Biophysical interactions in the plankton: A cross‐scale review

Abstract

The study of plankton ecology is by nature interdisciplinary, since both biology and physics interact to shape plankton distributions and population dynamics. Small‐scale turbulence affects how plankton feed and grow, while kilometer‐scale physical features can form large plankton patches. Recent findings also show that, in addition to physics affecting plankton dynamics, plankton may be able to influence ocean physics as well. For example, the fluid motion produced from a copepod swimming in pursuit of food can be detected by nearby organisms and might make it more vulnerable to its predators. The field of plankton biophysics has advanced rapidly in the past several decades, due in large part to technological advances that allow the study of interactions between fluid flow and plankton in their natural environment at smaller scales than ever before. Biophysical interactions in plankton ecology can occur at a wide range of scales: from the scale of individual organisms up to the scale of the world's oceans. In this article, we review biophysical interactions in plankton across a wide range of scales, focusing on the most recent research in the field. In addition, we discuss how these processes are linked with other processes that occur at smaller and larger scales. For example, plankton patches formed by ocean eddies can provide feeding grounds for other organisms, thus influencing global ocean food web dynamics. Finally, we discuss some of the potential effects of long‐term changes in global climate, which will affect ocean temperature and stratification, thus regulating the occurrence and intensity of biophysical plankton processes.In plankton ecology, biological and physical dynamics are coupled, structuring how plankton interact with their environment and other organisms. This interdisciplinary field has progressed considerably over the recent past, due in large part to advances in technology that have improved our ability to observe plankton and their fluid environment simultaneously across multiple scales. Recent research has demonstrated that fluid flow interacting with plankton behavior can drive many planktonic processes and spatial patterns. Moreover, evidence now suggests that plankton behavior can significantly affect ocean physics. Biophysical processes relevant to plankton ecology span a range of scales; for example, microscale turbulence influences planktonic growth and grazing at millimeter scales, whereas features such as fronts and eddies can shape larger‐scale plankton distributions. Most research in this field focuses on specific processes and thus is limited to a narrow range of spatial scales. However, biophysical interactions are intimately connected across scales, since processes at a given scale can have implications at much larger and smaller scales; thus, a cross‐scale perspective on how biological and physical dynamics interact is essential for a comprehensive understanding of the field. Here, we present a review of biophysical interactions in the plankton across multiple scales, emphasizing new findings over recent decades and highlighting opportunities for cross‐scale comparisons. By investigating feedbacks and interactions between processes at different scales, we aim to build cross‐scale intuition about biophysical planktonic processes and provide insights for future directions in the field.