High daily energy expenditure of incubating shorebirds on High Arctic tundra: a circumpolar study

1. Given the allometric scaling of thermoregulatory capacity in birds, and the cold and exposed Arctic environment, it was predicted that Arctic-breeding shorebirds should incur high costs during incubation. Using doubly labelled water (DLW), daily energy expenditure (DEE) during incubation was measured in eight shorebird species weighing between 29 and 142 g at various sites in the Eurasian and Canadian High Arctic. The results are compared with a compilation of similar data for birds at lower latitudes. 2. There was a significant positive correlation between species average DEE and body mass (DEE (kJ day−1) = 28·12 BM (g)^0·524, r^2 = 0·90). The slopes of the allometric regression lines for DEE on body mass of tundra-breeding birds and lower latitude species (a sample mostly of passerines but including several shorebirds) are similar (0·548 vs 0·545). DEE is about 50% higher in birds on the tundra than in temperate breeding areas. 3. Data for radiomarked Red Knots for which the time budgets during DLW measurements were known, indicated that foraging away from the nest on open tundra is almost twice as costly as incubating a four-egg clutch. 4. During the incubation phase in the High Arctic, tundra-breeding shorebirds appear to incur among the highest DEE levels of any time of the year. The rates of energy expenditure measured here are among the highest reported in the literature so far, reaching inferred ceilings of sustainable energy turnover rates.

Eggs in the Freezer: Energetic Consequences of Nest Site and Nest Design in Arctic Breeding Shorebirds

Birds construct nests for several reasons. For species that breed in the Arctic, the insulative properties of nests are very important. Incubation is costly there and due to an increasing surface to volume ratio, more so in smaller species. Small species are therefore more likely to place their nests in thermally favourable microhabitats and/or to invest more in nest insulation than large species. To test this hypothesis, we examined characteristics of nests of six Arctic breeding shorebird species. All species chose thermally favourable nesting sites in a higher proportion than expected on the basis of habitat availability. Site choice did not differ between species. Depth to frozen ground, measured near the nests, decreased in the course of the season at similar non-species-specific speeds, but this depth increased with species size. Nest cup depth and nest scrape depth (nest cup without the lining) were unrelated to body mass (we applied an exponent of 0.73, to account for metabolic activity of the differently sized species). Cup depth divided by diameter2 was used as a measure of nest cup shape. Small species had narrow and deep nests, while large species had wide shallow nests. The thickness of nest lining varied between 0.1 cm and 7.6 cm, and decreased significantly with body mass. We reconstruct the combined effect of different nest properties on the egg cooling coefficient using previously published quantitative relationships. The predicted effect of nest cup depth and lining depth on heat loss to the frozen ground did not correlate with body mass, but the sheltering effect of nest cup diameter against wind and the effects of lining material on the cooling coefficient increased with body mass. Our results suggest that small arctic shorebirds invest more in the insulation of their nests than large species

Tussenrapportage onderzoek Effecten van garnalenvisserij - onderdeel bijvangst

In juni 2012 is gestart met een uitgebreid onderzoek naar de bijvangsten in de garnalenvisserij. Dit onderzoek is onderdeel van een groter project, een studie naar de effecten van de garnalen visserij in Natura 2000 gebieden. IMARES voert dit project uit in opdracht van het ministerie van EZ en de sector. De resultaten moeten onder andere toeleveren aan de passende beoordeling die in 2013 zal worden uitgevoerd voor de vernieuwing van de vergunning voor de garnalenvisserij in 2014. Onderliggende rapportage beschrijft de resultaten van het eerste halfjaar van het onderzoek naar de bijvangsten

Herziening spieringadvisering

Het huidige spieringprotocol voor de openstelling van de visserij op spiering in het IJsselmeer en Markermeer-IJmeer dateert uit 1997 en is herzien in 2007. Het ministerie van LNV heeft aan WMR gevraagd om een advies over de herziening van het huidige afwegingskader (protocol). In 2013 is ook geprobeerd het protocol aan te passen, waarbij is geadviseerd om dit te doen door middel van een ecosysteemmodel (Osmose). Het model bleek niet uitvoerbaar omdat niet alle hiervoor benodigde gegevens en kennis aanwezig was. Om die reden is er nu een meer pragmatische en eenvoudiger aanpak toegepast

Biomonitoring of dairy farm emitted ammonia in surface waters using phytoplankton and periphyton

