210Po concentration in Perna perna mussels: looking for radiation effects

Twenty ropes with 400 Perna perna mussels seeds (3 cm shell size) were set-up on floating structures at Cabo Frio Island, Arraial do Cabo, approximately 100 km northeast of Rio de Janeiro city. A rope was taken out on a monthly basis, and the shell sizes of 100 seeds were measured. The haemolymph of 10 male and 10 female individuals was taken, and the same individuals were separated for 210Po/210Pb determination. After one year of monthly sampling, no clear correlation was observed between the 210Po concentration, mussel's age and weight. A mean 210Po concentration of 155 Bq kg(-1) wet weight basis, was obtained, which is comparable with data reported in the literature. The radiation dose did not have any observable effect on the micronuclei frequency and DNA breaks in the mussels. This was probably due to the low dose rate, 0.02 mGy d(-1), in comparison with the suggested potential dose limit of 10 mGy d(-1).     

Sexual segregation in timing of foraging by imperial shags (Phalacrocorax atriceps): is it always ladies first?

The time seabirds have to forage is restricted while breeding, as time at sea must be balanced against the need to take turns with the partner protecting the nest site or offspring, and timing constraints change once the breeding season is over. Combined geolocator-immersion devices were deployed on eleven Imperial Shags (four males and seven females) in Argentina (43°04′S; 64°2′W) in November 2006 and recovered in November 2007. During the breeding season, females foraged throughout the morning, males exclusively in the afternoon, and variability between individuals was low. Outside the breeding season, both sexes foraged throughout the day, and variability between individuals was high. Timing differences may be explained by higher constraints on foraging or greater demands of parental duties experienced by the smaller sex, females in this case. Sexual differences in reproductive role, feeding habits or proficiency can also lead to segregation in timing of foraging, particularly while breeding.     

Drawing the baseline of trace element levels in the vulnerable Mediterranean osprey Pandion haliaetus: variations by breeding location,habitats, and egg components

Environmental Science and Pollution Research - Due to its peculiarity to accumulate environmental contaminants, the osprey Pandion haliaetus is a sentinel species for the biomonitoring of...     

Oceanographic and biological landscapes used by the Southern Giant Petrel during the breeding season at the Patagonian Shelf

The study of how and why marine animals distribute themselves at sea has important conservation and management implications of the species and their habitats. We characterize the oceanographic and biological landscapes of the marine areas used by breeding Southern Giant Petrels (Macronectes giganteus) at Patagonian colonies and explore inter-sexual and inter-colony differences. The at-sea movements of 16 adults (7 males and 9 females) were studied by means of satellite telemetry techniques during 1999, 2000, 2002, and 2004 breeding seasons. Southern Giant Petrels utilized an oceanographic scenario characterized by high productivity, warm sea surface temperature, and shallow waters. The biological landscape was characterized by a high availability of squid and carrion nearby colonies. Females spent more time in the shelf break and exploited deeper waters than males. In contrast, males spent more time in coastal areas and they showed a higher spatial overlap with areas of high squid density than females. Such a prosperous foraging scenario for both sexes may play a key role in the growth of the breeding population of Southern Giant Petrel Patagonian colonies.     

Do national levels of individualism and internal locus of control relate to well‐being: an ecological level international study

Data were collected from managers in 24 nations/territories on work locus of control (LOC), individualism–collectivism (I–C), and well‐being (job satisfaction, absence of psychological strain, and absence of physical strain). There were significant mean differences across samples on all five of these measures, and consistent with our hypothesis, at the ecological or sample mean level well‐being was associated with an internal locus of control. However, contrary to our hypothesis, well‐being was not associated with I–C, despite a strong correlation between I–C and LOC. Findings at the ecological level were consistent with the literature concerning the salutary effects of control on well‐being. Copyright © 2001 John Wiley & Sons, Ltd.     

Sensitized photooxygenation of the fungicide furalaxyl

BACKGROUND: The photolysis of pesticides is of high current interest since light is one of the most important abiotic factors which are responsible for the environmental fate of these substances and may induce their conversion into noxious products. The action of light can also be mediated by oxygen and synthetic or naturally occurring substances which act as sensitizers. Our objective in this study was to investigate the photochemical behaviour of the systemic fungicide furalaxyl in the presence of oxygen and various sensitizers, and to compare the toxicity of the main photoproduct(s) to that of the parent compound. Previous reports on the direct photolysis of the pesticide demonstrated a very slow degradation and the only identified photoproducts were N-2,6-xylyl-D,L-alaninare and 2,6-dimethylaniline. METHODS: Solutions of furalaxyl in CH3CN were photooxygenate using a 500W high-pressure mercury lamp (through a Pyrex glass filter, lambda>300 nm) or a 650W halogen lamp or sunlight and the proper sensitizer. When sunlight was used, aqueous solutions were employed. The photodegradation was checked by NMR and/or GC-MS. The photoproducts were spectroscopically evidenced and, when possible, isolated chromatographically. Acute toxicity tests were performed on the rotifer Brachionus calyciflorus, the crustacean cladoceran Daphnia magna and the anostracan Thamnocephalus platyurus, while chronic toxicity tests (sublethal endpoints) comprised a producer, the alga Pseudokirchneriella subcapitata and the crustacean Ceriodaphnia dubia, as a consumer. RESULTS AND DISCUSSION: In the presence of both oxygen and sensitizer, furalaxyl underwent rapid photochemical transformations mainly to N-disubstituted formamide, maleic anhydride and a 2(5H)-furanone derivative. The formation of these products was rationalized in terms of a furan endoperoxide intermediate derived from the reaction of furalaxyl with active dioxygenated species (singlet oxygen, superoxide anion or ground state oxygen). The 2(5H)-furanone exhibited a higher toxicity than the parent compound. CONCLUSION: This work reports the first data on the photosensitized oxygenation of furalaxyl with evidence of the high tendency of the pesticide to undergo photodegradation under these conditions leading, among other things, to a 2(5H)-furanone, which is more toxic than the starting furalaxyl towards aquatic organisms. RECOMMENDATIONS AND OUTLOOK: Investigation highlights that the photolytic fate of a pesticide, although quite stable to direct photoreaction due to its low absorption of solar radiation at ground level, can be significantly influenced in the environment by the presence of substances with energy or electron-transfer properties as natural dyes, e.g. chlorophyll, or synthetic pollutants, e.g. polycyclic aromatic hydrocarbons (PAH).     

