The Importance of Statistical Power When Testing for Independence in Animal Movements

Slade, Norman A.

doi:10.2307/1938526

Cited by 59 publications

(17 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…This type of analysis is usually used to determine at what temporal scale data are sufficiently independent to be used as independent observations (Swihart & Slade, 1985; Underwood, 1997). The data used to construct these relationships were assumed to be independent after the autocorrelogram analysis showed no statistically significant temporal autocorrelation for all the possible time lags (Swihart & Slade, 1985, 1986). Considering the short‐term nature of these experiments in comparison with the whole summer season and the outcome of partial autocorrelogram analysis, we concluded that the time factor would have only a mild effect on the estimation of the regression parameters despite the lack of genuine replication.…”

Section: Discussionsupporting

confidence: 92%

Effects of experimentally induced cyanobacterial blooms on crustacean zooplankton communities

2003

View full text Add to dashboard Cite

SUMMARY 1. Large in situ enclosures were used to study the effects of experimentally induced cyanobacterial blooms on zooplankton communities. A combination of N and P was added to shallow (2 m) and deep enclosures (5 m) with the goal of reducing the TN : TP ratio to a low level (∼5 : 1) to promote cyanobacterial growth. After nutrient additions, high biomass of cyanobacteria developed rapidly in shallow enclosures reaching levels only observed during bloom events in eutrophic lakes. 2. In the shallow enclosures, particulate phosphorus (PP) was on average 35% higher in comparison with deep enclosures, suggesting that depth plays a key role in P uptake by algae. Phytoplankton communities in both deep and shallow enclosures were dominated by three cyanobacteria species –Aphanizomenon flos‐aquae, Anabaena flos‐aquae and Microcystis aeruginosa– which accounted for up to 70% of total phytoplankton biomass. However, the absolute biomass of the three species was much higher in shallow enclosures, especially Aphanizomenon flos‐aquae. The three cyanobacteria species responded in contrasting ways to nutrient manipulation because of their different physiology. 3. Standardised concentrations of the hepatotoxic microcystin‐LR increased as a result of nutrient manipulations by a factor of four in the treated enclosures. Increased biomass of inedible and toxin producing cyanobacteria was associated with a decline in Daphnia pulicaria biomass caused by a reduction in the number of individuals with a body length of >1 mm. Zooplankton biomass did not decline at moderate cyanobacteria biomass, but when cyanobacteria reached high biomass large cladocerans were reduced. 4. Our results demonstrate that zooplankton communities can be negatively affected by cyanobacterial blooms and therefore the potential to use herbivory to reduce algal blooms in such eutrophic lakes appears limited.

show abstract

Section: Discussionsupporting

confidence: 92%

Effects of experimentally induced cyanobacterial blooms on crustacean zooplankton communities

2003

View full text Add to dashboard Cite

show abstract

“…Secondly, we side‐stepped the problem of temporal autocorrelation in the data (Swihart & Slade 1985, 1986; Solow 1989; Cresswell & Smith 1992; Rooney, Wolfe & Hayden 1998; Salvatori et al . 1999) by using the individual as the sampling unit for estimating usage.…”

Section: Discussionmentioning

confidence: 99%

“…This assumption relied on the central limit theorem and therefore required that sampling units were independent. By using the individual, rather than the trip or the satellite location, as our sampling unit, we guaranteed that variability in spatial usage would not be underestimated as a result of serial autocorrelation (Swihart & Slade 1985, 1986; Hansteen, Andreassen & Ims 1997). We followed the advice of Otis & White (1999) that ‘if the objective of the study is to make inferences about the population of animals from a representative sample of radio‐tagged individuals then the appropriate sampling or experimental unit is the individual, not the single location’.…”

Section: Methodsmentioning

confidence: 99%

Using satellite telemetry and aerial counts to estimate space use by grey seals around the British Isles

Matthiopoulos

McConnell

Duck

et al. 2004

Journal of Applied Ecology

View full text Add to dashboard Cite

Summary1. In the UK, resolving conflicts between the conservation of grey seals, the management of fish stocks and marine exploitation requires knowledge of the seals' use of space. We present a map of grey seal usage around the British Isles based on satellite telemetry data from adult animals and haul-out survey data. 2. Our approach combined modelling and interpolation. To model the seals' association with particular coastal sites (the haul-outs), we divided the population into subpopulations associated with 24 haul-out groups. Haul-out-specific maps of accessibility were used to supervise usage estimation from satellite telemetry. The mean and variance of seal numbers at each haul-out group were obtained from haul-out counts. The aggregate map of usage for the entire population was produced by adding together the haulout-specific usage maps, weighted by mean number of animals using that haul-out. 3. Seal usage was primarily concentrated (i) off the northern coasts of the British Isles, (ii) closer to the coast than might be expected purely on the basis of accessibility from the haul-outs and (iii) in a limited number of marine hot-spots. 4. Although our results currently represent the best estimate of how grey seals use the marine environment around Britain, they are neither definitive nor equally precise for all haul-outs. Further data collection should focus in the south-west of the British isles and aerial counts should be repeated for all haul-outs. Synthesis and applications.This work provides environmental managers with current estimates of grey seal usage and describes a methodology for maximizing data efficiency. Our results could guide government departments in licensing marine exploitation by the oil industry, in estimating grey seal predation pressure on vulnerable or economically important prey and in delineating marine special areas of conservation (SAC). Our finding that grey seal usage is characterized by a limited number of hot-spots means that the species is particularly suited to localized conservation efforts.

