Trophic structure of mesopelagic fishes in the Gulf of Mexico revealed by gut content and stable isotope analyses

McClain‐Counts, Jennifer P.; Demopoulos, Amanda W.J.; Ross, Steve W.

doi:10.1111/maec.12449

Cited by 45 publications

(43 citation statements)

References 97 publications

(227 reference statements)

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“…Similar to zooplankton, we found that some migrating mesopelagic micronekton exhibited lower δ 15 N values than those of mesopelagic nonmigrators (as in Valls et al ; McClain‐Counts et al ; Fig. ).…”

Section: Discussionsupporting

confidence: 81%

Differences in the trophic ecology of micronekton driven by diel vertical migration

Romero-Romero

Choy

Hannides

et al. 2019

Limnology & Oceanography

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Many species of micronekton perform diel vertical migrations (DVMs), which ultimately contributes to carbon export to the deep sea. However, not all micronekton species perform DVM, and the nonmigrators, which are often understudied, have different energetic requirements that might be reflected in their trophic ecology. We analyze bulk tissue and whole animal stable nitrogen isotopic compositions (δ15N values) of micronekton species collected seasonally between 0 and 1250 m depth to explore differences in the trophic ecology of vertically migrating and nonmigrating micronekton in the central North Pacific. Nonmigrating species exhibit depth‐related increases in δ15N values mirroring their main prey, zooplankton. Higher variance in δ15N values of bathypelagic species points to the increasing reliance of deeper dwelling micronekton on microbially reworked, very small suspended particles. Migrators have higher δ15N values than nonmigrators inhabiting the epipelagic zone, suggesting the consumption of material during the day at depth, not only at night when they migrate closer to the surface. Migrating species also appear to eat larger prey and exhibit a higher range of variation in δ15N values seasonally than nonmigrators, likely because of their higher energy needs. The dependence on material at depth enriched in 15N relative to surface particles is higher in migratory fish that ascend only to the lower epipelagic zone. Our results confirm that stark differences in the food habits and dietary sources of micronekton species are driven by vertical migrations.

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Section: Discussionsupporting

confidence: 81%

Differences in the trophic ecology of micronekton driven by diel vertical migration

Romero-Romero

Choy

Hannides

et al. 2019

Limnology & Oceanography

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“…Herbivorous copepods and euphausiids are the mostly commonly used marine organisms (e.g. Marsh et al 2017, McClain-Counts et al 2017, thus propagating the isotopic error associated with low d 15 N Bulk values to consumer TP Bulk estimates through the food web. Finally, some maps of marine d 15 N Bulk isoscapes are modeled using zooplankton data sets (Graham et al 2010, McMahon et al 2013, with the direct potential biological outcome of erroneous interpretation of animal movements.…”

Section: Perspectivesmentioning

confidence: 99%

Amino acid δ13C and δ15N from sclerotized beaks: a new tool to investigate the foraging ecology of cephalopods, including giant and colossal squids

Cherel¹,

Bustamante²,

Richard³

2019

Mar. Ecol. Prog. Ser.

