The first global deep-sea stable isotope assessment reveals the unique trophic ecology of Vampire Squid Vampyroteuthis infernalis (Cephalopoda)

Abstract

Vampyroteuthis infernalis Chun, 1903, is a widely distributed deepwater cephalopod with unique morphology and phylogenetic position. We assessed its habitat and trophic ecology on a global scale via stable isotope analyses of a unique collection of beaks from 104 specimens from the Atlantic, Pacific and Indian Oceans. Cephalopods typically are active predators occupying a high trophic level (TL) and exhibit an ontogenetic increase in δ15N and TL. Our results, presenting the first global comparison for a deep-sea invertebrate, demonstrate that V. infernalis has an ontogenetic decrease in δ15N and TL, coupled with niche broadening. Juveniles are mobile zooplanktivores, while larger Vampyroteuthis are slow-swimming opportunistic consumers and ingest particulate organic matter. Vampyroteuthis infernalis occupies the same TL (3.0–4.3) over its global range and has a unique niche in deep-sea ecosystems. These traits have enabled the success and abundance of this relict species inhabiting the largest ecological realm on the planet.

Diet and life history reduce interspecific and intraspecific competition among three sympatric Arctic cephalopods

“…Ontogenetic isotopic niche decrease is common in cephalopods, including R. palpebrosa 32 , 33 , 41 , 42 , 84 and R. moelleri . On the other hand, R. megaptera demonstrated ontogenetic niche increase, similar to Vampyroteuthis infernalis , a deep-sea cephalopod with unique diet and life style 54 , but this is rarely found in ‘typical’ predatory cephalopods 32 , 83 . Within the Arctic, isotopic niches of all Rossia were narrower than of squid Gonatus fabricii (which was the widest among Arctic invertebrates 42 ) and of shrimp Pandalus borealis and fishes due to their higher degree of opportunism in diet 60 , 64 – 67 .…”

“…Lower beaks were taken for SIA, as they have been repeatedly used in related studies (e.g. 41 , 42 , 52 – 54 ), and their rostrums measured ( n = 133).…”

“…Therefore, this value was subtracted from muscle δ 15 N values available in the literature to enable comparison with the data reported here. However, when estimating TL, we added 4.8‰ to raw beak δ 15 N values, as proposed by 41 , 42 , 52 , 54 .…”

Functional traits explain trophic allometries of cephalopods

“…The background colour is Sea Surface Temperature for September 2017 from MODIS-Aqua extracted from the Integrated Marine Observing System (IMOS) data portal (http://imos.aodn.org. au/imos/) Carbon and nitrogen stable isotope signatures originate at the base of all food webs at the stage of primary production (Fry, 2006).…”

“…However, there may be other factors that contribute to variability across studies, as L. forbesii has been found to exhibit ontogenetic trophic shifts in a separate study (Chouvelon et al., 2011). Another species that has been shown to undergo no ontogenetic increase in trophic position is the vampire squid, Vampyroteuthis infernalis , in a global assessment of the species’ trophic ecology (Golikov et al., 2019). When assessed at a community level, cephalopods can exhibit ontogentic shifts in trophic position, but it is variable and not all species undergo shifts (Staudinger et al., 2019).…”