scholarly journals An integrated population model for estimating the relative effects of natural and anthropogenic factors on a threatened population of Pacific trout

2019 ◽  
Author(s):  
Mark D. Scheuerell ◽  
Casey P. Ruff ◽  
Joseph H. Anderson ◽  
Eric M. Beamer
Keyword(s):  
At Risk ◽  
Population Model ◽  
Habitat Restoration ◽  
Negative Relationship ◽  
Anthropogenic Factors ◽  
List Type ◽  
Population Demographics ◽  
Density Dependent ◽  
Integrated Population Model ◽  
The North

SummaryAssessing the degree to which at-risk species are regulated by density dependent versus density independent factors is often complicated by incomplete or biased information. If not addressed in an appropriate manner, errors in the data can affect estimates of population demographics, which may obfuscate the anticipated response of the population to a specific action.We developed a Bayesian integrated population model that accounts explicitly for interannual variability in the number of reproducing adults and their age structure, harvest, and environmental conditions. We apply the model to 41 years of data for a population of threatened steelhead troutOncorhynchus mykissusing freshwater flows, ocean indices, and releases of hatchery-born conspecifics as covariates.We found compelling evidence that the population is under strong density dependence, despite being well below its historical population size. In the freshwater portion of the lifecycle, we found a negative relationship between productivity (offspring per parent) and peak winter flows, and a positive relationship with summer flows. We also found a negative relationship between productivity and releases of hatchery conspecifics. In the marine portion of the lifecycle, we found a positive correlation between productivity and the North Pacific Gyre Oscillation. Furthermore, harvest rates on wild fish have been sufficiently low to ensure very little risk of overfishing.Synthesis and applications.The evidence for density dependent population regulation, combined with the substantial loss of juvenile rearing habitat in this river basin, suggests that habitat restoration could benefit this population of at-risk steelhead. Our results also imply that hatchery programs for steelhead need to be considered carefully with respect to habitat availability and recovery goals for wild steelhead. If releases of hatchery steelhead have indeed limited the production potential of wild steelhead, there are likely significant tradeoffs between providing harvest opportunities via hatchery steelhead production, and achieving wild steelhead recovery goals.

scholarly journals Efficient use of harvest data: a size‐class‐structured integrated population model for exploited populations

Ecography ◽  
2021 ◽  
Author(s):  
Marlène Gamelon ◽  
Chloé R. Nater ◽  
Éric Baubet ◽  
Aurélien Besnard ◽  
Laura Touzot ◽  
...  
Keyword(s):  
Population Model ◽  
Size Class ◽  
Integrated Population Model ◽  
Harvest Data

Negotiating North American Free Trade

2000 ◽  
Vol 5 (1) ◽  
pp. 43-68 ◽  
Author(s):  
◽  
Keyword(s):  
At Risk ◽  
Free Trade ◽  
North American ◽  
Negotiation Process ◽  
Divided Government ◽  
Weak States ◽  
Trade Negotiation ◽  
The North ◽  
The Future ◽  
Asymmetrical Power

AbstractNegotiators for powerful, self-reliant states tend to be less responsive to weak states relative to domestic constituents, while negotiators for states entangled in ties of asymmetric interdependence with more powerful states tend to be more responsive to the demands of powerful states than to the demands of domestic constituents. Asymmetrical power does not necessarily lead to asymmetrical results, however, because negotiators in weaker states may, nevertheless, have more attractive non-agreement alternatives and a longer shadow of the future. Negotiators with attractive non-agreement alternatives will be more willing to put agreement at risk by withholding concessions in the negotiation process. Centralized and vertical institutions are often a bargaining liability precisely because weak states tend to be less responsive to domestic constituents, whereas divided government can be a major asset. These propositions are demonstrated through an analysis and reconstruction of the North American Free Trade negotiation process.

Phytoplankton of cold-water lake ecosystems under the influence of natural and anthropogenic factors

2021 ◽  
pp. 42-49
Author(s):  
Andrey N. Sharov
Keyword(s):  
Heavy Metals ◽  
Cold Water ◽  
Arctic Lakes ◽  
Water Bodies ◽  
The Arctic ◽  
Anthropogenic Factors ◽  
Large Lakes ◽  
Arctic Water ◽  
The North ◽  
Natural And Anthropogenic Factors

Based on the study of the spatio-temporal aspects of the development of phytoplankton in the lakes of the North and North-West of the European territory of Russia (large lakes – Imandra, Onega and Chudsko-Pskovskoye and small lakes of the Arctic and Subarctic), the features of its structure and dynamics under the influence of natural and anthropogenic factors (eutrophication, heavy metal pollution, acidification, thermification). The species composition and quantitative characteristics of phytoplankton of large lakes of the North of Russia, small arctic lakes and lakes of subarctic regions are studied. It has been shown that diatoms predominate in arctic water bodies according to species diversity, and green and diatoms predominate in boreal ones. By biomass, diatoms dominate mainly in all cold-water lakes, with the exception of small arctic lakes, where golden algae lead. The features of the reorganization of phytoplankton in response to the action of anthropogenic factors are revealed. It is proved that in the northern water bodies the complex action of heavy metals and nutrients does not lead to inhibition of phytoplankton, and the effect of acidification in combination with heavy metals enhances the toxic effect of the latter. A feature of the response to acidification is an increase in the variability of the dynamics of the biomass of phytoplankton. It has been shown that in different types of lakes of East Antarctica under severe climate conditions under light and biogenic limitation, redistribution of autotrophic components in the formation of the biota of water bodies occurs: against the background of a decrease in the abundance and diversity of phytoplankton, the role of microphytobenthos and periphyton increases.

