Photo-identification, site fidelity, and movement of female gray seals (Halichoerus grypus) between haul-outs in the Baltic Sea

The growing gray seal population in the Baltic Sea has led to increased conflicts with fisheries. Despite limited data on gray seal ecology, management measures, such as culling, have been implemented recently. We studied movements and site fidelity of Baltic gray seals using mark-recapture analysis based on photographic identification of individuals (photo-id). Seals were photographed at the major summer haul-out sites. Profile photographs of the head and neck were matched using purpose-written software to generate a database of capture histories from 1995-2000. The haul-outs were grouped into seven areas. Darroch's method (20) for a two-sample capture-recapture census was adapted to estimate rates of movement between the areas. The majority of seals were estimated to remain within the same area, suggesting that Baltic gray seals exhibit a high degree of site fidelity during the summer, and that fidelity to a site lasts for more than one season.     

A new laboratory rig for evaluating helmets subject to oblique impacts

Current requirements and regulations governing motorcycle helmets around the world are based on test results of purely radial impacts, which are statistically rare in real accidents. This study presents a new impact rig for subjecting test helmets to oblique impacts, which therefore is able to test impacts of increased statistical relevance to real motorcycle accidents. A number of different head-helmet interfaces have been investigated. A test rig was constructed to produce oblique impacts to helmets simulating those occurring in real motorcycle accidents. A Hybrid III dummy head was fitted with accelerometers to measure the accelerations arising during impact testing. The equipment used for data collection was validated in both translational and rotational acceleration. In order to better resemble the human head, an artificial scalp was fitted to the hybrid dummy. The same test rig was used to investigate the performance of a number of different helmets. Impact velocities ranging from 7.3 to 9.9 m/s were tested using a number of different impact angles and impact areas. This study shows that the new test rig can be used to provide useful data at speeds of up to 50 km/h and with impact angles varying from purely tangential to purely radial. The rotational accelerations observed differ greatly depending on both helmet and scalp designs. For example, a helmet with a sliding outer shell placed on an experimental head fitted with an artificial scalp (made to resemble the human scalp) reduces rotational accelerations of the head by up to 56%, compared with those of an experimental head fitted with a fixed scalp and conventional helmet. The degree of slippage between the skull and the scalp, and between the scalp and the helmet, leads to considerable variation in the results. This innovative test rig appears to provide an accurate method for measuring accelerations in an oblique impact to a helmet. In order to obtain a good level of repeatability in oblique impact testing, it is crucial that the helmet be fixed to the head in the exact same way in each individual test. Both the position and the angle of impact must be reproduced identically in each test. The test rig used here has shown that this type of rig can be used to compare different helmet designs, and it therefore is able to contribute to achieving safer helmets.     

Persistence of the De-Icing Additive Benzotriazole at an Abandoned Airport

The environmental fate of many of the additives in the deicing agents used at airports is poorly understood. One and two years after deicing activities ceased, soil and groundwater samples were taken at an abandoned airport. Benzotriazole (BT), a corrosion and flame inhibitor, was found in low concentrations in soils along runways (mean 0.33 mg/kg), at a snow disposal site (0.66 mg/kg), as well as in sediments of a drainage ditch (13 mg/kg). Locally, high BT concentrations were found in the groundwater below the deicing pad, the regeneration plant and the snow disposal site (1.2 to 1100 g/l). Methyl substituted triazoles or tolytriazoles (MeBT) were found in concentrations less than 10% of the BT concentration. Propylene glycol was not detected in soil samples and in only one of the groundwater samples. Microtox tests of the water samples revealed no acute toxic response, however a reduction in nitrification rate was observed (14–43%). The nitrification response could not be related directly to the BT concentration in the samples, although samples with a high BT concentration showed the largest reduction in nitrification rate. BT showed very little sorption in various soil matrices, only peat and compost with a high organic carbon content showed significant sorption. Sorption could be best described using a Freundlich isotherm. These results indicate a high mobility and possibly long persistence of BT in soil and groundwater, which may be attributed to the absence of microbial degradation of BT.     

Simulations of stomatal conductance and ozone uptake to Norway spruce saplings in open-top chambers

A simulation model was developed to estimate the stomatal conductance and ozone flux to Norway spruce saplings in open-top chambers. The model was parameterized against needle conductance measurements that were made on 4-6-year-old spruce saplings, grown in open-top chambers, in July-September during three different seasons. The spruce saplings were either maintained well watered or subject to a 7-8 week drought period in July-September each year. The simulated conductance showed a good agreement with the measured conductance for the well-watered as well as the drought stress-treated saplings. The simulations were significantly improved when different vapour pressure deficit (VPD) functions were applied for well-watered and drought-stressed spruce saplings. The cumulated ozone uptake which was calculated from the conductance simulations showed less variation between years, compared to the cumulative ozone exposure index AOT40 (accumulated exposure over a threshold of 40 ppb or nl l(-1)) for the corresponding time periods. Measurements in May 1995 demonstrated the occurrence of long-term 'memory-effects' from the drought stress treatments on the conductance. Memory-effects need to be considered when simulation models for stomatal conductance are to be applied to long-lived forest trees under a multiple stress situation.     

The missing pieces for better future predictions in subarctic ecosystems: A Torneträsk case study

Arctic and subarctic ecosystems are experiencing substantial changes in hydrology, vegetation, permafrost conditions, and carbon cycling, in response to climatic change and other anthropogenic drivers, and these changes are likely to continue over this century. The total magnitude of these changes results from multiple interactions among these drivers. Field measurements can address the overall responses to different changing drivers, but are less capable of quantifying the interactions among them. Currently, a comprehensive assessment of the drivers of ecosystem changes, and the magnitude of their direct and indirect impacts on subarctic ecosystems, is missing. The Torneträsk area, in the Swedish subarctic, has an unrivalled history of environmental observation over 100 years, and is one of the most studied sites in the Arctic. In this study, we summarize and rank the drivers of ecosystem change in the Torneträsk area, and propose research priorities identified, by expert assessment, to improve predictions of ecosystem changes. The research priorities identified include understanding impacts on ecosystems brought on by altered frequency and intensity of winter warming events, evapotranspiration rates, rainfall, duration of snow cover and lake-ice, changed soil moisture, and droughts. This case study can help us understand the ongoing ecosystem changes occurring in the Torneträsk area, and contribute to improve predictions of future ecosystem changes at a larger scale. This understanding will provide the basis for the future mitigation and adaptation plans needed in a changing climate.Electronic supplementary materialThe online version of this article (10.1007/s13280-020-01381-1) contains supplementary material, which is available to authorized users.     

Redundancy and response diversity of functional groups: implications for the resilience of coral reefs

To improve coral reef management, a deeper understanding of biodiversity across scales in the context of functional groups is required. The focus of this paper is on the role of diversity within functional groups in securing important ecosystem processes that contribute to the resilience of coral-dominated reef states. Two important components of species biodiversity that confer ecosystem resilience are analyzed: redundancy and the diversity of responses within functional groups to change. Three critical functional groups are used to illustrate the interaction between these two components and their role in coral reef resilience: zooxanthellae (symbiotic micro algae in reef-building corals), reef-building corals, and herbivores. The paper further examines the consequences of undermining functional redundancy and response diversity and addresses strategies to secure ecological processes that are critical for coral reef resilience.