Stable isotopes challenge the perception of ocean sunfish <i>Mola mola</i> as obligate jellyfish predators

Syväranta, Jari; Harrod, Chris; Kubicek, Lukas; Cappanera, Valentina; Houghton, Jonathan D. R.

doi:10.1111/j.1095-8649.2011.03163.x

Cited by 41 publications

(70 citation statements)

References 34 publications

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“…8, stations near 26.5°N and 28°N), where the sunfish spent half of the total two-month tracking period. Zooplankton biovolume at both stations was dominated by salps, a known prey item for M. mola particularly those N1 m (Cardona et al, 2012;Harrod et al, 2013;Nakamura and Sato, 2014;Syvaranta et al, 2012). In contrast, a nearcoastal station sampled between these two high-abundance stations showed low biovolume (Fig.…”

Section: Forage Species In Relation To Frontsmentioning

confidence: 88%

Ecology of the Ocean Sunfish, Mola mola, in the southern California Current System

Thys

Ryan

Dewar

et al. 2015

Journal of Experimental Marine Biology and Ecology

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The common ocean sunfish, Mola mola, occupies a unique position in the eastern Pacific Ocean and the California Current Large Marine Ecosystem (CCLME) as the world's heaviest, most fecund bony fish, and one of the most abundant gelativores. M. mola frequently occur as bycatch in fisheries worldwide and comprise the greatest portion of the bycatch in California's large-mesh drift gillnet fishery. In this first long-term tagging study of any ocean sunfish species in the eastern Pacific, 15 M. mola (99 cm to 200 cm total length) were tagged in the southern California Bight (SCB) between 2003 and 2010 using 14 satellite pop-off archival tags (PATs) and one Fastloc Mk10 GPS tag. Ten tags provided positional data for a cumulative dataset of 349 tracking days during the months of July through March. Thirteen tags provided temperature and depth data. All M. mola remained within~300 km of the coast, and nearly all exhibited seasonal movement between the SCB and adjacent waters off northern and central Baja California, Mexico. No tagged individuals were tracked north of the SCB. Tag depth data showed diel vertical migration and occasional deep (N500 m) dives. Data from the Fastloc GPS tag allowed close examination of the relationship between the movements of the largest tagged ocean sunfish (2 m TL) and fine-scale oceanographic features. Near-instantaneous satellite sea surface temperature images showed this individual associated with upwelling fronts along its migration path, which exceeded 800 km and ranged from 6 to 128 km from the coast. Tag depth data showed active use of the water column within the frontal zones. Synthetic aperture radar (SAR) images demonstrated that surface slicks, which often indicate convergent circulation, coincided with this type of front. Zooplankton tows in the southern region of tracking off central Baja California, Mexico revealed dense populations of salps toward the warm side of these fronts. Satellite tag and ecosystem data suggest that bio-physical interactions in coastal upwelling fronts create favorable foraging habitat.

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Section: Forage Species In Relation To Frontsmentioning

confidence: 88%

Ecology of the Ocean Sunfish, Mola mola, in the southern California Current System

Thys

Ryan

Dewar

et al. 2015

Journal of Experimental Marine Biology and Ecology

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“…Benthic food webs are generally more enriched in both d 13 C and d 15 N than those in the pelagial (Hobson and Welch 1992;France 1995;Søreide et al 2006a;Syväranta et al 2012). The relationship between the gadoid predators and the five most frequent prey taxa is structured according to their d 15 N signal (Fig.…”

