Compressibility and shell failure in the European Atlantic <Emphasis Type="Italic">Patella</Emphasis> limpets

The specimens of Patella intermedia, Patella rustica, Patella ulyssiponensis and Patella vulgata were analysed for morphological and morphometric characters, and for the resistance to compression and crushing to a force applied at the apex. Shell shape in these species ranged from the high symmetrical cone, with a rounded base of P. rustica, to the flat, asymmetrical, narrow-pear-shaped base of P. ulyssiponensis. P. intermedia and P. vulgata showed intermediate morphologies. Shell thickness increased linearly with age, but differed in the four limpets. P. rustica had the thickest shells, and P. ulyssiponensis and P. vulgata had the thinnest shells. P. intermedia displayed intermediate shell thickness. Considering deformability and toughness, P. intermedia shells usually needed the highest force to compress in height, the highest pressure to collapse, and were appreciably deformed at collapse. On the opposite side, P. ulyssiponensis shells usually needed the lowest force to compress in height, the lowest pressure to collapse, and were much less deformed at collapse. P. intermedia shells were therefore the most deformable and tough, and P. ulyssiponensis, the most stiff and fragile. P. rustica and P. vulgata shells displayed intermediate behaviour. However, numerical simulations based on the finite element method using the experimentally determined shells’ geometry and thickness, but considering similar shells’ material and structure in the four species, predicted that shell toughness should be decreased in the order P. rustica >> P. intermedia > P. vulgata >> P. ulyssiponensis. P. rustica shells’ geometry (a high and centred cone) and thickness (very thick) were therefore, theoretically, the most fitted for shells to resist crushing by compression. Yet, in the experimental tests, they were not the most resistant shells. It was concluded that resistance to crushing was not a direct function of shell morphology and morphometry, but appeared to be mainly determined by shell deformability. This is most probably related to differences in the internal composition and architecture of the shell in the four species. By comparison with data reported in the literature on the pressures normally exerted by ocean waves, it was concluded that these limpets have resistances to crushing in far excess to pressures normally endured in nature, being therefore unlikely that these species are crushed by the action of even very strong waves on shores. Hard objects, like logs and boulders, can be hurled onto the shore by waves, and constitute a much greater threat to limpets than the waves themselves. The high toughness of the limpet shell can be related to resistance to the impact of incidental hard objects. There was no direct relationship between the habit preferences of these limpets and the resistance to crushing. Other factors are involved in the distribution of these species in the shores.     

A review of waste paper recycling networks focusing on quantitative methods and sustainability

Journal of Material Cycles and Waste Management - A discussion is currently under way in the literature on the sustainable benefits of recycling material, particularly paper, which has high global...     

Predator–prey fuzzy model

In this work we have used fuzzy rule-based systems to elaborate a predator–prey type of model to study the interaction between aphids (preys) and ladybugs (predators) in citriculture, where the aphids are considered as transmitter agents of the Citrus Sudden Death (CSD). Simulations were performed and a graph was drawn to show the prey population, the potentiality of the predators, and a phase-plane. From this phase-plane, a classic model of the Holling–Tanner type is fitted and its parameters were found. Finally, we have studied the stability of the critical points of the Holling–Tanner model.     

Do great tits rely on inadvertent social information from blue tits? A habitat selection experiment

Sympatric species sharing requirements are competitors, but recent evidence suggests that heterospecifics may also be used as a source of information. The heterospecific habitat copying hypothesis proposes that individuals of one species might use information inadvertently produced by the breeding performance of individuals of other species to assess habitat quality whenever the two species share needs. In this study, we provide the first experimental test of this hypothesis by examining whether the manipulated reproductive success of blue tits (Cyanistes caeruleus) is used as heterospecific inadvertent social information (ISI) in breeding-habitat selection by sympatric great tits (Parus major). The reproductive success of blue tits was manipulated 1year at the scale of patches by transferring nestlings from decreased to increased patches. No evidence was found of great tits using the reproductive success of blue tits as a source of heterospecific ISI. However, dispersal decisions by adult great tits correlated with information on con- and heterospecific densities, which constitute other sources of ISI. As density and breeding performance are tightly intertwined forms of information, the difficulty in distinguishing between them might lead great tits to use heterospecific ISI more in the form of density than breeding performance when making dispersal decisions.     

