Abstract
Ocean dynamics is known to have a strong effect on the global climate change and on the composition of the atmosphere. In particular, it is estimated that about 70% of the atmospheric oxygen is produced in the oceans due to the photosynthetic activity of phytoplankton. However, the rate of oxygen production depends on water temperature and hence can be affected by the global warming. In this paper, we address this issue theoretically by considering a model of a coupled plankton-oxygen dynamics where the rate of oxygen production slowly changes with time to account for the ocean warming. We show that a sustainable oxygen production is only possible in an intermediate range of the production rate. If, in the course of time, the oxygen production rate becomes too low or too high, the system's dynamics changes abruptly, resulting in the oxygen depletion and plankton extinction. Our results indicate that the depletion of atmospheric oxygen on global scale (which, if happens, obviously can kill most of life on Earth) is another possible catastrophic consequence of the global warming, a global ecological disaster that has been overlooked.
Highlights
Global warming has been an issue of huge debate and controversy over the last decade because of its potential numerous adverse effects on ecology and society [44]
The focus of attention has usually been on the population dynamics to address the possibility of extinction or invasion of particular species [6, 14] and/or possible changes in the community structure [7, 49]
One aspect of the plankton systems functioning that remains poorly investigated is the effect of warming on the oxygen production by phytoplankton
Summary
Global warming has been an issue of huge debate and controversy over the last decade because of its potential numerous adverse effects on ecology and society [44]. Functioning of marine ecosystems, with a particular interest in the plankton dynamics, has long been a focus in ecological and environmental research [33, 46, 76]. We consider the properties of the model (both analytically and numerically) and show that the system’s dynamics is only sustainable in a certain parameter range, namely, for an intermediate value of the oxygen production rate. We consider the system’s response to a gradual change in the oxygen production rate (the latter being assumed to be a result of the global warming) and show that, once the production rate surpasses a certain critical value, the system goes to extinction. The spatial system appears to be sustainable in a broader parameter range so that plankton and oxygen persist for values of the production rate where the nonspatial system goes extinct. We show that the spatial system may provide some early-warning signals for the approaching ecological disaster (i.e. plankton extinction and oxygen depletion); in particular, we observe that, prior to the disaster, the spatial distributions of plankton and oxygen become almost periodical
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