Fishers’ ecological knowledge on the reproduction of fish and shrimp in a subtropical coastal ecosystem

Hydrobiologia - Fishers’ ecological knowledge (FEK) has contributed to a better understanding about the reproduction of fishery resources, especially where biological data are scarce or...     

Impacts of inter-basin water transfer on the water quality of receiving reservoirs in a tropical semi-arid region

Inter-basin water transfer (IBWT) involves the transport of water from one geographically distinct basin to another to balance the distribution of water resources. Although the socio-economic benefits of implementing these projects are well recognized, little is known about the subsequent effects on the water quality of the receiving systems. We evaluated the effects of an IBWT on the water quality of three receiving reservoirs of an intermittent river in a semi-arid region. We compared the similarity among the reservoirs before and after the IBWT to assess how the reservoirs responded to the introduction of water. Although the last two reservoirs that have received water have become similar in terms of physical and chemical characteristics and algal biomass (chlorophyll-a), the first reservoir has not. The IBWT resulted in an improvement in the water quality of the first reservoir but a decrease in the water quality of the two successive reservoirs, along with a significant increase in algal biomass. Long river sections located upstream that were dry at the time of IBWT probably contributed nutrients to the water as it moved downstream and into the reservoirs. Significant differences in the water quality were observed for different sampling months after the IBWT, but not for different sampling depths. Before the IBWT, the predictor variables for algal biomass were basically transparency and non-algal turbidity, with which it established a positive relationship. After IBWT, however, algal biomass also showed a positive relationship with pH and temperature. We conclude that IBWT affects the water quality of receiving reservoirs and that the responses are reservoir specific. IBWT also increases the complexity of the correlations of physical and chemical variables with algal biomass.

     

A safe haven for potential reproductive aggregations of the critically endangered Brazilian guitarfish (Pseudobatos horkelii)

Brazilian endemic batoid elasmobranch populations have declined dramatically in the past 40 years due to anthropic activities (e.g., overfishing). The Brazilian guitarfish, Pseudobatos horkelii, included in the IUCN red list of endangered species [Critically Endangered (CR)], has been captured as by-catch by trawling fishing boats to the edge of extinction. Despite governmental conservation initiatives, the species is still caught and commercialized along the Brazilian coast. In this study, the authors report three rare aggregation events for the Brazilian coast of P. horkelii, inside the only nearshore no-entry Brazilian marine protected area. Strategies for its protection are also discussed.     

Stimulation of Bovicin HC5 Production and Selection of Improved Bacteriocin-Producing Streptococcus equinus HC5 Variants

Probiotics and Antimicrobial Proteins - Bovicin HC5 is a peptide that has inhibitory activity against various pathogenic microorganisms and food spoilage bacteria. Aiming to improve the...     

Non-native prey species supporting fish assemblage biomass in a Neotropical reservoir

The present study aimed to investigate the role of four non-native invertebrates in supporting fish biomass as well as their influence on the carbon flow into the Volta Grande reservoir food web. The fish samples were carried out quarterly between October 2015 and July 2016 using gillnets. At the sampled sites, four non-native invertebrates (golden mussel, Asian clam, trumpet snail and Amazonian prawn), which are potential prey for fish in the Volta Grande reservoir, were collected by targeted sampling using a Petersen-type bottom dredger and semi-circular sieves. The gut contents of the fish were collected and analyzed under stereoscope, and samples of muscle tissue of these fish, as well as the four non-native invertebrate species sampled, were submitted for isotopic analysis. Results obtained by the present study, by both gut content and stable isotopic analyses, pointed to a trophic structure where non-native species represent not only a strong component of the fish community, but also their main carbon source. Based on gut contents and isotopic mixing models, we found that together, non-native prey are essential carbon sources for the fish fauna, fuelling more than 40.0% of the biomass in four dominant fish species. The consumption rate of non-native bivalves by the native omnivorous fish Leporinus friderici suggested these filter-feeding organisms potentially constitute an important trophic connection between littoral consumers and pelagic energy sources. In addition, non-native prey were also prominent carbon sources for non-native fish, fuelling more than half of the biomass in peacock bass and silver croaker, suggesting these prey have a fundamental role in maintaining non-native fish populations in this system. Our results may help to understand fundamental ecological issues bringing to light the extent to which these new combinations of species influence the energy flow and ecosystem properties of the Volta Grande reservoir.

