Feeding ecology of the Common Tern Sterna hirundo in a wintering area in southern Brazil

The wintering diet of Common Terns Sterna hirundo was studied by using 714 pellets collected on roosting sites at the mouth of the Lagoa dos Patos and on adjacent coastal beaches, in Rio Grande do Sul, southern Brazil, from March 1999 to February 2000. A total of 12 340 individual prey items of 35 different food types was found. Fish was the most important food type in the diet, constituting 32% by number and 93% by mass. Insects contributed 67% by number but only 3% by mass. The main food types were sciaenid fishes Paralonchurus brasiliensis, Micropogonias furnieri, Cynoscion guatucupa and Macrodon ancylodon. Several of these are important commercial species; fisheries potentially impact food availability to the terns, and terns may contribute significantly to the natural mortality of these fishes. Clupeiform fishes, the urophycid fish Urophycis brasiliensis and flying ants (Camponotus sp.) were also important. Species composition of the diet (food types), both by number and by mass, differed significantly between months. Prey sizes ranged in length from 12.7 mm to 217.4 mm. The average estimated total length of fish taken was 77.7 mm, but the mean differed significantly among prey species. The importance of demersal sciaenids to the diet of the Common Tern, a surface predator, may be explained by their association with aquatic predators, especially adult Bluefish Pomatomus saltatrix and Striped Weakfish Cynoscion guatucupa, and the Franciscana Dolphin Pontoporia blainvillei, which drive these fish to the surface. The occurrence of flying ants in the diet was related to offshore winds, which carried these insects out to sea. The occasional high availability of insects possibly changed the cost/benefit relationship of several food types, causing diet changes. The high number of prey species, the temporal variations in the composition of the diet and the wide range of prey sizes are evidence of the high dietary plasticity of the Common Tern, at wintering areas in southern Brazil.     

Organic acid profile of isovaleric acidemia: a comprehensive metabolomics approach

Isovaleric acidemia (IVA, MIM 248600) can be a severe and potentially life-threatening disease in affected neonates, but with a positive prognosis on treatment for some phenotypes. This study presents the first application of metabolomics to evaluate the metabolite profiles derived from urine samples of untreated and treated IVA patients as well as of obligate heterozygotes. All IVA patients carried the same homozygous c.367 G > A nucleotide change in exon 4 of the IVD gene but manifested phenotypic diversity. Concurrent class analysis (CONCA) was used to compare all the metabolites from the original complete data set obtained from the three case and two control groups used in this investigation. This application of CONCA has not been reported previously, and is used here to compare four different modes of scaling of all metabolites. The variables important in discrimination from the CONCA thus enabled the recognition of different metabolic patterns encapsulated within the data sets that would not have been revealed by using only one mode of scaling. Application of multivariate and univariate analyses disclosed 11 important metabolites that distinguished untreated IVA from controls. These included well-established diagnostic biomarkers of IVA, endogenous detoxification markers, and 3-hydroxycaproic acid, an indicator of ketosis, but not reported previously for this disease. Nine metabolites were identified that reflected the effect of treatment of IVA. They included detoxification products and indicators related to the high carbohydrate and low protein diet which formed the hallmark of the treatment. This investigation also provides the first comparative metabolite profile for heterozygotes of this inherited metabolic disorder. The detection of informative metabolites in even very low concentrations in all three experimental groups highlights the potential advantage of the holistic mode of analysis of inherited metabolic diseases in a metabolomics investigation.     

Disclosure of a putative biosignature for respiratory chain disorders through a metabolomics approach

The diagnosis of respiratory chain deficiencies (RCDs) is complicated and the need for a diagnostic biomarker or biosignature has been widely expressed. In this study, the metabolic profile of a selected group of 29 RCD patients, with a predominantly muscle disease phenotype, and 22 controls were investigated using targeted and untargeted analyses of three sub-sections of the human metabolome, including urinary organic acids and amino acids [measured by gas chromatography–mass spectrometry (GC–MS)], as well as acylcarnitines (measured by electrospray ionization tandem MS). Although MS technologies are highly sensitive and selective, they are restrictive by being applied only to sub-sections of the metabolome; an untargeted nuclear magnetic resonance (NMR) spectroscopy approach was therefore also included. After data reduction and pre-treatment, a biosignature comprising six organic acids (lactic, succinic, 2-hydroxyglutaric, 3-hydroxyisobutyric, 3-hydroxyisovaleric and 3-hydroxy-3-methylglutaric acids), six amino acids (alanine, glycine, glutamic acid, serine, tyrosine and α-aminoadipic acid) and creatine, was constructed from uni- and multivariate statistical analyses and verified by cross-validation. The results presented here provide the first proof-of-concept that the metabolomics approach is capable of defining a biosignature for RCDs. We postulate that the composite of organic acids ≈ amino acids > creatine > betaine > carnitines represents the basic biosignature for RCDs. Validated through a prospective study, this could offer an improved ability to assign individual patients to a group with defined RCD characteristics and improve case selection for biopsy procedures, especially in infants and children.     

