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1. Diet of a threatened endemic fox reveals variation in sandy beach resource use on California Channel Islands

   https://doi.org/10.1371/journal.pone.0258919  

   Page, Henry M. ; Schamel, Juliann ; Emery, Kyle A. ; Schooler, Nicholas K. ; Dugan, Jenifer E. ; Guglielmino, Angela ; Schroeder, Donna M. ; Palmstrom, Linnea ; Hubbard, David M. ; Miller, Robert J. ( October 2021 , PLOS ONE)

   Hyrenbach, David (Ed.)

   The coastal zone provides foraging opportunities for insular populations of terrestrial mammals, allowing for expanded habitat use, increased dietary breadth, and locally higher population densities. We examined the use of sandy beach resources by the threatened island fox ( Urocyon littoralis ) on the California Channel Islands using scat analysis, surveys of potential prey, beach habitat attributes, and stable isotope analysis. Consumption of beach invertebrates, primarily intertidal talitrid amphipods ( Megalorchestia spp.) by island fox varied with abundance of these prey across sites. Distance-based linear modeling revealed that abundance of giant kelp ( Macrocystis pyrifera ) wrack, rather than beach physical attributes, explained the largest amount of variation in talitrid amphipod abundance and biomass across beaches. δ 13 C and δ 15 N values of fox whisker (vibrissae) segments suggested individualism in diet, with generally low δ 13 C and δ 15 N values of some foxes consistent with specializing on primarily terrestrial foods, contrasting with the higher isotope values of other individuals that suggested a sustained use of sandy beach resources, the importance of which varied over time. Abundant allochthonous marine resources on beaches, including inputs of giant kelp, may expand habitat use and diet breadth of the island fox, increasing population resilience during declines in terrestrial resources associated with climate variability and long-term climate change. 

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2. Arctic lagoon and nearshore food webs: Relative contributions of terrestrial organic matter, phytoplankton, and phytobenthos vary with consumer foraging dynamics

   https://doi.org/https://doi.org/10.1016/j.ecss.2021.107388  

   McMahon, Kelton W ; Ambrose, William G. ; Reynolds, Melinda J. ; Johnson, Beverly ; Whiting, A. ; Clough, Lisa M. ( May 2021 , Estuarine coastal and shelf science)

   null (Ed.)

   Characterizing energy flow and trophic linkages is fundamental to understanding the functioning and resilience of Arctic ecosystems under increasing pressure from climate change and anthropogenic exploitation. We used carbon and nitrogen stable isotopes to examine trophic dynamics and the relative contribution of terrestrial organic matter, water column phytoplankton, and phytobenthos (benthic micro- and macro-autotrophs as well as sea ice algae) to the food webs supporting 45 macroconsumers in three Arctic coastal lagoon ecosystems (Krusenstern, Sisualik, Akulaaq) and the adjacent Kotzebue Sound with varying degrees of connectivity in Cape Krusenstern National Monument, Alaska. A two-source (water column particulate organic matter and benthic sediment organic matter), two-isotope trophic dynamics model informed by a Bayesian isotope mixing model revealed that the Lagoon-Kotzebue Sound coastal ecosystem supported consumers along a trophic position continuum from primary consumers, including amphipods, copepods, and clams to trophic level five predators, such as seastars, piscivorous fishes, seals, and seabirds. The relative contribution of the three primary producer end members, terrestrial organic matter (41 ± 21%), phytoplankton (25 ± 21%), and phytobenthos (34 ± 23%) varied as a function of: 1) consumer foraging ecology and 2) consumer location. Suspension feeders received most of their carbon from food webs based on phytoplankton (49 ± 11%) and terrestrial organic matter (23 ± 5%), whereas herbivores and detritivores received the majority of their carbon from phytobenthos-based food webs, 58 ± 10% and 60 ± 8%, respectively. Omnivores and predators showed more even distributions of resource reliance and greater overall variance among species. Within the invertebrates, the importance of terrestrial organic matter decreased and phytobenthos increased with increasing trophic position. The importance of terrestrial organic matter contribution increased with lagoon proximity to major rivers inputs and isolation from Kotzebue Sound. Several taxa with cultural and subsistence food importance to local communities showed significant reliance (30–90% of baseline carbon) on food chains linked to fresh terrestrial organic matter. Our study indicates that terrestrial-marine linkages are important to the function of Arctic coastal lagoon ecosystems and artisanal fisheries. These linkages are likely to strengthen in the future with regional changes in erosion and runoff associated with climate change and anthropogenic disturbance. 