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Combining the use of predators as biological samplers together with measurements of the stable isotopic ratios (d 13 C Bulk and d 15 N Bulk ) of their sclerotized beaks help investigate foraging ecology of poorly known oceanic cephalopods. However, high chitin content (an amino-sugar macromolecule) lowers beak d 15 N Bulk values, thus precluding direct isotopic comparison with other tissues and organisms. To overcome the chitin effect, compound-specific isotopic analysis of amino acids (CSIA-AA) was performed on squid beaks. The method was applied on beaks and muscle, and the resulting d 13 C AA and d 15 N AA values compared between tissues. The usefulness of CSIA was tested by defining the habitat and trophic position (TP CSIA ) of squids using their d 13 C AA and d 15 N AA values. Beak d 13 C AA values were reliably measured on 12 AA that included 5 essential and 7 non-essential AA, and d 15 N AA values were quantified on at least 7 AA that included 2 source and 4 trophic AA. Importantly, d 13 C AA and d 15 N AA varied little between muscle and lower and upper beaks, and TP CSIA estimates were identical regardless of the tissue considered. Tissue d 13 C AA values of both essential and non-essential AA reflected the latitudinal baseline d 13 C gradient that occurs in the Southern Indian Ocean, while beak d 15 N AA from source and trophic AA allowed the disentangling of the baseline effect from the trophic effect, and thus better calculations of squid TP estimates than from d 15 N Bulk values. Beak d 13 C AA and d 15 N AA defined isotopic niches of colossal and giant squids, the 2 largest living invertebrates. In subantarctic waters, they segregate by having species-specific foraging habitats (using d 13 C Gly or d 15 N Phe ) and TP CSIA (using d 15 N Glx and d 15 N Phe ). TP CSIA is higher in colossal (4.7) than giant (4.3) squids, and both values compare well with those of myctophid-eaters, suggesting very large squids prey primarily upon small zoo plankti vorous fishes. As expected, CSIA-AA overcomes the chitin effect on beaks and it is a powerful tool to investigate trophic interactions of cephalopods. The method has a great potential with arthropods, because chitin is a main component of their exoskeleton but the deleterious effect of chitin is overlooked in isotopic studies focusing on crustaceans and insects.

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“…Trophic ecology of myctophid communities has been investigated through studies of gut content analyses (e.g. Clarke, 1980;Gartner, 1992, Hopkins et al, 1996;Bernal et al, 2015;McClain-Counts et al, 2017) which identified these groups of fishes as mainly zooplankton feeders. More recent studies based on bulk stable carbon (δ 13 C) and nitrogen (δ 15 N) signatures have determined the trophic levels of several species in the Tasman Sea (Flynn and Kloser, 2012), Mediterranean Sea (Fanelli et al, 2011;Valls et al, 2014), and Gulf of Mexico (McClain-Counts et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

Trophic position of lanternfishes (Pisces: Myctophidae) of the tropical and equatorial Atlantic estimated using stable isotopes

Olivar

Bode

López-Pérez

et al. 2018

ICES Journal of Marine Science

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Lanternfishes (Myctophidae) constitute the most important component of the daily vertically migrating mesopelagic fish community. This research addresses the estimation of the trophic position and diet of myctophids using stable isotope analyses. Fishes were collected across the central Atlantic, from a very productive zone influenced by the Mauritanian upwelling to the western oligotrophic equatorial waters. The survey also encompassed a zone of low oxygen concentration in the mesopelagic layers. Determinations of δ13C and δ15N values were made on the 20 most frequent and abundant myctophids, from small-sized species (e.g. Notolychnus valdivae) to larger ones (e.g. Myctophum punctatum). Isotope analyses on the seston and several plankton groups were also performed to assess the influence of zonal differences in trophic position (TP) calculations, and to use as food sources in diet estimations. Myctophids displayed a narrow range of trophic positions, being greater than 2 and less than 4, except for N. valdiviae (TP = 1.7). Comparisons of diets estimated through an isotopic mixing model differentiated the smallest species, with a strong seston signature (Diogenichthys atlanticus and N. valdiviae), from the Diaphus species of medium sizes, (D. brachycephalus, D. holti, and D. rafinesquii), which feed on prey of higher TP values.

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Trophic structure of mesopelagic fishes in the Gulf of Mexico revealed by gut content and stable isotope analyses

Cited by 45 publications

References 97 publications

Differences in the trophic ecology of micronekton driven by diel vertical migration

Differences in the trophic ecology of micronekton driven by diel vertical migration

Amino acid δ13C and δ15N from sclerotized beaks: a new tool to investigate the foraging ecology of cephalopods, including giant and colossal squids

Trophic position of lanternfishes (Pisces: Myctophidae) of the tropical and equatorial Atlantic estimated using stable isotopes

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