A laboratory approach for characterizing chronic fatigue: what does metabolomics tell us?

Metabolomics - Pre-eclampsia is a hypertensive gestational disorder that affects approximately 5% of all pregnancies. As the pathophysiological processes of pre-eclampsia are still uncertain, the...     

Expansion of mass-flowering crops leads to transient pollinator dilution and reduced wild plant pollination

Agricultural land use results in direct biodiversity decline through loss of natural habitat, but may also cause indirect cross-habitat effects on conservation areas. We conducted three landscape-scale field studies on 67 sites to test the hypothesis that mass flowering of oilseed rape (Brassica napus) results in a transient dilution of bees in crop fields, and in increased competition between crop plants and grassland plants for pollinators. Abundances of bumble-bees, which are the main pollinators of the grassland plant Primula veris, but also pollinate oilseed rape (OSR), decreased with increasing amount of OSR. This landscape-scale dilution affected bumble-bee abundances strongly in OSR fields and marginally in grasslands, where bumble-bee abundances were generally low at the time of Primula flowering. Seed set of Primula veris, which flowers during OSR bloom, was reduced by 20 per cent when the amount of OSR within 1 km radius increased from 0 to 15 per cent. Hence, the current expansion of bee-attractive biofuel crops results in transient dilution of crop pollinators, which means an increased competition for pollinators between crops and wild plants. In conclusion, mass-flowering crops potentially threaten fitness of concurrently flowering wild plants in conservation areas, despite the fact that, in the long run, mass-flowering crops can enhance abundances of generalist pollinators and their pollination service.     

Less input same output: simplified approach for population size assessment in Lepidoptera

With the aim of creating a simplified sampling scheme that would retain the accuracy of standard mark–release–recapture (MRR) sampling, but at a greatly reduced cost, we analysed 23 capture–recapture data sets from spatially closed populations of six Lepidoptera species according to the constrained Cormack–Jolly–Seber models. Subsequently the relationships between the estimates of population parameters were investigated in order to develop a regression equation that would enable us to calculate seasonal population size without sampling the population throughout the entire flight period. The proportion of individuals flying at peak population was highly variable (CV=0.39), but the variation decreased considerably (CV=0.14) after different life span and flight period length were accounted for. Over 90% of the variance of this proportion was explained by the life span:flight period length ratio. Simulations of hypothetical sampling schemes proved that schemes covering the second and third quarter of the flight period performed much better than those restricted to the second quarter only. The accuracy of seasonal population size estimated with the regression equation developed was comparable for intensive schemes (daily sampling) and non-intensive ones (sampling once in 2 or 3 days). We propose a simplified method of surveying butterfly populations that should be based on checking the presence of flying adults at the beginning and end of the flight period to assess its length, and MRR sampling covering its middle part, with intervals between capture days corresponding to the average life span of investigated butterflies.     

Mixed biodiversity benefits of agri-environment schemes in five European countries

Agri-environment schemes are an increasingly important tool for the maintenance and restoration of farmland biodiversity in Europe but their ecological effects are poorly known. Scheme design is partly based on non-ecological considerations and poses important restrictions on evaluation studies. We describe a robust approach to evaluate agri-environment schemes and use it to evaluate the biodiversity effects of agri-environment schemes in five European countries. We compared species density of vascular plants, birds, bees, grasshoppers and crickets, and spiders on 202 paired fields, one with an agri-environment scheme, the other conventionally managed. In all countries, agri-environment schemes had marginal to moderately positive effects on biodiversity. However, uncommon species benefited in only two of five countries and species listed in Red Data Books rarely benefited from agri-environment schemes. Scheme objectives may need to differentiate between biodiversity of common species that can be enhanced with relatively simple modifications in farming practices and diversity or abundance of endangered species which require more elaborate conservation measures.