Section: Discussionmentioning

confidence: 99%

Trophic ecology of sympatric Arctic gadoids, Arctogadus glacialis (Peters, 1872) and Boreogadus saida (Lepechin, 1774), in NE Greenland

et al. 2012

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Two gadoid fishes, Arctogadus glacialis and Boreogadus saida, often coexist (i.e. sympatric) in the fjords and shelf areas of the Arctic seas, where they likely share the same food resources. Diet composition from stomach contents, i.e. frequency of occurrence (FO) and Schoener's index (SI), and stable isotope signatures (d 13 C and d 15 N) in muscle of these sympatric gadoids were examined from two fjords in NE Greenland-Tyrolerfjord (TF, *748N, sill present) and Dove Bugt (DB, *768N, open). Twenty-three prey taxa and categories were identified and both gadoids ate mostly crustaceans. The SI values of 0.64-0.70 indicated possible resource competition, whereas FO differed significantly. A. glacialis fed mainly on the mysid Mysis oculata and other benthic-associated prey, whereas B. saida ate the copepod Metridia longa and other pelagic prey. Both diet and stable isotopes strongly suggest a spatial segregation in feeding habitat, with A. glacialis being associated with the benthic food web (mean d 13 C = -20.81%, d 15 N = 14.92%) and B. saida with the pelagic food web (mean d 13 C = -21.25%, d 15 N = 13.64%). The dietary differences and isotopic signals were highly significant in the secluded TF and less clear in the open DB, where prey and predators may be readily advected from adjacent areas with other trophic conditions. This is the first study on the trophic position of A. glacialis inferred from analyses of stable isotopes. The subtle interaction between the Arctic gadoids should be carefully monitored in the light of ocean warming and ongoing invasions of boreal fishes into the Arctic seas.

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“…Nevertheless, very often in ecological models the role of gelatinous organisms in the food web is simplified, considered as a single functional 'jellyfish' group, assumed to have the same diet and to occupy the same trophic level (Pauly et al 2009). In the near future, this problem might be overcome by an increasing number of studies that apply stable isotopes for analysing the role of gelatinous plankton in planktonic food chains (see Pitt et al 2009a for a review, Cardona et al 2012, Syväranta et al 2012, D'Ambra et al 2013a.…”

Section: Introductionmentioning

confidence: 99%

Jellyfish biochemical composition: importance of standardised sample processing

Kogovšek¹,

Tinta²,

Klun³

et al. 2014

Mar. Ecol. Prog. Ser.

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Jellyfish play a key role in many pelagic ecosystems, especially in areas of extensive bloom events. In order to understand their role in pelagic food webs and in biogeochemical cycling, the energy stored and the trophic level occupied by jellyfish need to be quantified. To date, the common protocols applied for quantifying jellyfish biomass and analyzing its biochemical composition have been the same as for crustacean zooplankton, despite the difference in the body composition of the 2 groups. With the goal of establishing a uniform and reliable protocol for assessing jellyfish biomass, elemental, stable isotope and amino acid pool composition, we compared several methods commonly used in zooplankton ecology. Our results show that jellyfish dry mass varied with ambient salinity changes, thus giving a poor representation of jellyfish biomass. Moreover, the content of organic matter determined as ash free dry mass was overestimated; it was on average 2.2 times higher when compared to the mass of the retained material after dialysis. Furthermore, we demonstrated that during oven-drying at 60°C the protein-rich jellyfish tissue underwent significant changes: samples were (1) depleted in elemental C and N and total amino acid pool and (2) enriched in 15 N, when compared to freeze-dried samples. We therefore suggest that freeze-drying should be selected over oven-drying before isotope and total amino acid analysis is applied. Overall, the results of this study suggest that the methods used to assess jellyfish biochemical composition should be carefully chosen.

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Stable isotopes challenge the perception of ocean sunfish Mola mola as obligate jellyfish predators

Abstract: Evidence is provided from stable isotope analysis that aggregations of small ocean sunfish Mola mola (total length <1 m) feed broadly within coastal food webs and their classification as obligate predators of gelatinous zooplankton requires revision.

Cited by 41 publications

References 34 publications

Ecology of the Ocean Sunfish, Mola mola, in the southern California Current System

Ecology of the Ocean Sunfish, Mola mola, in the southern California Current System

Trophic ecology of sympatric Arctic gadoids, Arctogadus glacialis (Peters, 1872) and Boreogadus saida (Lepechin, 1774), in NE Greenland

Jellyfish biochemical composition: importance of standardised sample processing

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