Bloom or bust: synchrony in jellyfish abundance, fish consumption, benthic scavenger abundance, and environmental drivers across a continental shelf

Abstract

Increases in gelatinous zooplankton (GZ) populations, their dominance of some ecosystems, their impacts to other taxa, and their questionable trophic value remain global concerns, but they are difficult to quantify. We compared trends in GZ abundance from direct sampling for the northeast U.S. continental shelf and tested their 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 environmental indices: Atlantic Multidecadal Oscillation, North Atlantic Oscillation, and sea surface and bottom temperatures. Defined as scyphozoans, siphonophores, ctenophores, and salps, the abundance of GZ on the shelf has oscillated with blooms approximately every 10–15 yr. Conservative estimates of annual removal of GZ by spiny dogfish ranged from approximately 0.3–298 g individual−1 with spiny dogfish being the primary GZ feeder sampled on the shelf. The examination of three abundance series for GZ identified one shelf‐wide trend and strong relationships with 2‐yr lagged consumption and scavenger abundance (namely hagfish), and sea surface temperature. With multimodel inference, 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’ 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 support for benthic scavenger productivity.

Sinking of Gelatinous Zooplankton Biomass Increases Deep Carbon Transfer Efficiency Globally

“…Part of the jelly‐C is eventually consumed and remineralized by bacteria after arrival at the seabed (Sweetman et al, ; Titelman et al, ), leading to shifts in dissolved nutrients and carbon (Chelsky et al, ) and decreased oxygen levels (Pitt et al, ; West et al, ). Before microbes respire jelly‐C at the seabed, much of it is often rapidly consumed by megafaunal organisms including fish, crustaceans, echinoderms, and arthropods (Lebrato & Jones, ; Smith et al, ; Sweetman et al, ). To what extent episodic jelly‐C falls can affect macrofaunal and megafaunal communities remains unknown, but it is expected to exert a temporarily strong ecological effect in areas where jelly‐C falls with a high transfer efficiency create sudden patches of food at the seabed (Ruhl, ).…”

Coastal marine ecosystem connectivity: pelagic ocean to kelp forest subsidies

“…Smith et al. () show marked temporal variability in the abundance of gelatinous zooplankton (GZ) on the Northeast Atlantic shelf, with periods of high abundance of GZ lasting for approximately five years. In addition, they find a positive correlation between increased abundance of GZ and abundance of benthic scavenging fishes known to consume GZ (Smith et al.…”

“…In addition, they find a positive correlation between increased abundance of GZ and abundance of benthic scavenging fishes known to consume GZ (Smith et al. ).…”

“…In the northeastern United States, researchers estimate that spiny dogfish ( Squalus acanthias ) remove 0.3–298 g of gelatinous zooplankters per individual annually, and posit that GZ provides important pulses of food for both spiny dogfish and several species of scavenging fishes (Smith et al. ). In California's kelp forests, several species of rockfish are known to consume large quantities of pelagic tunicates when particularly high abundances are present in the kelp forest (Hallacher and Roberts , Hobson et al.…”

“…Pulses of gelatinous zooplankton increase the abundance (with a two‐year lag) of two deep‐water benthic detritivores (Atlantic hagfish and grenadier; Smith et al. ). And in the kelp forest, foraging movements and distribution patterns of a planktivorous damselfish ( Chromis punctipinnis ) depend on the direction of current flow that delivers plankton subsidies into the forest (Bray , Kingsford and MacDiarmid ).…”