Reconstruction of trophic pathways between plankton and the North Iberian sardine ( Sardina pilchardus ) using stable isotopes

By A. Bode, M. T. Alvarez-Ossorio, P. Carrera, J. Lorenzo. 2004

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Feeding on phyto- and zooplankton by juvenile ( Sardina pilchardus ) was inferred from analyses of natural abundance of stable carbon and nitrogen isotopes in samples from the northwestern Iberian Peninsula (Spain) collected at the beginning of the upwelling season and peak spawning period of sardine. Plankton samples were fractionated through nets of 20, 200, 500, 1000 and 2000 ?m mesh-size and the muscle protein of individual sardines was isolated before isotopic determinations. Up to six planktonic components and two sardine feeding types were identified from the modes in the frequency distributions of isotope abundance values. Also, the most probable pathways for carbon and nitrogen flows between compartments were analysed. The resulting food web revealed a relatively large degree of omnivory, both in plankton and sardine components, which confirms that complex trophic interactions could also occur in pelagic upwelling ecosystems. Young sardines had isotope abundance values clustered around a single mode in the frequency distribution, while adult sardines displayed two main modes. These modes are interpreted as representative of two extreme feeding types: one related to the individual capture of zooplankton prey and the other to unselective filter-feeding. Although both types of feeding could include micro- (20-200 ?m) and mesozooplankton (200-2000 ?m) prey, phytoplankton appears to be ingested mainly by filter-feeding. However, even adult sardines must be mainly zoophagous to achieve the observed isotopic abundance values, taking into account current assumptions on stable isotope enrichment through trophic levels. From the differences in the resulting pathways using either carbon or nitrogen isotopes, we interpreted that sardines acquire most of the protein nitrogen from zooplankton while a substantial fraction of their carbon would derive from phytoplankton. These interpretations agree with the information available for this species on the gut contents and the anatomy of the filtering apparatus.

Subfields: Ecology, Global and Planetary Change

View Paper: https://www.semanticscholar.org/paper/abbc11d4ecca4ad9950792781c337d29f7fd3415

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Citations in the corpus

Diet of young Atlantic bluefin tuna (Thunnus thynnus) in eastern and western Atlantic foraging grounds (2010, background): “Similar d15N values for sardines and horse mackerel have been reported, but these values are higher for Atlantic mackerel and anchovies (Bode et al. 2004; Bode et al. 2007).”
Foraging ecology of five toothed whale species in the Northwest Iberian Peninsula, inferred using carbon and nitrogen isotope ratios (2012, methodology): “All isotopic values from plankton in the region were pooled to obtain representative estimates of isotopic composition taking into account spatial and temporal variability (Bode et al., 2004, 2007).”
Stable nitrogen isotope studies of the pelagic food web on the Atlantic shelf of the Iberian Peninsula (2007, background): “, 2003, 2006), the diet of sardines (Bode et al., 2004a) and the succession of zooplankton (Bode & Alvarez-Ossorio, 2004) in this region.”
Feeding habits and trophic levels of bluefin tuna Thunnus thynnus of different size classes in the Mediterranean Sea (2007, methodology): “Tuna displayed a wide range of trophic levels, shifting from about TL 3.0 for juveniles to about TL 4.8 for adults (by using the Mediterranean trophic baseline; 3.64&) or about TL 4.4 if using the Atlantic baseline ("5.0&; Bode et al., 2004).”
Factors affecting the spawning period of sardine in two highly oligotrophic Seas (2007, background): “2002), with conWrmed ability of preying upon phytoplankton species through Wlter feeding mechanisms (van der Lingen 1998; Bode et al. 2004).”
Diet and feeding intensity of sardine Sardina pilchardus: correlation with satellite-derived chlorophyll data (2008, background): “The difference of feeding intensity between sardine size classes may be due to different feeding behaviours or filtering efficiencies of small sardines when compared to larger individuals (van der Lingen 1998, Bode et al. 2004).”
Spawning habitat and daily egg production of sardine (Sardina pilchardus) in the eastern Mediterranean (2006, background): “The switching between particle and filter feedings can be triggered by factors like the decrease below a certain threshold of large zooplankton prey (Bode et al., 2004).”
Laboratory investigations on the effect of prey size and concentration on the feeding behaviour of Sardina pilchardus (2007, unknown): “Studies of the trophic ecology of sardines (Bode et al. 2003, 2004, Costa & Garrido 2004) have followed the assumption that the feeding ecology of small pelagic fishes is a key factor in regulating their abundance and distribution (e.g. Mathisen et al. 1978, Parrish et al. 1981, Schwartzlose et al.…”