From the epipelagic zone to the abyss: Trophic structure at two seamounts in the subtropical and tropical Eastern Atlantic - Part II Benthopelagic fishes

Denda, Anneke; Stefanowitsch, Benjamin; Christiansen, Bernd

doi:10.1016/j.dsr.2017.08.005

Cited by 11 publications

(13 citation statements)

References 85 publications

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“…In this study, we provided the first dedicated trophic assessment of the jelly web within the planktonic food web of the eastern tropical Atlantic based on stable isotope analysis. Overall, our findings confirmed the large isotopic ranges in both δ 15 N and δ 13 C reported previously for the planktonic food webs (including seston, zooplankton, and micronekton) of the eastern tropical Atlantic (Denda et al 2017). Expanding on this foundation, our findings highlighted the large proportion of this overall isotopic space covered by the jelly web, and illustrated substantial complexity resulting from patterns in trophic niche differentiation and overlap among gelatinous zooplankton groups and from variation on the spatial, depth, and taxon-specific level.…”

Section: Discussionsupporting

confidence: 91%

“…Moreover, scyphomedusae with the two dominant species Atolla wyvillei and Periphylla periphylla occupied the highest trophic level in the jelly web in our study, and these species have been classified as prominent predators in the mesopelagic community (Hunt and Lindsay 1998) occurring in coastal fjord ecosystems and meso-and bathypelagic depths. Finally, the isotopic niche space of chaetognaths was remarkably segregated between depth layers, which also confirm previous results in the same area (Denda et al 2017).…”

Section: Trophic Niche Differentiation and Overlap In The Jelly Websupporting

confidence: 91%

“…A combined view of trophic niches of a large range of gelatinous zooplankton taxa would in turn reflect the overall trophic niche space covered by the jelly web within planktonic oceanic communities and reveal patterns in resource partitioning and competition (Boecklen et al 2011), in line with community ecology studies on other systems. However, while a number of studies have addressed the composition and trophic structure of planktonic oceanic communities, including individual gelatinous zooplankton groups (Denda et al 2017), dedicated studies remain rare. One major problem has been the difficulty to obtain suitable sample sets.…”

mentioning

confidence: 99%

“…In recent years, there has been an increase in research activities to improve biological and oceanographic understanding of this oceanic region (Devey 2014). This includes, for example, studies of oxygen minimum zones (Teuber et al 2013), the role of seamounts as biodiversity hotspots (Hanel et al 2010), the influence of zooplankton on organic matter flux in mesoscale eddies (Christiansen et al 2018), the trophic ecology of pelagic and benthopelagic organisms (Merten et al 2017), and the trophic structure of communities, including individual gelatinous zooplankton groups (Denda et al 2017). A previous study has shown that gelatinous zooplankton in the eastern tropical Atlantic are highly abundant and diverse (Hoving et al 2019), but dedicated studies providing a more holistic view of characteristics of the trophic structure of gelatinous zooplankton communities in this area are lacking.…”

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confidence: 99%

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Tackling the jelly web: Trophic ecology of gelatinous zooplankton in oceanic food webs of the eastern tropical Atlantic assessed by stable isotope analysis

Chi

Dierking

Hoving

et al. 2020

Limnology & Oceanography

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Gelatinous zooplankton can be present in high biomass and taxonomic diversity in planktonic oceanic food webs, yet the trophic structuring and importance of this "jelly web" remain incompletely understood. To address this knowledge gap, we provide a holistic trophic characterization of a jelly web in the eastern tropical Atlantic, based on δ 13 C and δ 15 N stable isotope analysis of a unique gelatinous zooplankton sample set. The jelly web covered most of the isotopic niche space of the entire planktonic oceanic food web, spanning > 3 trophic levels, ranging from herbivores (e.g., pyrosomes) to higher predators (e.g., ctenophores), highlighting the diverse functional roles and broad possible food web relevance of gelatinous zooplankton. Among gelatinous zooplankton taxa, comparisons of isotopic niches pointed to the presence of differentiation and resource partitioning, but also highlighted the potential for competition, e.g., between hydromedusae and siphonophores. Significant differences in spatial (seamount vs. open ocean) and depth-resolved patterns (0-400 m vs. 400-1000m) pointed to additional complexity, and raise questions about the extent of connectivity between locations and differential patterns in vertical coupling between gelatinous zooplankton groups. Added complexity also resulted from inconsistent patterns in trophic ontogenetic shifts among groups. We conclude that the broad trophic niche covered by the jelly web, patterns in niche differentiation within this web, and substantial complexity at the spatial, depth, and taxon level call for a more careful consideration of gelatinous zooplankton in oceanic food web models. In light of climate change and fishing pressure, the data presented here also provide a valuable baseline against which to measure future trophic observations of gelatinous zooplankton communities in the eastern tropical Atlantic.

