Deterioration of Sediment Quality in Seagrass Meadows (<Emphasis Type="Italic">Posidonia oceanica</Emphasis>) Invaded by Macroalgae (<Emphasis Type="Italic">Caulerpa</Emphasis> sp.)

Species of the macroalgae Caulerpa sp. are increasingly being observed in meadows of the endemic Mediterranean seagrass Posidonia oceanica, and in particular Caulerpa taxifolia, has been considered as an invasive species leading to seagrass decline. Studies have so far failed to reveal the underlying mechanisms of the success of the macroalgae, and here, we examine how biogeochemical changes of the environment associated to indigenous (Caulerpa prolifera) and non-indigenous (Caulerpa racemosa and C. taxifolia) species affect the habitat of P. oceanica. Two of the species (C. prolifera and C. racemosa) affect the sediment biogeochemical conditions by increasing organic matter pools, microbial activity, and sulfide pools of the sediments, and limited effects were found for C. taxifolia. Biomass of the macroalgae contributed to the extent of impacts, and high sulfide invasion into the seagrasses and regression of the meadow were pronounced at the location with the highest Caulerpa biomass. This suggests that Caulerpa invasion contributes to seagrass decline probably because Caulerpa thrives better than the seagrasses in the modified environment.     

The Bloom-Forming Macroalgae, <Emphasis Type="Italic">Ulva</Emphasis>, Outcompetes the Seagrass, <Emphasis Type="Italic">Zostera marina</Emphasis>, Under High CO<Subscript>2</Subscript> Conditions

While multiple species of macroalgae and seagrass can benefit from elevated CO₂ concentrations, competition between such organisms may influence their ultimate responses. This study reports on experiments performed with a Northwest Atlantic species of the macroalgae, Ulva, and the seagrass, Zostera marina, grown under ambient and elevated levels of pCO₂, and subjected to competition with each other. When grown individually, elevated pCO₂ significantly increased growth rates and productivity of Ulva and Zostera, respectively, beyond control treatments (by threefold and 27%, respectively). For both primary producers, significant declines in tissue δ¹³C signatures suggested that increased growth and productivity were associated with a shift from use of HCO₃^? toward CO₂ use. When grown under higher pCO₂, Zostera experienced significant increases in leaf and rhizome carbon content as well as significant increases in leaf carbon-to-nitrogen ratios, while sediments within which high CO₂ Zostera were grown had a significantly higher organic carbon content. When grown in the presence of Ulva; however, above- and below-ground productivity and tissue nitrogen content of Zostera were significantly lower, revealing an antagonistic interaction between elevated CO₂ and the presence of Ulva. The presence of Zostera had no significant effect on the growth of Ulva. Collectively, this study demonstrates that while Ulva and Zostera can each individually benefit from elevated pCO₂ levels, the ability of Ulva to grow more rapidly and inhibit seagrass productivity under elevated pCO₂, coupled with accumulation of organic C in sediments, may offset the potential benefits for Zostera within high CO₂ environments.     

Toxicity effects of four typical nanomaterials on the growth of <Emphasis Type="Italic">Escherichia coli</Emphasis>, <Emphasis Type="Italic">Bacillus subtilis</Emphasis> and <Emphasis Type="Italic">Agrobacterium tumefaciens</Emphasis>

To offer an insight into the toxicity of nanomaterials (NM) on the growth of bacteria, Escherichia coli (E. coli), Bacillus subtilis (B. subtilis) and Agrobacterium tumefaciens (A. tumefaciens) were exposed to nano-Au, nano-Ag, nano-Fe and fullerene (C₆₀) in this study. As an effective bactericide, nano-Ag induced high toxicity on these three bacteria; C₆₀ could inhibit their growth; however, B. subtilis and E. coli could recover as exposure time extended. Nano-Au and nano-Fe had hardly any effect on three bacteria. A. tumefaciens showed the lowest resistance and slowest growth rate during exposure. Images obtained by scanning electron microscope (SEM) revealed that nano-Ag could cause damage to the cell structure of three bacteria at 1 μg/mL. Slight damage on E. coli was found when exposed to C₆₀, whereas no obvious physical damage was found after exposure to nano-Au or nano-Fe. It is assumed that surface activities of NM might be responsible for the different toxic effects on these bacteria.     

