Erroneous behaviour of MixSIR, a recently published Bayesian isotope mixing model: a discussion of Moore &amp; Semmens (2008)

Jackson, Andrew L.; Inger, Richard; Bearhop, Stuart; Parnell, Andrew C.

doi:10.1111/j.1461-0248.2008.01233.x

Cited by 185 publications

(168 citation statements)

References 7 publications

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“…Conversely, outputs for obtuse and more variable endmembers were worse. It is also noteworthy that whereas the largest normalized triangular polygon surveyed for this study had a surface area of 43 SD 2 , the polygon used as an example by Jackson et al (2009) when debating the attributes of these types of analyses had a surface area of 693 SD 2 . The fact that this hypothetical polygon was 15 times larger than the largest polygon observed in the meta-analysis conducted for this study could indicate that perceptions of what may constitute 'typical' resource mixing polygons are askew.…”

Section: Discussionmentioning

confidence: 99%

Resource polygon geometry predicts Bayesian stable isotope mixing model bias

Brett¹

2014

Mar. Ecol. Prog. Ser.

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Section: Discussionmentioning

confidence: 99%

Resource polygon geometry predicts Bayesian stable isotope mixing model bias

Brett¹

2014

Mar. Ecol. Prog. Ser.

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“…in late pregnancy and early lactation). Bayesian approaches allow incorporating not only isotopic values, elemental concentrations and fractionation factors within the mixing models, but also the uncertainties involved in all these values, thus providing results that are considerably more robust for quantifying feeding preferences than those in previous modelling approaches Moore and Semmens, 2008;Parnell et al, 2008;Jackson et al, 2009). Furthermore, as the resulting later distributions of the proportions of various sources within the diet of a consumer have associated probabilities, we can use the most likely solution as a single metric for a given dietary component in subsequent analyses Moore and Semmens, 2008;Jackson et al, 2009).…”

Section: Data Analysesmentioning

confidence: 99%

Change in the foraging strategy of female South American sea lions (Carnivora: Pinnipedia) after parturition

Drago¹,

Cardona²,

Crespo³

et al. 2010

Sci. Mar.

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SUMMARY: This study tests the hypothesis that female South American sea lions shift from off-shore, pelagic prey to coastal, benthic prey after parturition in order to reduce the foraging trip duration and hence the time pups remain unattended on the beach during early lactation. The δ 13 C and δ 15 N values of the serum and blood cells of 26 South American sea lion suckling pups from northern Patagonia were used to track the dietary changes of their mothers from late pregnancy to early lactation, after correction for differential isotopic fractionation between tissues. Primary producers and potential prey species were also analysed to establish a baseline for interpreting the stable isotope concentration of serum and blood cells. Isotopic ratios revealed a generalized increase in the consumption of coastal-benthic prey after parturition. Such a generalized postpartum shift will allow females to spend more time on land and look after their pups. The effects of this foraging strategy on the nutritional quality of the female's diet are discussed.Keywords: South American sea lion, diet, feeding strategy, suckling pup, lactating females, Otaria flavescens, stable isotopes, Bayesian mixing models. RESUMEN: Cambio en la estrategia de alimentación de las hembras del león marino sudamericano (Carnivora: Pinnipedia) tras el parto. -El presente estudio pretende comprobar si las hembras del león marino sudamericano adoptan una dieta más bentónica y costera tras el parto, con el fin de reducir la duración de los viajes de alimentación y reducir así el tiempo durante el cual las crías permanecen desatendidas en la playa. Para ello, se determinaron las concentraciones de isótopos estables de carbono y nitrógeno en el suero y las células sanguíneas de 26 crías lactantes de león marino sudamericano del norte de la Patagonia, con el fin de reconstruir la dieta de la madre durante la parte final de la gestación y el inicio de la lactancia, tras la correspondiente corrección del fraccionamiento isotópico entre tejidos. También se analizaron muestras de productores primarios y de presas potenciales para ayudar en la interpretación de los resultados. Las concentraciones de isótopos estables antes y después del parto confirmaron un incremento en el consumo de presas bentónicas costeras tras el parto. Este cambio generalizado de dieta tras el parto permitiría a las hembras incrementar el tiempo que pasan junto a las crías. Se discuten los efectos que esta estrategia puede tener sobre la calidad de la dieta de las hembras.Palabras clave: león marino sudamericano, dieta, estrategias tróficas, lactancia, Otaria flavescens, isótopos estables, modelos de mezcla bayesianos.

