Estimating abundance of killer whales in the nearshore waters of the Gulf of Alaska and Aleutian Islands using line-transect sampling

Killer whale (Orcinus orca Linnaeus, 1758) abundance in the North Pacific is known only for a few populations for which extensive longitudinal data are available, with little quantitative data from more remote regions. Line-transect ship surveys were conducted in July and August of 2001–2003 in coastal waters of the western Gulf of Alaska and the Aleutian Islands. Conventional and Multiple Covariate Distance Sampling methods were used to estimate the abundance of different killer whale ecotypes, which were distinguished based upon morphological and genetic data. Abundance was calculated separately for two data sets that differed in the method by which killer whale group size data were obtained. Initial group size (IGS) data corresponded to estimates of group size at the time of first sighting, and post-encounter group size (PEGS) corresponded to estimates made after closely approaching sighted groups. ‘Resident’-type (fish-eating) killer whales were more abundant than the ‘transient’-type (mammal-eating). Abundance estimates of resident killer whales (991 [95% CI = 379–2,585] [IGS] and 1,587 [95% CI = 608–4,140] [PEGS]), were at least four times greater than those of the transient killer whales (200 [95% CI = 81–488] [IGS] and 251 [95% CI = 97–644] whales [PEGS]). The IGS estimate of abundance is preferred for resident killer whales because the estimate based on PEGS data may show an upward bias. The PEGS estimate of abundance is likely more accurate for transients. Residents were most abundant near Kodiak Island in the northern Gulf of Alaska, around Umnak and Unalaska Islands in the eastern Aleutians, and in Seguam Pass in the central Aleutians. This ecotype was not observed between 156 and 164°W, south of the Alaska Peninsula. In contrast, transient killer whale sightings were found at higher densities south of the Alaska Peninsula between the Shumagin Islands and the eastern Aleutians. Only two sightings of ‘offshore’-type killer whales were recorded during the surveys, one northeast of Unalaska Island and the other south of Kodiak Island. These are the first estimates of abundance of killer whale ecotypes in the Aleutian Islands and Alaska Peninsula area and provide a baseline for quantifying the role of these top predators in their ecosystem. Electronic Supplementary Material  Supplementary material is available in the online version of this article at and is accessible for authorized users.

---

The Paris Agreement and climate change negotiations: Small Islands,big players

Climate change poses an existential threat to Small Island Developing States (SIDS). They have played a leading role in raising awareness of climate change on the international stage and advocating for strong climate action, notably through the Alliance of Small Island States (AOSIS). Despite their heterogeneity, they succeeded in building a common diplomatic discourse and influencing strategy, and mobilized political leaders as well as talented negotiators and advisors.Small Island States were a crucial group in the negotiating period up to, during the 21st Conference of the Parties to the United Nations Framework Convention on Climate Change (COP21), and for the entry into force of the Paris Agreement. SIDS succeeded to secure their special circumstances as vulnerable countries, demonstrated leadership in raising ambition to reduce greenhouse gas emissions to help secure an ambitious long-term temperature goal of limiting global warming to below 1.5 °C, and advanced the complex debate on loss and damage.Small Island States face major challenges to advance their leadership on climate change moving forward: securing immediate actions for those particularly vulnerable countries and increasing their influence within and outside the climate change negotiations. For Small Island states, the 1.5 °C goal should be considered “the visible part of the iceberg” for their diplomacy in a post-Paris context.     

Evolution of hybrid functional imaging in bioelectromagnetics research

The field of bioelectromagnetics, consisting of the study of the interaction between electromagnetic fields and biological systems, has been rapidly expanding in the recent years. One important factor that contributes importantly to the development of this field is the continuing advances in technology allowing researchers to investigate different endpoints, or to more precisely measure changes, if any. Hybrid functional imaging is a rapidly maturing field that opens new, important horizons for bioelectromagnetics research. Indeed, unraveling the interaction mechanisms of electromagnetic fields on biological systems (with an emphasis on the brain) requires a monitoring of electrical, functional, and metabolic activity of living tissue at different temporal and spatial scales. Individual tools (e.g., electroencephalography, EEG; functional magnetic resonance imaging, fMRI) are limited in their ability to detect the effects of electromagnetic interaction at specific temporal and spatial scales, so combining these imaging methods offers a unique opportunity to provide a more comprehensive view of effects in living tissue. In this paper, we will present the different imaging techniques that are available to bioelectromagnetics researchers, including their capabilities and how they are complemented by simultaneous hybrid imaging. Future possibilities of hybrid imaging technologies are discussed.     

