Diet and seasonal prey capture rates in the Mediterranean red coral (Corallium rubrum L.)

Gorgonians are passive suspension feeders, contributing significantly to the energy flow of littoral ecosystems. More than in active suspension feeders (such as bivalves, ascidians and sponges) their prey capture is affected by spatial and temporal prey distribution and water movement. Corallium rubrum is a characteristic gorgonian of Mediterranean sublittoral hard bottom communities. This study found a high variability in the annual cycle of prey capture rate, prey size and ingested biomass, compared to other Mediterranean gorgonians. Detrital particulate organic matter (POM) was found throughout the year in the polyp guts and constituted the main proportion of the diet (25–44%). Crustacean fragments and copepods (14–46%) accounted for the second major proportion, while invertebrate eggs (9–15%) and phytoplankton (8–11%) constituted the smallest part of the diet. To verify the importance of detrital POM in the energy input of this precious octocoral species, in situ experiments were carried out during the winter–spring period. The results confirm the importance of detrital POM as the main source of food for C. rubrum [0.13±0.04 μg C polyp⁻¹ h⁻¹ (mean±SD)]. This study also compares the prey capture rates of two colony size classes and two depth strata: Within the same patch, small colonies (<6 cm height) captured significantly more prey per polyp (0.038±0.09 prey polyp⁻¹ h⁻¹) than larger colonies (>10 cm high) (0.026±0.097 prey polyp⁻¹ h⁻¹) and showed a higher proportion of polyps containing prey (17% compared to 10%). Comparing colonies of similar size (<6 cm height) revealed that the colonies situated at 40 m depth captured significantly more prey (0.038±0.09 prey polyp⁻¹ h⁻¹) than the ones at 20 m (0.025±0.11 prey polyp⁻¹ h⁻¹). One pulse of copepods was recorded that constituted 16% of all captured prey during the 15-month period studied in one of the sampled populations. The data suggest that the variability of hydrodynamic processes may have a higher influence on the feeding rate than seasonal changes in the seston composition. The carbon ingestion combined with data on the density of the exploited population results in 0.4–9.6 mg C m⁻² day⁻¹. The grazing impact of current, heavily exploited and small-sized populations is comparable to that of larger Mediterranean gorgonians, suggesting that unexploited red coral populations may have a high impact compared with other passive suspension feeders.     

Chitosan for direct bioflocculation of wastewater

Environmental Chemistry Letters - Coagulation/flocculation is a major phenomenon occurring during industrial and municipal water treatment to remove suspended particles. Common coagulants are metal...     

Small-scale genetic structure in a marine population in relation to water circulation and egg characteristics

Until the last decade it was assumed that most marine species have pronounced gene flow over vast areas, largely because of their potential for dispersal during early life stages. However, recent genetic, modeling, and field studies have shown that marine populations may be structured at scales that are inconsistent with extensive dispersal of eggs and larvae. Such findings have stimulated the birth of new studies explaining the mechanisms that promote population structure and isolation in the oceans, in the face of high potential for dispersal. Here we study the vertical and horizontal distribution of cod (Gadus morhua) eggs in relation to small-scale circulation and water column hydrography in a coastal location of southern Norway. Previous studies conducted in this region have shown that cod populations inhabiting fjord locations, which are on average 30 km apart, are genetically differentiated, a remarkable outcome considering that Atlantic cod have pelagic egg stages and long pelagic larval duration. We document that cod eggs are found in greater abundance in shallow water layers, which on average are flowing up the fjord (away from the open ocean), and in the inner portion of the fjord, which is subject to lower current speeds compared to the outer or mouth of the fjord. Eggs were found to be neutrally buoyant at shallow depths, a trait that also favors local retention, given the local circulation. The same patterns held during two environmentally contrasting years. These results strongly suggest that population structure of Atlantic cod is favored and maintained by a balance between water circulation and egg characteristics.     

