Uncovering the Past: Fossil Record Reveals the Composition of Denuded Coastal Ecosystems

Key Highlights :

1. Scientists have been using fossils to study the health and stability of ecosystems, and to determine how groups are represented within the entire system.

2. The results of the new study suggest that fossils of various marine groups are preserved in proportion to their diversity.

3. Groups with scant existing diversity in the region, such as sea stars and brachiopods, weren't recovered from the fossil record.

4. The overall number of species in different groups remained consistent.

5. Marine ecosystems lack anything near a complete inventory of the species that inhabit them, and the existing roster is dwindling as some species decline in abundance and others succumb to extinction.

     Biologists are often faced with the difficult task of restoring and conserving denuded environments, with a limited understanding of what these environments looked like before humans arrived. This is especially true of coastal ecosystems, which have been drastically altered by pollution and overharvesting for centuries. However, a new study published in the journal PeerJ suggests that a faithful analogue of modern marine ecosystems lies just beneath the surface.

     The research, conducted by scientists from the Florida Museum of Natural History and the University of Nevada, Las Vegas, was based on more than 20 years of conservation paleobiology. It found that fossils of various marine groups, including worms, mollusks, crabs and sea urchins, are preserved in proportion to their diversity. The results suggest that researchers can use mollusks as a proxy for the overall health of ecosystems, and that the fossil record can be used to broadly infer the health and stability of an environment.

     To test this hypothesis, the researchers chose a comparatively unaltered environment off the coast of North Carolina that contained both living animals and dead skeletal remains. They collected samples from 52 localities along transects that extended from near-shore coastal waters out to sea. The habitats supported specialized communities, which allowed the scientists to test the preservation potential for a host of disparate organisms and environmental conditions.

     Over the course of two years, they counted more than 60,000 living and dead specimens representing hundreds of marine invertebrates. As expected, the thick shells of mollusks resulted in an overabundance of their remains in the fossil record compared with other groups. However, the fragments of dead corals, sand dollars, tube-forming worms and other non-mollusks were broadly represented at the same level of abundance and diversity as their living counterparts.

     The findings suggest that other marine ecosystems are likely archived with the same fidelity as those in North Carolina, and that researchers can use the fossil record to evaluate the longterm viability of the communities they support. This could be an invaluable tool for conservationists, as it allows them to assess the changes in an environment over time and make informed decisions on the best strategies for preserving it.

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