scholarly journals Trophic ecology of yellowtail rockfish (Sebastes flavidus) during a marine heat wave off central California, USA

PLoS ONE ◽  
2021 ◽  
Vol 16 (5) ◽  
pp. e0251499
Author(s):  
Jennifer A. Chiu ◽  
Joseph J. Bizzarro ◽  
Richard M. Starr
Keyword(s):  
Stable Isotope ◽  
Heat Wave ◽  
Diet Composition ◽  
Trophic Ecology ◽  
Trophic Position ◽  
Marine Ecosystem ◽  
Isotope Analysis ◽  
California Current ◽  
Central California ◽  
Marine Heat Wave

The yellowtail rockfish, Sebastes flavidus, is a widespread and abundant mesopredator in the California Current Large Marine Ecosystem. We utilized stomach content and stable isotope analyses to investigate the trophic ecology of this species at three sites off central California just before (August–October 2013) and during (August and October 2014) a marine heat wave. Sebastes flavidus largely consumed pelagic prey (zooplankton and micronekton). Diets were dominated by tunicates (salps and pyrosomes), pelagic crustaceans (euphausiids, hyperid amphipods, larval decapods), and fishes, with the relative contribution of these prey taxa varying spatially (sample location, longitude, depth) and temporally (year, month), based on complementary multivariate analyses. Prey-specific indices demonstrated that individual S. flavidus diet composition typically was dominated by one of these prey groups, and that prey switching occurred based on the relative availability of prey and their energetic importance. Stable isotope analysis of δ15N indicated that the S. flavidus populations sampled in 2014 had been feeding at an elevated trophic position and more variable prey spectrum relative to 2013, probably as a consequence of greater piscivory and the incorporation of temporal changes in diet composition. Because its opportunistic feeding behavior reflects the dynamism and heterogeneity of the pelagic forage preyscape, S. flavidus may be an important ecosystem indicator species. For example, the novel incorporation of pyrosomes as a large portion of the diet of S. flavidus during 2013–2014 directly related to the massive increase in pyrosome abundance in the California Current during the 2014 marine heat wave.

Trophic ecology of the blue shark (Prionace glauca) based on stable isotopes (δ13C and δ15N) and stomach content

2015 ◽  
Vol 96 (7) ◽  
pp. 1403-1410 ◽  
Author(s):  
Sandra Berenice Hernández-Aguilar ◽  
Ofelia Escobar-Sánchez ◽  
Felipe Galván-Magaña ◽  
Leonardo Andrés Abitia-Cárdenas
Keyword(s):  
Stable Isotope ◽  
Stomach Content ◽  
Trophic Ecology ◽  
Baja California ◽  
Marine Ecosystem ◽  
Isotope Analysis ◽  
Trophic Levels ◽  
Baja California Sur ◽  
Δ13c And Δ15n ◽  
Prionace Glauca

Occupying the upper levels of trophic webs and thus regulating prey at lower levels, sharks play an important role in the trophic structure and energy dynamics of marine ecosystems. In recent years, the removal of these individuals from upper trophic levels as a result of overfishing has negatively affected ecosystems. We analysed the diet of blue sharks (Prionace glauca) caught off the west coast of Baja California Sur, Mexico, during the months of February–June in 2001, 2005 and 2006. We employed both stomach content and stable isotope analyses as each method provides distinct yet important information regarding the role of blue sharks in marine food webs, allowing us to estimate the relative contribution of different prey items to this predator's diet. Of the 368 stomachs analysed, 210 contained food (57%) and 158 (43%) were empty. Based on stomach contents and the index of relative importance (IRI), the pelagic red crab (Pleuroncodes planipes) was the most important prey, followed by the squids Gonatus californiensis (34.1%) and Ancistrocheirus lesueurii (10.4%). The mean (±SD) values for δ15N (16.48 ± 0.94‰) and δ13C (−18.48 ± 0.63‰) suggest that blue sharks prefer feeding in oceanic waters. The trophic level based on stomach content analysis was 4.05, while that based on the stable isotope analysis was 3.8, making blue sharks top consumers in the marine ecosystem of Baja California Sur, Mexico.