<Emphasis Type="Italic">An </Emphasis><Emphasis Type="Italic">Inconvenient Truth</Emphasis>: a focus on its portrayal of the hydrologic cycle

An Inconvenient Truth (AIT) has earned Al Gore an Oscar and a share of the 2007 Nobel Peace Prize and has been widely acclaimed by the mass media. However, significant errors exist in the film, owing to alarmism and exaggeration. As this forum does not provide for a detailed examination of these errors, this paper will focus only on the portrayal of the hydrologic cycle by AIT—precipitation and floods, soil moisture and droughts, and storminess. AIT argues that precipitation and intense rainfalls, floods, droughts, and the total number, intensity, and duration of tropical cyclones have all increased due exclusively to anthropogenically-driven climate change; indeed, AIT paints a picture of near scientific certainty with an overwhelming bias toward catastrophe scenarios. A closer look at the science, however, reveals that the data do not support these claims and that the scientific community is divided as to what the impact of anthropogenic climate change on the hydrologic cycle will be. Thus, the film gives a false impression of both the current state of climate change and that ‘the science is settled’.

New thermoelastic parameters of natural <Emphasis Type="Italic">C</Emphasis>2/<Emphasis Type="Italic">c</Emphasis> omphacite

The compressibility at room temperature and the thermal expansion at room pressure of two disordered crystals (space group C2/c) obtained by annealing a natural omphacite sample (space group P2/n) of composition close to Jd₅₆Di₄₄ and Jd₅₅Di₄₅, respectively, have been studied by single-crystal X-ray diffraction. Using a Birch–Murnaghan equation of state truncated at the third order [BM3-EoS], we have obtained the following coefficients: V ₀ = 421.04(7) Å³, K _T0 = 119(2) GPa, K′ = 5.7(6). A parameterized form of the BM3 EoS was used to determine the axial moduli of a, b and c. The anisotropy scheme is β _c  ≤ β _a  ≤ β _b , with an anisotropy ratio 1.05:1.00:1.07. A fitting of the lattice variation as a function of temperature, allowing for linear dependency of the thermal expansion coefficient on the temperature, yielded α_V(1bar,303K) = 2.64(2) × 10⁻⁵ K⁻¹ and an axial thermal expansion anisotropy of α _b  ≫ α _a  > α _c . Comparison of our results with available data on compressibility and thermal expansion shows that while a reasonable ideal behaviour can be proposed for the compressibility of clinopyroxenes in the jadeite–diopside binary join [K _T0 as a function of Jd molar %: K _T0 = 106(1) GPa + 0.28(2) × Jd_(mol%)], the available data have not sufficient quality to extract the behaviour of thermal expansion for the same binary join in terms of composition.     

The Intertidal Burrowing Crab <Emphasis Type="Italic">Neohelice</Emphasis> (=<Emphasis Type="Italic">Chasmagnathus</Emphasis>) <Emphasis Type="Italic">granulata</Emphasis> Positively Affects Foraging of Rodents in South Western Atlantic Salt Marshes

The role of positive and indirect interactions is often crucial in communities with intense abiotic stress such as salt marshes. The burrowing crab, Neohelice (=Chasmagnathus) granulata, is the dominant benthic macroinvertebrate of southwest Atlantic marshes (southern Brazil to Northern Argentinean Patagonia), having strong direct and indirect effects on marsh soil and, in consequence, on marsh vegetation and primary consumers. In this work, we investigate if this crab indirectly modifies habitat use by the granivorous rodents, Akodon azarae and Oligoryzomys flavescens, by increasing nutrient availability and thus enhancing seed production by the marsh plant Spartina densiflora. The study was conducted at the Mar Chiquita Coastal Lagoon, Argentina (37°32′ S). Rodent frequencies in S. densiflora were positively correlated with crab densities throughout the low and middle marsh. Additionally, the highest quality of S. densiflora and inflorescence density was recorded at the highest crab densities. Experimental manipulation of crab densities shows that N. granulata indirectly enhances the performance of S. densiflora (e.g., decreased fiber content and C/N ratios) and increases density of seeds. Moreover, N. granulata also facilitates S. densiflora seed availability to rodents by concentrating them in sediment mound at their burrows entrances. Experimental rodent exclusions showed that rodent species used S. densiflora seeds, a variable positively related to crab burrow density. Thus, our results show that N. granulata drives the granivorous rodent distribution and the intensity of seeds–rodent interaction trough facilitative and indirect interactions in marsh community.     