Environmental Biolog

Effecten van garnalenvisserij in Natura 2000 gebieden

De garnalenvisserij is economisch en in aantallen schepen één van de belangrijkste visserijen in Nederland en opereert vooral binnen Natura 2000 gebieden. Voor zowel de Noordzeekustzone als de Waddenzee is er binnen de Natura 2000 wetgeving een verbeterdoelstelling geformuleerd voor Habitattype 1110 (permanent overstroomde zandbanken). Het effect van het garnalentuig op het ecosysteem is echter niet goed bekend. Om in dit kennishiaat te voorzien, is er in de periode 2012-2014 onderzoek uitgevoerd naar een aantal aspecten van de mogelijke effecten van de garnalenvisserij. Enerzijds is de bijvangst in kaart gebracht, anderzijds is experimenteel onderzoek verricht naar de korte termijneffecten van het garnalentuig op de bodemfauna

A circumpolar study unveils a positive non-linear effect oftemperature on arctic arthropod availability that may reduce therisk of warming-induced trophic mismatch for breeding shorebirds

Seasonally abundant arthropods are a crucial food source for many migratorybirds that breed in the Arctic. In cold environments, the growth and emergence ofarthropods are particularly tied to temperature. Thus, the phenology of arthropodsis anticipated to undergo a rapid change in response to a warming climate, potentiallyleading to a trophic mismatch between migratory insectivorous birds and their prey.Using data from 19 sites spanning a wide temperature gradient from the Subarcticto the High Arctic, we investigated the effects of temperature on the phenology andbiomass of arthropods available to shorebirds during their short breeding seasonat high latitudes. We hypothesized that prolonged exposure to warmer summertemperatures would generate earlier peaks in arthropod biomass, as well as higherpeak and seasonal biomass. Across the temperature gradient encompassed by ourstudy sites (>10°C in average summer temperatures), we found a 3-day shift inaverage peak date for every increment of 80 cumulative thawing degree-days.Interestingly, we found a linear relationship between temperature and arthropodbiomass only below temperature thresholds. Higher temperatures were associatedwith higher peak and seasonal biomass below 106 and 177 cumulative thawingdegree-days, respectively, between June 5 and July 15. Beyond these thresholds,no relationship was observed between temperature and arthropod biomass. Ourresults suggest that prolonged exposure to elevated temperatures can positivelyinfluence prey availability for some arctic birds. This positive effect could, in part,stem from changes in arthropod assemblages and may reduce the risk of trophicmismatch. Sarctic arthropods, arctic breeding shorebirds, climate warming, insectivorous birds,invertebrate biomass, phenology, trophic mismatcpublishedVersio

Uncertainty-aware estimation of population abundance using machine learning

Machine Learning is widely used for mining collections, such as images, sounds, or texts, by classifying their elements into categories. Automatic classification based on supervised learning requires groundtruth datasets for modeling the elements to classify, and for testing the quality of the classification. Because collecting groundtruth is tedious, a method for estimating the potential errors in large datasets based on limited groundtruth is needed. We propose a method that improves classification quality by using limited groundtruth data to extrapolate the po-tential errors in larger datasets. It significantly improves the counting of elements per class. We further propose visualization designs for understanding and evaluating the classification un-certainty. They support end-users in considering the impact of potential misclassifications for interpreting the classification output. This work was developed to address the needs of ecologists studying fish population abundance using computer vision, but generalizes to a larger range of applications. Our method is largely applicable for a variety of Machine Learning technologies, and our visualizations further support their transfer to end-users

A Quorum Sensing Regulated Small Volatile Molecule Reduces Acute Virulence and Promotes Chronic Infection Phenotypes

A significant number of environmental microorganisms can cause serious, even fatal, acute and chronic infections in humans. The severity and outcome of each type of infection depends on the expression of specific bacterial phenotypes controlled by complex regulatory networks that sense and respond to the host environment. Although bacterial signals that contribute to a successful acute infection have been identified in a number of pathogens, the signals that mediate the onset and establishment of chronic infections have yet to be discovered. We identified a volatile, low molecular weight molecule, 2-amino acetophenone (2-AA), produced by the opportunistic human pathogen Pseudomonas aeruginosa that reduces bacterial virulence in vivo in flies and in an acute mouse infection model. 2-AA modulates the activity of the virulence regulator MvfR (multiple virulence factor regulator) via a negative feedback loop and it promotes the emergence of P. aeruginosa phenotypes that likely promote chronic lung infections, including accumulation of lasR mutants, long-term survival at stationary phase, and persistence in a Drosophila infection model. We report for the first time the existence of a quorum sensing (QS) regulated volatile molecule that induces bistability phenotype by stochastically silencing acute virulence functions in P. aeruginosa. We propose that 2-AA mediates changes in a subpopulation of cells that facilitate the exploitation of dynamic host environments and promote gene expression changes that favor chronic infections