One century of hydrological monitoring in two small catchments with different forest coverage

Long-term data on precipitation and runoff are essential to draw firm conclusions about the behavior and trends of hydrological catchments that may be influenced by land use and climate change. Here the longest continuous runoff records from small catchments (<1 km(2)) in Switzerland (and possibly worldwide) are reported. The history of the hydrological monitoring in the Sperbel- and Rappengraben (Emmental) is summarized, and inherent uncertainties in the data arising from the operation of the gauges are described. The runoff stations operated safely for more than 90% of the summer months when most of the major flood events occurred. Nevertheless, the absolute values of peak runoff during the largest flood events are subject to considerable uncertainty. The observed differences in average, base, and peak runoff can only partly be attributed to the substantial differences in forest coverage. This treasure trove of data can be used in various ways, exemplified here with an analysis of the generalized extreme value distributions of the two catchments. These distributions, and hence flood return periods, have varied greatly in the course of one century, influenced by the occurrence of single extreme events. The data will be made publicly available for the further analysis of the mechanisms governing the runoff behavior of small catchments, as well as for testing stochastic and deterministic models.     

Fish dispersal in fragmented landscapes: a modeling framework for quantifying the permeability of structural barriers

Dispersal is a key determinant of the spatial distribution and abundance of populations, but human-made fragmentation can create barriers that hinder dispersal and reduce population viability. This study presents a modeling framework based on dispersal kernels (modified Laplace distributions) that describe stream fish dispersal in the presence of obstacles to passage. We used mark-recapture trials to quantify summer dispersal of brook trout (Salvelinus fontinalis) in four streams crossed by a highway. The analysis identified population heterogeneity in dispersal behavior, as revealed by the presence of a dominant sedentary component (48-72% of all individuals) characterized by short mean dispersal distance (<10 m), and a secondary mobile component characterized by longer mean dispersal distance (56-1086 m). We did not detect evidence of barrier effects on dispersal through highway crossings. Simulation of various plausible scenarios indicated that detectability of barrier effects was strongly dependent on features of sampling design, such as spatial configuration of the sampling area, barrier extent, and sample size. The proposed modeling framework extends conventional dispersal kernels by incorporating structural barriers. A major strength of the approach is that ecological process (dispersal model) and sampling design (observation model) are incorporated simultaneously into the analysis. This feature can facilitate the use of prior knowledge to improve sampling efficiency of mark-recapture trials in movement studies. Model-based estimation of barrier permeability and its associated uncertainty provides a rigorous approach for quantifying the effect of barriers on stream fish dispersal and assessing population dynamics of stream fish in fragmented landscapes.     

Distribution of common dolphins (Delphinus spp.) in the western Atlantic Ocean: a critical re-examination

Due to indications that misidentification (largely confusion among dolphins of the genera Delphinus and Stenella) in the past had led to erroneous assumptions of distribution of the two species of common dolphins (Delphinus delphis and D. capensis) in the western Atlantic Ocean, we conducted a critical re-examination of records of the genus Delphinus from this region. We compiled 460 ‘plottable’ records, required support for confirmation of genus and species identifications, and found many records lacking (and some clearly misidentified). When we plotted only the valid records (n = 364), we found evidence of populations in only three areas, and apparent absence throughout much of the tropical/subtropical regions. Off the east coast of the US and Canada, D. delphis is found from the Georgia/South Carolina border (32°N) north to about 47–50°N off Newfoundland. Since the 1960s, they have apparently been absent from Florida waters. There is no evidence that dolphins of the genus occur in the Gulf of Mexico. Reports of common dolphins from most of the Caribbean Basin are also rejected, and the only place in that region where they are confirmed to occur is off central-eastern Venezuela (a coastal D. capensis population). Off eastern South America, common dolphins appear to be restricted to south of 20°S. There is a coastal long-beaked population found in the South Brazil Bight, and one or more short-beaked populations south and offshore of this (ranging south to at least northern Argentina). The results are very different from commonly-accepted patterns of distribution for the genus in the Atlantic. Most areas of distribution coincide with moderate to strong upwelling and common dolphins appear to avoid warm, tropical waters. This study shows that great care must be taken in identification of similar-appearing long-beaked delphinids, and that uncritical acceptance of records at face value can lead to incorrect assumptions about the ranges of the species involved.     

