Do Red Knots (Calidris Canutus Islandica) routinely skip Iceland during southward migration?

Subspecies Calidris canutus islandica of the Red Knot breeds on the arctic tundra of northeastern Canada and northern Greenland and winters along the coasts of northwestern Europe. During northward migration, it stops over in either Iceland or northern Norway. It has been assumed that it does the same during southward migration. Using ratios of stable carbon isotopes (&delta; 13 C) in whole blood, blood cells, and plasma, we investigated evidence for a stopover in Iceland en route from the breeding grounds to the Dutch Wadden Sea. With the expected diet (shellfish) and stopover duration at Iceland (12-15 days, maximum 17 days) and the turnover rates of blood cells (15.1 days) and plasma (6.0 days), Red Knots that stopped in Iceland should arrive with a blood (cell) &delta; 13 C midway between a tundra (-24.7[per thousand]) and a marine value (-14.0[per thousand]) and a plasma &delta;13 C approaching the marine value (-15.3[per thousand]). However, many adults arriving at the Wadden Sea had &delta;13 C ratios in blood (cells) and plasma below these levels, and some arrived with clear tundra signals in blood cells, suggesting that they skipped Iceland during southward migration. Surprisingly, available data suggest this also to be true for juveniles during their first southward migration. The &delta; 13 C signature of second-year birds confirmed that they oversummered in the Wadden Sea. Our findings contradict the largely untested idea that juvenile shorebirds make more stopovers than adults as well as the idea that the migration between the Nearctic and Europe is necessarily a two-leg process. <br /

Mapping Agricultural Biodiversity:Legacy data and tensions between ways of seeing fields

Mapping is a core approach used to investigate and display spatial dynamics of biological diversity and habitats. In the Netherlands, agricultural lands occupy nearly two-thirds of the land surface and provide the greatest potential for habitat restoration; particularly in grassland-based dairy production systems, which comprise the largest share of these agricultural lands. When a crop rotation is applied to a long-term grassland, the resulting disruption of ecological complexity requires years–if not decades–to restore, even after reconversion. The availability of high-quality land-use data for measuring the spatio-temporal distribution of grassland legacies is thus essential for monitoring the dynamics of biodiversity in production grasslands. In this study, we reflect on the Basic Crop Registration (BRP) of the Netherlands, an open spatial data infrastructure developed for parcel-level crop registration and examine how it shapes our spatio-temporal understanding of land use. The BRP serves as an administrative basis for numerous national and local-level regulatory and financial arrangements, mainly aimed at agricultural actors. In this study, we repurposed BRP data to introduce a new perspective on depicting the stability of grasslands in a high-intensity agricultural region. We used this data to map the frequency of grassland-to-cropland conversions using 17 years of longitudinal crop records in southwest Friesland, Netherlands. The legacy effects of grassland-to-cropland conversion were investigated in a field study, where significant differences were found between new and long-term grasslands in plant community composition, soil organic matter content, bulk density, soil penetration resistance, and pH. In our analysis of BRP data, we discovered a significant number of grasslands that were recently converted from cropland but that were recorded as long-term grasslands. This affected approximately 12% of the study area from 2005–2021, which prevents the accurate tracking of grassland stability over time. This misclassification also adds uncertainty to the temporal context of the decline in grassland-dependent species in the region. However, using a spatially-explicit mapping approach, these misclassifications can be corrected and help produce an effective measure of grassland stability with potential as an agroecosystem monitoring tool for researchers, land-use planners, and policymakers

Unusual patterns in 15N blood values after a diet switch in red knot shorebirds

When a diet switch results in a change in dietary isotopic values, isotope ratios of the consumer's tissues will change until a new equilibrium is reached. This change is generally best described by an exponential decay curve. Indeed, after a diet switch in captive red knot shorebirds (Calidris canutus islandica), the depletion of 13C in both blood cells and plasma followed an exponential decay curve. Surprisingly, the diet switch with a dietary 15N/14N ratio (δ15N) change from 11.4 to 8.8 ‰ had little effect on δ15N in the same tissues. The diet-plasma and diet-cellular discrimination factors of 15N with the initial diet were very low (0.5 and 0.2 ‰, respectively). δ15N in blood cells and plasma decreased linearly with increasing body mass, explaining about 40 % of the variation in δ15N. δ15N in plasma also decreased with increasing body-mass change (r 2=.07). This suggests that the unusual variation in δ15N with time after the diet switch was due to interferences with simultaneous changes in body-protein turnover.

Rat bite fever in a total knee arthroplasty:an unusual case of periprosthetic joint infection

BACKGROUND: Periprosthetic joint infection (PJI) is a serious complication of orthopedic arthroplasty surgery. Rat bite fever is a rare infection with Streptobacillus moniliformis (S. moniliformis). Rat bite fever can lead to serious complications such as pyogenic infection of joints, bacteremia, endocarditis and even death. We hereby present the first case of a patient with a total knee arthroplasty, infected with S. moniliformis, successfully treated by surgical debridement, antibiotics and implant retention (DAIR). CASE PRESENTATION: The patient was a 64-year-old female. S. moniliformis was isolated from blood cultures and an aspirate of the left knee by 16S rRNA gene polymerase chain reaction technique. It was assumed that the S. moniliformis had a systemic origin and secondarily infected the knee due to fever nine days before the onset of symptoms of the knee. The patient was successfully managed with DAIR and intravenous administration of ceftriaxone for six weeks and oral doxycycline for another six weeks. CONCLUSIONS: S. moniliformis is a rare pathogen and is difficult to culture. The 16S rRNA sequencing is helpful in the determination of a causative microorganism in the case of a culture-negative PJI. A DAIR procedure in combination with 12 weeks of antibiotics could successfully treat S. moniliformis prosthetic joint infection

Shellfish Dredging Pushes a Flexible Avian Top Predator out of a Marine Protected Area

There is a widespread concern about the direct and indirect effects of industrial fisheries; this concern is particularly pertinent for so-called “marine protected areas” (MPAs), which should be safeguarded by national and international law. The intertidal flats of the Dutch Wadden Sea are a State Nature Monument and are protected under the Ramsar convention and the European Union's Habitat and Birds Directives. Until 2004, the Dutch government granted permission for ~75% of the intertidal flats to be exploited by mechanical dredgers for edible cockles (Cerastoderma edule). Here we show that dredged areas belonged to the limited area of intertidal flats that were of sufficient quality for red knots (Calidris canutus islandica), a long-distance migrant molluscivore specialist, to feed. Dredging led to relatively lower settlement rates of cockles and also reduced their quality (ratio of flesh to shell). From 1998 to 2002, red knots increased gizzard mass to compensate for a gradual loss in shellfish quality, but this compensation was not sufficient and led to decreases in local survival. Therefore, the gradual destruction of the necessary intertidal resources explains both the loss of red knots from the Dutch Wadden Sea and the decline of the European wintering population. This study shows that MPAs that do not provide adequate protection from fishing may fail in their conservation objectives