Muscle and scale isotopic offset of three fish species in the Mediterranean Sea: Dentex dentex, Argyrosomus regius and Xyrichtys novacula

Abstract

Diet information of organisms was traditionally acquired by the use of lethal techniques (gut content or muscle delta(13)C and delta(15)N isotopic ratios). An increase in the number of isotopic ratio studies and the vulnerability of some species have led to increased use of non-lethal methodologies for conservation purposes. In the present work we have compared the delta(13)C and delta(15)N isotopic signals of muscle and scales of three different fish species in order to test fish-scale sampling as a non-lethal technique in fish trophodynamics. A positive correlation was found between muscle and scales in Argyrosomus regius and Xyrichtys novacula, while Dentex dentex showed no correlation due to the small length range of this species. The isotopic offset (Delta(13)C and Delta(15)N) between muscle and scales was significantly different among species (analysis of variance (ANOVA), p < 0.001) with Tukey's post-hoc HSD indicating a tissue offset difference (p < 0.001) for both stable isotopes in all species, except for Delta(13)C between A. regius and X. novacula and for Delta(15)N between D. dentex and X. novacula (p > 0.05). Mean delta(13)C and delta(15)N values between species showed significant differences (paired t-test, p < 0.01) between muscle and scale with an enrichment for delta(13)C and a depletion for delta(15)N. Spatial differences were found in the Delta(13)C of X. novacula between the studied locations, while no differences were found for Delta(15)N, indicating that non-geographical differences should be considered in the application of scales instead of muscle for (15)N, while for (13)C differences in the geographical isotopic offset should be considered.

Evaluating stable isotopic signals in bivalve Pinna nobilis under different human pressures

“…Survival rates were calculated as the number of surviving individuals respect the initial deployed P. nobilis. Additionally, the Tissue Enrichment Factor (TiEF) to study isotopic traits between mantle and adductor muscle was calculated following Blanco et al (2009) procedure; ΔX adductor muscle-mantle (TiEF) = δX adductor muscle − δX mantle , where X is the 13 C or 15 N individual values of each P. nobilis.…”

Evaluating the need for acid treatment prior to δ13C and δ15N analysis of freshwater fish scales: effects of varying scale mineral content, lake productivity and CO2 concentration

“…Therefore, the use of scales as a substitute or a surrogate of muscle for stable isotope analysis requires either removal of the scale mineral matrix (Estep & Vigg, 1985;Perga & Gerdeaux, 2003;Grey et al, 2009), as commonly done by archaeologists to describe changes in stable isotope composition of bone or other animal tissues (e.g. Chisholm et al, 1983;Lee-thorp et al, 1989), or species-specific calibration of scale and muscle for each habitat (Kelly et al, 2006;Sinnatamby et al, 2008;Syväranta et al, 2008;Blanco et al, 2009;Rennie et al, 2009). Only few studies have specifically tested the effects of acidification on scale carbon and nitrogen stable isotope composition, and opposite conclusions have been reached.…”

Reproductive investment of the pen shell Pinna nobilis Linnaeus, 1758 in Cabrera National Park (Spain)

“…Reproduction in bivalves represents an energetic cost and discerning whether energy is fuelled to gametes via stored resources and further remobilisation (endogenous factors) or is being channelled from food availability (exogenous factors) is crucial for the conservation of vulnerable species such as the pen shell. Stable isotopes ratios of C and N, as ecological tracers, might provide information on these processes and have been used successfully to understand the dynamics of marine ecosystems (Deudero et al, 2004(Deudero et al, , 2011(Deudero et al, , 2014Box et al, 2010), providing information on tissue fractionation and species´ diets (Blanco et al, 2009).…”