Cyanobacterial toxins in Italian freshwaters

This study focuses on the occurrence and distribution of cyanobacterial toxins from 1989 to 2006 in several Italian lakes of different characteristics and human uses, the latter including drinking water abstraction and recreation. Phytoplankton and LC/MS/MS toxin analyses were performed on surface water samples collected from 28 lakes. The most widespread species associated with toxin production belonged to the genera Microcystis, Planktothrix and Anabaena. Extracellular concentrations varied from non-detectable values up to 226.16 ng/mL for microcystins (sum of all variants), to 126 ng/mL for total cylindrospermopsin, and to 100 μg/g (dry weight) for anatoxin-a.The toxin concentrations in the lake waters did not always correlate with the cyanobacteria cell densities. This implies a need for control studies including toxin detection in water together with microscopic cell evaluations, in order to avoid possible toxin underestimates.     

Rotifer abundance, biomass, and secondary production after the recovery of hydrologic connectivity between a river and two marginal lakes (São Paulo, Brazil)

Rotifera density, biomass, and secondary production on two marginal lakes of Paranapanema River were compared after the recovery of hydrologic connectivity with the river (São Paulo State, Brazil). Daily samplings were performed in limnetic zone of both lakes during the rainy season immediately after lateral inflow of water and, in the dry period, six months after hydrologic connectivity recovery. In order to identify the factors that affect rotifer population dynamics, lake water level, volume, depth, temperature, transparency, dissolved oxygen, pH, alkalinity, conductivity, suspended solids, nutrients, and chlorophyll-a were determined. Variations of water physical and chemical factors that affect rotifer population were related to the lake-river degree of connection and to water level rising after drought. The water lateral inflow from the river resulted in an increase in lake water volume, depth, and transparency and a decrease in water pH, alkalinity, and suspended solids. The lake with the wider river connection, more frequent biota exchange, and larger amount of particulate and dissolved materials was richer and more diverse, while rotifer density, biomass, and productivity were lower in both periods studied. Density, biomass, and secondary production were higher in the lake with the smaller river connection and the higher physical and chemical stability. Our results show that the connectivity affects the limnological stability, associated to seasonality. Stable conditions, caused by low connectivity in dry periods, were related with high density, biomass and secondary production. Conversely, instability conditions in rainy periods were associated to elevated richness and diversity values, caused by exchange biota due to higher connectivity.     

Empirical estimate of fundamental frequencies and damping for Italian buildings

The aim of this work is to estimate the fundamental translational frequencies and relative damping of a large number of existing buildings, performing ambient vibration measurements. The first part of the work is devoted to the comparison of the results obtained with microtremor measurements with those obtained from earthquake recordings using four different techniques: horizontal‐to‐vertical spectral ratio, standard spectral ratio, non‐parametric damping analysis (NonPaDAn) and half bandwidth method. We recorded local earthquakes on a five floors reinforced concrete building with a pair of accelerometers located on the ground and on top floor, and then collected microtremors at the same location of the accelerometers. The agreement between the results obtained with microtremors and earthquakes has encouraged extending ambient noise measurements to a large number of buildings. We analysed the data with the above‐mentioned methods to obtain the two main translational frequencies in orthogonal directions and their relative damping for 80 buildings in the urban areas of Potenza and Senigallia (Italy). The frequencies determined with different techniques are in good agreement. We do not have the same satisfactory results for the estimates of damping: the NonPaDAn provides estimates that are less dispersed and grouped around values that appear to be more realistic. Finally, we have compared the measured frequencies with other experimental results and theoretical models. Our results confirm, as reported by previous authors, that the theoretical period–height relationships overestimate the experimental data. Copyright © 2008 John Wiley & Sons, Ltd.     

Controls on the geometry of a Holocene crater row: a field study from southwest Iceland

The Reykjanes Peninsula rift zone in southwest Iceland is a highly oblique segment of the Mid-Atlantic ridge system which accommodates NW–SE extension during rifting episodes that consist of eruptions and normal faulting, and E–W left-lateral shear strain along strike-slip faults during longer amagmatic periods. Dominant tectonic features on the peninsula are a series of generally NE-striking, sub-parallel eruptive fissures and normal faults, and a cross-cutting zone of N–S striking, right-lateral strike-slip faults. The last series of rifting episodes ended in 1227, and a proposed 1,000 year cyclicity predicts the start of a new series of eruptions within the next 200 years. In order to more accurately characterize the nature of eruptions on the Reykjanes Peninsula, we present a new, spatially accurate map of the ∼2,350 year old Sundhnúkur crater row in the western part of the peninsula, which was examined in detail in order to determine the structural controls on crater row geometry and to understand the interactions that take place between eruptive fissures and pre-existing geological structures. Volcanism is sometimes influenced by small perturbations in the surroundings such as gravitational loading, topography, changes in crustal properties or the presence of fault zones, but there are few field examples showing how fissures are influenced by these pre-existing structures. We identify 27 fissure segments, ranging in strike from 006° to 053°, with varying spacing and overlap between them. Significant local variability in strike and stepping sense of segments occurs in proximity to topographic highs as well as within zones of faulting that pre-date the crater row. Strike also varies at the northern end of the crater row as it approaches a region of older crust at the rift margin. Our data support numerical and laboratory modeling results which show that local topography, pre-existing fractures and crustal properties influence the path taken by magma on its way through the shallow crust.     

