188 Linking Biodiversity Loss to Environmental Stressors Through Integrated Approaches (Posters)

Biodiversity crises serve as natural experiments to explore extinction selectivity and ecosystem restructuring. We highlight studies using model-data comparisons to link biodiversity loss with environmental stressors by integrating paleobiology, geochemistry, ecophysiology, and Earth system modeling.

Tuesday, 21 October 2025
8:00 AM - 5:30 PM
HBGCC, Hall 1

Evaluating Caspian Seal Resilience to Habitat Threats through Ecosystem Stable Isotope Analysis.

Paper number: 188-0
Program: Technical Sessions
Time: 8:00 AM – 8:00 AM

Authors

  • Tessa Holzmann Presenting Author
    Univ California - Santa Cruz, Dept. of Earth & Planetary Sciences, Santa Cruz, CA
  • George Colaco
    Univ California - Santa Cruz, Dept. of Ecology & Evolutionary Biology, Santa Cruz, CA
  • Robin Trayler
    Univ California - Merced, Merced, CA
  • Dan Costa
    Univ California - Santa Cruz, Dept. of Ecology & Evolutionary Biology, Santa Cruz, CA
  • Paul Koch
    Univ California - Santa Cruz, Dept. of Earth & Planetary Sciences, Santa Cruz, CA

Abstract

The Caspian seal (Pusa caspica) has experienced a catastrophic (90%) population decline over the past century due to compounded anthropogenic pressures, including the hunting and pelting of pups, rising temperature, industrial pollution, mortality as fishing bycatch, oil and gas extraction, overfishing, and the introduction of invasive competitors. Despite this alarming decline, ecological knowledge of the species remains limited, hindering targeted conservation strategies, such as protecting critical habitats and managing prey resources. A deeper understanding of Caspian seal ecology can be used to inform regulations on fisheries and spatial management plans. Stable isotope analysis provides a powerful tool to reconstruct ecological patterns across time, because an animal’s isotopic values reflect both environmental baselines and individual life history. In this study, we assess the population ecology of the Caspian seal using carbon (δ13C) and nitrogen (δ15N) values from seal tissues, regional phytoplankton, and a diverse assemblage of fish species. These results are paired with satellite tracking data from each seal to refine spatial interpretations of dietary breadth and habitat use. Together, these data allow us to evaluate niche width, detect potential shifts in foraging behavior, and assess vulnerability to ecological stress. Understanding the trophic flexibility and ecological constraints of modern marine mammals like the Caspian seal provides a valuable comparative framework for interpreting niche specialization, trophic dynamics, and understanding extinction in ancient marine mammal communities. 

Geological Society of America Abstracts with Programs. Vol. 57, No. 6

doi: 10.1130/abs/2025AM-412047

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