Bacterial Community Dynamics in a Seagrass (<Emphasis Type="Italic">Posidonia oceanica</Emphasis>) Meadow Sediment

Some traits of the bacterial community dynamics associated to the rhizosphere of the Mediterranean seagrass Posidonia oceanica, growing in carbonate sediments, were analyzed during a 2-year period in an enclosed bay of the Balearic Islands. The diversity of the bacterial community was studied by the construction of 16S rDNA clone library. For testing temporal and vertical differences in the abundance of total cells and active Bacteria, we used 4′,6-diamidino-2-phenylindole (DAPI) staining and fluorescence in situ hybridization (FISH). Moreover, some relevant groups of sulfate-reducing bacteria (SRB) were occasionally assessed by FISH. Despite the observed decrease in the total DAPI-stained cells, bacterial counts, and sulfate reduction rates throughout the sampling time, we found an increase in both the pore-water sulfide concentration and the proportion of SRB. Overall, the results revealed a very high bacterial diversity and indicated shifts in bacterial dynamics that could not be related to temperature-dependent factors, suggesting a link between the documented regression of the seagrass meadow and the decline of the microbial community, likely due to large organic matter inputs to the bay.     

<Emphasis Type="Italic">BV I</Emphasis><Subscript><Emphasis Type="Italic">c</Emphasis></Subscript> photometry of RR Lyrae stars

We have obtained 26 372 CCD frames in the B, V, and I _c filters for 81 RR Lyrae stars in 2008–2010, using the 76-cm telescope of the South African Astronomical Observatory and the 40-cm telescope of the Cerro Armazones Observatory, North Catholic University (Chile) using an SBIG ST-10XME CCD camera. For 12 of these RR Lyrae stars, we also obtained 337 brightness measurements in the B and V bands in 2000–2001 using the 60-cm telescope of the High Altitude Mt. Maidanak Observatory (Republic of Uzbekistan). We present tables of observations, light curves, and improved light-curve elements for all these RR Lyrae stars. The Blazhko effect was detected for SU Hor.     

Toxicity of vegetable tannin extract from <Emphasis Type="Italic">Acacia mearnsii</Emphasis> in <Emphasis Type="Italic">Saccharomyces cerevisiae</Emphasis>

Vegetable tannins are complex polyphenols, which occur widely in nature. Traditionally, natural tannins have been used for tanning leather. In Brazil, the main tannin-based products are obtained from Acacia mearnsii, which is a leguminous tree native to Southeastern of Australia, and the first seeds were brought to Brazil in 1928. The main cultivation of acacia was established in Rio Grande do Sul state due to the possibility of raw material for charcoal, adhesives to fuel and for tanning leather. The leather tanning processes based on plant tannins are thought to be less harmful than chromium-based tanning, and it has been used as a sustainable alternative. However, there is scarce information about the environmental impact of the leather tanning processes, with most studies reporting inhibitory effects against microorganisms at high doses and stimulatory and positive health effects at low concentrations. The aim of this study was to evaluate the toxicity of tannin preparations extracted from A. mearnsii in Saccharomyces cerevisiae. Vegetable tannin toxicity in yeast was tested using two tannin treatments in different concentrations. In general, the results showed toxicity of vegetable in yeast, BY4741 and gsh1Δ strains.     

Physiological Constraints in Juvenile <Emphasis Type="Italic">Ostrea chilensis</Emphasis> Fed the Toxic Dinoflagellate <Emphasis Type="Italic">Alexandrium catenella</Emphasis>