Efficacy of adapted estuarine fish-based multimetric indices as tools for evaluating ecological status of the marine environment

The assessment of ecological status of marine fish communities required by the marine strategy framework directive (MSFD) emphasises the need for fish-based ecological indices in marine waters. In this study we adapt five estuarine multimetric indices to the marine environment and apply them in three types of substrates, analysing the metrics responsible for the obtained patterns of ecological status. The results show inefficiency of the community degradation index (CDI) and the biological health index (BHI) in ecological status assessment and disagreement between the estuarine biotic integrity index (EBI), the estuarine fish community index (EFCI) and the transitional fish classification index (TFCI). Analysis of individual metrics suggests lack of representativeness and consideration for the particularities of each substrate’s typical fish communities. None of the tested indices were efficient on the marine environment, urging the need for new marine indices that account for differences between types of substrate and depth.     

Industrial pollution at Bagnoli (Naples, Italy): benthic foraminifera as a tool in integrated programs of environmental characterisation

In the 20th century an important industrial plant operated on the coastal area of Bagnoli. After its closing, an integrated study of environmental characterisation aimed at restoration started. The survey conducted was based on chemical and sedimentological analyses integrated with benthic foraminifera analyses. Statistical analysis of the data shows sectors with a distinct type and degree of pollution. Particularly, pollution linked to the silty sediment fraction, mainly due to Pb and Zn, was recognised in front of the southern sector of the plant. The study of benthic foraminifera provides evidence for a pollution-tolerant character in some species like Haynesina germanica and Quinqueloculina parvula. In addition, two species among the 113 recognised show high percentages of abnormal specimens. These percentages show a statistical correlation with some pollutants (PAHs, Mn, Pb and Zn). In addition, Energy Dispersive Spectrometry shows small amounts of Fe ions included in deformed tests of Miliolinella subrotunda. Because the number of these deformations is positively correlated to the concentration of PAHs, Mn and Zn, the inability of some specimens to exclude the foreign elements from the crystalline reticulum of the test could be attributed to the potential toxic effect of these pollutants.     

Immunotoxicity of the xenoestrogen 4-nonylphenol to the cockle Cerastoderma glaucum

The in vivo effects of 4-nonylphenol (NP) on functional responses of haemocytes from the cockle Cerastoderma glaucum were investigated after 7 days exposure to sublethal NP concentrations (0, 0+acetone, 0.0125, 0.025, 0.05 and 0.1 mg/l NP). Haemocytes from both controls and exposed cockles were collected, and the effects of NP on total haemocyte count (THC) and volume of circulating cells, intracellular superoxide anion () levels, acid phosphatase and lysozyme-like activities in both haemocyte lysate (HL) and cell-free haemolymph (CFH) were evaluated. Exposure of cockles to 0.1 mg/l NP significantly increased THC (p < 0.05) with respect to controls. Analysis of haemocyte size frequency distribution showed that the haemocyte fraction of about 7–8 μm in diameter and 250 femtolitres in volume increased markedly in cockles exposed to the highest NP concentration tested. Apoptosis resulting in cell volume reduction in NP-exposed animals cannot be excluded. No statistically significant variation in intracellular levels was observed. Conversely, significant increases (p < 0.05) in acid phosphatase activity were observed in CFH from 0.05 and 0.1 mg/l NP-exposed animals; no significant differences in enzyme activity were recorded in HL. Lysozyme-like activity also increased significantly in CFH from cockles exposed to 0.05 mg/l NP (p < 0.05) and 0.1 mg/l NP (p < 0.001). Instead, lysozyme-like activity decreased significantly (p < 0.05) in the HL of animals exposed to 0.05 mg/l NP. Our results suggest that NP induces variations in the functional responses of haemocytes of C. glaucum, mainly by reducing cell membrane stability and promoting cell degranulation.     

