Bloom or Bust: Relating Trends in Jelly Abundance to Fish Consumption, Benthic Scavenger Abundance, and Climate Across a Continental Shelf

Increases in gelatinous zooplankton (GZ) and their dominance of ecosystems are global concerns, but difficult to quantify.  We compared trends in GZ abundance from direct sampling of  the northeast U.S. continental shelf and tested for  association with GZ consumption by spiny dogfish (Squalus acanthias); the abundance of two benthic scavengers, Atlantic hagfish (Myxine glutinosa) and grenadiers (Family: Macrouridae); and four climate variables.  Defined as scyphozoans, siphonophores, ctenophores, and salps, the abundance of GZ on the shelf has oscillated over time with 10-15 year periods as blooms.  We examined three GZ abundance series and identified one shelf-wide trend and strong relationships with 2-year lagged consumption and scavenger abundance, Atlantic Multidecadal Oscillation, and sea surface temperature.  Based on Akaike’s information criterion, these covariates led to an optimal model of GZ abundance.  Blooms of GZ abundance on this shelf were influenced by environmental change, provide surges of food for spiny dogfish, and may offer food falls or benthic resources for scavenging fishes.  The bioenergetic tradeoffs of consuming greater amounts of GZ compared to other major prey (e.g. fishes) remain unknown; however, these surges of food in the northwest Atlantic appear to be important for fishes including the support of benthic scavenger productivity.