From spatial pattern to ecological process through imaging zooplankton interactions

Abstract

Ecological interactions among marine zooplankton are poorly described because conventional sampling gears, such as plankton nets and traps, obscure the physical and biological environment that individuals experience. With in situ imagery, however, it is possible to resolve these interactions and potentially convert snapshot distributions into process-oriented oceanographic and ecological understanding. We describe a variety of imagery-detected ecological interactions with high spatial resolution in the northern Gulf of Mexico shelf waters (20-35 m bottom depth), providing new evidence of parasitism, predation, and life stage spatial structuring for different zooplankton groups. Chaetognaths were infected with an anteriorly attached, parasitic polychaete (1.1% of 33 824 individuals), and these infected chaetognaths were more common further offshore, south of a nearshore patch where unparasitized individuals reached concentrations of ∼90 m-3. Predation by Liriope spp. hydromedusae tended to occur in the shallowest 10-15 m, and doliolids formed distinct patches of different life stages, indicating that the environment is replete with sharp transitions among various ecological processes. Similar patterns in other marine ecosystems likely exist, and we encourage hybrid (machine/human expertise) approaches that broaden the scope for analysis of plankton images, which are rich sources of new ecological information and hypotheses yet to be examined quantitatively.