Air quality and PM10-associated poly-aromatic hydrocarbons around the railway traffic area: statistical and air mass trajectory approaches

Diesel engine railway traffic causes atmosphere pollution due to the exhaust emission which may be harmful to the passengers as well as workers. In this study, the air quality and PM₁₀ concentrations were evaluated around a railway station in Northeast India where trains are operated with diesel engines. The gaseous pollutant (e.g. SO₂, NO₂, and NH₃) was collected and measured by using ultraviolet–visible spectroscopy. The advanced level characterizations of the PM10 samples were carried out by using ion chromatography, Fourier-transform infrared, X-ray diffraction, inductively coupled plasma optical emission spectrometry , X-ray photoelectron spectroscopy, field-emission scanning electron microscopy with energy-dispersive spectroscopy, and high-resolution transmission electron microscopy with energy-dispersive spectroscopy techniques to know their possible environmental contaminants. High-performance liquid chromatography technique was used to determine the concentration of polycyclic aromatic hydrocarbons to estimate the possible atmospheric pollution level caused by the rail traffic in the enclosure. The average PM₁₀ concentration was found to be 262.11 µg m⁻³ (maximum 24 hour) which indicates poor air quality (AQI category) around the rail traffic. The statistical and air mass trajectory analysis was also done to know their mutual correlation and source apportionment. This study will modify traditional studies where only models are used to simulate the origins.

     

Strong site fidelity and longer internesting interval for solitary nesting olive ridley sea turtles in Brazil

Olive ridley sea turtles display two different types of nesting behavior: in arribada (synchronous mass nesting) or solitarily. Contrarily to arribadas, little has been published about solitary nesters. This study aimed to expand the knowledge on internesting interval and site fidelity of solitary nesting olive ridleys and to test a possible development of arribada nesting behavior. Data were collected in Sergipe (Brazil) over 125 km of beach from 10°30′S/36o23′W to 11°26′S/37o19′W, between nesting seasons 2004/2005 and 2006/2007. From 962 tagged females, 173 were seen renesting. The average internesting interval found was longer (22.35 ± 7.01 days) than previously described, which might relate to lower water temperatures during the internesting period. Olive ridleys at Sergipe showed high nesting site fidelity, with consecutive nesting events occurring in close proximity, non-randomly and dependently of previous events. Most of the consecutive nests were separated by 4.06–5.59 km. Development of arribada nesting behavior was not confirmed.     

Diet of juvenile green turtles (<Emphasis Type="Italic">Chelonia mydas</Emphasis>) associating with artisanal fishing traps in a subtropical estuary in Brazil

The diet of 50 juvenile green turtles Chelonia mydas live-captured incidentally by fixed fishing traps between January and June 2009 in Cananéia Estuarine–Lagoon complex, Brazil, was studied through analysis of esophageal lavage samples. Green turtles consumed an omnivorous diet, with 18 food components identified and grouped into 4 categories as follows: terrestrial plants, algae, invertebrates, and seagrass. Black mangrove leaves were of the greatest importance to diet. Turtles incidentally get into fixed traps probably because these devices are located on mangrove margins, where they forage. The additional foods suggest that green turtles also feed opportunistically on material adhered to the trap structure and/or on items that cross into its interior. Green turtle diet in estuarine environments appears to be determined by the availability of food components, with some selectivity toward items of apparently greater nutritional value.     