     

Body movements during the off-ice execution of back spins in figure skating

Using an optoelectronic motion capture system, we quantitatively assessed the arrangement of body segments and the displacement of the horizontal projection of the center of mass (CM) in seven skaters performing off-ice back spins on a rotating device (spinner). The position of the CM at the beginning of the spins was not a determining factor, but its rapid stabilization towards the center of the spinner, together with the achievement of a stable arrangement of trunk and limbs, was crucial to get the dynamic equilibrium, necessary for a lasting performance. At full spinning, however, there was an indicative variety of individual body postures. A final deceleration, associable with the loss of body equilibrium, was detected in the last spin of most of skaters.In conclusion, the current investigation demonstrated that the off-ice execution of back spin, a critical movement of ice skating, can be measured in laboratory, thus providing quantitative information to both the skaters and the coaches. The analysis is not invasive, and it may be proposed also for longitudinal evaluations of skating and postural training.     

Resprouting Ability of Dry Forest Tree Species after Disturbance Does Not Relate to Propagation Possibility by Stem and Root Cuttings

Tropical dry forest tree species are recognized for their high resprouting ability after disturbance. We tested whether species that commonly produce root and stem suckers can be propagated by large stem and root cuttings, a useful method for landscape restoration programs. We performed four experiments: (1) In a greenhouse, we tested the propagation of six species using large stem cuttings collected from early successional sites. We used the following treatments: (i) dry season collection and planting; (ii) dry season collection, storage in humid soil, and wet season planting; (iii) wet season collection and planting; and (iv) wet season collection and planting after treatment with commercial NAA auxin. (2) Stem cuttings of Myracrodruon urundeuva were planted in a pasture during the rainy season after either NAA, IBA, or no auxin treatment. (3) As a control experiment, we also planted cuttings of Spondias mombin, a species known for successfully regenerating from cuttings. (4) Root cuttings of six species were collected in recently plowed pastures and planted in the greenhouse with and without treatment with NAA auxin. No root cuttings rooted. Only M. urundeuva and Astronium fraxinifolium stem cuttings rooted. Maximum success was obtained for stem cuttings collected and planted in the dry season (23%). Only 13% of M. urundeuva had sprouted by the 15th month of the field experiment. As a result, large cuttings are not recommended for propagation of the studied species. Future studies should include development of suitable methods of root harvesting and prospection of traditional knowledge for species selection.     

Correlation between macrophyte vegetation and some water properties in the irrigation system of the Lower river Po Plane

Abstract

The distribution of macrophytic plant communities, defined by phytosociological numerical methods, in the irrigation system of the Lower river Po Plane was correlated with water characteristich. Water samples were collected periodically within phytocoena well-characterized from the phytosociological viewpoint. Nymphaeid-dominated communities (all. Nymphaeion) usually occur in deeper waters than elodeid- myriophyllid-, and ceratophyllid-dominated vegetation types (all. Potamogetonion). Hydrochemically, all of the studied waterbodies can be classified as rich in electrolytes and in bicarbonates. The distribution of phytocoena reflects a gradient in nutrient content: the Nymphoidetum peltatae characterizes waters moderately rich; the Myriophyllum spicatum community and the Trapetum natantis fairly rich; the Potamogetonetum pectinati and the Ceratophyllum demersum community very rich in nutrients.     

Azione Della Luce Sull'Assorbimento,L'Utilizzazione Ed Il Trasporto Dei Glucidi

Abstract

Effect of light on the uptake, utilization and transport of sugars. — The effect of light on the uptake of saccharides, their incorporation into insoluble fractions and their transport by green tissues has been studied under conditions of complete inhibition of the photosynthetic assimilation of CO₂. Such conditions were obtained by means of either an inhibitor of O₂ evolution (CMU), or by running the experiment in CO₂-free atmosphere. When Wolffia arryza plants are incubated with glucose-C¹⁴, light stimulates the incorporation of C¹⁴ into all fractions examined, and especially into the polysaccharides, like cellulose,' which are synthesized outside the chloroplasts.

Experiments with Elodea canadensis have shown that light stimulates the transport of glucose-C¹⁴ from the leaves to the stems, independently of the presence or absence of CO₂ assimilation.

These experiments support the hypothesis that ATP synthesyzed in the light by chloroplasts can be utilized by green cells as an energy source for biosyntheses outside the plastids, as well as for other types of biological work, such as active uptake and transport.