Understanding the picture: the promise and challenges of in-situ imagery data in the study of plankton ecology

Planktons are a fundamental piece of all ocean ecosystems yet, sampling plankton at the high resolution required to understand their dynamics remains a challenge. In-situ imaging tools offer an approach to sample plankton at fine scales. Advances in technology and methodology provide the ability to make in-situ imaging a common tool in plankton ecology. Despite the massive potential of in-situ imaging tools, there are no standard approaches for analyzing the associated data. Consequently, studies are inconsistent in analyzing in-situ imaging data, even for similar questions. This introduces challenges in comparing across studies and sampling devices. In this review, we briefly summarize the increasing use, potential and novel applications of in-situ imaging tools in plankton ecology. Then, we synthesize the common analyses used across these studies. Finally, we address the major statistical challenges associated with the unique sampling mechanisms of in-situ imaging tools and discuss the theoretical uncertainties, which arise from the low-sampling volumes of many in-situ imaging tools. To fully unlock the power of in-situ imaging tools in plankton ecological studies, researchers must carefully consider how to analyze their data. We provide recommendations for processing and analyzing data while also acknowledging a large need for developing new statistical tool.