Dear Alessandro,

The following publications cover the answer to yourquestion.

1-C.M. Wurster, D.A. McFarlane, M.I. Bird, P. Ascough, and N.B. Athfield – Stable isotopes of subfossil bat guano as a long-term

environmental archive: insights from a Grand Canyon cave deposit. Journal of Cave and Karst Studies, v. 72, no. 2, p. 111–121. DOI:

10.4311/jcks2009es0109

STABLE ISOTOPES OF SUBFOSSIL BAT GUANO AS A

LONG-TERM ENVIRONMENTAL ARCHIVE: INSIGHTS

FROM A GRAND CANYON CAVE DEPOSIT

CHRISTOPHER M. WURSTER1

*, DONALD A. MCFARLANE2

, MICHAEL I. BIRD1

, PHILIPPA ASCOUGH3

, AND

NANCY BEAVAN ATHFIELD4

Abstract: We investigated the utility of subfossil bat guano as a paleoenvironmental

archive by comparing elemental ratios and d13C, d15N, and dD values of various simple extracts from bulk material. Solvent-extracted guano yielded consistent C:N and N:H ratios, and d13C values of solvent-extracted guano exhibited strong covariation with dD values, as well as with the d13C values of other simple extracts (bulk guano, bulk lipid). The results suggest that reliable records are easily recovered for d13C, and also indicate that d15N values may have utility as a paleoenvironmental archive. Despite coeval d13C values of bulk guano and solvent-extracted guano, 14C ages of the different fractions did not always yield similar ages, indicating that future refinement of a suitable extraction protocol is required. Applying these protocols to an ancient bat guano deposit allowed us to infer that climate at the Grand Canyon during the late Pleistocene was more variable and generally cooler and wetter, relative to Holocene climate. We conclude that guano deposits are an underutilized, yet powerful continental paleoenvironmental archive of climate change for semi-arid and tropical regions.

2-Methods in Ecology and Evolution 2013, 4, 944–953

Important impacts of tissue selection and lipid extraction

on ecological parameters derived from stable isotope

ratios

Matthew J. Perkins1

*, Robbie A. McDonald2

, F. J. Frank van Veen1

, Simon D. Kelly3

,

Gareth Rees3 and Stuart Bearhop1

1

Centre for Ecology & Conservation, School of Biosciences, University of Exeter, Cornwall Campus, Penryn, Cornwall, TR10

9EZ, UK; 2

Environment and Sustainability Institute, University of Exeter, Cornwall Campus, Penryn, Cornwall, TR10 9EZ, UK;

and 3

Food and Environment Research Agency, York, Sand Hutton, YO41 1LZ, UK

Summary

1. The nitrogen (d15N) and carbon (d13C) isotope ratios of animal tissues can help identify the composition of diets and open up a myriad of ecological applications. However, consumers do not ingest or assimilate all components of food items, and it is not well understood how sampling different tissues of sources and consumers

may affect isotopic values ascribed, and thereby how such variation affects derived ecological measures.

2. Utilizing a simple prey–predator feeding relationship in insects, we examined isotopic differences in soft, exoskeleton and whole tissues using samples with and without lipid extraction. As a derived ecological measure, we calculated trophic discrimination factors, changes in d15N or d13C between source and consumer, for the different prey–predator tissue combinations.

3. Lipid extraction did not affect d15N values, and we found significant tissue differences in d15N that varied between prey and predator.Lipid extraction enrichedd13C valuesinmostinstances, andit was only after extraction oflipids that we observed consistent depletion of d13Cin exoskeleton relative to soft tissuesin prey and predator.

4. Isotopic differences between tissue types propagated marked variation in derived ecological parameters. Common sampling practice using whole tissue for prey and predator (whole/whole) resulted in a trophic discrimination factor of 048& for d15N, compared with correct factors of 097& (soft/whole) and 218& (soft/soft) using

prey soft tissue actually ingested by the predator. For d13C, variation across discrimination factors was less, with whole/whole tissue of 014&, whilst correct factors were 055& (soft/whole) and 004& (soft/soft).

