The spawning, embryonic and early larval development of the green wrasse Labrus viridis (Linnaeus, 1758) (Labridae) in controlled conditions

Green wrasse, Labrus viridis (Linnaeus, 1758), is an endangered species in the southern Adriatic Sea, but it is also of interest for potential rearing in polyculture with other commercial species for the repopulation of areas where it is endangered or as a new aquaculture species. A parental stock of the green wrasse was kept in aquaria for six years. The spawning, embryonic and early larval development maintained under controlled laboratory conditions are described and illustrated. The average diameter of newly spawned eggs was 1.01±0.03 mm. Mature and fertilized eggs were attached to the tank bottom by mucus. Hatching started after 127 h at a mean temperature of 14.4±0.8°C. The average total length of newly hatched larvae was 4.80±0.22 mm. Absorption of the yolk-sac was completed after the 5th day when larvae reached 5.87±0.28 mm. Larvae were fed with the rotifers Brachionus plicatilis. The pigmentation of L. viridis larvae is similar to that of Labrus merula and Labrus bergylta, but the main differences between these species are in the size of larvae and the development time of the melanophores on the anal fin-fold (five days later than with L. merula) and on top of the head (nine days earlier than with L. merula).     

Diet of young-of-the-year bluefin tuna, Thunnus thynnus (Linnaeus, 1758), in the southern Tyrrhenian (Mediterranean) Sea

The diet of juvenile bluefin tuna (Thunnus thynnus) caught 2 to 8 miles off NE Sicily was investigated in order to improve knowledge of the species’ early life history. From 1998 to 2000, 107 specimens ranging from 63 to 495 mm (total length) were fished between July and November. Fishes were caught by trolling line or purse seine in a Fish Aggregating Devices (FADs) area 2 to 8 miles offshore and as by‐catch of the purse‐seine sardine fishery 2 to 4 miles offshore. Most frequently found items in the T. thynnus stomachs were fishes (84.5%), crustaceans (54.6%) and cephalopods (50.5%). The largest contribution in weight was provided by cephalopods (47.3%) and fishes (46.5%), while the most abundant items were fishes (51%), cephalopods (27.2%) and crustaceans (21.1%). These results suggest that young‐of‐the‐year tuna have an essentially piscivorous diet, although invertebrate prey provide a substantial contribution to the food array. Prey show little relationship with FADs, although one prey species (blue runner, Caranx crysos) is associated with FADs in the Mediterranean.     

Age and growth of pearly razorfish,Xyrichtys novacula (Linnaeus 1758), in the central Mediterranean Sea

Age and growth of pearly razorfish Xyrichtys novacula (Labridae) were determined in specimens caught on sandy bottoms by surrounding nets and lines (depth range 5–30 m) between January 2000 and December 2002. The study location was in the central Mediterranean Sea. For this purpose the annual growth increments (annuli) in sagittae were analysed. A total of 470 individuals of X. novacula, ranging from 49 to 200 mm TL (total length), were examined. Conversion between total length and standard length was calculated and represented by the relationship: . Edge analysis on otoliths was carried out to validate seasonality deposition. Seven age‐classes were determined from 0+ to 6+. The linear relationship between maximum otolith length (OL) and TL was summarized in the equation . The estimated parameters of the von Bertalanffy growth function were L = 175.05 mm, k = 0.80 year^?1, t₀ =?0.73 years and the growth performance index calculated as (Φ = 2.39). The length–weight relationship W = 0.0139 TL^2.9326 described an isometric growth for the species in this area.     

Effect of dietary supplements of mussel and polychaetes on spawning performance of captive sole, Solea solea (Linnaeus, 1758)

