scholarly journals Habitat-mediated population limitation in a colonial central-place forager: the sky is not the limit for the black-browed albatross

2014 ◽  
Vol 281 (1778) ◽  
pp. 20132883 ◽  
Author(s):  
Ewan D. Wakefield ◽  
Richard A. Phillips ◽  
Jason Matthiopoulos
Keyword(s):  
Resource Availability ◽  
Net Primary Production ◽  
Strong Dependence ◽  
Resource Limitation ◽  
Central Place ◽  
Population Limitation ◽  
Animal Populations ◽  
Temporal Predictability ◽  
Spatio Temporal ◽  
The Cost

Animal populations are frequently limited by the availability of food or of habitat. In central-place foragers, the cost of accessing these resources is distance-dependent rather than uniform in space. However, in seabirds, a widely studied exemplar of this paradigm, empirical population models have hitherto ignored this cost. In part, this is because non-independence among colonies makes it difficult to define population units. Here, we model the effects of both resource availability and accessibility on populations of a wide-ranging, pelagic seabird, the black-browed albatross Thalassarche melanophris . Adopting a multi-scale approach, we define regional populations objectively as spatial clusters of colonies. We consider two readily quantifiable proxies of resource availability: the extent of neritic waters (the preferred foraging habitat) and net primary production (NPP). We show that the size of regional albatross populations has a strong dependence, after weighting for accessibility, on habitat availability and to a lesser extent, NPP. Our results provide indirect support for the hypothesis that seabird populations are regulated from the bottom-up by food availability during the breeding season, and also suggest that the spatio-temporal predictability of food may be limiting. Moreover, we demonstrate a straightforward, widely applicable method for estimating resource limitation in populations of central-place foragers.

scholarly journals Superficial venous insufficiency from the infernal to the endothermal

2014 ◽  
Vol 96 (1) ◽  
pp. 5-10 ◽  
Author(s):  
D Carradice
Keyword(s):  
Gold Standard ◽  
Venous Insufficiency ◽  
Varicose Veins ◽  
Treatment Options ◽  
Resource Limitation ◽  
Skin Damage ◽  
The Common ◽  
Modern Treatment ◽  
The Cost ◽  
Superficial Venous Insufficiency

This review presents the common diseases associated with superficial venous insufficiency of the leg. These include varicose veins, swelling, skin damage and ulceration. The benefits and rationale behind treatment are discussed, followed by the historical advances from ancient mortality and prayer to the modern endovenous revolution. Finally, an overview of modern treatment options will discuss the evidence supporting the gold standard of endothermal ablation and the cost effectiveness of treatment at this time of challenging resource limitation.

scholarly journals Optimal spatio-temporal design for water quality monitoring networks in maximizing economic value of information

2019 ◽  
Vol 281 ◽  
pp. 03004 ◽  
Author(s):  
François Destandau ◽  
Youssef Zaiter
Keyword(s):  
Water Quality ◽  
Value Of Information ◽  
Cost Benefit Analysis ◽  
Economic Value ◽  
Cost Benefit ◽  
Water Quality Monitoring ◽  
Quality Monitoring ◽  
Monitoring Networks ◽  
Spatio Temporal ◽  
The Cost

The Water Framework Directive 2000/60/EC draw attention to Water Quality Monitoring Networks (WQMN) that allows the acquisition of information regarding water streams. Information could be acquired by a spatial and/or temporal approach. However, there is a cost for monitoring water quality. Hence, to determine the spatio-temporal design of the network, the Economic Value of Information must be known to undertake a cost-benefit analysis. In this study, we show how the calculation of the EVOI can help the network manager to answer questions such as: is the cost of monitoring justified? How to allocate a budget between adding a monitoring station or increasing the frequency of measurement of existing stations?

scholarly journals The influence of spatio-temporal resource fluctuations on insular rat population dynamics

2011 ◽  
Vol 279 (1729) ◽  
pp. 767-774 ◽  
Author(s):  
James C. Russell ◽  
Lise Ruffino
Keyword(s):  
Population Dynamics ◽  
Resource Availability ◽  
Rattus Rattus ◽  
Resource Subsidies ◽  
Driven Systems ◽  
Resource Pulses ◽  
State Capture ◽  
Main Driver ◽  
Capture Recapture ◽  
Spatio Temporal

Local spatio-temporal resource variations can strongly influence the population dynamics of small mammals. This is particularly true on islands which are bottom-up driven systems, lacking higher order predators and with high variability in resource subsidies. The influence of resource fluctuations on animal survival may be mediated by individual movement among habitat patches, but simultaneously analysing survival, resource availability and habitat selection requires sophisticated analytical methods. We use a Bayesian multi-state capture–recapture model to estimate survival and movement probabilities of non-native black rats ( Rattus rattus ) across three habitats seasonally varying in resource availability. We find that survival varies most strongly with temporal rainfall patterns, overwhelming minor spatial variation among habitats. Surprisingly for a generalist forager, movement between habitats was rare, suggesting individuals do not opportunistically respond to spatial resource subsidy variations. Climate is probably the main driver of rodent population dynamics on islands, and even substantial habitat and seasonal spatial subsidies are overwhelmed in magnitude by predictable annual patterns in resource pulses. Marked variation in survival and capture has important implications for the timing of rat control.