scholarly journals Trophic Relations of the Red-Necked Grebe on Lakes in the Western Boreal Forest: A Stable-Isotope Analysis

The Condor ◽  
2004 ◽  
Vol 106 (3) ◽  
pp. 638-651 ◽  
Author(s):  
Cynthia A. Paszkowski ◽  
Beverly A. Gingras ◽  
Kayedon Wilcox ◽  
Paul H. Klatt ◽  
William M. Tonn
Keyword(s):  
Stable Isotope ◽  
Food Web ◽  
Stable Isotope Analysis ◽  
Trophic Ecology ◽  
Trophic Position ◽  
Isotope Analysis ◽  
Gut Contents ◽  
Isotopic Ratios ◽  
Trophic Relations ◽  
Podiceps Grisegena

Abstract We compared trophic ecology of grebes inferred from stable-isotope analysis to that from gut contents, and compared isotopic ratios of Red-necked Grebes (Podiceps grisegena) from lakes differing in their food webs. Analyses of different grebe tissues (egg yolk and albumen, pectoral and leg muscle, breast and primary feathers) also allowed us to assess the effectiveness of these tissues at representing grebe trophic relations. Isotopic ratios from pectoral and leg muscles were similar, based on comparisons within individual birds. Enriched values of δ15N and δ13C suggested that breast and primary feathers were molted over winter, and therefore reflected a marine food web. Albumen and yolk of grebe eggs and muscle tissues from downy chicks, however, matched isotopic characteristics of the local food web, indicating that female Red-necked Grebes use nutrients from the breeding lake for egg formation. Eggs, therefore, can provide excellent material for isotopic analysis aimed at assessing trophic relations of Red-necked Grebes on breeding lakes. Gut contents and stable isotopes both indicated that grebes from lakes with fish consumed a mixed diet of fish and macroinvertebrates and occupied the highest trophic level, at or above the level of piscivorous fishes. In contrast, grebes from lakes lacking fish occupied a lower trophic position. Relaciones Tróficas de Podiceps grisegena en Lagos del Bosque Boreal del Oeste: Un Análisis de Isótopos Estables Resumen. Comparamos la ecología trófica de Podiceps inferida a partir de análisis de isótopos estables con la de contenidos estomacales y comparamos las relaciones isotópicas de P. grisegena entre lagos que difieren en sus redes tróficas. Los análisis de diferentes tejidos de P. grisegena (yema y albumen del huevo, músculo pectoral y de la pierna, plumas del pecho y primarias) también nos permitieron evaluar la efectividad de estos tejidos para representar las relaciones tróficas de P. grisegena. Las relaciones isotópicas de los músculos pectorales y de las piernas basadas en comparaciones realizadas para cada ave individual fueron similares. Valores enriquecidos de δ15N y δ13C sugirieron que las aves mudaron las plumas del pecho y las primarias durante el invierno, y por lo tanto reflejaron una red trófica marina. El albumen y la yema del huevo de P. grisegena y los tejidos musculares de pichones emplumados, sin embargo, coincidieron con las características isotópicas de la red alimenticia local, indicando que las hembras de P. grisegena usan nutrientes del lago donde nidifican para la formación de los huevos. Los huevos, por lo tanto, pueden constituir un material excelente para análisis isotópicos centrados en evaluar las relaciones tróficas de P. grisegena en los lagos donde se reproducen. Los contenidos estomacales y los isótopos estables indicaron que los individuos de P. grisegena provenientes de lagos con peces consumieron una dieta mixta de peces y macroinvertebrados y ocuparon la posición trófica más alta, al mismo nivel o por arriba de los peces piscívoros. En contraste, los individuos provenientes de lagos sin peces ocuparon una posición trófica menor.

