Integrating siphonophores into marine food-web ecology

Abstract

Siphonophores are a clade of understudied colonial hydrozoans (Cnidaria) that are abundant predators in oceanic ecosystems, with species present across the water column. We (1) synthesize current knowledge about siphonophore trophic ecology and predator–prey interactions, (2) analyze siphonophore-prey networks to compare food-web topology between shallow and deep-pelagic habitats, (3) discuss contemporary techniques that will allow for more integrative studies of siphonophore feeding ecology, and (4) and present a vision for future research. We found distinct diet differences between siphonophore species, indicating that siphonophores occupy multiple trophic niches and prey on a diversity of taxa. Our results suggest that siphonophore-prey networks may be more specialized in the deep pelagic than in the epipelagic, suggesting potential trophic differences between depth habitats. This study highlights niche differentiation and trophic complexity among siphonophores and demonstrates the importance of gelatinous zooplankton in shaping food web structure in pelagic ecosystems.