scholarly journals Role of Healthy Work Environments in Sustainability of Goal Achievement; Ethical Leadership, Intention to Sabotage, and Psychological Capital in Jordanian Universities

2018 ◽  
Vol 10 (10) ◽  
pp. 3559 ◽  
Author(s):  
Shadi Mohammad Altahat ◽  
Tarik Atan
Keyword(s):  
Ethical Leadership ◽  
Structural Equation ◽  
Psychological Capital ◽  
Critical Role ◽  
Negative Relationship ◽  
Goal Achievement ◽  
Self Control ◽  
Equation Modeling ◽  
Healthy Environment ◽  
The North

(1) Background: Long-term competitiveness and sustainability of goal achievement are constantly being sought out by organizations. This study examined the link between ethical leadership, intention to sabotage, and psychological capital in Jordanian universities and how they provide a healthy environment conducive to goal achievement sustainability. The literature indicated gaps in knowledge regarding the correlation between these variables in non-western countries, which this study intends to fill. The study drew from social learning theory and self-control theory. (2) Methods: Data was obtained by collecting survey questionnaires from a sample of 376 employees in different universities in the north of Jordan, and was analyzed with Statistical Package for the Social Sciences (SPSS) and Structural Equation Modeling. (3) Results: A significant and direct negative relationship was found between both ethical leadership and psychological capital on employees’ intention to sabotage. Also, a significant and direct positive effect was found between ethical leadership and psychological capital. Furthermore, it was found that psychological capital mediated the relationship between ethical leadership and employees’ intention to sabotage. (4) Conclusions: Leaders have a critical role in increasing employee psychological capital and decreasing intention to sabotage. Many implications indicated by the study’s findings, both theoretical and practical, were discussed.

scholarly journals Exploring Combined Influences of Seasonal East Atlantic (EA) and North Atlantic Oscillation (Nao) on the Temperature-Precipitation Relationship in the Iberian Peninsula

2021 ◽  
Author(s):  
Fernando S. Rodrigo
Keyword(s):  
North Atlantic Oscillation ◽  
Iberian Peninsula ◽  
North Atlantic ◽  
Negative Relationship ◽  
Correlation Coefficients ◽  
East Atlantic ◽  
Teleconnection Patterns ◽  
The North ◽  
Spatial Coverage ◽  
The North Atlantic Oscillation

The combined influence of the North Atlantic Oscillation (NAO) and the East Atlantic (EA) patterns on the covariability of temperatures and precipitation in 35 stations of the Iberian Peninsula during the period 1950-2019 is analysed in this work. Four EA-NAO composites were defined from teleconnection patterns positive and negative phases: EA+NAO+, EA+NAO-, EA-NAO+, and EA-NAO-. Daily data of maximum and minimum temperature were used to obtain seasonal means (TX, and TN, respectively), and the covariability of these variables with accumulated seasonal rainfall (R) was studied comparing results obtained for different NAO and EA composites. Main results indicate slight differences in the spatial coverage of correlation coefficients between R and temperature variables, except in spring when the generalized negative relationship between R and TX under EA+NAO+ and EA-NAO- disappears under EA-NAO+ and EA+NAO- composites. This result may be useful to interpret and discuss historical reconstructions of Iberian climate.

scholarly journals Metabarcoding reveals different zooplankton communities in northern and southern areas of the North Sea

2020 ◽  
Author(s):  
Jan Niklas Macher ◽  
Berry B. van der Hoorn ◽  
Katja T. C. A. Peijnenburg ◽  
Lodewijk van Walraven ◽  
Willem Renema
Keyword(s):  
North Sea ◽  
Zooplankton Community ◽  
Taxonomic Diversity ◽  
Molecular Techniques ◽  
Trophic Levels ◽  
List Type ◽  
The North ◽  
Shelf Sea ◽  
The North Sea ◽  
Zooplankton Communities

