Temperature changes and plate tectonics determine coral distribution over time

A new study has revealed the fact that prehistoric coral reefs 250 million years old extended far beyond the Earth’s equator in the past.

Image Credit: Volodymyr Goinyk/Shutterstock.com

The new study, published in the journal Nature Communicationillustrates how changes in temperature and plate tectonics, where the positions of the Earth’s continents were in very different positions compared to today, have influenced the distribution of corals over the ages.

Although climate has long been thought to be the main driver of where coral reefs are located, due to the paucity of the fossil record, this had not yet been established. For the first time, a group of international researchers have used habitat modeling and climate reconstructions to predict the distribution of favorable environments for coral reefs over the past 250 million years.

Scientists, from the University of Vigo, Spain, on University of Bristoland University College London in the UK also verified their predictions using fossilized evidence from warm-water coral reefs.

They found that corals existed much farther from the equator in the past, 250 to 35 million years ago, due to warmer climatic conditions and a more even distribution of shallow ocean floors.

Our work demonstrates that warm-water coral reefs follow tropical to subtropical climatic conditions on geologic time scales. In warmer intervals, coral reefs extended poleward. However, in colder intervals they became constrained to tropical and subtropical latitudes.

Dr Lewis Jones, first author of the study and research fellow in computational paleobiology, University of Vigo

About 35 million years ago, suitable coral habitats were confined to tropical regions given global cooling and rising shallow oceans caused by tectonic changes in the Indo-Australian archipelago, known as a point warm marine biodiversity.

While this implies that warm temperatures in the past allowed corals to grow poleward over long periods of time, scientists believe that coral reef ecosystems will not be able to keep up with the rapid pace of human-induced climate change.

Current anthropogenic climate change will result in the poleward expansion of suitable coral reef habitat. In fact, we are already seeing the expansion of some tropical reef corals. However, whether coral reef ecosystems – and all the biodiversity they support – can keep up with the current rapid pace of anthropogenic climate change is another question..

Dr Lewis Jones, first author of the study and research fellow in computational paleobiology, University of Vigo

Jones added: “Limiting global warming is fundamental to saving coral reefs, as well as the biodiversity they shelter. Yet perhaps even more important is to reduce the rate of global warming.”

Warm-water coral reefs, also known as “rainforests of the sea”, are home to the greatest biodiversity of marine organisms on Earth. In the oceans that currently exist, biologically rich ecosystems, such as reef fish, are restricted to the tropics and subtropics. Here, ocean surface temperatures do not normally drop below 18ºC.

A considerable part of modern biodiversity has been discovered in the Indo-Australian archipelago. However, in the geological past, coral reef ecosystems have also survived outside the tropics and subtropics, with their fossil remains being discovered much further from the equator.

The climate has changed significantly over geological time, but understanding its impact on coral reef ecosystems has been difficult due to a lack of quantifiable data that has significant gaps.. Using this new combined data model approach, we can begin to better understand the evolution and behavior of reef ecosystems..

Dr Alex Farnsworth, Study Co-Author and Senior Research Associate, Meteorology and Climate Modelling, Cabot Institute for the Environment, University of Bristol

Early work failed to determine a powerful relationship between temperature and coral reef distribution since the fossil record is biased and incomplete.

For example, not all remains of past organisms or ecosystems are documented in the fossil record, and the most important factor describing the sampled distribution of ancient reefs has been shown to be gross domestic product, with the proportion body of known data on fossil reefs. come from wealthy countries, only because that’s where researchers started looking the most.

Co-author Dan Lunt, professor of climate science at the Cabot Institute for the Environment at the University of Bristol, added: “This work highlights that climate and ecosystems have been intimately linked in Earth’s past history. This has crucial implications for ecosystems today, given the current global warming.”

Journal reference:

Jones, LA, et al. (2022) Climatic and tectonic factors have shaped the tropical distribution of coral reefs. Nature Communication. https://www.nature.com/articles/s41467-022-30793-8

Source: https://www.bristol.ac.uk/

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