A new approach to the solution of the linear mixing model for a single isotope: application to the case of an opportunistic predator

Hall-Aspland, Sophie; Hall, A. P.; Rogers, Tracey L.

doi:10.1007/s00442-004-1783-0

Cited by 40 publications

(19 citation statements)

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“…A 4-prey mixing model incorporating a Moore-Penrose pseudoinverse analysis (Hall-Aspland et al 2005) was applied to vibrissae δ 15 N values from Antarctic seals A, B 1 , B 2 and C 1 to determine the proportions of prey consumed. The method is applicable to the case of a single isotope, in this case nitrogen N, and a set of mixing fractions (f 1 , f 2 , ..., f k , ..., f n ) associated with a set of prey isotopic signatures (δ 15 N 1 , δ 15 N 2 , ..., δ 15 N k , ..., δ 15 N n ), which are assumed to produce a mixture δ 15 N Mix for the prey.…”

Section: Methodsmentioning

confidence: 99%

Stable carbon and nitrogen isotope analysis reveals seasonal variation in the diet of leopard seals

Hall-Aspland¹,

Rogers²,

Canfield³

2005

Mar. Ecol. Prog. Ser.

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In order to assess seasonal and spatial changes in diet, the δ 15 N and δ 13 C signatures of vibrissae from leopard seals Hydrurga leptonyx obtained from Prydz Bay, Eastern Antarctica, were compared with those of a captive seal on a known diet. Using the isotopic signatures of known prey, and those revealed by the assimilation rates of vibrissae, we constructed trophic models to estimate diet composition. Assuming that current diet was reflected only in the actively growing portion of the vibrissae, the latter were sectioned. Each section was then analysed independently. Two methods of analysis of the vibrissae isotopic data were compared in order to ascertain the best analytical approach to these data. A simple linear model and a von Bertalanffy growth model were used to estimate section age and vibrissae growth rates. The age predictions of the von Bertalanffy growth model allowed the existence of repeated seasonal oscillations in both δ 15 N and δ 13 C values. Temporal variations in stable isotope ratios consistent with changes in source of feeding (inshore vs. offshore) and prey types were identified in the Antarctic leopard seals, but not in the captive seal. This preliminary study has possible implications for the use of vibrissae to track dietary changes over time and may serve as a tool for investigating foraging preferences of highly mobile or migratory pinniped species.KEY WORDS: Leopard seal · Stable isotope · Vibrissae · von Bertalanffy · Antarctic · Prey switching Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 305: [249][250][251][252][253][254][255][256][257][258][259] 2005 al. 2004). Changes along the length of whale baleen have provided an isotopic record of seasonal variation in the location of feeding (Best & Schell 1996, Hobson & Schell 1998, Lee et al. 2005) and diet (Schell et al. 1989, Hobson & Schell 1998. Vibrissae may be a useful tissue for isotopic analysis and the study of longterm and seasonal dietary changes. Vibrissae lengths may be transformed into measurements of time, which can then be related to isotopic ratios.Growth rates have been determined for a number of pinniped species using dated vibrissae. Harbour seal vibrissae growth rates were irregular (Hirons et al. 2001) or variable (Zhao & Schell 2004), while growth rates in the case of grey seals Halichoerus grypus varied according to the length and age of the vibrissae and involved asynchronous shedding and discontinuous replacement (Greaves et al. 2004). Conversely, Steller sea lions Eumetobias jubatus displayed more consistent growth and annual retention of their vibrissae (Hirons et al. 2001). Greaves et al. (2004) suggested that vibrissae growth follows a von Bertalanffy growth curve.This study aims to transform vibrissae lengths into time lines using both a simple linear and von Bertalanffy growth model. With information gained through stable carbon and nitrogen isotope analysis of sequentially segmented vibrissae, their potential as indicators of seasonal cha...

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Section: Methodsmentioning

confidence: 99%

Stable carbon and nitrogen isotope analysis reveals seasonal variation in the diet of leopard seals

Hall-Aspland¹,

Rogers²,

Canfield³

2005

Mar. Ecol. Prog. Ser.

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“…ISOSOURCE samples across all possible resource combinations at user-defined intervals, identifies any points producing isotope values consistent with the observed mixture, and then summarizes the distribution of those valid points (mean, standard deviation, ranges, etc.). This allows researchers to model resource contributions in circumstances where no unique solution exists (e.g., Benstead et al, 2006;Codron et al, 2009;Hall-Aspland et al, 2005;Urton and Hobson, 2005;Coltrain, 2009). SISUS achieves the same end in a more efficient and accurate way, analyzing multiple mixtures simultaneously and allowing for differences in isotopic enrichment factors, source concentration, and assimilation efficiency (Erhardt, 2007(Erhardt, , 2010.…”

Section: Sisusmentioning

confidence: 99%

Stable isotopes, diet, and taphonomy: a look at using isotope-based dietary reconstructions to infer differential survivorship in zooarchaeological assemblages

Ugan

Coltrain

2012

Journal of Archaeological Science

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“…The IsoSource model has been employed in recent food web studies (Hall-Aspland et al 2005;Benstead et al 2006;Gerardo Herrera et al 2006;Herwig et al 2007), but the utilization of IsoSource to approach the issue of contaminant transfer in food webs is far less common. In our study, we found a correlation between the mean contributions of some OM sources and the concentrations of THg and MeHg in consumers.…”

Section: Links Between Hg Concentrations and Om Sourcesmentioning

confidence: 99%

Sources of organic matter and methylmercury in littoral macroinvertebrates: a stable isotope approach

et al. 2009

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The main objective of this study was to assess organic matter (OM) and methylmercury (MeHg) sources for freshwater littoral macroinvertebrate primary consumers. The carbon and nitrogen stable isotope ratios (d 13 C, d 15 N) of sources (epiphytes, macrophytes, suspended particulate matter _SPM) and of macroinvertebrate consumers were measured in a fluvial lake with extensive macrophyte beds (emergent and submerged). To determine the relative contribution of each OM source to macroinvertebrate diets we used the IsoSource model that examines all possible combinations of solutions for each source. Total and MeHg concentrations of consumers were also measured. Results show that epiphytes and macrophytes are dominant in the diet of macroinvertebrates, especially in early summer (July). In mid-summer (August), SPM constitutes a non-negligible OM source to the primary consumers. Hg concentrations were higher in epiphytes than in the other OM sources. The proportion of epiphytes in macroinvertebrate diet was positively correlated with the percentage of MeHg in their tissues. There was no relationship between SPM assimilation and Hg concentration in macroinvertebrate consumers. These results suggest that epiphytes and macrophytes constitute the main pathway of Hg bioaccumulation in littoral food webs.

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A new approach to the solution of the linear mixing model for a single isotope: application to the case of an opportunistic predator

Cited by 40 publications

References 13 publications

Stable carbon and nitrogen isotope analysis reveals seasonal variation in the diet of leopard seals

Stable carbon and nitrogen isotope analysis reveals seasonal variation in the diet of leopard seals

Stable isotopes, diet, and taphonomy: a look at using isotope-based dietary reconstructions to infer differential survivorship in zooarchaeological assemblages

Sources of organic matter and methylmercury in littoral macroinvertebrates: a stable isotope approach

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