Award: OCE-1830015

Ctenophores are frequently inconspicuous, apparently inanimate components of many marine planktonic ecosystems. However, research on one lobate ctenophore, Mnemiopsis leidyi, has demonstrate that their slow moving, ciliary-powered body design houses ferocious predatory machinery (Fig. 1) that can lead to domination of plankton communities by ctenophores. However, Mnemiopsis is a coastal species limited to nearshore environments and does not extend into oceanic waters. Instead, it is replaced over the much larger oceanic realm by oceanic lobate species (pictured in Fig. 2). But do these oceanic species affect the world's open oceans similarly to Mnemiopsis in coastal areas? Answers to this question have been elusive because the gelatinous bodies of these oceanic species are too fragile to transport and manipulate in laboratory conditions. As a result, the role and impact of these widespread oceanic lobate species has remained unassessed.

This project approached the problem by reversing the typical research process that limits the range of study organisms to species capable of thriving in laboratory environments. Instead of bringing animals into the laboratory, investigators translated their laboratory imaging techniques to underwater designs so that fragile oceanic species can be studied in their natural environments. This created a range of novel in-situ imaging systems (example in Fig. 3) for application to these animals as well as potentially other species. The oceanic species considered, from both Atlantic and Pacific sites, were found to share hydrodynamic stealth predation strategies (Figure 4) and capture prey at similar rates to the well-studied coastal relative, Mnemiopsis. Oceanic species often occur together and, while mutually consuming several prey types, each ctenophore species possessed traits that allowed it to specialize on different portions of the available prey spectrum. During the research process, new methods and equipment were developed and undergraduate and graduate students as well as postdoctoral researchers were trained in these approaches. The results clarify the roles played by these ubiquitous predators and provide a basis for their inclusion into broader models of trophic and material transport in the world’s oceans.

Last Modified: 12/23/2023
Modified by: John H Costello