Sea bass fry were fed a fixed ration of one of six isonitrogenous diets differing in essential amino acid balance or physical and chemical state of the protein source (Hydrolysate vs. intact protein) to induce different growth rates. The reference diet was based on fish meal, whereas the other diets contained fish protein hydrolysate, greaves meal (i.e., defatted collagen meal) or hydrolyzed feather meal added at 30 or 50% of crude protein at the expense of fish meal protein. Digestibility as well as fractional rate of whole-body protein synthesis was assessed. Whole-body protein synthesis was determined for each group of fish using a single injection of flooding dose of tritiated phenylalanine. Protein digestibility of the diets varied only by 5.5%. Specific growth rate and fractional protein specific growth rate, i.e., fractional protein accretion, were higher in fish fed the reference diet than in those fed the diets in which 50% of fish meal protein had been replaced by greaves or hydrolyzed feather meal protein. Compared with the reference group, whole-body protein synthesis was higher in fish fed these latter diets as well as in those fed the diet containing 30% greaves meal protein. The fractional protein accretion to fractional protein synthesis ratio, i.e., the efficiency of protein deposition, was lower in fish fed poorer dietary amino acid balance than in the reference group. The substitution of fish protein hydrolysate for intact fish protein led to a similar, though less pronounced phenomenon: nonsignificant increase in protein synthesis accompanied by significant increase in protein degradation.(ABSTRACT TRUNCATED AT 250 WORDS)

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The presence of marine alien species in El-Kouf National Park and the neighbouring areas was assessed using a compilation of available information and observations, a field survey conducted on October 2010 in the framework of the MedMPAnet project and results of further monitoring during June and September 2012. A total of 9 alien species were reported: the Rhodophyta Asparagopsis taxiformis (Delile) Trevisan de Saint-Léon, the Chlorophyta Caulerpa racemosa var. cylindracea (Sonder) Verlaque, Huisman & Boudouresque, the crab Percnon gibbesi (H. Milne-Edwards, 1853) and the fishes Fistularia commersonii Rüppell, 1838, Siganus luridus (Rüppell, 1829), Siganus rivulatus Forsskål, 1775, Pempheris vanicolensis Cuvier, 1831, Lagocephalus sceleratus (Gmelin, 1789) and Sphyraena flavicauda Rüppell, 1838. Several of them were until now unknown for the National Park. The list of alien marine species of Libya is updated and discussed. Until now 63 marine aliens species were recorded along the Libyan coasts. These include 3 Foraminifera, 3 Ochrophyta, 5 Rhodophyta, 5 Chlorophyta, 1 Magnoliophyta, 11 Arthropoda, 13 Mollusca, 1 Echinodermata and 21 Chordata. Among these Non Indigenous Species, 43 are known as established along the Libyan coast including 8 invasive, 11 casual, 6 questionable, 3 cryptogenic and 1 unknown. An in-depth study of the marine organisms would substantially increase the number of alien species occurring in Libya. Monitoring of marine assemblages of MPAs is a valuable opportunity to go further into the knowledge of native and introduced species.

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Age and growth of Paracentrotus li7idus Lamarck, 1816 (Echinodermata-Echinoidea) in the gulf of Tunis (Méditerranean Sea). The age of Paracentrotus li6idus in the gulf of Tunis was evaluated by analysing the natural growth banding in the interambulacral plates from the oral part of the test. It appeared that growth rates increased in spring and summer, and decreased in autumn and winter. The maximum age and diameter were estimated to be 8 years and 53 mm respectively. Compared to populations of Paracentrotus li6idus from NW Mediterranean and Atlantic, that of the gulf of Tunis presented a more rapid growth. © 2000 É ditions scientifiques et médicales Elsevier SAS Résumé-L'évaluation de l'âge de Paracentrotus li6idus du golfe de Tunis a été réalisée à l'aide de la méthode d'analyse des stries d'accroissement des plaques interambulacraires de la partie orale du test. Le rythme de croissance est élevé au printemps et en été, et faible en automne et en hiver. La longévité et le diamètre maximal des individus ont été estimés respectivement à 8 ans et à 53 mm. Comparé aux populations de Paracentrotus li6idus de la Méditerranée nord-occidentale et de l'Atlantique, celles du golfe de Tunis présentent une croissance plus rapide. © 2000 É ditions scientifiques et médicales Elsevier SAS Mediterranean sea / sea urchin / age and growth Méditerranée / oursin comestible / âge et croissance

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