show abstract

“…Se realizó una prueba de independencia de los datos (ArcMAp versión 9.2, y la extensión "Hawths Tools"), para verificar si el intervalo escogido para la toma de datos fue el adecuado (Swihart & Slade 1985, 1986Rodgers et al 2005).…”

Section: Materiales Y Métodosunclassified

Dinámica espacial de la liebre ibérica (Lepus granatensis) en una zona sometida a restauración vegetal (escombrera de lignitos Meirama, a Coruña-España). Spatial dynamics of Iberian hare (Lepus granatensis) in an area under vegetation restoration (Meirama lignite dump, A Coruña-Spain).

Jaramillo-Fayad

Pérez‐Torres

Rodríguez

et al. 2015

AZM

View full text Add to dashboard Cite

. 2015. Dinámica espacial de la Liebre Ibé-rica (Lepus granatensis) en una zona sometida a restauración vegetal (Escombrera de lignitos Meirama, A Coruña-España). Acta Zoológica Mexicana (n.s.), 31(3): 380-390. RESUMEN.La Liebre Ibérica (Lepus granatensis) es una de las principales especies cinegéticas en España. Presenta una amplia distribución y poblaciones estables en casi la totalidad del territorio. En Galicia, en los últimos años, factores como la modificación del hábitat, el aumento en la presión de caza y la construcción de infraestructuras viales han venido afectando a muchas poblaciones, llevando a la especie a una reducción e inclusive desaparición en algunas zonas atlán-ticas. La acelerada modificación de los hábitats naturales ha obligado a la especie a ocupar nuevos territorios, no existiendo actualmente información sobre la forma en la que el animal responde a estos nuevos medios. Es el caso de una población de Liebre Ibérica que habita en la Escombrera Exterior del Yacimiento Minero de Meirama (A Coruña), zona sometida a un proceso de restauración vegetal. En este trabajo se pretende evaluar la dinámica espacial de Lepus granatensis bajo las condiciones particulares de la escombrera. Para tal fin, se radio-marcaron 8 ejemplares que fueron seguidos durante 18 meses, en jornadas de las 18:00 a 08:00 horas, cada 10 días. Se registraron 1671 rumbos que generaron 547 localizaciones. Los resultados de rango de acción, área núcleo y superposición, fueron analizados por medio de pruebas de Anova de medidas repetidas, rangos asignados de Wilcoxon, Chi-cuadrado, Bonferroni y t. Los análisis muestran que los terrenos restaurados con coníferas fueron seleccionados por las liebres por encima de los hábitats con características más cercanas a los naturales. El rango de acción descrito (24 ha) es inferior al encontrado en otros estudios en la península ibérica. La heterogeneidad vegetal, la importante fuente de alimentación que representan los retoños de pinos y eucaliptos y la gran disponibilidad de encames, son la base para que en estos nuevos hábitats pueda mantenerse una población viable y estable de Liebre Ibérica. Palabras clave: Liebre Ibérica, Rango de acción, Área Núcleo Dinámica Espacial, Hábitas Intervenidos, Galicia. ABSTRACT. The Iberian hare (Lepus granatensis)is one of the primary game species in Spain, has a wide distribution and stable populations in almost the entire territory. In Galicia, in recent years, factors such as habitat modification, increased hunting pressure and the construction of road infrastructure have been affecting many populations; therefore, the species has been reduced and even has disappeared being reduced and even disappeared in some Atlantic areas. Rapid modification of natural habitats has forced the species to occupy new territories, there is currently no information on how the animal responds to these new media. This is the case in a population of Iberian hare, inhabiting Foreign Mining Dump Reservoir Meirama (A Coruña), an area under vegetation restoration process....

show abstract

The Importance of Statistical Power When Testing for Independence in Animal Movements

Cited by 59 publications

References 17 publications

Effects of experimentally induced cyanobacterial blooms on crustacean zooplankton communities

Effects of experimentally induced cyanobacterial blooms on crustacean zooplankton communities

Using satellite telemetry and aerial counts to estimate space use by grey seals around the British Isles

Dinámica espacial de la liebre ibérica (Lepus granatensis) en una zona sometida a restauración vegetal (escombrera de lignitos Meirama, a Coruña-España). Spatial dynamics of Iberian hare (Lepus granatensis) in an area under vegetation restoration (Meirama lignite dump, A Coruña-Spain).

Contact Info

Product

Resources

About