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1.
The influence of multiple anchored fish aggregating devices (FADs) on the spatial behavior of yellowfin (Thunnus albacares) and bigeye tuna (T. obesus) was investigated by equipping all thirteen FADs surrounding the island of Oahu (HI, USA) with automated sonic receivers
(“listening stations”) and intra-peritoneally implanting individually coded acoustic transmitters in 45 yellowfin and 12 bigeye
tuna. Thus, the FAD network became a multi-element passive observatory of the residence and movement characteristics of tuna
within the array. Yellowfin tuna were detected within the FAD array for up to 150 days, while bigeye tuna were only observed
up to a maximum of 10 days after tagging. Only eight yellowfin tuna (out of 45) and one bigeye tuna (out of 12) visited FADs
other than their FAD of release. Those nine fish tended to visit nearest neighboring FADs and, in general, spent more time
at their FAD of release than at the others. Fish visiting the same FAD several times or visiting other FADs tended to stay
longer in the FAD network. A majority of tagged fish exhibited some synchronicity when departing the FADs but not all tagged
fish departed a FAD at the same time: small groups of tagged fish left together while others remained. We hypothesize that
tuna (at an individual or collective level) consider local conditions around any given FAD to be representative of the environment
on a larger scale (e.g., the entire island) and when those conditions become unfavorable the tuna move to a completely different
area. Thus, while the anchored FADs surrounding the island of Oahu might concentrate fish and make them more vulnerable to
fishing, at a meso-scale they might not entrain fish longer than if there were no (or very few) FADs in the area. At the existing
FAD density, the ‘island effect’ is more likely to be responsible for the general presence of fish around the island than
the FADs. We recommend further investigation of this hypothesis.
相似文献
Laurent Dagorn (Corresponding author)Email: |
Kim N. HollandEmail: |
David G. ItanoEmail: |
2.
John E. Hathaway G. Bruce Schaalje Richard O. Gilbert Brent A. Pulsipher Brett D. Matzke 《Environmental and Ecological Statistics》2008,15(3):313-327
Composite sampling can be more cost effective than simple random sampling. This paper considers how to determine the optimum
number of increments to use in composite sampling. Composite sampling terminology and theory are outlined and a method is
developed which accounts for different sources of variation in compositing and data analysis. This method is used to define
and understand the process of determining the optimum number of increments that should be used in forming a composite. The
blending variance is shown to have a smaller range of possible values than previously reported when estimating the number
of increments in a composite sample. Accounting for differing levels of the blending variance significantly affects the estimated
number of increments.
相似文献
John E. HathawayEmail: |
3.
Chang Xuan Mao 《Environmental and Ecological Statistics》2007,14(4):473-481
Consider the removal experiment used to estimate population sizes. Statistical methods towards testing the homogeneity of
capture probabilities of animals, including a graphical diagnostic and a formal test, are presented and illustrated by real
biological examples. Simulation is used to assess the test and compare it with the χ2 test.
相似文献
Chang Xuan MaoEmail: |
4.
B. Gail Ivanoff 《Environmental and Ecological Statistics》2009,16(2):153-171
The concept of the renewal property is extended to processes indexed by a multidimensional time parameter. The definition
given includes not only partial sum processes, but also Poisson processes and many other point processes whose jump points
are not totally ordered. Various properties of renewal processes are discussed. Renewal processes are proposed as a basis
for modelling the spread of a forest fire under a prevailing wind.
相似文献
B. Gail IvanoffEmail: |
5.
Andrew O. Finley Sudipto Banerjee Ronald E. McRoberts 《Environmental and Ecological Statistics》2008,15(2):241-258
In efforts such as land use change monitoring, carbon budgeting, and forecasting ecological conditions and timber supply,
there is increasing demand for regional and national data layers depicting forest cover. These data layers must permit small
area estimates of forest area and, most importantly, provide associated error estimates. This paper presents a model-based
approach for coupling mid-resolution satellite imagery with plot-based forest inventory data to produce estimates of probability
of forest and associated error at the pixel-level. The proposed Bayesian hierarchical model provides access to each pixel’s
posterior predictive distribution allowing for a highly flexible analysis of pixel and multi-pixel areas of interest. The
paper presents a trial using multiple dates of Landsat imagery and USDA Forest Service Forest Inventory and Analysis plot
data. The results describe the spatial dependence structure within the trial site, provide pixel and multi-pixel summaries
of probability of forest land use, and explore discretization schemes of the posterior predictive distributions to forest
and non-forest classes. Model prediction results of a holdout set analysis suggest the proposed model provides high classification
accuracy, 88%, for the trial site.
相似文献
Ronald E. McRobertsEmail: |
6.
Frederic Paik Schoenberg Jamie Pompa Chien-Hsun Chang 《Environmental and Ecological Statistics》2009,16(2):251-269
This paper explores the use of, and problems that arise in, kernel smoothing and parametric estimation of the relationships
between wildfire incidence and various meteorological variables. Such relationships may be treated as components in separable
point process models for wildfire activity. The resulting models can be used for comparative purposes in order to assess the
predictive performance of the Burning Index.
相似文献
Frederic Paik SchoenbergEmail: |
7.
