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1. Domestic herbivore mobility and herd management at Bronze Age Politiko-Troullia, Cyprus

   https://doi.org/10.1007/s12520-025-02226-2  

   Pilaar_Birch, Suzanne E; Metzger, Mary; Ridder, Elizabeth; Falconer, Steven E; Fall, Patricia L (May 2025, Archaeological and Anthropological Sciences)

   Abstract This study presents stable isotope analysis of carbon (δ¹³C) and oxygen (δ¹⁸O) from goat, sheep, and cattle teeth excavated from the Bronze Age village of Politiko-Troullia, Cyprus. The δ¹⁸O of local water sources and converted δ¹⁸O_{drinking water}values are used to demonstrate the dietary inputs for goats as compared to those for sheep and cattle. We infer the browsing and grazing behavior of these taxa to reflect different herd management strategies implemented by agropastoral villages during the development of pre-urban Bronze Age society. The δ¹³C and δ¹⁸O values suggest higher mobility and a more diverse diet for goats in contrast to more constrained ranges and dietary supplementation for sheep and cattle. These conclusions augment our interpretations of animal management at Politiko-Troulliabased on previous osteological and isotopic analysis of faunal remains from the site. We contextualize our findings with those of closely comparable faunal and isotopic studies of herd management at contemporaneous Bronze Age settlements. 

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2. Mesophotic corals in Hawai‘i maintain autotrophy to survive low-light conditions

   https://doi.org/10.1098/rspb.2023.1534  

   Backstrom, Callum H; Padilla-Gamiño, Jacqueline L; Spalding, Heather L; Roth, Melissa S; Smith, Celia M; Gates, Ruth D; Rodrigues, Lisa J (February 2024, Proceedings of the Royal Society B: Biological Sciences)

   In mesophotic coral ecosystems, reef-building corals and their photosynthetic symbionts can survive with less than 1% of surface irradiance. How depth-specialist corals rely upon autotrophically and heterotrophically derived energy sources across the mesophotic zone remains unclear. We analysed the stable carbon (δ¹³C) and nitrogen (δ¹⁵N) isotope values of aLeptoseriscommunity from the ‘Au‘au Channel, Maui, Hawai‘i (65–125 m) including four coral host species living symbiotically with three algal haplotypes. We characterized the isotope values of hosts and symbionts across species and depth to compare trophic strategies. Symbiontδ¹³C was consistently 0.5‰ higher than hostδ¹³C at all depths. Mean colony host and symbiontδ¹⁵N differed by up to 3.7‰ at shallow depths and converged at deeper depths. These results suggest that both heterotrophy and autotrophy remained integral to colony survival across depth. The increasing similarity between host and symbiontδ¹⁵N at deeper depths suggests that nitrogen is more efficiently shared between mesophotic coral hosts and their algal symbionts to sustain autotrophy. Isotopic trends across depth did not generally vary by host species or algal haplotype, suggesting that photosynthesis remains essential toLeptoserissurvival and growth despite low light availability in the mesophotic zone. 

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3. Stable isotopes disentangle niche partitioning and co‐occurrence in a multi‐species marine mutualism

   https://doi.org/10.1111/oik.10553  

   Titus, Benjamin M; Froehlich, Catheline_Y M; Vondriska, Clayton; Baker, Ronald; Caves, Eleanor M (February 2025, Oikos)

   Ecologists have long sought general explanations for the co‐occurrence of ecologically similar taxa. Niche theory explains co‐occurrence via functional differences among taxa that reduce competition and promote resource partitioning. Alternatively, the unified neutral theory of biodiversity and biogeography suggests that co‐occurrence can be attributed to stochastic processes, and thus, presupposes that ecologically similar species that occur in sympatry are functionally analogous. We test these hypotheses using the most diverse crustacean‐sea anemone symbiosis from coral reefs in the Tropical Western Atlantic. δ¹³C and δ¹⁵N stable isotope analyses of six crustacean symbionts that co‐occur around the host anemoneBartholomea annulataexhibit highly differentiated isotopic niche space spanning several trophic levels. As multiple crustacean species within the symbiosis have been documented as cleaners that remove parasites from reef fishes, we extended our investigation into the broader cleaner community. Our stable isotope analyses of cleaners shows that Pederson's cleaner shrimpAncylomenes pedersoniexhibits the highest δ¹⁵N isotopic values‐ significantly higher than all other putative cleaner species and consistent with expectations of a dedicated cleaning lifestyle. However, for other species previously described or observed to clean reef fishes, includingPericlimenes yucatanicus, Stenopus hispidusandStenorhynchus seticornis,δ¹⁵N isotopic values were substantially lower, raising questions about the degree to which these species rely on cleaning interactions to meet their nutritional requirements. Taken together, our data are consistent with the expectations of niche theory: co‐occurring symbiotic crustaceans have highly partitioned niche space with low levels of functional redundancy. 

