Gelatinous Zooplankton

Abstract

Gelatinous zooplankton (GZ) is a non-taxonomic term for jelly-like organisms that have a high proportion of water in body tissues. Advantages in being gelatinous include better buoyancy, transparency, larger sizes with lower carbon investment, rapid growth, and body plasticity. Most GZ taxa have different pathways of asexual reproduction and their populations rapidly increase in response to favorable conditions, forming extensive agglomerations (blooms). Bloom dynamics depend on multiple environmental drivers and can be enhanced by physical transport. GZ blooms have implications for vertical flux of particulate matter via production of fecal pellets and carcasses. Feeding mechanisms and trophic niches of GZ are diverse, ranging from suspension-feeding on small particles to voracious predators, but GZ have been historically considered trophic dead ends; however, a variety of animals feed occasionally, regularly, or exclusively on these organisms. It has been hypothesized that GZ blooms are increasing globally, in response to anthropogenic stressors such as climate change, eutrophication, hypoxia, and overfishing. Although GZ blooms have been recurrently reported, evidence to support a global GZ increase is relatively weak. Most data on GZ are spatially, temporally, and taxonomically limited, cover few populations, and cannot account for the role of multiple natural drivers (e.g. ocean-atmosphere oscillations).