Life and Planet project II
Early Evolution of Modern Marine Ecosystems

PI: Richard Twitchett (University of Plymouth)

Team: 3 institutions, 5 academics, 3 postdocs, 3 PhD students

Photo by S. X. Hu

Short Introduction of the project:

Currently, our marine ecosystems are threatened by a number of environmental changes, including rising global temperatures and changes in ocean circulation patterns. Recent surveys have shown that parts of the world’s oceans are becoming anoxic ‘dead zones’ where no marine animals can live. As these dead zones continue to expand significant numbers of marine species may become extinct.

Although these present-day environmental changes are of great concern, it is not the first time that marine ecosystems have faced such threats. The fossil record shows that at many times in the past global temperatures have risen, ocean circulation has slowed down, and oxygen-starved dead zones have expanded throughout the world's oceans. Modern marine ecosystems are the result of millions of years of evolution. Many of the animal groups that comprise modern marine ecosystems first appeared or radiated during the Mesozoic, in the aftermath of the Late Permian extinction event. This major biotic crisis was associated with rising global temperatures, changes in ocean circulation and expansion of oxygen-poor dead zones - the very same threats facing modern ecosystems today. As early modern-style ecosystems appeared and evolved after the Late Permian and through the Mesozoic, they were struck by a succession of similar environmental catastrophes, with similar combinations of global warming, expanding dead zones and widespread extinction.

The aim of our study is to understand the effect that global warming, changes in ocean circulation, and expansion of the oxygen-starved dead zones had on these early modern-style marine ecosystems of the Mesozoic. We will determine how the structure of these ecosystems changed through time, and in particular how well they functioned, in response to changing environmental conditions. Furthermore, we will evaluate whether there been an improvement in the resistance of marine ecosystems to changes in temperature, ocean circulation and available oxygen over time. In order to address these questions, we will undertake a series of linked studies at two contrasting scales: (a) global-scale analyses of marine ecosystem response to long-term changes in global temperature and atmospheric carbon dioxide and oxygen levels; and (b) local-scale, high-resolution analyses of ecosystem response to local environmental changes in dissolved temperature, oxygen concentration, and ocean circulation. Local-scale analyses will involve field expeditions to various sites that are known to contain a detailed record through four key events in our study interval. Global-scale analyses will involve ecological study of published information and museum collections of all known marine taxa that existed through the Mesozoic. The results from our multidisciplinary study will represent a step-change in our understanding of the role(s) that environmental changes in temperature, ocean circulation and levels of dissolved oxygen had on the structure, function and early evolution of modern marine ecosystems.