in Europe and elsewhere, sometimes reaching nuisance proportions, are probably the result of enhanced breakdown of peat or other organic-rich soils leading to an increased export of organic phosphate to drainage streams. Atmospheric N deposition, climatic warming and catchment disturbance are all known to be factors enhancing peat degradation. If climatic warming proves the most important, the effect on D. geminata may be due to an increased and extended period of high organic phosphate concentrations in spring.