Can leftovers from predators be reliably used to monitor marine turtle hatchling sex-ratios? The implications of prey selection by ghost crabs

In marine turtles, the sex of an individual is determined by temperatures experienced during embryonic development. Gonad histological observation is still the only reliable way to determine hatchling sex, hampering the study of reproduction and of the demographic consequences of context-dependent sex-ratios, a subject of interest in a warming planet. We investigated whether hatchling remains from predation by Ocypode cursor can be used to estimate sex-ratio trends in a green turtle rookery at Poilão, Guinea-Bissau (10°52′N, 15°43′W). Sex could be readily determined in 77 and 79% of the predated hatchlings in 2008 and 2009, respectively. By comparing hatchlings killed by crabs, hatchlings accidentally dying on the reefs, and live hatchlings, we show that ghost crabs select the smaller prey, but do not select according to hatchling sex, which is explained by the lack of hatchling size dimorphism in this population. The proportion of male hatchlings was 0.45 ± 0.06 and 0.15 ± 0.06 for early and late-season clutches, respectively, these differences most likely being explained by rainfall. Using leftovers from predation by crabs may be a good solution to non-invasively monitor broad trends in sex-ratios of sea turtles.     

Mortality of large trees and lianas following experimental drought in an Amazon forest

Severe drought episodes such as those associated with El Ni?o Southern Oscillation (ENSO) events influence large areas of tropical forest and may become more frequent in the future. One of the most important forest responses to severe drought is tree mortality, which alters forest structure, composition, carbon content, and flammability, and which varies widely. This study tests the hypothesis that tree mortality increases abruptly during drought episodes when plant-available soil water (PAW) declines below a critical minimum threshold. It also examines the effect of tree size, plant life form (palm, liana, tree) and potential canopy position (understory, midcanopy, overstory) on drought-induced plant mortality. A severe, four-year drought episode was simulated by excluding 60% of incoming throughfall during each wet season using plastic panels installed in the understory of a 1-ha forest treatment plot, while a 1-ha control plot received normal rainfall. After 3.2 years, the treatment resulted in a 38% increase in mortality rates across all stems >2 cm dbh. Mortality rates increased 4.5-fold among large trees (>30 cm dbh) and twofold among medium trees (10-30 cm dbh) in response to the treatment, whereas the smallest stems were less responsive. Recruitment rates did not compensate for the elevated mortality of larger-diameter stems in the treatment plot. Overall, lianas proved more susceptible to drought-induced mortality than trees or palms, and potential overstory tree species were more vulnerable than midcanopy and understory species. Large stems contributed to 90% of the pretreatment live aboveground biomass in both plots. Large-tree mortality resulting from the treatment generated 3.4 times more dead biomass than the control plot. The dramatic mortality response suggests significant, adverse impacts on the global carbon cycle if climatic changes follow current trends.     

Bioconcentration of trichlorfon insecticide in pacu (Piaractus mesopotamicus)

Pacu (Piaractus mesopotamicus) is one of the most representative fish species of Brazilian fish culture, produced in most Brazilian States due to its importance for food diet and sport fishery. This research work investigated the bioconcentration of trichlorfon [phosphonic acid, (2,2,2-trichloro-1-hydroxyethyl)-dimethyl ester] insecticide in pacu under fish ponds culture conditions and a first-order kinetic insecticide dissipation in the water. Trichlorfon was applied at a rate of 4.62 x 10(4) mg to each of three nurseries containing 4.2 x 10(5)l of water. The fish ponds were built on the soil and supported 60 young pacus fishes. The concentrations of trichlorfon fitted to an equivalent non-linear kinetic type model, allows estimate the values of trichlorfon concentration in the water and fishes. These estimations together with the bioconcentration factor determined in the fishes, allowed establishing theoretical reference limit values for human consumption of fishes produced under cultivation systems with trichlorfon. This information will contribute to enlarge the database on pesticide use in Brazilian commercial fish farming, especially about the use of trichlorfon as chemotherapy for the control of fish ectoparasites.