Morphostructure and evolution of the central and Eastern Bransfield Basins (NW Antarctic Peninsula)

The Bransfield Basin is a narrow and elongated active rift basin located between the Antarctic Peninsula and the South Shetland Islands. The Bransfield Basin is composed of three small basins, and two of them, the Central and Eastern Bransfield Basins, were surveyed during a recent cruise (GEBRA 93). The full swath bathymetry coverage as well as the single-channel seismic reflection and magnetic profiles that have been acquired, help us to better understand the morphostructure and recent evolution of the Bransfield Basin. Six large volcanic edifices aligned with the basin axis stick out of the sedimented seafloor of the Central Bransfield Basin. In contrast, the Eastern Bransfield Basin is characterised by four deep troughs displaying a rhombic-shape, and small, scattered volcanic cones located in the southwestern half basin. Seamount volcanism plays an important role in the formation of new crust in the Bransfield Basin. The larger seamounts of the Central Bransfield Basin are located at the intersection of the two main orthogonal sets of faults (longitudinal ENE-WSW and transversal NNW-SSE). Morphological analysis of the seamounts indicates a multi-staged volcano-tectonic construction. The distribution and shape of these edifices suggests that both volcanism and extension are concentrated at the same preferential areas through time. This might be related to the fracturation style of the continental crust. The Central and Eastern Bransfield Basins are very different in morphostructure, volcanism, and sedimentary cover. The Central Bransfield Basin shows evidence of NW-SE extensional faulting and focused active MORB-volcanism interpreted as result of incipient seafloor spreading. The Eastern Bransfield Basin is still in a rifting stage, mainly dominated by a NW-SE extension and some left-lateral strike-slip component probably related to the South Scotia Ridge.J. Acosta, J. Baraza, P. Bart, A.M. Calafat, J.L. Casamor, M. De Batist, G. Ercilla, G. Francés, E. Ramos, J.L. Sanz, and A. Tassone.     

River temperature forecasting: case study for Little Southwest Miramichi River (New Brunswick,Canada)

River temperature models play an increasingly important role in the management of fisheries and aquatic resources. Among river temperature models, forecasting models remain relatively unused compared to water temperature simulation models. However, water temperature forecasting is extremely important for in-season management of fisheries, especially when short-term forecasts (a few days) are required. In this study, forecast and simulation models were applied to the Little Southwest Miramichi River (New Brunswick, Canada), where water temperatures can regularly exceed 25–29°C during summer, necessitating associated fisheries closures. Second- and third-order autoregressive models (AR2, AR3) were calibrated and validated using air temperature as the exogenous variable to predict minimum, mean and maximum daily water temperatures. These models were then used to predict river temperatures in forecast mode (1-, 2- and 3-day forecasts using real-time data) and in simulation mode (using only air temperature as input). The results showed that the models performed better when used to forecast rather than simulate water temperatures. The AR3 model slightly outperformed the AR2 in the forecasting mode, with root mean square errors (RMSE) generally between 0.87°C and 1.58°C. However, in the simulation mode, the AR2 slightly outperformed the AR3 model (1.25°C < RMSE < 1.90°C). One-day forecast models performed the best (RMSE ~ 1°C) and model performance decreased as time lag increased (RMSE close to 1.5°C after 3 days). The study showed that marked improvement in the modelling can be accomplished using forecasting models compared to water temperature simulations, especially for short-term forecasts.

EDITOR M.C. Acreman ASSOCIATE EDITOR S. Huang     

Response of phenological events to climate warming in the southern and south-eastern regions of Romania

The analysis of phenological changes in vegetation is essential for the assessment of the response and adaptation of ecosystems/agro-ecosystems to climate change. This study analyses spatial and temporal changes in phenological events (phenophases) and in the climatic growing season in southern and south-eastern Romania, based on mean monthly temperature values recorded between 1961 and 2010 at 24 weather stations, spread out uniformly in the study area. By using the histophenogram method for extracting the mean phenophases length (eight in total, i.e. growing season onset, budding–leafing, flowering, fruiting, maturing, dissemination, start of leaf loss and end of leaf loss) and that of the overall growing season, this paper aims to analyse current phenological changes (in three periods, 1991–2000, 2001–2010 and 1991–2010) in relation to 1961–1990, which is the reference interval in various global climatic studies. Following the analysis of the theoretical phenology length, based on the temperature thresholds (between 5 and 25 °C) that differentiate biological cycles of vegetation, results showed an overall increase in phenological activity (especially in the past decade, 2001–2010), except for two phenophases (fruiting and dissemination), for which largely dominant length decreases were identified. Quantitatively, increases (and null changes, in a few cases) in phenological length generally range between 0–5 days/0–10% (e.g. in the budding–leafing phenophase) and 11–15 days/10.1–20% (maturing), considering the absolute changes or percentages in the three periods, compared to the reference interval 1961–1990. For the most part, the current decrease in the fruiting and dissemination phenophases falls in the interval ?1 to ?5 days/?10.1 to ?20%, compared to the reference period. At the same time, it was noticed that the entire growing season has been expanding, especially in the past decade, when numerous increase instances of up to 15 days were recorded, corresponding to a dominant interval of 0–10% from the period 1961–1990. The results can be particularly useful for adapting the different types of crops to future climate changes, considering that the study area has a high agro-ecological importance.