Frequent blooms of the dinoflagellate Alexandrium catenella in southern Chile encouraged undertaking the present study which uses the oyster Ostrea chilensis as a model for evaluating the feeding, growth, lipid storage and mortality responses to diets containing paralytic shellfish poisoning (PSP) produced by A. catenella. Medium-term (30 days) physiological responses of two groups of juvenile oysters were measured every 10 days. Five replicates were exposed to diets containing A. catenella and other five replicates were fed with a diet containing the non-toxic algae Isochrysis galbana. Diets were continuously supplied at a concentration of 2 mg L^?1, in which the feeding and metabolic activity was measured, and the scope for growth calculated. Lipids storage, actual growth and mortality were also measured every 10 days. The results showed that the toxic diet has dramatic negative effects on feeding and metabolism of the juvenile individuals of O. chilensis, with high reduction of the lipid storage and growth. Mortality was also increased in individuals fed with the contaminated diet. This study supports the conclusion that the toxic dinoflagellate A. catenella restricts the energy acquisition in the juvenile O. chilensis, an important fishery and aquaculture resource in southern Chile.     

<Emphasis Type="Italic">Rhizedra lutosa</Emphasis>, a natural enemy of<Emphasis Type="Italic">Phragmites australis</Emphasis> in North America

Rhizedra lutosa (Hübner) (Lepidoptera: Noctuidae), native to Europe, was first found in North America in 1988 in southern New Jersey. The insect is reported to cause serious damage toPhragmites australis in the Netherlands, but it now appears to be relatively unimportant throughout central Europe. We are investigating this insect as part of an effort to characterize existing natural enemies ofP. australis in North America toward a goal of biological control of this invasive plant. We trapped adults ofR. lutosa with blacklights in Rhode Island, Massachusetts, Connecticut, New York, Delaware, and Maryland; we also found it in Ohio and Pennsylvania.R. lutosa larvae feed in stems and rhizomes ofP. australis growing in dry sites. Based uponR. lutosa damage surveys andP. australis biomass measurements, we have determined that this insect does cause a reduction of plant growth in some sites, however, because of low moth densities, this effect is small. Despite spreading rapidly,R. lutosa densities do not appear to be increasing at sites we have investigated, and this insect does not currently appear to have much of an impact uponP. australis in North America.     

Feeding Behavior of the Native Mussel <Emphasis Type="Italic">Ischadium recurvum</Emphasis> and the Invasive Mussels <Emphasis Type="Italic">Mytella charruana</Emphasis> and <Emphasis Type="Italic">Perna viridis</Emphasis> in FL,USA, Across a Salinity Gradient

The feeding behavior of three species of mussels, the native Ischadium recurvum and the invasives Mytella charruana and Perna viridis, was studied in an invaded ecosystem in Florida (USA). In situ feeding experiments using the biodeposition method were performed along a salinity gradient in four different locations along the St. Johns River. Water characteristics, such as salinity, temperature, dissolved oxygen, and seston loads, were recorded to identify relationships between these variables and the feeding behavior of the mussels. Feeding behavior of the species varied by study site. Clearance, filtration, organic ingestion, and absorption rates of I. recurvum were negatively affected by salinity. For the invasive mussel, M. charruana, rejection was positively related to salinity while total ingestion, organic ingestion, and absorption rates were positively related to the percentage of organic matter in the seston. For P. viridis, total and organic ingestion rates were negatively affected by salinity but positively affected by total particulate matter. Condition indices for P. viridis and M. charruana were 13.16?±?0.64 and 6.63?±?0.43, respectively, compared to 4.82?±?0.41 for the native species I. recurvum, indicating that these mussels are well adapted to the environmental conditions in the area. This study indicates that the three species have different preferred habitats because of their specific responses to water characteristics. Thus, the invasive mussels will not totally occupy the niche of the native mussel in Florida despite overlapping zones. These data may help identify potential invaded areas and understand the extent of the invasion.     

Evaluation of <Emphasis Type="Italic">smtA</Emphasis> expression and <Emphasis Type="Italic">E. coli</Emphasis> survival against cadmium ions

Cadmium and other heavy metals lead to environmental danger, and these heavy metals are a great threat to human and other animal’s health. Investigation of the relationship between survival of E. coli and metallothionein smtA gene expression against cadmium ion is the goal of this research. Survival of recombinant bacteria containing smtA gene was analyzed against various concentrations of cadmium chloride salt using optical density (OD). At the resistive range, recombinant bacteria were subjected to different treatments. At the logarithmic phase of bacterial growth, sampling, RNA extraction and cDNA synthesis were performed and smtA gene expression was then analyzed by real-time PCR using designed primers for smtA gene and Amp resistance (as the calibrator gene). Relative gene expression was calculated using the ??C_t method. The resistive range against cadmium chloride was 0.5–0.7 mM (minimum inhibitory concentration (MIC = 0.5 mM)). Survival and gene expression analysis showed that in induced bacteria, smtA expression was increased significantly that in turn conferred resistance to cadmium chloride prominently. There was a direct relationship between increased smtA gene expression and survival of the recombinant bacteria. Therefore, our result may help to confront to cadmium metal environmental pollution using overexpression of smtA gene expression in recombinant bacteria.     

