Understanding Marine Mammal Communities through Time using Stable Metal Isotopes
Embedded Files
Background & Vocabulary:
Isotope: an element with the same number of protons and electrons as detailed in the periodic table, but a different number of neutrons, creating a slight difference in mass and bond affinity.
Isotope Fractionation: the process by which one isotope of an element is enriched relative to another. This natural process occurs when heavier and lighter isotopes are separated between different phases in a system-- usually due to bond affinity.
Stable isotope ecology primarily compares the fractionation of individual elements between members of an ecosystem to understand their behavior and physiology. Everything you eat and your environment leaves a distinct isotope fingerprint on your soft and hard tissues. Stable isotopes do not radioactively decay and can reflect an ancient animal's diet and environment.
Calcium Trophic Proxy
The main fractionation of Ca isotopes is believed to occur between soft and calcified tissues, causing a decrease in 44Ca/40Ca (reported as δ44Ca values) with increasing trophic levels. Ca is less susceptible to diagenesis during fossilization than other elements due to its strong ionic bonds and high concentration in bones and teeth (hydroxyapatite Ca10(PO4)6(OH)2). This opens the potential for reliable analysis of Ca isotopes not only in more resistant tooth enamel but also in bone and dentin.
Image Source: Tessa Holzmann, Pliocene Marine Food Web (Allodesmus, Scaldicetus, Phocidae, Balaenopteridae, sneaky Megalodon)
Marine Mammal Evolutionary Ecology
Marine mammals have shaped ecosystems around them for 50 million years as architects of trophic structure. Understanding marine mammal diet, behavior, and past responses to global events is essential to modern conservation efforts. Yet much of their ancient ecology remain unknown, and many modern species are difficult to observe. Stable isotope analysis of carbon, nitrogen, and oxygen has proven valuable in unraveling the diet and behavior of both ancient and modern animals. Yet, nitrogen isotope values, the leading trophic proxy, are typically unavailable in ancient systems due to protein loss. Ca has significant potential for use in these ancient systems due to its resistance to postmortem alteration. My thesis research will use metal isotopes to reveal the evolution and resilience of marine mammals in changing oceans by reconstructing ancient trophic structure, niche partitioning, and diet.
Image Source: Science Photo Library
Page updated
Google Sites
Report abuse