In a context of high occupation of the coastal area, we studied this occupation impact measuring developmental stability of post-larvae and juveniles (Oblada melanura in nursery zones and Dicentrarchus labrax in aquariums). We intend to provide information for the management of these aquaculture and seaside resort zones. We expect to create a new mid/long-term stress indicator using otolith Fluctuating Asymmetry (FA).

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Figure 1 : 79 Days old D. Labrax sagittae.
Foto: Pierre Vandenbussche 2013

FA is used to measure bilateral individual developmental stability. Departure from symmetry is described by frequency distribution of right minus left part. In case of FA this frequency distribution should be a Normal curve centred around 0 (Palmer 1994). If stress occur, this Normal curve tend to present an augmentation of the kurtosis (a perfect Normal law present a ketosis of 0).

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Figure 2: FA ideal distribution, right curve present a bigger kurtosis sign of a higher level of FA.
From Palmer 1994

In order to obtain FA information, we use an intern-ear hard structure called otolith. Fish present 3 pairs of otolith. Those otoliths are used by fish for earing and space recognition. They are called sagittae, lappili, asterisci. We use the sagittae pair in our works.

We chose this structure for 3 reasons:

First, it presents, like a pearl, a successive ring structure which is easily recognisable on microscopy. This is due to the way it is formed. Every day a new ring, or increment, (Chambers and Miller 1995) is deposited. So if a change occurs in the fish environment, traces of this change will appear on the concerned ring (Arai, Ohji et al. 2007).

Second, the sagittae pair is generally the biggest of the three otolith pairs and so can be collected more easily. It also reduces the risk of misinterpretation during analyses.

Third, we use otolith because it’s an internal structure, meaning there is less risk of deterioration during sampling time.

This Precaution was really important because of the use of post-larvae and juveniles. At this early life stage fish are really fragile. As sampling method could damages the external part of fish the utilisation of external symmetric traits is impossible.

Arai, T., M. Ohji, et al. (2007). "Trace Metal Deposition in Teleost Fish Otolith as an Environmental Indicator." Water Air Soil Pollut(179): 255-263.

Chambers, R. C. and T. J. Miller (1995). Evaluating Fish Growth by Mean of Otolith Increment Analysis: Special Proprieties of Individual-level Longitudinal Data. Recent Development in Otolith Research, Columbia, South Carolina, United States of America, University of South Carolina Press.

Palmer, A. R. (1994). Fluctuating asymmetry analyses: A primer. Developmental Instability: Its Origins and Evolutionary Implications, Tempe, Arizona, Springer Netherlands.


The family Tetraodontidae includes highly toxic species such as the famous Japanese fugu. Several species live in the Mediterranean. Some came through the Suez Canal and are present throughout the eastern basin of the Mediterranean, such as Lagocephalus sceleratus. Other species have an uncertain origin: native of the Mediterranean, or entered from the Atlantic or Red Sea? This is the case of Sphoeroides pachygaster.

news un tetraodon sur nos cotes

(by P. Francour)

This species was not known the French Mediterranean coast yet. On May 9th, 2014, this fish was caught at Vauban harbour, Antibes. It was determined by Patrice Francour and is currently preserved at the Oceanographic Museum of Monaco.
You will find in the Nice Matin article details about the capture. This is an example of how citiziens may help scientists in recording new species.

Read more: A Tetraodontid fish along our coasts

Tous ces articles sont disponibles en PDF sur simple demande (This email address is being protected from spambots. You need JavaScript enabled to view it. )

Articles sur les sciences participatives

Bodilis P., Louisy P., Draman M., Francour P. 2014. Can citizen science survey non-indigenous fish species in the Eastern Mediterranean sea? Environmental Management, 53: 172-180.

Signalisations de nouvelles espèces

Bodilis P., Arceo H., Cheminée A., Miniconi R., Francour P. 2012. Occurrences of the Atlantic species, Pisodonophis semicinctus (Osteichthyes: Ophichthidae), along the Mediterranean coast. Journal of Applied Ichthyology, 28(4):652-654.

