Marine life is controlled by multiple physical and chemical drivers and by diverse ecological processes. Many of these oceanic properties are being altered by climate change and other anthropogenic pressures. These drivers may change simultaneously, and can interact in different ways. For example, greenhouse gasses can affect many other drivers.
The IPCC (Intergovernmental Panel on Climate Change) discusses many of these drivers in the context of global change. Working Group 1 focuses on bottom up drivers only; Working Group 2 looks at both bottom up (factors that control the ability of a population to grow by limiting the resources it can access or use) and top down (the action of higher trophic levels on a population) drivers. In the Single Driver sections, you will find a quick introduction to some of the most commonly studied single drivers. MEDDLE has a very brief overview of some environmental ‘bottom-up’ drivers, such as nutrient levels. We have not covered ‘top-down drivers’ (such as grazers, predators, and viruses), and other interactions between organisms. We’ve also mentioned a few interactions between drivers; these are illustrative examples, but our lists of interactions are not exhaustive.
Choosing the relevant drivers for your experiment is vital. The decision making tool can help. Remember that the most relevant drivers for your experiment may not be here!