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“…To estimate contributions of basal production sources to consumers, we performed mixing analysis with MixSIR version 1.04 with uninformative priors, the model specifies Dirichlet (=1) for priors on all source contributions [52][53][54]. All possible combinations of source contributions are a priori equally likely.…”

Section: Estimation Of Diet Compositionmentioning

confidence: 99%

Herbivory of Omnivorous Fish Shapes the Food Web Structure of a Chinese Tropical Eutrophic Lake: Evidence from Stable Isotope and Fish Gut Content Analyses

Gao

Zhong

Ning

et al. 2017

Water

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Studies suggest that, unlike the situation in temperate lakes, high biomasses of omnivorous fish are maintained in subtropical and tropical lakes when they shift from a turbid phytoplankton-dominated state to a clear water macrophyte-dominated state, and the predation pressure on large-bodied zooplankton therefore remains high. Whether this reflects a higher degree of herbivory in warm lakes than in temperate lakes is debatable. We combined food web studies using stable isotopes with gut content analyses of the most dominant fish species to elucidate similarities and differences in food web structure between a clear water macrophyte-dominated basin (MDB) and a turbid phytoplankton-dominated basin (PDB) of Huizhou West Lake, a shallow tropical Chinese lake. The δ 13 C-δ 15 N biplot of fish and invertebrates revealed community-wide differences in isotope-based metrics of the food webs between MDB and PDB. The range of consumer δ 15 N (NR) was lower in MDB than in PDB, indicating shorter food web length in MDB. The mean nearest neighbor distance (MNND) and standard deviation around MNND (SDNND) were higher in MDB than in PDB, showing a markedly low fish trophic overlap and a more uneven packing of species in niches in MDB than in PDB. The range of fish δ 13 C (CR) of consumers was more extensive in MDB than in PDB, indicating a wider feeding range for fish in MDB. Mixing model results showed that macrophytes and associated periphyton constituted a large fraction of basal production sources for the fish in MDB, while particulate organic matter (POM) contributed a large fraction in PDB. In MDB, the diet of the dominant fish species, crucian carp (Carassius carassius), consisted mainly of vegetal matter (macrophytes and periphyton) and zooplankton, while detritus was the most important food item in PDB. Our results suggest that carbon from macrophytes with associated periphyton may constitute an important food resource for omnivorous fish, and this may strongly affect the feeding niche and the strength of the top-down trophic cascade between fish and zooplankton in the restored, macrophyte-dominated basin of the lake. This dual effect (consumption of macrophytes and zooplankton) may reduce the chances of maintaining the clear water state at the prevailing nutrient levels in the lake, and regular removal of large crucian carp may therefore be needed to maintain a healthy ecosystem state.

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Erroneous behaviour of MixSIR, a recently published Bayesian isotope mixing model: a discussion of Moore & Semmens (2008)

Cited by 185 publications

References 7 publications

Resource polygon geometry predicts Bayesian stable isotope mixing model bias

Resource polygon geometry predicts Bayesian stable isotope mixing model bias

Change in the foraging strategy of female South American sea lions (Carnivora: Pinnipedia) after parturition

Herbivory of Omnivorous Fish Shapes the Food Web Structure of a Chinese Tropical Eutrophic Lake: Evidence from Stable Isotope and Fish Gut Content Analyses

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