Short-term effects of environmental factors on the asexual reproduction of Aurelia sp. polyps

ABSTRACT

Aurelia is a jellyfish genus common in coastal and estuarine habitats, that are typically affected by human pressures such as heavy metals contamination. Mercury is one of the most dangerous due to its high toxicity, persistence and bioaccumulation. In this paper, we tested for the first time the independent and combined effects of a level of mercury allowable by European regulation in force and hyposalinity on the asexual reproduction of Aurelia sp. polyps, mirroring a realistic scenario. Both mercury (0.07?µg/L, Maximum Allowable Concentration) and salinity (18 and 23 PSU) and the combination of the two factors stimulated the asexual reproduction increasing the number of polyps and buds during the 41 days of experiments. The increment of the asexual reproduction and the absence of suffering and mortality suggest that levels of mercury below the concentration fixed by the law and hyposalinity conditions could promote jellyfish proliferations, according to the hormesis hypothesis.     

Vibrational communication between hitchhikers and foragers in leaf-cutting ants (Atta cephalotes)

Abstract In a foraging column of the leaf-cutting ant Atta cephalotes, minim workers (the smallest worker subcaste) hitchhike on leaf fragments carried by larger workers. It has been demonstrated that they defend leaf carriers against parasitic phorid flies. The present study examines the cues used by the potential hitchhikers to locate leaf carriers. As recently reported, foraging workers stridulate while cutting a leaf fragment, and the stridulatory vibrations serve as closerange recruitment signals. We tested the hypothesis that these plant-borne stridulatory vibrations are used by the potential hitchhikers to locate workers engaged in cutting. Three different lines of evidence support this view. Firstly, the repetition rate of the stridulations produced by foraging workers increases significantly as foragers maneuver the leaf fragment into the carrying position and walk loaded to the nest. This is the moment when hitchhikers usually climb on the leaf. Although the leaf-borne stridulatory vibrations are considerably attenuated when transmitted through the workers' legs, they can nevertheless be detected at short distances by minims. This subcaste is several times more sensitive to substrate-borne vibrations than larger workers. Secondly, when a stridulating and a silent leaf were simultaneously presented at the foraging site, minim workers spent significantly more time on the stridulating than on the silent leaf. Thirdly, hitchhiking was more frequent in leaf carriers which cut fragments out of the stridulating leaf than in those cutting the silent leaf.Abstract In a foraging column of the leaf-cutting ant Atta cephalotes, minim workers (the smallest worker subcaste) hitchhike on leaf fragments carried by larger workers. It has been demonstrated that they defend leaf carriers against parasitic phorid flies. The present study examines the cues used by the potential hitchhikers to locate leaf carriers. As recently reported, foraging workers stridulate while cutting a leaf fragment, and the stridulatory vibrations serve as closerange recruitment signals. We tested the hypothesis that these plant-borne stridulatory vibrations are used by the potential hitchhikers to locate workers engaged in cutting. Three different lines of evidence support this view. Firstly, the repetition rate of the stridulations produced by foraging workers increases significantly as foragers maneuver the leaf fragment into the carrying position and walk loaded to the nest. This is the moment when hitchhikers usually climb on the leaf. Although the leaf-borne stridulatory vibrations are considerably attenuated when transmitted through the workers' legs, they can nevertheless be detected at short distances by minims. This subcaste is several times more sensitive to substrate-borne vibrations than larger workers. Secondly, when a stridulating and a silent leaf were simultaneously presented at the foraging site, minim workers spent significantly more time on the stridulating than on the silent leaf. Thirdly, hitchhiking was more frequent in leaf carriers which cut fragments out of the stridulating leaf than in those cutting the silent leaf.Communicated by P. Pamilo     

Energy expenditure and food consumption of foraging Imperial cormorants in Patagonia, Argentina

Energy management during the breeding season is crucial for central place foragers since parents need to feed themselves and their offspring while being spatially and temporally constrained. In this work, we used overall dynamic body acceleration as a measure of activity and also to allude to the foraging energy expenditure of breeding Imperial cormorants Phalacrocorax atriceps. We also analyzed how changes in the time or energy allocated to different activities affected the foraging trip energy expenditure and estimated the daily food requirements of the species. Birds spent 42 % of the total energy flying to and from the feeding areas and 16 % floating at sea. The level of activity underwater was almost 1.5 times higher for females than for males. The most expensive diving phase in terms of rate of energy expenditure was descending though the water column. The total foraging trip energy expenditure was particularly sensitive to variation in the amount of time spent flying. During the breeding season, adult cormorants breeding along the Patagonian coast would consume approximately 10,000 tons of food.