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Section: Discussionsupporting

confidence: 91%

Section: Trophic Niche Differentiation and Overlap In The Jelly Websupporting

confidence: 91%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Tackling the jelly web: Trophic ecology of gelatinous zooplankton in oceanic food webs of the eastern tropical Atlantic assessed by stable isotope analysis

Chi

Dierking

Hoving

et al. 2020

Limnology & Oceanography

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“…Moreover, little is known about the biology of C. profundicolus in general, especially in comparison to C. armatus. Dietary studies in C. profundicolus have not identified an ontogenetic shift (Denda et al, 2017), so it is not possible to establish whether the apparent ontogenetic shift from vision to olfaction identified here is correlated with a change in feeding strategy or behavior in this species.…”

Section: Ontogenetic Shifts In Sensory Capability In Coryphaenoidesmentioning

confidence: 71%

Ontogenetic Shifts in the Number of Axons in the Olfactory Tract and Optic Nerve in Two Species of Deep-Sea Grenadier Fish (Gadiformes: Macrouridae: Coryphaenoides)

2018

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Neuroanatomical studies of the peripheral sense organs and brains of deep-sea fishes are particularly useful for predicting their sensory capabilities and ultimately their behavior. Over the abyssal plane (between 2,000 and 6,000 m), communities of grenadiers (Gadiformes: Macrouridae) play an important ecological role as predator-scavengers. Previous studies suggest that these fishes rely heavily on chemosensation, especially olfaction. Furthermore, at least one species, Coryphaenoides armatus, undergoes an ontogenetic shift in the relative size of the optic tectum and the olfactory bulbs, suggesting. a shift from a reliance on vision to olfaction during ontogeny, apparently in association with a shift to a more scavenging lifestyle. Here, we compared the olfactory and visual sensory inputs to the brain in C. armatus, and in a second, closely-related species, Coryphaenoides profundicolus, by assessing the total number of axons (myelinated and unmyelinated) in the olfactory tract and optic nerve in a range of individuals from both species. In C. armatus, the numbers of axons in both tract and nerve increased with body size, with the total number of axons in the olfactory tract being far greater than the number of axons in the optic nerve. These differences became more pronounced in larger animals. In the two smaller C. profundicolus individuals (≤315 mm SL), there were more axons in the optic nerve than in the olfactory tract, but the opposite situation was found in larger individuals. As in C. armatus, the number of olfactory tract axons also increased with body size in C. profundicolus, but in contrast, the number of optic nerve axons decreased in this species. These results suggest that both C. armatus and C. profundicolus undergo an ontogenetic shift in sensory orientation, with olfaction becoming relatively more important than vision in larger animals. The differences in the ratio of olfactory tract to optic nerve axons in C. armatus indicate that olfaction is of Lisney et al. Olfactory and Visual Inputs in Deep-Sea Fish particular importance to larger individuals of this species. In both species, the percentage of myelinated axons in the olfactory tract was relatively low, but we found evidence for interspecific and ontogenetic variation in the percentages of myelinated axons in the optic nerve.

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Near-bottom zooplankton over three seamounts in the east Canary Islands: Influence of environmental variables on distribution and composition.

Papiol

Cartes

Vélez‐Belchí

et al. 2019

Deep Sea Research Part I: Oceanographic Research Papers

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The near-bottom zooplankton over three seamounts of the eastern Canary Islands (Amanay, El Banquete and Concepción) was analyzed, identifying the environmental variables that explain biomass distributions over them. Zooplankton composition changed between adjacent water masses, except for the two deepest assemblages associated with Atlantic Antarctic Intermediate Water (AAIW) and Mediterranean Water (MW). The highest biomass of total zooplankton and of main taxa (e.g. copepods, chaetognaths, siphonophores) were recorded at the seamount summits, i.e., over Amanay-El Banquete (summit depths of 23-24 m) associated with Surface Water (SF) and over Concepción (150 m) in upper levels of the North Atlantic Central Water (NACW). Biomass minima at the three banks were found at ca. 250-650 m, in the deepest levels of NACW. At ca. 700-1000 m (the level occupied by AAIW) and below 1000 m (MW level) biomass increased again. Near-bottom fluorometry (f 5mab , 5 m above bottom) and dissolved oxygen (O 2 5mab) were the main variables explaining changes of total zooplankton/main taxa biomass. Biomass minima (250-650 m) coincided with decreases of O 2 5mab (3.30-3.99 ml/l at 400-700 m) at deepest depths occupied by NACW. Other variables not included in our models like turbidity (resuspension of particles) may have locally enhanced zooplankton aggregation, as they may locally occur alongside Concepcion at the NACW-AAIW confluence (at ca. 700 m), probably from the effects of internal waves. Our results suggest that observations regarding the attraction of organisms to the stationary substrates of seamounts could be related to elevated chlorophyll fluorescence and O 2 5mab concentration. Peaks in those variables apparently enhance zooplankton aggregation.

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From the epipelagic zone to the abyss: Trophic structure at two seamounts in the subtropical and tropical Eastern Atlantic - Part II Benthopelagic fishes

Cited by 11 publications

References 85 publications

Tackling the jelly web: Trophic ecology of gelatinous zooplankton in oceanic food webs of the eastern tropical Atlantic assessed by stable isotope analysis

Tackling the jelly web: Trophic ecology of gelatinous zooplankton in oceanic food webs of the eastern tropical Atlantic assessed by stable isotope analysis

Ontogenetic Shifts in the Number of Axons in the Olfactory Tract and Optic Nerve in Two Species of Deep-Sea Grenadier Fish (Gadiformes: Macrouridae: Coryphaenoides)

Near-bottom zooplankton over three seamounts in the east Canary Islands: Influence of environmental variables on distribution and composition.

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