Thomas Kneib Jörg Müller Torsten Hothorn 《Environmental and Ecological Statistics》2008,15(3):343-364
Precise knowledge about factors influencing the habitat suitability of a certain species forms the basis for the implementation
of effective programs to conserve biological diversity. Such knowledge is frequently gathered from studies relating abundance
data to a set of influential variables in a regression setup. In particular, generalised linear models are used to analyse
binary presence/absence data or counts of a certain species at locations within an observation area. However, one of the key
assumptions of generalised linear models, the independence of observations is often violated in practice since the points
at which the observations are collected are spatially aligned. In this paper, we describe a general framework for semiparametric
spatial generalised linear models that allows for the routine analysis of non-normal spatially aligned regression data. The
approach is utilised for the analysis of a data set of synthetic bird species in beech forests, revealing that ignorance of
spatial dependence actually may lead to false conclusions in a number of situations.
相似文献
Thomas KneibEmail: |
8.
M. M. Manzano-Sarabia E. A. Aragón-Noriega C. A. Salinas-Zavala D. B. Lluch-Cota 《Marine Biology》2007,152(5):1021-1029
Life histories of penaeid shrimp have been classified according to the preferred habitats of postlarval, juvenile, and adult
stages, ranging from exclusively estuarine to exclusively offshore waters. Brown shrimp Farfantepenaeus californiensis migrate to an offshore habitat at the juvenile stage or even a smaller body size. This paper presents results of monthly
samplings from 24 stations over 1 year in the Agiabampo Lagoon complex, a hypersaline lagoon in northwestern Mexico. Five
species of penaeid shrimp were identified, with brown shrimp the most abundant during the year of sampling. Results suggest
that residency of brown shrimp inside this lagoon is longer than reported in previous studies. An interaction between length
and environmental variables (near-surface temperature, salinity, and rainfall) appear to be cues concerning migration.
相似文献
C. A. Salinas-ZavalaEmail: |
9.
We propose a hierarchical modeling approach for explaining a collection of spatially referenced time series of extreme values.
We assume that the observations follow generalized extreme value (GEV) distributions whose locations and scales are jointly
spatially dependent where the dependence is captured using multivariate Markov random field models specified through coregionalization.
In addition, there is temporal dependence in the locations. There are various ways to provide appropriate specifications;
we consider four choices. The models can be fitted using a Markov Chain Monte Carlo (MCMC) algorithm to enable inference for
parameters and to provide spatio–temporal predictions. We fit the models to a set of gridded interpolated precipitation data
collected over a 50-year period for the Cape Floristic Region in South Africa, summarizing results for what appears to be
the best choice of model.
相似文献
Alan E. GelfandEmail: |
10.
We present a simple model of within-group leveling coalitions among male primates. The model assumes that the value of the coalition is the sum of the payoffs of its members, that the individuals payoff is monotonically decreasing with its rank and that coalitions do not cause rank changes. It predicts that mainly mid- to low rankers engage in leveling coalitions, and that most coalition partners are of adjacent ranks. These predictions agree reasonably well with observations in nature. The model also makes the novel predictions that leveling coalitions are found where male mating competition has only a moderate contest component, and that male dominance ranks will become poorly differentiated where leveling coalitions are frequent. Both these predictions are consistent with observations on groups of macaques and baboons. The model also may account for leveling coalitions among egalitarian human foragers, without making additional assumptions about special human capabilities.
相似文献
Carel P. van SchaikEmail: |
11.
Direct observations of the plankton vertical distribution performed from a manned submersible were made in the Charlie-Gibbs Fracture Zone (Atlantic Ocean). Plankton was counted using a standard 3-m2 frame in the depth layer from 170 to 4361 m and plotted for every 50 m. The most abundant components of the macroplankton were pelagic shrimps, chaetognaths and gelatinous animals, with peak of densities corresponding to the main pycnocline. Mucous houses of appendicularians were abundant at 150 m above the seabed—up to 0.07–0.09 m–3, compared to 0–0.006 m–3 in the upper layers. The new observations confirm that the near-bottom peak of appendicularian abundance is characteristic of at least the entire Central Atlantic, and it is not associated with certain biotopes on the bottom.Communicated by O. Kinne, Oldendorf/Luhe
相似文献
G. M. VinogradovEmail: |
12.
Glen D. Johnson 《Environmental and Ecological Statistics》2008,15(3):293-311
Infectious disease surveillance has become an international top priority due to the perceived risk of bioterrorism. This is
driving the improvement of real-time geo-spatial surveillance systems for monitoring disease indicators, which is expected
to have many benefits beyond detecting a bioterror event. West Nile Virus surveillance in New York State (USA) is highlighted
as a working system that uses dead American Crows (Corvus brachyrhynchos) to prospectively indicate viral activity prior to human onset. A cross-disciplinary review is then presented to argue that
this system, and infectious disease surveillance in general, can be improved by complementing spatial cluster detection of
an outcome variable with predictive “risk mapping” that incorporates spatiotemporal data on the environment, climate and human
population through the flexible class of generalized linear mixed models.
相似文献
Glen D. JohnsonEmail: |
13.
