The standard error of a weighted mean concentration—I. Bootstrapping vs other methods

Gatz, Donald F.; Smith, Luther

doi:10.1016/1352-2310(94)00210-c

Cited by 119 publications

(98 citation statements)

References 11 publications

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“…To investigate associations between different size categories and environmental conditions, weighted averages for all categories were plotted for organic matter content and mean shear stress. Standard errors of weighted averages were calculated following Cochran (1977), as suggested by Gatz and Smith (1995). LOI and mean shear stress were chosen among the other environmental factors based on biological knowledge and lack of collinearity, which was likely due to different levels of precision in the estimation, i.e., LOI values were measured in the field and therefore better reflected local variability, while mean shear stress values were estimated on larger areas by models that did not account for factors locally modifying the hydrodynamic regime.…”

Section: Discussionmentioning

confidence: 99%

The body-size structure of macrobenthos changes predictably along gradients of hydrodynamic stress and organic enrichment

et al. 2015

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the smallest size categories in habitats with high hydrodynamic energy. This was probably due to the local sheltering effects, which together with biodeposition also increased organic matter in the sediment, likely favoring large deposit feeders as well. Our results suggest that body size can be a useful trait for estimating effects of anthropogenic stressors, such as organic enrichment or alteration of hydrodynamic regime and could therefore be effectively included in current monitoring programs of intertidal macrobenthic communities.

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Section: Discussionmentioning

confidence: 99%

The body-size structure of macrobenthos changes predictably along gradients of hydrodynamic stress and organic enrichment

et al. 2015

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“…Depth of capture was reported from soundings recorded at the time of net recovery. We estimated standard errors around weighted means according to Cochran (1977), a method that provides similar estimates of variance around weighted means to those of more intensive bootstrapping estimation methods (Gatz and Smith 1995). Comparisons of weighted mean depth of whiteWsh capture and thermocline depth between invaded versus non-invaded years were performed with t tests assuming unequal variance using the Welch modiWcation of degrees of freedom (Zar 1999).…”

Section: Depth Of Benthic Invertebrates and Lake Whitewshmentioning

confidence: 99%

Resource switching in fish following a major food web disruption

2009

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Dreissenid mussels (Dreissena polymorpha and D. bugensis) have re-engineered Great Lakes ecosystems since their introduction in the late 1980s. Dreissenids can have major indirect impacts on profundal habitats by redirecting nutrients and energy away from pelagic production (which supplies profundal production) and depositing nutrients and energy in the nearshore zones that they occupy. However, strong empirical evidence for the effects of this redirection of resources on fish populations is currently lacking. Here, we report significant shifts in isotopic signatures, depth distribution and diets of a coldwater profundal fish population that are all consistent with a greater reliance on nearshore resources after the establishment of dreissenid mussels in South Bay, Lake Huron. Isotopic signatures of scales collected from 5-year-old lake whitefish (Coregonus clupeaformis) demonstrated remarkable stability over the 50-year period prior to the establishment of dreissenids (1947-1997) and a sudden and significant change in isotopic signatures (3 per thousand enrichment in delta13C and 1 per thousand depletion in delta(15)N) after their establishment (2001-2005). These dramatic shifts in isotopic signatures were accompanied by a coincident shift in the mean depth of capture of lake whitefish towards the nearshore. A comparison of previously unpublished pre-invasion diets of lake whitefish from South Bay with contemporary diets collected between 2002 and 2005 also indicate a greater reliance on nearshore prey after the invasion of dreissenid mussels. This study is the first to report changes in the carbon source available to lake whitefish associated with restructured benthic communities after the appearance of dreissenid mussels. Further, this study contributes to a growing body of work that demonstrates the ecological insights that can be gained through isotopic analysis of archived fish bony tissues in ecosystems that have experienced significant levels of disturbance.

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“…Due to an unbalanced number of observation months on different individuals, the reported means and standard errors were weighted by the number of observation months for each individual and season. Weighted standard errors were estimated according to Cochrane (1977) following Gatz & Smith (1995). We used linear mixed models (LMM) to evaluate effects of sex and season on distance to nearest home range border and the spatial clustering of dens.…”

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confidence: 99%

Temporal patterns of den use suggest polygamous mating patterns in an obligate monogamous mammal

et al. 2012

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The standard error of a weighted mean concentration—I. Bootstrapping vs other methods

Cited by 119 publications

References 11 publications

The body-size structure of macrobenthos changes predictably along gradients of hydrodynamic stress and organic enrichment

The body-size structure of macrobenthos changes predictably along gradients of hydrodynamic stress and organic enrichment

Resource switching in fish following a major food web disruption

Temporal patterns of den use suggest polygamous mating patterns in an obligate monogamous mammal

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