Determining diet is a key prerequisite for understanding species interactions, food web structure and ecological dynamics. In recent years, there has been considerable development in both the methodology and application of novel and more traditional dietary tracing methods, yet there is no comprehensive synthesis that systematically and quantitatively compares the different approaches. Here we conceptualise diet tracing in ecology, provide recommendations for method selection, and illustrate the advantages of method integration. We summarise empirical evidence on how different methods quantify diet mixtures, by contrasting estimates of dietary proportions from multiple methods applied to the same consumer‐resource datasets, or from experimental studies with known diet compositions. Our data synthesis revealed an urgent need for more experiential comparisons among the dietary methods. The comparison of diet quantifications from field observations showed that different techniques aligned well in cases with less than six diet items, but diverged considerably when applied to more complex diet mixtures. Efforts are ongoing to further advance dietary estimation, including how reliably compound specific stable isotope analyses and fatty acid profiles can quantify more prey items than bulk stable isotope analyses. Similarly, DNA analyses, which can depict trophic interactions at a higher resolution than any other method, are generating new ways to better quantify diets and differentiate among life‐stages of prey. Such efforts, combined with more empirical testing of each dietary method and establishment of open data repositories for dietary data, promise to greatly advance community and ecosystem ecology.

Estimating trophic structures is a common approach used to retrieve information regarding energy pathways, predation, and competition in complex ecosystems. The application of amino acid (AA) compound-specific nitrogen (N) isotope analysis (CSIA) is a relatively new method used to estimate trophic position (TP) and feeding relationships in diverse organisms. Here, we conducted the first meta-analysis of δ(15)N AA values from measurements of 359 marine species covering four trophic levels, and compared TP estimates from AA-CSIA to literature values derived from food items, gut or stomach content analysis. We tested whether the AA trophic enrichment factor (TEF), or the (15)N enrichment among different individual AAs is constant across trophic levels and whether inclusion of δ(15)N values from multiple AAs improves TP estimation. For the TEF of glutamic acid relative to phenylalanine (Phe) we found an average value of 6.6‰ across all taxa, which is significantly lower than the commonly applied 7.6‰. We found that organism feeding ecology influences TEF values of several trophic AAs relative to Phe, with significantly higher TEF values for herbivores compared to omnivores and carnivores, while TEF values were also significantly lower for animals excreting urea compared to ammonium. Based on the comparison of multiple model structures using the metadata of δ(15)N AA values we show that increasing the number of AAs in principle improves precision in TP estimation. This meta-analysis clarifies the advantages and limitations of using individual δ(15)N AA values as tools in trophic ecology and provides a guideline for the future application of AA-CSIA to food web studies.

This paper presents a new minimally invasive surgical (MIS) tool design paradigm that enables enhanced dexterity, intuitive control, and natural force feedback in a low-cost compact package. The paradigm is based on creating a tool frame that is attached to the surgeon’s forearm, making the tool shaft an extension of the latter. Two additional wristlike rotational degrees of freedom (DoF) provided at an end-effector that is located at the end of the tool shaft are manually actuated via a novel parallel-kinematic virtual center mechanism at the tool input. The virtual center mechanism, made possible by the forearm-attached tool frame, creates a virtual two-DoF input joint that is coincident with the surgeon’s wrist, allowing the surgeon to rotate his/her hand with respect to his/her forearm freely and naturally. A cable transmission associated with the virtual center mechanism captures the surgeon’s wrist rotations and transmits them to the two corresponding end-effector rotations. This physical configuration allows an intuitive and ergonomic one-to-one mapping of the surgeon’s forearm and hand motions at the tool input to the end-effector motions at the tool output inside the patient’s body. Moreover, a purely mechanical construction ensures low-cost, simple design, and natural force feedback. A functional decomposition of the proposed physical configuration is carried out to identify and design key modules in the system—virtual center mechanism, tool handle and grasping actuation, end-effector and output joint, transmission system, tool frame and shaft, and forearm brace. Development and integration of these modules leads to a proof-of-concept prototype of the new MIS tool, referred to as FlexDex™, which is then tested by a focused end-user group to evaluate its performance and obtain feedback for the next stage of technology development.

The effects of climate warming on ecosystem dynamics are widespread throughout the world's oceans. In the Northeast Pacific, large‐scale climate patterns such as the El Niño/Southern Oscillation and Pacific Decadal Oscillation, and recently unprecedented warm ocean conditions from 2014 to 2016, referred to as a marine heatwave (MHW), resulted in large‐scale ecosystem changes. Larval fishes quickly respond to environmental variability and are sensitive indicators of ecosystem change. Categorizing ichthyoplankton dynamics across marine ecosystem in the Northeast Pacific can help elucidate the magnitude of assemblage shifts, and whether responses are synchronous or alternatively governed by local responses to regional oceanographic conditions. We analyzed time‐series data of ichthyoplankton abundances from four ecoregions in the Northeast Pacific ranging from subarctic to subtropical: the Gulf of Alaska (1981–2017), British Columbia (2001–2017), Oregon (1998–2017), and the southern California Current (1981–2017). We assessed the impact of the recent (2014–2016) MHW and how ichthyoplankton assemblages responded to past major climate perturbations since 1981 in these ecosystems. Our results indicate that the MHW caused widespread changes in the ichthyoplankton fauna along the coast of the Northeast Pacific Ocean, but impacts differed between marine ecosystems. For example, abundances for most dominant taxa were at all‐time lows since the beginning of sampling in the Gulf of Alaska and British Columbia, while in Oregon and the southern California Current species richness increased as did abundances of species associated with warmer waters. Lastly, species associated with cold waters also increased in abundances close to shore in southern California during the MHW, a pattern that was distinctly different from previous El Niño events. We also found several large‐scale, synchronized ichthyoplankton assemblage composition shifts during past major climate events. Current climate projections suggest that MHWs will become more intense and thus our findings can help project future changes in larval dynamics, allowing for improved ecosystem management decisions.