Incidence of kyphosis deformities in natural population of <Emphasis Type="Italic">Atherina lagunae</Emphasis> (Trabelsi et al. 2002) from the Tunis North Lake,Tunisia

Vertebral abnormalities are common among fish and this constitutes a problem of quality and cost-efficiency in aquaculture and in fisheries. Information is presented on the occurrence of spinal deformities in natural population of Atherina lagunae (Teleostei, Atherinidae) in Tunis North Lake (Tunisia). This species is euryhaline and lives in most Mediterranean lagoons. A total of 2,175 fish were caught, in monthly samples, from October 2004 to August 2005. Deformed fishes were counted, photographed and radiographed. According to X-ray radiographies, kyphosis were the most common externally visible vertebral deformities. This abnormality was observed in 212 atherines (140 males and 72 females). The spinal deformity levels varied between 5.34% in December 2004 and 15.85% in June 2005, and averaged 9.75%. The rate of deformed fish varied considerably according to sex and size. The possible reasons of this deformity are also discussed.     

Spinal deformities in the black-striped pipefish Syngnathus abaster (Pisces, Syngnathidae) from the Tunis North Lake, Tunisia

Spinal deformities are seen in fishes. Deformities in the family Syngnathidae is rarely reported. Spine curvatures in natural population of pipefish, Syngnathus abaster are reported from the Tunis North Lake. The species is euryhaline and occurs along the Mediterranean coasts. Four hundred specimens of S. abaster were collected from January 2006 to December 2007 from the Tunis North Lake. Two specimens with skeletal abnormalities were described for the first time. X-rays radiographies revealed several vertebral deformities for each deformed specimen, especially at five curvation places of the caudal part. Several factors are believed to be the cause of spinal deformities of S. abaster in the Tunis North Lake, such as environmental disturbances, parasitism infection and nutritional factors.     

Existence of two widespread semi-isolated genetic entities within Mediterranean anchovies

We investigated genetic transitions in European anchovies (Engraulidae) by analysing one mitochondrial and six nuclear microsatellite loci in samples from 28 geographical locations, primarily in the Western Mediterranean with external samples from the Black Sea in the East, and the Gulf of Biscay in the West. Four samples were collected from lagoons or shallow waters in France, Morocco and Tunisia. Two strongly differentiated loci and nucleo-cytoplasmic disequilibrium allowed us unambiguously to confirm the existence of a coastal genetic entity that is distinct from the more offshore marine populations. By contrast, four microsatellites were undifferentiated within the entire set of samples, testifying to a variable permeability of the two interacting genomes. Our findings strengthen and extend previous reports of the existence of a coastal anchovy entity that is widespread in Mediterranean lagoons.