Den Boychuk W. John Braun Reg J. Kulperger Zinovi L. Krougly David A. Stanford 《Environmental and Ecological Statistics》2009,16(2):133-151
We consider a stochastic fire growth model, with the aim of predicting the behaviour of large forest fires. Such a model can
describe not only average growth, but also the variability of the growth. Implementing such a model in a computing environment
allows one to obtain probability contour plots, burn size distributions, and distributions of time to specified events. Such
a model also allows the incorporation of a stochastic spotting mechanism.
相似文献
Reg J. KulpergerEmail: |
14.
15.
Rudolf Izsák 《Environmental and Ecological Statistics》2008,15(2):143-156
In this paper some properties and analytic expressions regarding the Poisson lognormal distribution such as moments, maximum
likelihood function and related derivatives are discussed. The author provides a sharp approximation of the integrals related
to the Poisson lognormal probabilities and analyzes the choice of the initial values in the fitting procedure. Based on these
he describes a new procedure for carrying out the maximum likelihood fitting of the truncated Poisson lognormal distribution.
The method and results are illustrated on real data. The computer program for calculations is freely available.
相似文献
Rudolf IzsákEmail: |
16.
In this paper we examine the use of data augmentation techniques for simplifying iterative simulation in the context of both
Bayesian and classical statistical inference for survival rate estimation. We examine two distinct model families common in
population ecology to illustrate our ideas, ring-recovery models and capture–recapture models, and we present the computational
advantage of this approach. We discuss also the fact that problems associated with identifiability in the classical framework
can be overcome using data augmentation, but highlight the dangers in doing so under both inferential paradigms.
相似文献
I. C. OlsenEmail: |
17.
Missing covariate values in linear regression models can be an important problem facing environmental researchers. Existing
missing value treatment methods such as Multiple Imputation (MI), the EM algorithm and Data Augmentation (DA) have the assumption that both observed and unobserved data come from the same distribution,
most commonly a multivariate normal or a conditionally multivariate normal family. These methods do try to incorporate the
missing data mechanism and rely on the assumption of Missing At Random (MAR). We present a DA method which does not rely on
the MAR assumption and can model missing data mechanisms and covariate structure. This method utilizes the Gibbs Sampler as
a tool for incorporating these structures and mechanisms. We apply this method to an ecological data set that relates fish
condition to environmental variables. Notice that the presented DA method detects relationships that are not detected when
other missing data methods are employed.
相似文献
Edward L. BooneEmail: |
18.
Amanda S. Hering Cynthia L. Bell Marc G. Genton 《Environmental and Ecological Statistics》2009,16(2):225-250
We analyze and model the structure of spatio-temporal wildfire ignitions in the St. Johns River Water Management District
in northeastern Florida. Previous studies, based on the K-function and an assumption of homogeneity, have shown that wildfire events occur in clusters. We revisit this analysis based
on an inhomogeneous K-function and argue that clustering is less important than initially thought. We also use K-cross functions to study multitype point patterns, both under homogeneity and inhomogeneity assumptions, and reach similar
conclusions as above regarding the amount of clustering. Of particular interest is our finding that prescribed burns seem
not to reduce significantly the occurrence of wildfires in the current or subsequent year over this large geographical region.
Finally, we describe various point pattern models for the location of wildfires and investigate their adequacy by means of
recent residual diagnostics.
相似文献
Marc G. Genton (Corresponding author)Email: Email: |
19.
Fishery resource management in Chilika lagoon: a study on coastal conservation in the Eastern Coast of India 总被引:1,自引:0,他引:1
A significant proportion of the fishing population comprises small-scale fishermen and many studies illustrate that these
people are exploited by middlemen in the process of fish marketing combined with money lending. The negative dependency gives
rise to poverty and triggers indiscriminate fish catch that threatens fishery resources depletion. This article explores the
root causes of failures in resource-led development from the viewpoint of coastal resource conservation. The study presents
a case study of Chilika lagoon, India and focuses on the interaction between small-scale fishermen and middlemen. The findings
reveal that most of the small-scale fishermen have been exploited by specific middlemen and the underlying causes of the present
fish marketing structure stem from (i) indebtedness and (ii) the unstable situation because of perpetual conflicts over fishery
resources among the fishers across Chilika lagoon. Based on these observations, this article presents some recommendations
on fishery resource conservation from the perspective of a fish marketing structure.
相似文献
Rajib ShawEmail: |
20.
Brooke E. Buckley Walter W. Piegorsch R. Webster West 《Environmental and Ecological Statistics》2009,16(1):53-62
In modern environmental risk analysis, inferences are often desired on those low dose levels at which a fixed benchmark risk
is achieved. In this paper, we study the use of confidence limits on parameters from a simple one-stage model of risk historically
popular in benchmark analysis with quantal data. Based on these confidence bounds, we present methods for deriving upper confidence
limits on extra risk and lower bounds on the benchmark dose. The methods are seen to extend automatically to the case where
simultaneous inferences are desired at multiple doses. Monte Carlo evaluations explore characteristics of the parameter estimates
and the confidence limits under this setting.
相似文献
R. Webster WestEmail: |