How water use of <Emphasis Type="Italic">Salix</Emphasis><Emphasis Type="Italic">psammophila</Emphasis> bush depends on groundwater depth in a semi-desert area

To investigate the groundwater levels changes effects on the transpiration of Salix psammophila (S. psammophila) bush, systemic measurements of meteorological conditions, sap flow of S. psammophila, soil water contents and groundwater levels were conducted in the Hailiutu River catchment, NW of China. Based on the collected field data, Hydrus-1D software package was used to calibrate water movement for root uptake in the saturated–unsaturated zone. The soil hydraulic parameters and root uptake function parameters were calibrated. The simulated results of soil water contents and sap flow fitted well with the observed ones. Based on the calibrated hydraulic parameters, different groundwater levels were imposed at the low boundary to simulate the groundwater levels changes effects on the transpiration. The relationship between ratio of actual transpiration and potential (T/T _p) and groundwater water table depth was established. The results shows that the ratio of actual transpiration and potential transpiration decreases with groundwater table depth increase as inverse ‘S’ shape. And the turn point is corresponding to the extinct depth, i.e., no groundwater contribution to S. psammophila transpiration. To further verify this phenomenon is universal, the soil hydraulic parameters were replaced with the other five groups in the calibrated forward model. The results confirmed the similar changes of T _a/T _p with the groundwater levels changed, i.e. inverse ‘S’ shape. However, the extinction depth is different corresponding to different soil hydraulic parameters. So, the research results indicated the relationship between transpiration and groundwater levels is non-linear function.     

Hybridization and Plasticity Contribute to Divergence Among Coastal and Wetland Populations of Invasive Hybrid Japanese Knotweed <Emphasis Type="Italic">s</Emphasis>.<Emphasis Type="Italic">l</Emphasis>. (<Emphasis Type="Italic">Fallopia</Emphasis> spp.)

Japanese knotweed s.l. (Fallopia spp.) is a highly invasive clonal plant, best known from roadside and riparian habitats. Its expansion into beaches on Long Island, NY, USA, represents a major habitat shift. I surveyed populations from beaches and wetlands and conducted a common garden experiment to test for variation in drought tolerance and phenotype among populations and habitats. All populations were composed mostly of first- and later-generation hybrids. I found significant variation among populations in growth, lamina size, specific leaf area (SLA), and biomass allocation, in both the field and the common garden. Lamina size, growth, and root-to-shoot responded plastically to drought treatment. Wetland populations tolerated drought as well as beach populations. Differentiation in SLA between habitats suggests that some selection for beach genotypes may have occurred. It appears that both hybridization and phenotypic plasticity are contributing to the expansion of Fallopia spp. into novel habitat.     

<Emphasis Type="Italic">In situ</Emphasis> Agrobiodiversity Conservation for Regional Development in Nepal

The majority of rural communities have limited agricultural development opportunities within the hills and mountains of Nepal. While the dominant development model, which focuses on technology transfer and the evolution of commercial production systems, is effective when access to inputs and markets enables farmers to produce and trade successfully, many communities are marginalised from development opportunities by poverty and poor infrastructure. Complementary development approaches that value, conserve, develop and market agrobiodiversity could alleviate the extreme poverty where these conditions prevail as in the hills and mountains, the rural margins of Nepal. Formalised in situ approaches to agrobiodiversity conservation are in their infancy in Nepal, yet suggest that opportunities exist for a complementary agricultural development approach in the rural margins based on working with the local diversity, rather than its elimination. The obstacles of widespread poverty and inadequate infrastructure ensure that effective in situ agrobiodiversity conservation programs must provide for the needs of local people for sustainable development.