A multi-scale approach to modelling spatial and dynamic ecological patterns for reservoir's water quality management

With growing levels of urbanization and agriculture throughout the world, it is increasingly important that both research and management efforts take into account the effects of this widespread landscape alteration and its consequences for natural systems. Freshwater ecosystems, namely reservoirs, are particularly sensitive to land use changes. In this context, modelling can be very useful, for decision support, as an investigative tool to forecast the outcome of various scenarios, to guide current management in order to meet future targets and to develop integrated frameworks for management accordingly to the Water Framework Directive (WFD). The present paper examined the applicability of a holistic Stochastic-Dynamic Methodology (StDM), coupled with a Cellular Automata (CA) model, in capturing how expected changes at land use level will alter the ecological status of lentic ecosystems, namely at physicochemical and biological levels. The methodology was applied to Portuguese reservoirs located in the Douro's basin and illustrated with a series of stochastic-dynamic and spatial outputs taking into account expected scenarios regarding land use changes. Overall, the simulation results are encouraging since they seem to demonstrate the tool reliability in capturing the stochastic environmental dynamics of the selected metrics facing spatial explicit scenarios. The ultimate goal was to couple monitoring assessment and the described modelling techniques to ease management and decision making regarding the practical implementation of the WFD, both at the scale of the reservoir body and at the scale of the respective river watershed dynamics.     

Turbulence characteristics within sparse and dense canopies

Boundary layer interactions with canopies control various environmental processes. In the case of dense and homogeneous canopies, the so-called mixing layer analogy is most generally used. When the canopy becomes sparser, a transition occurs between the mixing layer and the boundary layer perturbed by interactions between element wakes. This transition has still to be fully understood and characterized. The experimental work presented here deals with the effect of the canopy density on the flow turbulence and involves an artificial canopy placed in a fully developed turbulent boundary layer. One and two-component velocity measurements are performed, both within and above the canopy. The influence of the spacing between canopy elements is studied. Longitudinal velocity statistical moments and Reynolds stresses are calculated and compared to literature data. For spacings greater than the canopy height, evidences of this transition are found in the evolution of the skewness factor, shear length scale and mixing length.     

Effects of remarriage after widowhood on long-term fitness in a monogamous historical human population

The fitness benefits of multiple mating determine the strength of sexual selection in each sex. This is traditionally quantified by the number of offspring born to once versus multiply mated individuals. In species with (bi)parental care, however, this measure may overestimate the benefits of multiple mating since having several mates can increase offspring number but decrease offspring quality. We analyzed short- and long-term fitness consequences of multiple marriages for both sexes in humans in preindustrial Finnish populations, where monogamy was socially enforced and remarriage was possible only after widowhood. Remarriage increased the lifetime number of offspring sired by men by lengthening their reproductive span but was unrelated to the lifetime number of births for women. However, neither men's nor women's long-term fitness, measured as their number of grandchildren, was significantly increased or decreased by remarriage. These associations were not modified by individual wealth. Our results suggest that despite increasing the number of offspring sired by men, the long-term fitness benefits of serial monogamy may be negligible for both sexes when parental investment is crucial for offspring success and continues to adulthood. They also demonstrate the importance of incorporating long-term fitness measures when quantifying the benefits of mating and reproductive strategies.     

Calibration and validation of an integrated nitrate transport model within a well capture zone

Groundwater contamination by nitrate was investigated in an agricultural area in southern Quebec, Canada, where a municipal well is the local source of drinking water. A network of 38 piezometers was installed within the capture zone of the municipal well to monitor water table levels and nitrate concentrations in the aquifer. Nitrate concentrations were also measured in the municipal well. A Water flow and Nitrate transport Global Model (WNGM) was developed to simulate the impact of agricultural activities on nitrate concentrations in both the aquifer and municipal well. The WNGM first uses the Agriflux model to simulate vertical water and nitrate fluxes below the root zone for each of the seventy agricultural fields located within the capture zone of the municipal well. The WNGM then uses the HydroGeoSphere model to simulate three-dimensional variably-saturated groundwater flow and nitrate transport in the aquifer using water and nitrate fluxes computed with the Agriflux model as the top boundary conditions. The WNGM model was calibrated by reproducing water levels measured from 2005 to 2007 in the network of piezometers and nitrate concentrations measured in the municipal well from 1997 to 2007. The nitrate concentrations measured in the network of piezometers, however, showed greater variability than in the municipal well and could not be reproduced by the calibrated model. After calibration, the model was validated by successfully reproducing the decrease of nitrate concentrations observed in the municipal well in 2006 and 2007. Although it cannot predict nitrate concentrations in individual piezometers, the calibrated and validated WNGM can be used to assess the impact of changes in agricultural practices on global nitrate concentrations in the aquifer and in the municipal well.