AbstractZooplankton are key players in marine ecosystems, linking primary production to higher trophic levels. The high abundance and high taxonomic diversity renders zooplankton ideal for biodiversity monitoring. However, taxonomic identification of the zooplankton assemblage is challenging due to its high diversity, subtle morphological differences and the presence of many meroplanktonic species, especially in coastal seas. Molecular techniques such as metabarcoding can help with rapid processing and identification of taxa in complex samples, and are therefore promising tools for identifying zooplankton communities. In this study, we applied metabarcoding of the mitochondrial cytochrome c oxidase I gene to zooplankton samples collected along a latitudinal transect in the North Sea, a shelf sea of the Atlantic Ocean. Northern regions of the North Sea are influenced by inflow of oceanic Atlantic waters, whereas the southern parts are characterised by more coastal waters. Our metabarcoding results indicated strong differences in zooplankton community composition between northern and southern areas of the North Sea, particularly in the classes Copepoda, Actinopterygii (ray-finned fishes) and Polychaeta. We compared these results to the known distributions of species reported in previous studies, and by comparing the abundance of copepods to data obtained from the Continuous Plankton Recorder (CPR). We found that our metabarcoding results are mostly congruent with the reported distribution and abundance patterns of zooplankton species in the North Sea. Our results highlight the power of metabarcoding to rapidly assess complex zooplankton samples, and we suggest that the technique could be used in future monitoring campaigns and biodiversity assessments.HighlightsZooplankton communities are different in northern and southern areas of the North SeaMetabarcoding results are consistent with known species distributions and abundanceMetabarcoding allows for fast identification of meroplanktonic species

scholarly journals Causes and consequences of facultative sea crossing in a soaring migrant

2019 ◽  
Author(s):  
Paolo Becciu ◽  
Shay Rotics ◽  
Nir Horvitz ◽  
Michael Kaatz ◽  
Wolfgang Fiedler ◽  
...  
Keyword(s):  
Flapping Flight ◽  
Transport Cost ◽  
List Type ◽  
Route Selection ◽  
Atmospheric Conditions ◽  
Related Factors ◽  
Spatial And Temporal Scales ◽  
The North ◽  
Related Energy ◽  
White Storks

AbstractStudying the causes and consequences of route selection in animal migration is important for understanding the evolution of migratory systems and how they may be affected by environmental factors at various spatial and temporal scales. One key decision during migration is whether to cross “high transport cost” areas, or to circumvent them. Soaring birds may face this choice when encountering waterbodies where convective updrafts are weak or scarce. Crossing these waterbodies requires flying using energetically costly flapping flight, while circumventing them over land permits energetically cheap soaring.We tested how several atmospheric factors (e.g., wind, thermal uplift) and geographic, seasonal and state-related factors (sex and age) affected route selection in migrating white storks (Ciconia ciconia). We used 196 GPS tracks of 70 individuals either crossing or circumventing the north-easternmost section of the Mediterranean Sea, over Iskenderun Bay in southern Turkey.We found that westward and southward winds promoted a cross-bay journey in spring and autumn, respectively, acting as tailwinds. Also, overall weaker winds promoted a sea crossing in spring. Sea crossing was associated with flapping flight and higher values of Overall Dynamic Body Acceleration (ODBA) and resulted in higher ground speed than travel over land.The combined environmental conditions and the effects of route selection on movement-related energy costs and speed were likely responsible for an increase in the time spent flying and distance travelled of migrating storks that decided to cross the bay during spring. Notably, daily travel distances of spring migrants crossing the bay were 60 kilometres longer than those of land-detouring birds, allowing them to reach their destination faster but likely incurring a higher energetic flight cost. No such benefit was found during autumn.Our findings confirm that atmospheric conditions can strongly affect bird route selection. Consequently, migration timing, speed and movement-related energy expenditure differed considerably between the two migratory seasons and the two route choices, highlighting a time-energy trade-off in the migration of white storks.

scholarly journals Combining single- and repeated-visit occupancy models to make the best of monitoring surveys

2019 ◽  
Author(s):  
Valentin Lauret ◽  
Hélène Labach ◽  
Matthieu Authier ◽  
Olivier Gimenez
Keyword(s):  
Bottlenose Dolphins ◽  
Ecological Monitoring ◽  
Western Mediterranean ◽  
List Type ◽  
Occupancy Models ◽  
Single Visit ◽  
The North ◽  
Aerial Surveys ◽  
Single Method ◽  
Repeated Visit

AbstractA major challenge in applied ecology consists in integrating knowledge from different datasets to produce robust ecological indicators. To estimate species distribution, occupancy models are a flexible framework that can accommodate several datasets obtained from different sampling methods. However, repeating visits at sampling sites is a prerequisite for using standard occupancy models, which may limit their use. Under certain conditions, detection/non-detection data collected during single visit can be analysed with occupancy models. To date however, single-visit occupancy models have never been used to combine several different datasets.Here, we developed an approach that combines multi-method and single-visit occupancy models. As a case study, we estimated the distribution of Bottlenose dolphins (Tursiops truncatus) over the North-western Mediterranean Sea by combining 24,624 km of aerial surveys and 21,464 km of at-sea monitoring. We compared the outputs of single-vs. repeated-visit multi-method occupancy models, and that of single-method occupancy models.Multi-method models allowed a better sampling coverage in both coasts and high seas and provided a better precision for occupancy estimates than single-method occupancy models using aerial surveys or at-sea surveys in isolation.Overall, single- and repeated-visit multi-method occupancy models produced similar inference about the distribution of bottlenose dolphins. This suggests that single-visit occupancy models provide robust occupancy estimates, which open promising perspectives for the use of non-standardized datasets.Synthesis and applications: Single-visit multi-method occupancy models can help making the best out of ecological monitoring programs by optimizing cost effectiveness through the formal combination of datasets.

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