scholarly journals Clarifying a trophic black box: stable isotope analysis reveals unexpected dietary variation in the Peruvian anchovy Engraulis ringens

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e6968 ◽  
Author(s):  
Jessica Pizarro ◽  
Felipe Docmac ◽  
Chris Harrod
Keyword(s):  
Stable Isotope ◽  
Stable Isotope Analysis ◽  
Trophic Ecology ◽  
Trophic Position ◽  
Isotope Analysis ◽  
Trophic Levels ◽  
Mixing Models ◽  
Jack Mackerel ◽  
Humboldt Current ◽  
Engraulis Ringens

Background Small fishes play fundamental roles in pelagic ecosystems, channelling energy and nutrients from primary producers to higher trophic levels. They support globally important fisheries in eastern boundary current ecosystems like the Humboldt Current System (HCS) of the SE Pacific (Chile and Peru), where fish catches are the highest in the world (per unit area). This production is associated with coastal upwelling where fisheries target small pelagic fishes including the Peruvian anchovy (Engraulis ringens). The elevated biomass attained by small pelagics is thought to reflect their low trophic position in short/simple food chains. Despite their global importance, large gaps exist in our understanding of the basic ecology of these resources. For instance, there is an ongoing debate regarding the relative importance of phytoplankton versus animal prey in anchovy diet, and ecosystem models typically assign them a trophic position (TP) of ∼2, assuming they largely consume phytoplankton. Recent work based on both relative energetic content and stable isotope analysis (SIA) suggests that this value is too low, with δ15N values indicating that anchovy TP is ca. 3.5 in the Peruvian HCS. Methods We characterised the trophic ecology of adult anchovies (n = 30), their putative prey and carnivorous jack mackerel (n = 20) captured from N Chile. SIA (δ13C and δ15N) was used to estimate the relative contribution of different putative prey resources. δ15N was used to estimate population level trophic position. Results Anchovies showed little variability in δ13C (−18.7 to −16.1‰) but varied greatly in δ15N (13.8 to 22.8‰)—individuals formed two groups with low or high δ15N values. When considered as a single group, mixing models indicated that anchovy diet was largely composed of zooplankton (median contribution: 95% credibility limits), with major contributions of crustacean larvae (0.61: 0.37–0.77) and anchovy (preflexion) larvae (0.15: 0.02–0.34), and the assimilation of phytoplankton was negligible (0.05: 0–0.22). The modal (95% credibility limits) estimate of TP for the pooled anchovy sample was 3.23 (2.93–3.58), overlapping with recent SIA-based estimates from Peru. When the two δ15N groups were analysed separately, our results indicate that the lower δ15N group largely assimilated materials from crustacean larvae (0.73: 0.42–0.88), with a TP of 2.91 (2.62–3.23). Mixing models suggested high δ15N anchovies were cannibalistic, consuming anchovy preflexion larvae (0.55: 0.11–0.74). A carnivorous trophic niche was supported by high TP (3.79: 3.48–4.16), mirroring that of carnivorous juvenile jack mackerel (Trachurus murphyi; 3.80: 3.51–4.14). Our results support recent conclusions regarding high TP values of anchovy from Peru and reveal new insights into their trophic behaviour. These results also highlight the existence of cryptic trophic complexity and ecosystem function in pelagic food webs, classically considered as simple.

