Utilization of the filter feeder polychaete Sabella

The filter feeder sabellid Sabella spallanzanii Gmelin (Polychaeta, Sabellidae) was proposed as biofilter in the treatment of wastes from intensive aquaculture. The species was previously studied concerning reproductive traits and ecological requirements; moreover, previous laboratory experiments indicated a positive action of its feeding activity on solid removal from water column coupled with an interesting microbiological activity. In the present paper data on settlement and growth rate from a natural population, together with data on the bioremediation activity of an adult population, relative to an experiment conducted in a small fish farm are reported. Results seem to encourage further studies on S. spallanzanii for a future utilization in bioremediation of fish farms with recycled water. Data from natural annual settlement indicated, however, the unreliability in obtaining settlers from natural populations, so that the artificial reproduction of the target species will be one of the main points of further investigations.     

Weak effects of habitat type on susceptibility to invasive freshwater species: an Italian case study

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Comparison on accuracy of different nonlinear models in predicting growth of Podolica bulls

Animal growth does not follow a linear pattern, being explained mathematically by functions that have parameters with biological meaning. These parameters are used to estimate the expected weight of animals at specific ages. Several nonlinear models have been used to describe growth. This study was carried out to estimate the parameters of logistic, Gompertz, Richards and von Bertalanffy growth curve models in a sample of Podolica young bulls to determine the goodness of fit. Animals were weighed every 3 months from birth to 810 days of age. The results indicate that all the growth models used were easily fitted to the observed data with Gompertz and logistic functions presenting less computational difficulty in terms of number of iterations to achieve convergence. Moreover, logistic and Richards equations provided the best overall fit being useful to describe the growth of Podolica bulls. Considering that the literature lacks information on growth curves in Podolica breed, the study of a mathematical model for growth describing the developmental pattern of a specific population within a peculiar environment is a useful tool to improve Podolica breed production.     

Different levels of organic trace minerals in diets for Nile tilapia juveniles alter gut characteristics and body composition,but not growth

Thirty groups of twenty juveniles each of Nile tilapia (Oreochromis niloticus, initial average weight 23.93 ± 0.80 g) were fed diets containing increasing amounts (0%, 25%, 50%, 75%, and 100% of levels used by the tilapia feed industry) of organic trace mineral (Fe, Zn, Mn, Cu, Se) supplementation for 56 days. Growth was not affected by the dose of mineral supplementation. However, body protein increased in fish fed intermediate doses of organic minerals, reaching a maximum at 40.44% supplementation. Doses >50% showed mild damage to the intestinal tissue. Body Fe, Zn and Cu deposition were highest at 28.32%, 24.43% and 78.45% supplementation, respectively. Tilapia could modulate intestinal morphology when fed different doses of organic minerals. As the supplementation doses increased, hemosiderin staining increased in the distal intestine and total body Fe content, indicating that the distal region of the intestine plays an important role in iron excretion by tilapia. Supplementation of organic trace minerals at intermediate doses does not harm Nile tilapia growth, but excessive trace mineral supplementation can impair body protein retention and promote histological alterations in the gut.     

A survey of chemical and nutritional characteristics of halophytes plants used by camels in Southern Tunisia

The camel (Camelus dromedarius) is well adapted to the utilization of vegetation of low nutritional value in its natural habitat zone, thanks to its aptitude to vary food and to search plants that are rich in water content and that can make up for its nutritional deficits, particularly as concerns mineral elements. Therefore, a survey was carried out to determine camels pasture quality, dietary preference and to characterize the chemical characteristics and nutritional value of different halophytes plants in a region of Southern Tunisia during spring season. Laboratory analysis were conducted on fourteen vegetable species appertained to seven different botanical families: Chenopodiaceae, Graminaceae, Tamaricaceae, Zygophyllaceae, Asteraceae, Frankeniaceae and Plumbaginaceae. Data obtained indicate an high variability of nutritional content of halophytes plants preferred by camels, specially for dry matter, crude protein, fiber fractions, ash and mineral elements.     

Effect of beta‐aminoproprionitrile on eggshell formation

1. Eggshells are bioceramic‐biopolymer composites made by a cell‐mediated deposition of an extracellular matrix which drives the organisation of the inorganic phase. Ultrastructurally, eggshells are composed of shell membranes, mammillary knobs, palisade, and cuticle. Shell membranes are two nets of type X collagen‐containing fibrils. On to these membranes, the mammillary knobs, that is, the crystal nucleation sites, are deposited. Type X collagen is highly cross‐linked and insoluble.

2. In order to evaluate the role of type X collagen cross‐linking on eggshell formation, hens were injected with different doses of β‐aminoproprionitrile, which specifically interferes with cross‐link formation.

3. Changes in egg size and shape were observed. Scanning electron micrographs analysis of these eggs demonstrated marked changes in crystal growth and shell membrane structure and arrangement. A dot‐blot analysis, using a monoclonal antibody against chicken type X collagen, shows a dose‐dependent increase in shell membrane collagen extractability.

4. It is concluded that the formation of β‐aminoproprionitrile‐sensitive cross‐links among the type X collagen molecules of the shell membranes play an essential role in normal eggshell formation.     