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4. Sea otter effects on trophic structure of seagrass communities in southeast Alaska

   https://doi.org/10.3354/meps13819  

   Raymond, WW; Schram, JB; Eckert, GL; Galloway, AWE (September 2021, Marine Ecology Progress Series)

   Previous research in southeast Alaska on the effects of sea otters Enhydra lutris in seagrass Zostera marina communities identified many but not all of the trophic relationships that were predicted by a sea otter-mediated trophic cascade. To further resolve these trophic connections, we compared biomass, carbon (δ 13 C) and nitrogen (δ 15 N) stable isotope (SI), and fatty acid (FA) data from 16 taxa at 3 sites with high and 3 sites with low sea otter density (8.2 and 0.1 sea otters km -2 , respectively). We found lower crab and clam biomass in the high sea otter region but did not detect a difference in biomass of other seagrass community taxa or the overall community isotopic niche space between sea otter regions. Only staghorn sculpin differed in δ 13 C between regions, and Fucus , sugar kelp, butter clams, dock shrimp, and shiner perch differed in δ 15 N. FA analysis indicated multivariate dissimilarity in 11 of the 15 conspecifics between sea otter regions. FA analysis found essential FAs, which consumers must obtain from their diet, including 20:5ω3 (EPA) and 22:6ω3 (DHA), were common in discriminating conspecifics between sea otter regions, suggesting differences in consumer diets. Further FA analysis indicated that many consumers rely on diverse diets, regardless of sea otter region, potentially buffering these consumers from sea otter-mediated changes to diet availability. While sea otters are major consumers in this system, further studies are needed to understand the mechanisms responsible for the differences in biomarkers between regions with and without sea otters. 

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5. Stable isotope fingerprinting traces essential amino acid assimilation and multichannel feeding in a vertebrate consumer

   https://doi.org/10.1111/2041-210X.13903  

   Manlick, Philip J.; Newsome, Seth D. (August 2022, Methods in Ecology and Evolution)

   Abstract Animals often consume resources from multiple energy channels, thereby connecting food webs and driving trophic structure. Such ‘multichannel feeding’ can dictate ecosystem function and stability, but tools to quantify this process are lacking. Stable isotope ‘fingerprints’ are unique patterns in essential amino acid (EAA) δ 13 C values that vary consistently between energy channels like primary production and detritus, and they have emerged as a tool to trace energy flow in wild systems. Because animals cannot synthesize EAAs de novo and must acquire them from dietary proteins, ecologists often assume δ 13 C fingerprints travel through food webs unaltered. Numerous studies have used this approach to quantify energy flow and multichannel feeding in animals, but δ 13 C fingerprinting has never been experimentally tested in a vertebrate consumer. We tested the efficacy of δ 13 C fingerprinting using captive deer mice Peromyscus maniculatus raised on diets containing bacterial, fungal and plant protein, as well as a combination of all three sources. We measured the transfer of δ 13 C fingerprints from diet to consumer liver, muscle and bone collagen, and we used linear discriminant analysis (LDA) and isotopic mixing models to estimate dietary proportions compared to known contributions. Lastly, we tested the use of published δ 13 C source fingerprints previously used to estimate energy flow and multichannel feeding by consumers. We found that EAA δ 13 C values exhibit significant isotopic (i.e. trophic) fractionation between consumer tissues and diets. Nevertheless, LDA revealed that δ 13 C fingerprints are consistently routed and assimilated into consumer tissues, regardless of isotopic incorporation rate. Isotopic mixing models accurately estimated the proportional diets of consumers, but all models overestimated plant‐based protein contributions, likely due to the digestive efficiencies of protein sources. Lastly, we found that δ 13 C source fingerprints from published literature can lead to erroneous diet reconstruction. We show that δ 13 C fingerprints accurately measure energy flow to vertebrate consumers across tissues with different isotopic incorporation rates, thereby enabling the estimation of multichannel feeding at various temporal scales. Our findings illustrate the power of δ 13 C fingerprinting for quantifying food web dynamics, but also reveal that careful selection of dietary source data is critical to the accuracy of this emerging technique. 

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