scholarly journals Identifying Priority Conservation Areas of Largehead Hairtail (Trichiurus japonicus) Nursery Grounds in the East China Sea

2022 ◽  
Vol 8 ◽  
Author(s):  
Zunlei Liu ◽  
Yan Jin ◽  
Liping Yan ◽  
Yi Zhang ◽  
Hui Zhang ◽  
...  
Keyword(s):  
East China Sea ◽  
Net Primary Production ◽  
East China ◽  
Abundance Distribution ◽  
The East China Sea ◽  
Conservation Areas ◽  
Nursery Grounds ◽  
China Sea ◽  
Sea Bottom ◽  
Spatio Temporal

Identifying the spatio-temporal distribution hotspots of fishes and allocating priority conservation areas could facilitate the spatial planning and efficient management. As a flagship commercial fishery species, Largehead hairtail (Trichiurus japonicus) has been over-exploited since the early 2000s. Therefore, the spatio-temporal management of largehead hairtail nursery grounds could effective help its recovery. This study aims to predict juvenile largehead hairtail distribution patterns and identify priority conservation areas for nursery grounds. A two-stage hierarchical Bayesian spatio-temporal model was applied on independent scientific survey data (Catch per unit effort, CPUE) and geographic/physical variables (Depth, Distance to the coast, Sea bottom temperature, Dissolved oxygen concentration and Net primary production) to analyze the probability of occurrence and abundance distribution of juvenile largehead hairtail. We assessed the importance of each variable for explaining the occurrence and abundance. Using persistence index, we measured the robustness of hotspots and identified persistent hotspots for priority conservation areas. Selected models showed good predictive capacity on occurrence probability (AUC = 0.81) and abundance distribution (r = 0.89) of juvenile largehead hairtail. Dissolved oxygen, net primary production, and sea bottom temperature significantly affected the probability of occurrence, while distance to the coast also affected the abundance distribution. Three stable nursery grounds were identified in Zhejiang inshore waters, the largest one was located on the east margin of the East China Sea hairtail national aquatic germplasm resources conservation zones (TCZ), suggesting that the core area of nursery grounds occurs outside the protected areas. Therefore, recognition of these sites and their associated geographic/oceanic attributes provides clear targets for optimizing largehead hairtail conservation efforts in the East China Sea. We suggested that the eastern and southern areas of TCZ should be included in conservation planning for an effective management within a network of marine protected areas.

Spatio-temporal patterns of foraging behaviour in a wide-ranging seabird reveal the role of primary productivity in locating prey

2020 ◽  
Vol 646 ◽  
pp. 175-188
Author(s):  
A Kane ◽  
E Pirotta ◽  
S Wischnewski ◽  
EJ Critchley ◽  
A Bennison ◽  
...  
Keyword(s):  
Habitat Use ◽  
Foraging Behaviour ◽  
Food Resource ◽  
Biotic Interactions ◽  
Central Place ◽  
Ocean Dynamics ◽  
Environmental Predictors ◽  
Nocturnal Foraging ◽  
Spatio Temporal ◽  
Marine Productivity

Predicting the distribution and behaviour of animals is a fundamental objective in ecology and a cornerstone of conservation biology. Modelling the distribution of ocean-faring species like seabirds remains a significant challenge due to ocean dynamics, colony-specific effects and the vast ranges seabirds can cover. We used a spatial and behavioural approach to model the distribution of the Manx shearwater Puffinus puffinus, a pelagic, central-place forager that can cover great distances while foraging. GPS data from birds tagged in 2 colonies over 3 yr were modelled with a range of environmental predictors of marine productivity. For both colonies, transitions to foraging behaviour correlated with chlorophyll a, and the distribution of foraging behaviour was also associated with areas of high chlorophyll a concentration in coastal but not offshore areas for one colony. Furthermore, there was evidence for colony differences in habitat use, prevalence of nocturnal foraging, and for some competitive exclusion on foraging grounds, even though the colonies were 170 km apart. Despite the extensive dataset, our models had modest predictive power, which we suggest can probably only be improved by including biotic interactions, including more direct measures of food resource distribution. Our results highlight the importance of including spatial complexity and data from multiple sites when predicting the distribution of wide-ranging predators, because patterns of distribution and habitat use likely differ across the range of a population.