5. Our results indicate that tissue selection and preparation are important considerations for isotopic studies using arthropods. Lipid extraction is necessary to derive accurate d13C values based on proteins, whilst consequences

of tissue selection are likely context-dependent: In poorly defined systems where sources are isotopically similar or have larger variance, our results indicate that tissue selection within sources is important to avoid significant error, whether estimating trophic positions or dietary proportions using mixing models. In such cases, we strongly recommend exclusion of source materials not assimilated in consumers.

http://onlinelibrary.wiley.com/doi/10.1111/2041-210X.12098/pdf

3-Ecology Letters, (2008) 11: 1328–1337 doi: 10.1111/j.1461-0248.2008.01252.x

Coupling of canopy and understory food webs

by ground-dwelling predators

Robert M. Pringle1

* and

Kena Fox-Dobbs2

1

Department of Biological

Sciences, Stanford University,

Stanford, CA 94305, USA

2

Department of Zoology and

Physiology, University of

Wyoming, Laramie, WY 82071,

USA

*Correspondence: E-mail:

[email protected]

Author contributed equally to

this work. E-mail:

[email protected]

Abstract

Understanding food-web dynamics requires knowing whether species assemblages are compartmentalized into distinct energy channels, and, if so, how these channels are structured in space. We used isotopic analyses to reconstruct the food web of a Kenyan wooded grassland. Insect prey were relatively specialized consumers of either C3 (trees and shrubs) or C4 (grasses) plants. Arboreal predators (arthropods and geckos) were also specialized, deriving c. 90% of their diet from C3-feeding prey. In contrast, grounddwelling predators preyed considerably upon both C3- and C4-feeding prey. This asymmetry suggests a gravity-driven subsidy of the terrestrial predator community, whereby tree-dwelling prey fall and are consumed by ground-dwelling predators. Thus, predators in general couple the C3 and C4 components of this food web, but grounddwelling

predators perform this ecosystem function more effectively than tree-dwelling

ones. Although prey subsidies in vertically structured terrestrial habitats have received little attention, they are likely to be common and important to food-web organization.

4-Proc. R. Soc. B (2007) 274, 2471–2480 doi:10.1098/rspb.2007.0700

Published online 7 August 2007

Stable isotopes, ecological integration and

environmental change: wolves record atmospheric

carbon isotope trend better than tree rings

Joseph K. Bump1,*, Kena Fox-Dobbs2

, Jeffrey L. Bada3

, Paul L. Koch2

,

Rolf O. Peterson1 and John A. Vucetich1

1

School of Forest Resources and Environmental Science, Michigan Technological University, Houghton, MI 49931, USA 2

Earth & Planetary Sciences Department, University of California, Santa Cruz, CA 95064, USA 3

Scripps Institute of Oceanography, La Jolla, San Diego, CA 92093, USA

Large-scale patterns of isotope ratios are detectable in the tissues of organisms, but the variability in these patterns often obscures detection of environmental trends. We show that plants and animals at lower trophic levels are relatively poor indicators of the temporal trend in atmospheric carbon isotope ratios

(d13C) when compared with animals at higher trophic levels. First, we tested how differences in atmospheric d13C values were transferred across three trophic levels. Second, we compared contemporary d13C trends (1961–2004) in atmospheric CO2 to d13C patterns in a tree species (jack pine, Pinus

banksiana), large herbivore (moose, Alces alces) and large carnivore (grey wolf, Canis lupus) from North America. Third, we compared palaeontological (approx. 30 000 to 12 000 14C years before present) atmospheric CO2 trends to d13C patterns in a tree species (Pinus flexilis, Juniperus sp.), a megaherbivore (bison, Bison antiquus) and a large carnivore (dire wolf, Canis dirus) from the La Brea tar pits (southern California, USA) and Great Basin (western USA). Contrary to previous expectations, we found that the environmental isotope pattern is better represented with increasing trophic level. Our results indicate that museum specimens of large carnivores would best reflect large-scale spatial and temporal patterns of

carbon isotopes in the palaeontological record because top predators can act as ecological integrators of environmental change.

Hoping this will be helpful,

Rafik

Dear Rafik, that was really really helpfull thanks a lot. Can I ask u one big favour? Do you have perhaps also the manuscript in pdf from Schimmelmann and De Niro 1986? I cannot find it (free) online. I guess that would be really helpfull. Ale

Dear Alessandro,

Please send me the full details of the paper and I will order it for you.

Rafik

Rafik actually I was thinking about those two manuscripts what do you think?

1 - Schimmelmann, A., and DeNiro, M.J., 1986a, Stable isotopic studies on

chitin, measurements on chitin/chitosan isolates and d-glucosamine

hydrochloride from chitin, in Muzzarelli, R., Jeuniauz, C., and

Gooday, G., eds., Chitin in nature and technology, New York,

Plenum, p. 357–364.

2 - Schimmelmann, A., and DeNiro, M.J., 1986b, Stable isotopic studies on

chitin. II: The 13C/12C and 15N/14N ratios in arthropod chitin:

Contributions in Marine Science, v. 29, p. 113–130.

That would be great, I don´t know how to thank you