Trophic ecology of a large-bodied marine predator, bluntnose sixgill shark Hexanchus griseus, inferred using stable isotope analysis

2020 ◽  
Vol 103 (2) ◽  
pp. 147-162
Author(s):  
Jonathan C. P. Reum ◽  
Gregory D. Williams ◽  
Chris J. Harvey ◽  
Kelly S. Andrews ◽  
Phillip S. Levin
Keyword(s):  
Stable Isotope ◽  
Stable Isotope Analysis ◽  
Trophic Ecology ◽  
Isotope Analysis ◽  
Marine Predator ◽  
Hexanchus Griseus

scholarly journals Trophic ecology of sea urchins in coral-rocky reef systems, Ecuador

PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e1578 ◽  
Author(s):  
Nancy Cabanillas-Terán ◽  
Peggy Loor-Andrade ◽  
Ruber Rodríguez-Barreras ◽  
Jorge Cortés
Keyword(s):  
Stable Isotope ◽  
Trophic Ecology ◽  
Habitat Degradation ◽  
Sea Urchins ◽  
Relative Proportion ◽  
Isotope Analysis ◽  
Niche Overlap ◽  
Trophic Niche ◽  
Rocky Reef ◽  
Trophic Overlap

Sea urchins are important grazers and influence reef development in the Eastern Tropical Pacific (ETP).Diadema mexicanumandEucidaris thouarsiiare the most important sea urchins on the Ecuadorian coastal reefs. This study provided a trophic scenario for these two species of echinoids in the coral-rocky reef bottoms of the Ecuadorian coast, using stable isotopes. We evaluated the relative proportion of algal resources assimilated, and trophic niche of the two sea urchins in the most southern coral-rocky reefs of the ETP in two sites with different disturbance level. Bayesian models were used to estimate the contribution of algal sources, niche breadth, and trophic overlap between the two species. The sea urchins behaved as opportunistic feeders, although they showed differential resource assimilation.Eucidaris thouarsiiis the dominant species in disturbed environments; likewise, their niche amplitude was broader than that ofD. mexicanumwhen conditions were not optimal. However, there was no niche overlap between the species. The Stable Isotope Analysis in R (SIAR) indicated that both sea urchins shared limiting resources in the disturbed area, mainlyDictyotaspp. (contributions of up to 85% forD. mexicanumand up to 75% forE. thouarsii). The Stable Isotope Bayesian Ellipses in R (SIBER) analysis results indicated less interspecific competition in the undisturbed site. Our results suggested a trophic niche partitioning between sympatric sea urchin species in coastal areas of the ETP, but the limitation of resources could lead to trophic overlap and stronger habitat degradation.

Stable isotope analysis reveals partitioning in prey use by Kajikia audax (Istiophoridae), Thunnus albacares, Katsuwonus pelamis, and Auxis spp. (Scombridae) in the Eastern Tropical Pacific of Ecuador

2021 ◽  
Vol 19 (4) ◽  
Author(s):  
Rigoberto Rosas-Luis ◽  
Nancy Cabanillas-Terán ◽  
Carmen A. Villegas-Sánchez
Keyword(s):  
Stable Isotope ◽  
Food Web ◽  
Stable Isotope Analysis ◽  
Trophic Ecology ◽  
Isotope Analysis ◽  
Middle Level ◽  
Food Sources ◽  
Thunnus Albacares ◽  
Katsuwonus Pelamis ◽  
Δ13c And Δ15n

Abstract Kajikia audax, Thunnus albacares, Katsuwonus pelamis, and Auxis spp. occupy high and middle-level trophic positions in the food web. They represent important sources for fisheries in Ecuador. Despite their ecological and economic importance, studies on pelagic species in Ecuador are scarce. This study uses stable isotope analysis to assess the trophic ecology of these species, and to determine the contribution of prey to the predator tissue. Isotope data was used to test the hypothesis that medium-sized pelagic fish species have higher δ15N values than those of the prey they consumed, and that there is no overlap between their δ13C and δ15N values. Results showed higher δ15N values for K. audax, followed by T. albacares, Auxis spp. and K. pelamis, which indicates that the highest position in this food web is occupied by K. audax. The stable isotope Bayesian ellipses demonstrated that on a long time-scale, these species do not compete for food sources. Moreover, δ15N values were different between species and they decreased with a decrease in predator size.

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