Trophic Diversity of Plankton in the Epipelagic and Mesopelagic Layers of the Tropical and Equatorial Atlantic Determined with Stable Isotopes

Bode, Antonio; Hernández‐León, Santiago

doi:10.3390/d10020048

Cited by 12 publications

(9 citation statements)

References 59 publications

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“…Opportunistic feeding on prey that are scarce (i.e., low plankton biomass) and diverse would cause large variations in the isotopic composition of both prey and consumers, and therefore would produce large isotopic niches. Similar results were found in plankton from deep layers of the Atlantic, where the communities living in tropical, oligotrophic zones showed isotopic niches of large size (Bode and Hernández-León, 2018). From an ecological perspective, it can be suggested that the U-OLIGO-Z, representing a special ecosystem of the South Pacific central gyre, may be less sensitive to a changing environment upon a greater plasticity of species to exploit highly diverse resources.…”

Section: Discussionsupporting

confidence: 69%

Zooplankton Taxonomic and Trophic Community Structure Across Biogeochemical Regions in the Eastern South Pacific

et al. 2019

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Biochemical conditions and taxonomic composition of size-fractioned mesozooplankton were studied after a cruise conducted in September 2015 between the Chilean coast (70 • W) and Easter Island (110 • W) within the central south Pacific gyre. Taxonomy was assessed with an automated method based on image analysis and biochemical conditions assessed by analyses of C and N contents and stable isotope composition. Based on surface Chlorophyll-a levels, four regions were distinguished across the zonal gradient: eutrophic (Chilean upwelling zone), mesotrophic (Coastal Transition Zone), oligotrophic (open ocean water) and ultraoligotrophic (central south Pacific gyre). The zones had marked differences in temperature, oxygen, salinity and Chlorophyll-a, and they also exhibited significant differences in zooplankton composition, C/N ratios and δ 13 C and δ 15 N for all size fractions of zooplankton. Variability in the sources of C and N, linked to biogeochemical processes, such as new production and denitrification in the upwelling zone, potential diazotrophy, highly regenerated C and N and extreme oligotrophy (N-deficiency) in oceanic areas, are suggested as the key drivers of these differences. Our findings also suggest a strong coupling between taxonomic and size zooplankton-diversity and the sources of nutrients that fuel phytoplankton, the major food source for zooplankton. Although multiple factors and processes can modulate C and N and their isotopes composition of zooplankton biomass, our study shows that changes in community structure are linked to different biogeochemical regions across the zonal gradient, providing the basis for ecological zonation associated with nutrient utilization at lower trophic levels.

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Section: Discussionsupporting

confidence: 69%

Zooplankton Taxonomic and Trophic Community Structure Across Biogeochemical Regions in the Eastern South Pacific

et al. 2019

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“…The high variability observed in δ 13 C values among blue whales sampled just a few days apart suggests that individuals within the population foraged across a strong gradient in baseline δ 13 C values. Such gradients are often associated with sharp transitions in biogeochemistry, oceanography and productivity across major biogeographic domains [27,65,66].…”

Section: Discussionmentioning

confidence: 99%

Stable isotopes reveal winter feeding in different habitats in blue, fin and sei whales migrating through the Azores

et al. 2019

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Knowing the migratory movements and behaviour of baleen whales is fundamental to understanding their ecology. We compared δ 15 N and δ 13 C values in the skin of blue ( Balaenoptera musculus ), fin ( Balaenoptera physalus ) and sei ( Balaenoptera borealis ) whales sighted in the Azores in spring with the values of potential prey from different regions within the North Atlantic using Bayesian mixing models to investigate their trophic ecology and migration patterns. Fin whale δ 15 N values were higher than those recorded in blue and sei whales, reflecting feeding at higher trophic levels. Whales' skin δ 15 N and δ 13 C values did not reflect prey from high-latitude summer foraging grounds; instead mixing models identified tropical or subtropical regions as the most likely feeding areas for all species during winter and spring. Yet, differences in δ 13 C values among whale species suggest use of different regions within this range. Blue and sei whales primarily used resources from the Northwest African upwelling and pelagic tropical/subtropical regions, while fin whales fed off Iberia. However, determining feeding habitats from stable isotope values remains difficult. In conclusion, winter feeding appears common among North Atlantic blue, fin and sei whales, and may play a crucial role in determining their winter distribution. A better understanding of winter feeding behaviour is therefore fundamental for the effective conservation of these species.

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“…Ratios of nitrogen also varied between provinces, according to the differences found in δ 15 N values of Oncaeidae. Low δ 15 N values could be due to diazotrophy since the atmospheric nitrogen presents δ 15 N = 0‰, and it can be traced through the food web (McClelland et al, 2003;Mompeán et al, 2016a;Bode and Hernández-León, 2018). This process is mediated by specialized prokaryotes -diazotrophs -which thrive in usually nitrate-poor, warm and stratified waters such as the ones of the subtropical and tropical gyres (Falkowski, 1997;Zehr et al, 2003;Capone et al, 2005;Luo et al, 2012) and introduce into the ocean bioavailable nitrogen depleted in δ 15 N (Somes et al, 2010).…”

Section: Discussionmentioning

confidence: 99%

Trophic Structure of Neuston Across Tropical and Subtropical Oceanic Provinces Assessed With Stable Isotopes

et al. 2021

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The marine neuston, organisms living in the vicinity of the ocean surface, is one of the least studied zooplankton groups. Neuston occupies a restricted ecological niche and is affected by a wide range of endogenous and exogenous processes while also being a food source to zooplankton fish migrating from the deep layers and seabirds. In this study, the neustonic communities were characterized along the Malaspina global expedition sampling tropical and subtropical oceanic provinces using stable carbon and nitrogen isotopes to explore their trophic structure and relationships with environmental variables. The differences in stable isotopes mirrored the patterns in environmental characteristics of each province. High δ13C values were associated with atmospheric carbon inputs, while the presence of dinoflagellates, coccolithophorids, and upwelling influence is related to low δ13C values. Similarly, provinces presenting high δ15N values were associated with denitrification and nitrate diffusive fluxes, whereas the presence of low δ15N is attributable to nitrogen supplied through N2 fixation by diazotrophs. Neuston showed a large overlap among the isotopic niches of four functional groups, with chaetognaths and detritivores generally exhibiting a smaller degree of overlap compared to carnivores and omnivores/herbivores. These results support the hypothesis of a common trophic structure in the neuston community across the ocean. However, the size of the niche, small in coastal areas and those influenced by upwelling and large in oligotrophic regions, and their overlap, low in more productive provinces and high in oligotrophic provinces, may be associated with food availability. Small trophic niches are associated with a dominance of specialized over-opportunistic feeding in productive environments.

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Trophic Diversity of Plankton in the Epipelagic and Mesopelagic Layers of the Tropical and Equatorial Atlantic Determined with Stable Isotopes

Cited by 12 publications

References 59 publications

Zooplankton Taxonomic and Trophic Community Structure Across Biogeochemical Regions in the Eastern South Pacific

Zooplankton Taxonomic and Trophic Community Structure Across Biogeochemical Regions in the Eastern South Pacific

Stable isotopes reveal winter feeding in different habitats in blue, fin and sei whales migrating through the Azores

Trophic Structure of Neuston Across Tropical and Subtropical Oceanic Provinces Assessed With Stable Isotopes

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