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3. Effects of environmentally relevant concentrations of microplastic fibers on Pacific mole crab ( Emerita analoga ) mortality and reproduction

   https://doi.org/10.1002/lol2.10137  

   Horn, Dorothy A. ; Granek, Elise F. ; Steele, Clare L. ( December 2019 , Limnology and Oceanography Letters)

   Microplastics are ubiquitous in marine systems; however, knowledge of the effects of these particles on marine fauna is limited. Ocean‐borne plastic debris accumulates in littoral ecosystems worldwide, and invertebrate infauna inhabiting these systems can ingest small plastic particles and fibers, mistaking them for food. We examined the effect of microplastic fibers on physiological and reproductive outcomes in a nearshore organism by exposing Pacific mole crabs (Emerita analoga) to environmentally relevant concentrations of microsized polypropylene rope fibers. We compared adult gravid female crab mortality, reproductive success, and embryonic developmental rates between microfiber‐exposed and control crabs. Pacific mole crabs exposed to polypropylene rope had increased adult crab mortality, and decreased retention of egg clutches, causing variability in embryonic development rates. These effects of microplastic ingestion on a nearshore prey species have implications for predators such as surf perf and shore birds, as plastic use, and resultant microplastic presence in nearshore environments increases. Microplastics are ubiquitous in marine and sandy beach environments, posing a significant threat to the marine organisms that reside therein. The most predominant classification of microplastics found have been microfibers. Although a number of biological effects of microplastics have been measured, with documented effects on growth, little research has examined how microplastic fibers affect reproductive output and subsequent development of offspring. We examined the effects of exposure to microfibers on adult mortality, reproductive output, and embryonic development of the filter feeding Pacific mole crab (E. analoga), a dominant infaunal organism on sandy beaches. We demonstrate the effects of microplastic ingestion on mole crab mortality and embryonic development, filling a gap in the current knowledge on the impact of microplastics.

    

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4. Hurricane disturbance drives trophic changes in neotropical mountain stream food webs

   https://doi.org/10.1002/ecy.4202  

   Gutiérrez‐Fonseca, Pablo E. ; Pringle, Catherine M. ; Ramírez, Alonso ; Gómez, Jesús E. ; García, Pavel ( November 2023 , Ecology)

   Food webs are complex ecological networks that reveal species interactions and energy flow in ecosystems. Prevailing ecological knowledge on forested streams suggests that their food webs are based on allochthonous carbon, driven by a constant supply of organic matter from adjacent vegetation and limited primary production due to low light conditions. Extreme climatic disturbances can disrupt these natural ecosystem dynamics by altering resource availability, which leads to changes in food web structure and functioning. Here, we quantify the response of stream food webs to two major hurricanes (Irma and María, Category 5 and 4, respectively) that struck Puerto Rico in September 2017. Within two tropical forested streams (first and second order), we collected ecosystem and food web data 6 months prior to the hurricanes and 2, 9, and 18 months afterward. We assessed the structural (e.g., canopy) and hydrological (e.g., discharge) characteristics of the ecosystem and monitored changes in basal resources (i.e., algae, biofilm, and leaf litter), consumers (e.g., aquatic invertebrates, riparian consumers), and applied Layman's community‐wide metrics using the isotopic composition of¹³C and¹⁵N. Continuous stream discharge measurements indicated that the hurricanes did not cause an extreme hydrological event. However, the sixfold increase in canopy openness and associated changes in litter input appeared to trigger an increase in primary production. These food webs were primarily based on terrestrially derived carbon before the hurricanes, but most taxa (includingAtyaandXiphocarisshrimp, the consumers with highest biomass) shifted their food source to autochthonous carbon within 2 months of the hurricanes. We also found evidence that the hurricanes dramatically altered the structure of the food web, resulting in shorter (i.e., smaller food‐chain length), narrower (i.e., lower diversity of carbon sources) food webs, as well as increased trophic species packing. This study demonstrates how hurricane disturbance can alter stream food webs, changing the trophic base from allochthonous to autochthonous resources via changes in the physical environment (i.e., canopy defoliation). As hurricanes become more frequent and severe due to climate change, our findings greatly contribute to our understanding of the mechanisms that maintain forested stream trophic interactions amidst global change.

    

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5. Effects of elk and bison carcasses on soil microbial communities and ecosystem functions in Yellowstone, USA

   https://doi.org/10.1111/1365-2435.13611  

   Risch, Anita C. ; Frossard, Aline ; Schütz, Martin ; Frey, Beat ; Morris, Aaron W. ; Bump, Joseph K. ; Leroux, ed., Shawn ( June 2020 , Functional Ecology)

   Carrion is long recognized as important to scavengers. How carrion may affect soil microbial biodiversity and ecosystem processes in natural systems is comparatively unknown, but is important for the intersection of vertebrate food webs, below‐ground processes and ecological heterogeneity.

   We assessed in situ soil and plant responses to wolf‐killed mammal carrion in Yellowstone National Park, USA.

   Bison and elk carcasses increased soil respiration and vegetation nutrient concentration and the carcasses contain altered bacterial and fungal communities compared to control plots. The ‘fingerprints’ of soil microbial taxa associated with bison compared to elk carcasses differed considerably and taxa are found dependent upon abiotic gradients and soil properties.

   We found evidence that soil microbial community changes associated with carcasses may not be as generalizable as previously thought, which is important for a mechanistic understanding of the links between carrion and soil heterogeneity and potentially for applications in forensic science.

   This work demonstrates the importance of carrion studies in natural systems. Our findings show that carrion creates distinct ecological patterns that contribute to both above‐ and below‐ground biological heterogeneity, linking carrion distribution dynamics with soil microbial biodiversity and ecosystem functions.

    

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