Stable nitrogen isotope studies of the pelagic food web on the Atlantic shelf of the Iberian Peninsula

Bode, Antonio; Alvarez-Ossorio, M. T.; Cunha, Maria Emília; Garrido, Susana; Peleteiro, J.B.; Porteiro, Carmela; Valdés, Luis; Varela, Manuel

doi:10.1016/j.pocean.2007.04.005

Cited by 98 publications

(71 citation statements)

References 43 publications

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“…Most zooplankton and nekton were within the δ 13 C bounds of nearshore and offshore waters (Fig. 1, as (Vander Zanden & Fetzer 2007) and coastal upwelling zones, based either on stomach content (Yodzis 1998) or stable isotope analysis (3.7 TL, Bode et al 2007). The addition of northern sea lions from the same region as our study (Sydeman et al 1997) added an additional trophic level (total, 5.0).…”

Section: Discussionmentioning

confidence: 99%

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Prey dominance shapes trophic structure of the northern California Current pelagic food web: evidence from stable isotopes and diet analysis

Miller¹,

Brodeur²,

Rau³

et al. 2010

Mar. Ecol. Prog. Ser.

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Eastern boundary current (EBC) upwelling zones are among the most productive of marine ecosystems globally and have been generalized in terms of their food web structure. Little empirically based evidence exists to suggest that there is any one form of trophic control of EBC systems and, because of logistical constraints, knowledge of food web structure is limited in these large marine ecosystems. To determine principal trophic links within the pelagic food web, we combined stable isotope and diet analysis of 21 dominant species of nekton found within the northern California Current, a highly productive EBC upwelling ecosystem. Samples of nekton and zooplankton were collected in June and August 2000 and 2002 from the shelf-slope waters of northern California to Washington. Results showed most nekton consumed mixed diets of zooplankton and larval-juvenile or adult fishes, indicating the importance of omnivory in this system. Euphausiids were overwhelmingly the most prevalent zooplankton taxa in the diets of nekton across multiple trophic levels, accounting for > 50% of the index of relative importance in 10 of 21 nekton species analyzed. Nitrogen stable isotopes (δ 15 N) reflected trophic patterns observed in the diets, with most nekton species (~62%) falling between trophic levels (TL) of full zooplanktivores (TL = 3) and full piscivores (TL = 4). The prevalence of omnivory observed here is probably due to high primary production that supports an abundance of large zooplankton prey, such as euphausiids, which may be a more available prey resource for a broad range of predators. A modification of this form of bottom-up control, termed bottom-up omnivory, is presented.

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Section: Discussionmentioning

confidence: 99%

“…3). Based upon δ 15 N analysis of the food web off the Iberian Peninsula, Bode et al (2007) showed rather distinct differences between zooplankton, fish, and the common dolphin Delphinus delphinus. Most of the 10 fish species they examined were at nonintegral trophic levels and relatively low on the food web (TL of 3.4 to 3.7).…”

Section: Discussionmentioning

confidence: 99%

Prey dominance shapes trophic structure of the northern California Current pelagic food web: evidence from stable isotopes and diet analysis

Miller¹,

Brodeur²,

Rau³

et al. 2010

Mar. Ecol. Prog. Ser.

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“…Badalamenti et al (2002Badalamenti et al ( , 2008 and Fanelli et al (2010) demonstrated that in littoral systems the trophic level of benthic fish such as red mullet and common pandora, which prey upon carnivore polychaetes, is close to that of larger piscivorous predators. Conversely, pelagic food webs are relatively simple (Bode et al 2007, Fanelli et al, 2011b and small pelagic fish such as clupeoids, feeding on zooplankton, exhibit lower δ 15 N values than fish from benthic and suprabenthic assemblages that belong to more complex food webs organized into at least three trophic levels (from deposit feeders to carnivores: Carlier et al 2007, Fanelli et al 2009a, 2011c, with small fish occupying the same trophic level as carnivorous polychaetes or small decapods.…”

Section: The Effect Of the Trawl Ban On The Isotopic Composition And mentioning

confidence: 99%

Assessing the effects of a trawling ban on diet and trophic level of hake, <i>Merluccius merluccius</i>, in the southern Tyrrhenian Sea

Sinopoli¹,

Fanelli²,

D’Anna³

et al. 2011

Sci. Mar.