Refuse derived soluble bio-organics enhancing tomato plant growth and productivity

Municipal bio-refuse (CVD), containing kitchen wastes, home gardening residues and public park trimmings, was treated with alkali to yield a soluble bio-organic fraction (SBO) and an insoluble residue. These materials were characterized using elemental analysis, potentiometric titration, and 13C NMR spectroscopy, and then applied as organic fertilizers to soil for tomato greenhouse cultivation. Their performance was compared with a commercial product obtained from animal residues. Plant growth, fruit yield and quality, and soil and leaf chemical composition were the selected performance indicators. The SBO exhibited the best performance by enhancing leaf chlorophyll content, improving plant growth and fruit ripening rate and yield. No product performance-chemical composition relationship could be assessed. Solubility could be one reason for the superior performance of SBO as a tomato growth promoter. The enhancement of leaf chlorophyll content is discussed to identify a possible link with the SBO photosensitizing properties that have been demonstrated in other work, and thus with photosynthetic performance.     

Spatially-balanced sampling versus unbalanced stratified sampling for assessing forest change: evidences in favour of spatial balance

Large-scale remote sensing-based inventories of forest cover are usually carried out by combining unsupervised classifications of satellite pixels into forest/non forest classes (map data) with subsequent time-consuming visual on-screen imagery classification of a probabilistic sample of pixels taken as the ground truth (reference data). In this paper the estimation of forest change from a sample of reference data is approached by: (i) exploiting map data to construct strata in which changes are occurred, and then adopting the stratified sampling joined with the HT estimator with most sampling effort devoted to strata where changes are occurred irrespective of their size, as suggested in most remote sensing literature regarding land change assessments; (ii) adopting a spatial scheme ensuring spatially balanced samples, as suggested in most recent statistical literature regarding spatial surveys, and exploiting the map data in the difference estimator. The results of a comparison performed on an artificial population of reference data generated from a real population of map data recorded in Sardinia (Italy) discourage the use of unbalanced stratified samples that achieve the worst precision. The best results are obtained by means of spatially balanced samples or stratification with nearly proportional allocation to strata.     

Effects of selected metal oxide nanoparticles on Artemia salina larvae: evaluation of mortality and behavioural and biochemical responses

The aim was to investigate the toxicity of selected metal oxide nanoparticles (MO-NPs) on the brine shrimp Artemia salina, by evaluating mortality and behavioural and biochemical responses. Larvae were exposed to tin(IV) oxide (stannic oxide (SnO₂)), cerium(IV) oxide (CeO₂) and iron(II, III) oxide (Fe₃O₄) NPs for 48 h in seawater, with MO-NP suspensions from 0.01 to 1.0 mg/mL. Mortality and behavioural responses (swimming speed alteration) and enzymatic activities of cholinesterase, glutathione-S-transferase and catalase were evaluated. Although the MO-NPs did not induce any mortality of the larvae, they caused changes in behavioural and biochemical responses. Swimming speed significantly decreased in larvae exposed to CeO₂ NPs. Cholinesterase and glutathione-S-transferase activities were significantly inhibited in larvae exposed to SnO₂ NPs, whereas cholinesterase activity significantly increased after CeO₂ NP and Fe₃O₄ NP exposure. Catalase activity significantly increased in larvae exposed to Fe₃O₄ NPs. In conclusion, swimming alteration and cholinesterase activity represent valid endpoints for MO-NP exposure, while glutathione-S-transferase and catalase activities appear to be NP-specific.     

Nitrate,sulphate and chloride contents in public drinking water supplies in Sicily,Italy

Water samples collected from public drinking water supplies in Sicily were analysed for electric conductivity and for their chloride, sulphate and nitrate contents. The samples were collected as uniformly as possible from throughout the Sicilian territory, with an average sampling density of about one sample for every 7,600 inhabitants. Chloride contents that ranged from 5.53 to 1,302 mg/l were correlated strongly with electric conductivity, a parameter used as a proxy for water salinity. The highest values are attributable to seawater contamination along the coasts of the island. High chloride and sulphate values attributable to evaporitic rock dissolution were found in the central part of Sicily. The nitrate concentrations ranged from 0.05 to 296 mg/l, with 31 samples (4.7% of the total) exceeding the maximum admissible concentration of 50 mg/l. Anomalous samples always came from areas of intensive agricultural usage, indicating a clear anthropogenic origin. The same parameters were also measured in bottled water sold in Sicily, and they all were within the ranges for public drinking water supplies. The calculated mean nitrate intake from consuming public water supplies (16.1 mg/l) did not differ significantly from that of bottled water (15.2 mg/l). Although the quality of public water supplies needs to be improved by eliminating those that do not comply with the current drinking water limits, at present it does not justify the high consumption of bottled water (at least for nitrate contents).