Bioaccumulation of metals in tissues of Solea vulgaris from the outer coast and Ria de Vigo, Ne atlantic [Spain]

Ria and coastal zone are, in particular, vulnerable to heavy metals pollution. Concentrations of 10 metals in liver, muscle and kidney of the sole [Solea vulgaris] from Ria of Vigo and its coastal zone [Spain] were measured from April 2006 to February 2007 and the relationships between fish size age and metal concentrations in the tissues was investigated. Concentrations of the heavy metals in examined fish ranged as follows: Cd [0.01 - 0.7], Pb [0.1 - 2.5], Hg [0.01 - 0.7], Cu [3.3- 46.7], Zn [15- 274], As [3-151], Se [0.9- 18.2], Mn [0.9- 9.76] microg/g dryweight. Kidney and liver showed the highest levels of Cd, Cu, Pb and Zn. The concentration of metals was significantly affected by the sampling site and fish tissues. Our results indicated that all heavy metals were found the highest in muscle tissue. A comparison of metals concentration in fishes from both sites showed higher bioaccumulation in the examplars captured in Ria. This indicates that there is a trend of higher metal pollution level in the estuarine environment. Although, metals levels in the tissues in the area do not exceed contamination levels, measures are recommended for lowering heavy metals inputs into Ria of Vigo. Heavy metals in the edible parts of the investigated fish were in the permissible safety levels for human uses

Toxic effects of acute exposure of diazinon in turbot [Psetta maxima] early life stage [ELS]

In the present study, the toxic effects on the embryos and larvae of the turbot were used as a model to investigate the diazinon, which contaminates aquatic ecosystems. The number of dead embryos significantly increased in response to diazinon concentrations 0.2, 0.4, 0.8, 1.6, 3.2, and 7.4 mg/L. The 48h LC[50] value of diazinon for turbot embryos was estimated at 1.85 mg/L. Dose-response decreases in hatching success were recorded as 97, 92.4, 80.3, 60.3, 38.7 and 27.1%, respectively. The number of dead larvae significantly increased with increasing diazinon concentrations exposed for 24-96 h [p < 0.05]. The 24, 48, 72 and 96h LC[50] values of diazinon for turbot larvae were estimated at 4.8 [6.4-5.12], 3.3 [4.73-2.52], 2.1 [3.29-1.65] and 1.23 [0.87-2.38] mg/L, respectively. There were significant differences in the LC[50] values obtained at different exposure times [p <0.05]. Diazinon caused lethal toxicity as well as nonlethal malformations during embryo-larvae development

Les oligochetes et aphanoneura des eaux courantes de Tunisie II: cle pour la determination des especes actuellement recencees

The authors have elaborated a key, abundantly illustrated, for the determination of Oligochaeta and Aphanoneura presently known from Tunisian running waters

Repartition et ecologie des ephemeropteres de Tunisie [1ere partie] [insecta, ephemeroptera]

The study of 51 localities distributed throughout most of Tunisia has permitted the first establishment of a faunistic inventory of 11 species of Ephemeropterans [excluding Baetidae]. 7 of these are newly recorded for Tunisia and one is new for North Africa, Species distributions depend essentially on chemical parameters [salinity, CL-, Ca++, etc.] and on conductivity. Increases in the ionic concentration of the water quickly cause large decreases in population diversity, as is seen in eastern, central and southern waters. In Kroumirie, in the North West, the waters are less mineralized and so support a richer fauna. The species Caenis luctuosa possesses by tar the greatest range of ecological tolerance. It is the most abundant and most frequent throughout the region, being followed by Ecdyonurus rothschildi. Distributional maps are established and the species' biogeographies and periods of flight are studied

Les simuliidae [diptera, nematocera] de la Tunisie: II cles pour la reconnaissance des especes actuellement recencees

The authors give keys for the knowledge of species of Simuliidae [larval, pupal and adult stages]. The collected samples represented 44 localities situated on the main tunisian hydrographic networks

Contribution a la limnologie de la Tunisie: etude physicochimique

Several chemical and physical parameters are measured in forty seven stations, distributed on the most part of the hydrographic systems of Tunisia. Some parameters temperature of the water [T], salinity [S, electric conductivity [CE], chloride [C1-], total hardness [DT] and turbidity [TUR] show great variations in the Northern hydrographic systems, In these systems, the parameters [S CE, Cl-, DT] are generally elevated in the tributaries of the south bank of the Medjerda, the North-East streams, Melah and Tine Streams which flow in the lchkeul lake. The waters in these septentrional systems are sometimes very turbid. The waters of the meridional hydrological system are very clear. The resurgence thermal waters are characterized by the small amplitude of variations of the studied parameters. The waters are alkaline, generally very mineralized they are well oxygenized in the no-polluted stations