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SUMMARY: This study assesses the effects of a trawling ban on the diet and trophodynamics of the hake Merluccius merluccius by comparing stomach contents and stable isotopes (δ 15 N and δ 13 C) in two trawled gulfs and one untrawled gulf in northern Sicily (western Mediterranean). Comparisons were made for three size classes of hake encompassing 60 to 410 mm total length. Fish were collected from 50 to 200 m depth on muddy bottoms. The diets of hake of small and medium size were similar overall but more selective in the untrawled gulf. Greater differences were detected between the diets of larger specimens from trawled and untrawled areas. In the untrawled gulf large hake mainly preyed on clupeoid fish, while in the trawled gulfs other fish prey were found in the stomach contents. δ 15 N values of hake did not vary significantly between trawled and untrawled areas, while there was a clear effect of size, with larger individuals being significantly more enriched than juveniles. Conversely, δ 13 C values were generally more depleted for individuals collected in the untrawled area, suggesting a more pelagic source of carbon. The results from the mixing model agree fairly well with the known feeding habits found for each size class in each area.Keywords: diet, fishing impact, Merluccius merluccius, stable isotopes, trophodynamics, Mediterranean. RESUMEN: Efectos de un área de veda a la pesca de arrastre sobre la dieta y el nivel trófico de la merluza, Merluccius Merluccius, en el sur del Mar Tirreno. -Este estudio evaluó los efectos de la pesca de arrastre comercial en la dieta y la trofodinámica de la merluza mediterránea, Merluccius merluccius, mediante la comparación de sus contenidos estomacales y de la composición isotópica (δ 15 N y δ 13 C) en dos golfos donde está permitida la pesca de arrastre y en uno donde está prohibida, en el norte de Sicilia (Mediterráneo Occidental). Las comparaciones se hicieron para tres clases de talla que abarca la merluza entre 60 y 410 mm de longitud total. Los peces fueron recolectados en los fondos fangosos de la plataforma continental de 50 a 200 m de profundidad. Los hábitos alimenticios de las merluzas pequeñas y medianas eran similares, pero más selectivo en el golfo donde la pesca está prohibida. Las mayores diferencias se produjeron en la dieta de los especímenes más grandes comparando los golfos arrastrados con el golfo protegido. En el área protegida las merluzas grandes cazaban sobre todo en clupeidos y engráulidos, mientras que otros peces se encuentran en el contenido estomacal de M. merluccius de las áreas de pesca. Los valores de δ 15 N de la merluza no variaron significativamente entre las áreas protegidas y no protegidas, mientras que hubo un efecto claro de la talla: valores más alto, se han observado en los animales más grandes. Por el contrario los valores de δ 13 C fueron en general más empobrecidos (más negativos) en los ejemplares recolectados en el área protegida, esto indica una fuente más planctónica de carbono. Los resultados de los mixing models concue...

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“…Moreover, such factors as river discharge and other oceanographic characteristics of the Atlantic coast maintain higher levels of productivity in the Atlantic sector. An increase of planktonic δ 13 C and δ 15 N has been correlated with higher levels of productivity , and plankton sampled in the Atlantic sector has shown higher isotopic values than plankton sampled in more northern zones (Bode et al 2007).…”

Section: Methodsmentioning

confidence: 99%

“…For this purpose, we chose the food web of a coastal seabird species breeding along the northwest coast of Spain, the European shag Phalacrocorax aristotelis, analysing the δ 15 N, δ 13 C, δ 34 S and Hg concentrations in chick feathers and fish prey species. The food webs of this area provide an ideal opportunity for analysing the simultaneous influence of spatial variation and feeding and foraging ecology on isotopic values for the following reasons: (1) the European shag breeds in small colonies scattered throughout the study area and is relatively accessible to sampling during the breeding season; (2) the European shag is a strictly piscivorous species whose main prey is well known (Álvarez 1998, Velando & Freire 1999; (3) the breeding area that we studied can be clearly divided into 2 sectors that differ in productivity and isotopic baseline values (Fraga 1981, Figueiras et al 2002, Bode et al 2007); (4) geomorphological and hydrodynamic differences between these 2 sectors are known to result in differences in food web length and structure (Bode et al 2003, Signa et al 2008); (5) the stable isotope diettissue fractionation for the European shag has been previously studied in a fish-feeding experiment (Bear hop et al 1999); (6) chick feathers of this species are a suitable sampling unit because they represent a delimited spatial and temporal frame (Becker et al 1993, Sanpera et al 2007, and because, in contrast to adult feathers, interpretation problems caused by mobility, Hg bioaccumulation and differences between Hg and isotopic turnovers are avoided (Bond 2010). In order to be able to compare and appropriately interpret the δ 15 N of shags and prey from the 2 sectors, we calculated the shag's and prey's trophic level, which essentially normalized the δ 15 N of shags and prey, relating it to the δ 15 N of the bases of their respective food webs.…”

Section: Introductionmentioning

confidence: 99%

Influence of trophic ecology and spatial variation on the isotopic fingerprints of seabirds

Moreno¹,

Jover²,

Velando³

et al. 2011

Mar. Ecol. Prog. Ser.

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Stable nitrogen isotope studies of the pelagic food web on the Atlantic shelf of the Iberian Peninsula

Cited by 98 publications

References 43 publications

Prey dominance shapes trophic structure of the northern California Current pelagic food web: evidence from stable isotopes and diet analysis

Prey dominance shapes trophic structure of the northern California Current pelagic food web: evidence from stable isotopes and diet analysis

Assessing the effects of a trawling ban on diet and trophic level of hake, <i>Merluccius merluccius</i>, in the southern Tyrrhenian Sea

Influence of trophic ecology and spatial variation on the isotopic fingerprints of seabirds

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