Award: OCE-1829805

Award Title: Collaborative research: The effects of predator traits on the structure of oceanic food webs
Funding Source: NSF Division of Ocean Sciences (NSF OCE)
Program Manager: David L. Garrison

Outcomes Report

Siphonophores are free-swimming marine animals which ? despite their relative unfamiliarity ? are abundant throughout the ocean. They typically have an elongated shape, with feeding polyps and tentacles budding off of a central tube. This morphology lets them form a curtain of stinging tentacles that can simultaneously capture multiple prey. Their predatory prowess makes them significant members of marine food webs. For this project we used a variety of approaches to see what siphonophores eat, how they selecct and capture their prey, and how they have adapted to share resources, even down into the deep sea. Morphological observations of their prey capture apparatus ? called tentilla ? were mapped onto a phylogenetic tree to see how specialized structures and prey preferences have arisen through evolutionary history. Video annotations were mined to find examples of siphonophore+prey interactions, and these patterns were compared with gut-content analyses. Gene sequencing was applied to siphonophore gut contents to find traces of ingested prey, and stable isotopes were used to reconstruct the chemical history of the food web connecting to siphonophores. How we think about life in the deep ocean depends on the tools we use to view it. In the past, we had used three different survey methods to near-simultaneously sample a portion of the deep-sea. For this project, we analyzed the data and found divergent pictures of deep-sea communities from the three methods. Nets grossly undersampled fragile jellies, while video surveys were blind to the small but abundant crustaceans. Importantly, no single method could provide a fully accurate estimate of animal biomass, although the large insulated trawl seemed to give the best value. Estimates of open-ocean carbon varied accordingly. Most critically the relative contribution of microbes to the total carbon was vastly overestimated by data from the most commonly used type of trawl. As part of our outreach, we used the citizen-science web site Jellywatch.org to foster two-way communication with the public. Community observations are the most globally distributed and temporally persistent source of information about sightings of jellies. A major effort of this funded period was updating our app for submitting sightings from mobile devices. Participants were able to document hundreds of occurrences of By-the-Wind sailors (Velella), and siphonophores (Physalia), as well as a diverse assemblage of other animals. Data from the site were used by teachers for classroom projects and by other scientists for meta-analyses of global trends. Field work is a critical component of our research, and during the course of this project, we welcomed dozens of students and scientists to experience the deep-sea first hand. Students, interns, and postdocs gained valuable experience and training in data analysis and presentation. In all, it was extremely rewarding and enriching to help lead this project. In addition to generating insights about marine food webs, it drew the PIs and their labs even closer together, fostered new scientific relationships, and led to fruitful collaborations that continue into the future. Last Modified: 05/31/2023 Submitted by: Steven H Haddock

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Principal Investigator: Steven H. Haddock (Monterey Bay Aquarium Research Institute)