Using otolith shape for intraspecific discrimination: the case of gurnards (Scorpaeniformes, Triglidae)
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1
University of Bologna, BiGeA - Department of Biological, Geological and Environmental Sciences , Italy
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2
Laboratory of Marine Biology and Fisheries, University of Bologna, Italy
The sagittal otoliths are sound transducers and play an important role in fish hearing. Triglidae (Teleostei, Scorpaeniformes) are known for sound producing ability in agonistic contexts related to territorial defence, reproduction and competitive feeding (Amorim et al., 2004). Chelidonichthys cuculus and C. lucerna show a significant body size-depth relationship and specie-specific feeding strategies with growth. Both juveniles and adults of C. cuculus prey necto-benthic invertebrates while C. lucerna specimens change diet from crustaceans to teleost during growth (Stagioni et al., 2012; Vallisneri et al., 2014; Montanini et al., 2015). The goal of this study was to analyze intraspecific shape variations in sagitta of model species of gurnards. 217 specimens were collected during bottom trawl surveys in Adriatic sea (northeastern Mediterranean). Each left sagitta was removed, cleaned in ultrasounds bath and kept dry. The otolith digital images were processed to calculate five shape indices (aspect ratio, roundness, rectangularity, ellipticity and circularity). Indices were normalised to avoid allometric effects according to Lleonart et al. (2000), than processed by linear discriminant analysis (LDA). The SHAPE program was used to extract the outline and to assess the variability of shapes (EFA method) and estimated it through the study of principal component analysis (PCA). Considering the first two discriminant functions, LDA plot showed a clearly separation between juvenile and adults for both species. About EFA, the first 4 principal component discriminated over 80% of variance and significant differences were found at critical size between juveniles and adults for all the components analysed. The allometric trends corresponded to a relative elongation of the sulcus acusticus and an increase of excisura ostii. The combined use of the two external outlines methods should be highly informative for intraspecific discrimination and might be related to endogenous (sexual maturity) and exogenous causal factors (depth, substrate, diet). In conclusion, it is important evaluate the differences in the shape of sagittal otolith during growth because these ontogenetic variations could be confused with stocks variations.
Acknowledgements
We thank Pr. Corrado Piccinetti for his logistic support
References
AMORIM M.C.P., STRATOUDAKIS Y., HAWKINS A.D. (2004) - Sound production during competitive feeding in the grey gurnard. Journal of Fish Biology, 65: 182-194.
LLEONART J., SALAT J., TORRES G.J. (2000) - Removing allometric effects of body size in morphological analysis. Journal of Theoretical Biology, 205: 85-93.
MONTANINI S., STAGIONI M., VALDRÈ G., TOMMASINI S., VALLISNERI M. (2015) - Intra-specific and intra-specific variability of the sulcus acusticus of sagittal otoliths in two gurnard species (Scorpaeniformes, Triglidae). Fisheries Research,161: 93-101.
STAGIONI M., MONTANINI S.,VALLISNERI M. (2012). Feeding of tub gurnard Chelidonichthys lucerna (Scorpaeniformes: Triglidae) in the north-east Mediterranean. Journal of Marine Biological Association U. K., 92 (3): 605-612.
VALLISNERI M., TOMMASINI S., STAGIONI M., MANFREDI C., ISAJLOVIĆ I., MONTANINI S. (2014). Distribution and some biological parameters of the red gurnard, Chelidonichthys cuculus (Actinopterygii, Scorapeniformes, Triglidae) in the north-central Adriatic Sea. Acta Ichtyologica et Piscatoria, 44 (3): 173-180.
Keywords:
otolith,
Morphometric analysis,
Shape Analysis,
Adriatic sea,
Triglidae
Conference:
XV European Congress of Ichthyology, Porto, Portugal, 7 Sep - 11 Sep, 2015.
Presentation Type:
Poster Presentation
Topic:
Otoliths as a tool to study fish life cycles
Citation:
Montanini
S,
Stagioni
M,
Benni
E,
Randi
M and
Vallisneri
M
(2015). Using otolith shape for intraspecific discrimination: the case of gurnards (Scorpaeniformes, Triglidae).
Front. Mar. Sci.
Conference Abstract:
XV European Congress of Ichthyology.
doi: 10.3389/conf.FMARS.2015.03.00143
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Received:
27 Nov 2015;
Published Online:
27 Nov 2015.
*
Correspondence:
Dr. Stefano Montanini, University of Bologna, BiGeA - Department of Biological, Geological and Environmental Sciences, Bologna, 40126, Italy, stefano.montanini2@unibo.it