Consumer depletion alters seagrass resistance to an invasive macroalga

Few field studies have investigated how changes at one trophic level can affect the invasibility of other trophic levels. We examined the hypothesis that the spread of an introduced alga in disturbed seagrass beds with degraded canopies depends on the depletion of large consumers. We mimicked the degradation of seagrass canopies by clipping shoot density and reducing leaf length, simulating natural and anthropogenic stressors such as fish overgrazing and water quality. Caulerpa racemosa was transplanted into each plot and large consumers were excluded from half of them using cages. Potential cage artifacts were assessed by measuring irradiance, scouring by leaf movement, water flow, and sedimentation. Algal invasion of the seagrass bed differed based on the size of consumers. The alga had higher cover and size under the cages, where the seagrass was characterized by reduced shoot density and canopy height. Furthermore, canopy height had a significant effect depending on canopy density. The alteration of seagrass canopies increased the spread of C. racemosa only when large consumers were absent. Our results suggest that protecting declining habitats and/or restoring fish populations will limit the expansion of C. racemosa. Because MPAs also enhance the abundance and size of fish consuming seagrass they can indirectly promote algal invasion. The effects of MPAs on invasive species are context dependent and require balancing opposing forces, such as the conservation of seagrass canopy structure and the protection of fish grazing the seagrass

Radiocesium Contamination in Samples of Blueberries Jams Collected in Stores of NE Italy (2013-2017)

The monitoring of radioactivity in foodstuffs is carried out for the purposes of food safety in order to follow the evolution of the contamination as result of incidents that occurred both in the past (eg Chernobyl) and in more recent times (eg, Fukushima). Then, the movement of goods from these countries to European Union may cause the propagation of foods potentially toxic for health. At the Port of Trieste, in the period of September 2013, some loads of blueberries (Vaccinum mirtyllus L.) were examined within the application of EC Regulation 733/2008, on the conditions governing imports of agricultural products originating in the countries affected by the nuclear accident of Chernobyl in 1986. The fruits came from Ukraine and were intended for the food preparations containing blueberries, in particular jams and marmalades. As in some cases significant values of Radiocesium concentrations (Cesium-137) were found in blueberries, though below the limit of 600 Bq/kg as required by the Regulations, it was decided to verify whether the presence of this contaminant in the raw material at the tested levels could interest the finished products. In this work, we have therefore collected and analyzed some samples of concentrated blueberries products in different large stores, in order to verify the magnitude of the possible contamination by radio Cesium

The interactive effect of herbivory, nutrient enrichment and mucilage on shallow rocky macroalgal communities

This paper focuses on the interactive short and long-term effect of three different stressors on a macroalgal assemblage. Three stressors are considered: herbivory, nutrients and mucilage. The experiment was conducted in Tavolara Punta Coda Cavallo Marine Protected Area (Mediterranean Sea) during a bloom of the benthic mucilage-producing microalga Chrysophaeum taylorii (Pelagophyceae); this microalga is recently spreading in the Mediterranean Sea. On a rocky substratum, 36 plots 20 × 20 cm in size were prepared. Factorial combinations of three experimental treatments were applied in triplicate, including three grazing levels crossed with two nutrient enrichment and two mucilage removal treatments. Significant differences were observed among treatments 8 weeks later, at the end of summer. In particular, dark filamentous algae were more abundant in all enriched plots, especially where mucilage and macroalgae had been removed; a higher percent cover of crustose coralline algae was instead observed where nutrients had been increased and no grazing pressure acted. Furthermore, the abundance of Dictyota spp. and Laurencia spp. was significantly higher in enriched mucilage-free plots where the grazing pressure was null or low. However, the effects of the treatments on the overall assemblage of the macroalgal community were not long persistent (36 weeks later). These results illustrate the capacity of a shallow-water macroalgal community to quickly recover from the simultaneous impacts of herbivory, nutrient enrichment, and mucilage

Evaluation of Radiocesium Contamination in Samples of Blueberries Jams

For the purposes of food safety the monitoring of radioactivity in foodstuffs is carried out in order to follow the progress of the contamination as a result of incidents that occurred both in the past (eg Chernobyl) and in more recent times (eg, Fukushima). Then, the movement of goods from these countries to Europe may be due to the propagation of potentially toxic foods for health. At the Port of Trieste in the period of August and September 2013, some loads of blueberries (Vaccinum mirtyllus L.) were examined witin the application of EC Regulation 733/2008 on the conditions governing imports of agricultural products originating in the countries affected by the nuclear accident of Chernobyl in 1986. The fruits came from Ukraine and were intended for the production of foods containing blueberries in particular, jams and marmalades. Because in some cases Radiocesium concentrations (cesium 137) had been found with significant values, though below the limit of 600 Bq /kg as required by the Regulations, it was decided to undertake a research to verify whether and as was extended the presence of this contaminant in the raw material at the levels tested. In this way it is possible define as the contamination could be reflected significantly on finished products intended for consumption. It can not be excluded in principle the possibility of a phenomenon of concentration and accumulation of the fraction saline in finished products such as marmalades, jams, concentrates etc., as result of the different operations and technological treatment necessary for their preparation. Then the results of tests carried out on samples of major brands of jams and marmalades, made with blueberries and cranberries will be presented; they in fact represent samples of blueberries food with significant and great circulation, and therefore may characterizing the quality and healthiness of these foods on the national territory

ANOVAs to evaluate environmental variables.

<p>Effects of Herbivore (fenced vs. unfenced), Canopy Density (100%, 50%, and 20%), and Canopy Height (natural vs. halved) on irradiance, scour, water flow, and sediment deposition. SNK test for comparisons of the significant interaction. Significant (p<0.05) results are in bold. Degrees of freedom of the Residual refer to irradiance/all other analyses.</p><p>ANOVAs to evaluate environmental variables.</p

Fish occurrence at the study site.

<p>Mean±SE fish biomass (g/50m²) estimated at the study site. Minimum fish length (L) per species excludable by cages was calculated by L = FH/PLH where FH = fish height and PLH = proportional length height coefficient. Species in bold can potentially contribute to the differences based on length frequency. Trophic guilds are Her herbivore, Pla Planktotrophic, Car Carnivorous, and Omn Omnivorous.</p><p>Fish occurrence at the study site.</p

Mean (±SE) <i>Caulerpa racemosa</i> frond size at the four sampling times for the six <i>Posidonia oceanica</i> combinations of shoot density (100%, 50%, and 20%) and height (Natural N and halved H) at Fenced (F, checked bars) and Unfenced (UF, black bars) treatments.

<p>Mean (±SE) <i>Caulerpa racemosa</i> frond size at the four sampling times for the six <i>Posidonia oceanica</i> combinations of shoot density (100%, 50%, and 20%) and height (Natural N and halved H) at Fenced (F, checked bars) and Unfenced (UF, black bars) treatments.</p