Bodilis P., Arceo H., Francour P. 2011. Further evidence of the establishement of Fistularia commersonii Rüppel, 1838 (Osteichthyes: Fistulariidae) in the North-Western Mediterranean Sea. Marine Biodiversity Records, 4, e18: doi:10.1017/S1755267211000194.

Bodilis P., Crocetta F., Langeneck J., Francour P. 2013. The spread of an Atlantic fish species, Pomadasys incisus (Bowdich, 1825) (Osteichthyes: Haemulidae), within the Mediterranean Sea with new additional records from the French Mediterranean coast. Italian Journal of Zoology, 80(2): 273-278.

Daniel B., Piro S., Charbonnel E., Bachet F., Francour P., Letourneur Y. 2009. Lessepsian rabbitfish Siganus luridus reached the French Mediterranean coasts. Cybium, 33(2): 163-164.

Francour P., Cottalorda J.M., Aubert M., Bava S., Colombey M., Gilles P., Kara H., Lelong P., Mangialajo L., Miniconi R., Quignard J.P. 2010. Recent occurrences of Opah Lampris guttatus (Lampridae) in the western Mediterranean Sea. Acta Ichthyologica et Piscatoria, 40(1): 91-98.

Francour P., Mouine N. 2008. First record of Kyphosus sectator (Linnaeus, 1758) (Kyphosidae) along the French Mediterranean coast. Cybium, 32(3): 275-276.

Pastor J., Francour P. 2010. Occurrence and distribution range of Parablennius pilicornis (Cuvier, 1829) (Actinopterygii: Perciformes: Blenniidae) along the French Mediterranean coast. Acta Ichthyologica et Piscatoria, 40(2): 179-185.

Schrembi P.J., Bodilis P., Evans J., Francour P. 2010. Occurrence of barred knifejaw, Oplegnathus fasciatus (Actinopterygii: Perciformes: Oplegnathidae), in Malta (Central Mediterranean) with a discussion on possible modes of entry. Acta Ichthyologica et Piscatoria, 40(2): 101-104.

Articles ou ouvrages de synthèse

Abdul Malak D., Livingstone S.R., Pollard D., Polidoro B.A., Cuttelod A., Bariche M., Bilecenoglu M., Carpenter K.E. , Collette B.B., Francour P., Goren M., Kara H., Massutí E., Papaconstantinou C., Tunesi L. 2011. Overview of the Conservation Status of the Marine Fishes of the Mediterranean Sea. Gland, Switzerland and Malaga, Spain: IUCN. vii + 61p.

Bodilis P., Francour P., Langar H., El Asmi S. 2011. Espèces non-indigènes en Méditerranée: qui, quand, comment, pourquoi ? UNEP-MAP-RAC/SPA, RAC/SPA publ., Tunis: 28 pp.

Curd A., Bachelet G., Bertrand J., Doré A., Dauvin J.C., François C., Francour P., Girard S., Goulletquer P., Iglesias S., Miossec L., Sauriau P.G., Viard F. ICES Working Group on Introductions and Transfers of Marine Organisms. France National Report 2012. in: Report of the ICES Working Group on Introduction and Transfers of Marine Organisms (WGITMO), 20 - 22 March 2013, Montreal, Canada. ICES CM 2013/ACOM, 30: 77-86.

Francour P., Mangialajo L., Pastor J. 2010. Mediterranean marine protected areas and non-indigenous fish spreading. in: Fish Invasions of the Mediterranean Sea: Change and renewal. D. Golani & B. Appelbaum-Golani eds., Pensoft Publisher, Sofia-Moscow: 127-144.

Otero M., Cebrian E., Francour P., Galil B., Savini D. 2013. Monitoring marine invasive species in Mediterranean marine protected areas (MPAs): A strategy and practical guide for managers. IUCN publ., Malaga, Spain: 136 pp.

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