Phenolic compounds and saponins in quinoa samples (Chenopodium quinoa Willd.) grown under different saline and nonsaline irrigation regimens

Quinoa is a pseudocereal from South America that has received increased interest around the world because it is a good source of different nutrients and rich in antioxidant compounds. Thus, this study has focused on the effects of different agronomic variables, such as irrigation and salinity, on the phenolic and saponin profiles of quinoa. It was observed that irrigation with 25% of full water restitution, with and without the addition of salt, was associated with increases in free phenolic compounds of 23.16 and 26.27%, respectively. In contrast, bound phenolic compounds were not affected by environmental stresses. Saponins decreased if samples were exposed to drought and saline regimens. In situations of severe water deficit, the saponins content decreased 45%, and 50% when a salt stress was added. The results suggest that irrigation and salinity may regulate the production of bioactive compounds in quinoa, influencing its nutritional and industrial values.     

Mating type and fungicide resistance in populations of Podosphaera xanthii in south Italy

Powdery mildew is one of the most common and severe diseases of cucurbits, causing heavy yield losses in all growing areas when not successfully controlled. Two different fungal species, Podosphaera xanthii and Golovinomyces orontii, are generally recognized as causal agents. The results of monitoring carried out in 2016 and 2018 confirmed that P. xanthii is the exclusive pathogen causing cucurbit powdery mildew (CPM) in southern Italy. P. xanthii is a bipolar heterothallic fungus; a PCR-based method for distinguishing MAT1-1 and MAT1-2 idiomorphs was applied for assessing mating type distribution in fungal populations present on cucurbits in different sites. The idiomorph MAT1-2 was prevalent over the MAT1-1 in 2016, whereas they were approximately in a 1:1 ratio in 2018; this finding corroborated the hypothesis that the MAT1-1 idiomorph was more recently introduced in the area. Cyflufenamid-resistant isolates were widespread in commercial greenhouses and field plantings even though use of this fungicide had been drastically reduced by the farmers 1 year before the monitoring due to the effectiveness losses observed in CPM control. Occurrence of cyflufenamid resistance and its impact on efficacy were evaluated in a field trial comparing different fungicide spray schedules. Cyflufenamid-resistant isolates were detected even at the first appearance of symptoms on leaves, increasing over time. Isolates resistant to cyflufenamid showed a resistance factor as high as 900. Generally, P. xanthii was better controlled when cyflufenamid was used in integrated strategies rather than in spray schedules based on the exclusive use of the fungicide.     

Natural sinks of CO2: Technical synthesis from the palmas Del Mar Workshop

Natural CO₂ sinks in terrestrial and marine environments are important components of the global carbon cycle, yet the sign and magnitudes of key fluxes among them are unknown. The results of the Palmas Del Mar Workshop — Natural Sinks of CO₂ presented in this special issue and its companion hardbound volume of Water, Air, & Soil Pollution, provide a synthesis of current research on the carbon cycle, CO₂ sinks and associated processes and fluxes, and critical research needs to assess the potential role of forest and land-use management in carbon sequestration. The papers in this volume present data, observations, and model simulations that demonstrate: 1) the existence of natural CO₂ sinks that could mitigate a significant amount of CO₂ emissions from fossilfuel combustion; 2) probable, human-caused imbalances in C exchanges among vegetation, soils, and the atmosphere; 3) enhanced C storage in vegetation in response to excess atmospheric CO₂; 4) strong interactions among carbon, nutrient and hydrological cycles; and 5) an excess of carbon production over consumption in several, large managed forests. Although it appears unlikely that the search for the “missing” C sink required to balance the C budget will end in the open ocean, new estimates of C storage in mangrove wood and peat, suggest that coastal ecosystems have the capacity to store significant amounts of carbon in vegetation and sediments. Convincing analyses are also presented indicating the technical and economical feasibility of managing existing lands to sequester additional carbon. Long-term field studies of CO₂ fertilization effects and carbon cycling by plants and soils in geographically important systems, native forests, and coastal ecosystems will go a long way toward meeting the research needs identified at the workshop.     

The rapid oxidation of atmospheric CO to CO2 by soils

Gas exchange rates over soils were measured in a closed, flowing-gas system. ¹⁴CO was rapidly oxidized to ¹⁴CO₂ with only a minor loss in atmospheric radioactivity. Incorporation of ¹⁴C into the soil was slight and was via ¹⁴CO₂ rather than ¹⁴CO. CO oxidation was a microbial process and no oxidation occurred when soils had been autoclaved. The rate of CO depletion was concentration dependent and followed Michaelis-Menten kinetics. The rate constants K_m and V_max ranged from 18 to 51 μ 1^?1 CO and from 0.58 to 4.35 mg C kg^?1 dry soil h^?1 respectively. The maximum rate of reaction for Hubbard Brook soil was about an order of magnitude greater than any soil previously reported. The oxidation reaction was accompanied initially by a reduction in net soil respiration. This was then followed by a period of high respiration which continued until CO levels were reduced to about 5μll^?1. Thereafter respiration fell below the pretreatment rate and only returned to that rate 45 min after CO had been depleted from the atmosphere. The data suggest that at high CO concentrations (40–100 μll^?1CO) autotrophic carboxydobacteria comprise the main component of the CO-oxidizing population and, as the concentration declines towards ambient levels they are replaced by heterotrophic microorganisms possessing a cometabolic process.