Biomass allocation and multiple resource limitation in tree seedlings

1996 ◽  
Vol 26 (9) ◽  
pp. 1521-1530 ◽  
Author(s):  
C.D. Canham ◽  
A.R. Berkowitz ◽  
V.R. Kelly ◽  
G.M. Lovett ◽  
S.V. Ollinger ◽  
...  
Keyword(s):  
Resource Availability ◽  
Sugar Maple ◽  
Resource Limitation ◽  
Tree Seedlings ◽  
Red Maple ◽  
White Pine ◽  
Soil Resource ◽  
Light Levels ◽  
Aboveground Growth ◽  
Soil Resource Availability

We conducted a greenhouse experiment to determine how differences among tree species in allocation of biomass to roots versus shoots affected their responses to different combinations of light, water, and soil nutrients. Across a full range of light levels, we were specifically interested in examining the sensitivity of tree seedlings to additional reductions in aboveground growth due to soil resource limitation, and the relative sensitivity of seedlings to water versus nutrient stress under different light regimes. The four tree species used in our experiment included two species that are the most common initial tree invaders of abandoned agricultural lands (old fields) in the Hudson Valley (red maple (Acerrubrum L.) and white pine (Pinusstrobus L.)) and two species that are less frequently found in old fields, but that are dominant forest species, and are noted for their tolerance of either light stress or water stress (sugar maple (Acersaccharum Marsh.) and red oak (Quercusrubra L.), respectively). At the lowest light levels (2% of full sun), there was no effect of variation in soil resource availability on shoot growth of any of the four species. At the 9% full sun light level, red maple seedlings showed clear evidence of simultaneous limitation by light, water, and nitrogen. At higher light levels (20–100% of full sun), all four species responded to variation in at least one of the two soil resources. The four species showed two contrasting patterns of allocation of biomass to roots. Red maple and white pine responded to an increase in soil resource availability by reducing relative allocation to roots and increasing aboveground growth. Sugar maple and red oak had much more conservative root allocation patterns: root allocation was high (58–75% of added biomass allocated to roots) and did not vary in response to soil resource availability. Allocation to roots was affected more strongly by variation in soil nitrogen availability than it was by soil moisture availability.

scholarly journals Effects of floating (solar PV) platforms on hydrodynamics and primary production in a coastal sea

2019 ◽  
Author(s):  
Thodoris Karpouzoglou ◽  
Brigitte Vlaswinkel ◽  
Johan van der Molen
Keyword(s):  
Primary Production ◽  
Water Column ◽  
Net Primary Production ◽  
Strong Dependence ◽  
Biogeochemical Model ◽  
Solar Pv ◽  
Column Model ◽  
Coastal Sea ◽  
Floating Platforms ◽  
The Impact

Abstract. An improved understanding of the effects of floating solar platforms on the ecosystem is necessary to define acceptable and responsible real-world field implementations of this new marine technology. This study examines a number of potential effects of offshore floating solar PV platforms on the hydrodynamics and net primary production in a coastal sea for the first time. Three contrasting locations within the North Sea (a shallow and deeper location with well-mixed conditions and a summer-stratifying location) have been analysed using a water column physical-biogeochemical model (GOTM-ERSEM-BFM). The results show strong dependence on the characteristics of the location (e.g. mixing and stratification) and on the density of coverage with floating platforms. The overall response of the system was separated into contributions by platform shadow, shielding by the platforms of the sea surface from wind, and friction induced by the platforms on the currents. For all three locations, platform shadow was the dominant effect on the net primary production. For the two well-mixed locations, the other effects of the platforms resulted in partial compensation for the impact of platform shadow, while for the stratified location, they enhanced the effects of platform shadow. For up to 20 % coverage of the model surface with platforms, the spread in the results between locations was relatively small, and the changes in net primary production were less than 10 %. For higher percentages of coverage, primary production decreased substantially, with an increased spread in response between the sites. The water-column model assumes horizontal homogeneity in all forcings and simulated variables, also for coverage with floating platforms, and hence the results are applicable to very large-scale implementations of offshore floating platforms that are evenly distributed over areas of at least several hundreds of square kilometres. To confirm these results, and to investigate more realistic cases of floating platforms distributed unevenly over much smaller areas with horizontally varying hydrodynamic conditions, in which phytoplankton can be expected to spend only part of the time underneath a farm, spatial detail and additional processes need to be included. To do so, further work is required to advance the water-column model towards a 3D modelling approach.

scholarly journals Self-Supervised Video Representation Learning with Space-Time Cubic Puzzles

2019 ◽  
Vol 33 ◽  
pp. 8545-8552 ◽  
Author(s):  
Dahun Kim ◽  
Donghyeon Cho ◽  
In So Kweon
Keyword(s):  
Action Recognition ◽  
Large Scale ◽  
State Of The Art ◽  
Representation Learning ◽  
Space Time ◽  
Temporal Relation ◽  
Still Images ◽  
Video Frames ◽  
Spatio Temporal ◽  
The Cost

Self-supervised tasks such as colorization, inpainting and zigsaw puzzle have been utilized for visual representation learning for still images, when the number of labeled images is limited or absent at all. Recently, this worthwhile stream of study extends to video domain where the cost of human labeling is even more expensive. However, the most of existing methods are still based on 2D CNN architectures that can not directly capture spatio-temporal information for video applications. In this paper, we introduce a new self-supervised task called as Space-Time Cubic Puzzles to train 3D CNNs using large scale video dataset. This task requires a network to arrange permuted 3D spatio-temporal crops. By completing Space-Time Cubic Puzzles, the network learns both spatial appearance and temporal relation of video frames, which is our final goal. In experiments, we demonstrate that our learned 3D representation is well transferred to action recognition tasks, and outperforms state-of-the-art 2D CNN-based competitors on UCF101 and HMDB51 datasets.

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