Three diets were compared for the feeding of captive common sole broodstock (Solea solea) kept under ambient photoperiod and temperature conditions. A group of 70 adults were caught in the wild and the 38 males and 32 females distributed at random in six tanks. All the fish were acclimated to the same semi-moist diet (M) in the pre-experimental period from December to February. Three dietary treatments were offered in the experimental period from March to May with two replicates (tanks) per treatment. The treatments were M alone, M supplemented with fresh mussels (Mytilus edulis) (M+M), and M supplemented with live polychaetes (Perinereis cultrifera) (M+P). Spawning occurred during April and May when water temperature was 17 and 18 degrees C, respectively, and salinity around 34-35ppt. Average daily dry matter intake expressed as a proportion of body weight was M 0.65+/-0.34%, M+M 0.43+/-0.18%, and M+P 0.56+/-0.27%, and differed significantly (P<0.05) between treatments. The average daily dry matter intake within a tank ranged from 0.31+/-0.04% in February to 0.98+/-0.26% in May (P<0.05), apparently due to changes in the photo-thermal regime. Diet significantly affected the number of days when spawning occurred, the number of days when hatched eggs were produced, and the proportion of fertilized eggs (P<0.05); and affected the number of days on which viable eggs were produced during April (NS). In all cases, the results were lowest for M+M, while those for the other two treatments did not differ significantly. Differences in hatching rate were not significant in April. During May, no spawning occurred in fish given the M+M treatment, and the differences between the other two treatments were not significant. Values for all variates tended to be higher for M+P than M+M in April and lower for M+P and M in May. These results suggest that supplementing the semi-moist diet with mussels depressed feed intake and, consequently, reproductive performance; the semi-moist diet alone and semi-moist diet supplemented with polychaetes allowed satisfactory food intake and reproductive performance in broodstock sole.     

When selection deceives phylogeographic interpretation: the case of the Mediterranean house gecko, Hemidactylus turcicus (Linnaeus, 1758)

A previous study on Hemidactylus turcicus based on mtDNA makers indicated that this gecko has a Middle-East origin, and that the current phylogeographic pattern is the result of a very rapid spread from the east to the west of the species’ range. The same study identified two distinct mitochondrial lineages with low differentiation and genetic diversity. Since H. turcicus is known to be closely associated to humanized environments, its present distribution range and phylogeography is frequently interpreted to be the result of recurrent human-mediated introductions. These conclusions used to be the same as those used to interpret the results obtained for the European populations of another gecko, Tarentola mauritanica. However, a recent study has revealed that the phylogeographic pattern of T. mauritanica is not solely the result of a recent colonization, but also of a mitochondrial selective sweep. Could the same be occurring in H. turcicus? To answer this question, two mitochondrial (12S rRNA and cytochrome b) and two nuclear genes (ACM4 and Rag2) were used in this study. From the mtDNA data we confirmed the existence of two distinct phylogeographic lineages; one occurring exclusively in the northern Mediterranean (Clade A), and another one more widespread that is the only lineage present in North Africa (Clade B). In light of these results, we could hypothesize that H. turcicus had its origin in Turkey, and from there Clade A moved to Europe and Clade B to North Africa spreading latter into Europe. However, Clade A presents significantly higher nucleotide diversity for the nuclear DNA compared to the mtDNA, and neutrality tests gave significant results for the mitochondrial data. These results suggest that the lack of mtDNA genetic diversity and structure in the European population of H. turcicus could also be due to a selective sweep, and not only because of a recent colonization. Together with the situation reported in T. mauritanica, the identification of a hitch-hiking process occurring in H. turcicus, represents two unprecedented cases of a selective sweep taking place in the same geographic area shaping the phylogeographic patterns of two unrelated genera of geckos.     

Distribution and biological features of the common pandora,Pagellus erythrinus (Linnaeus, 1758), in the southern Tyrrhenian Sea (Central Mediterranean)

A synthetic analysis of the distribution, abundance and some biological traits of the common pandora (Pagellus erythrinus) was performed. Data were gathered in 15 experimental bottom trawl surveys carried out off the southern Tyrrhenian Sea from 1994 to 2008. A total of 2,166 P. erythrinus were found in the investigated area, with a preference for the upper continental shelf (10–100 m). The highest persistence was recorded in the trawl-banned areas. The sex ratio Sr = F/(F + M) ranged between 0.60 and 0.96 (overall 0.78). The size at which 50 % of the individuals were mature was 157 and 170 mm total length for females and males, respectively. The length–weight relationship for all individuals was described by the following parameters: a = 0.016 and b = 2.905. Growth was evaluated (sexes combined) by applying length-based methods; up to eight significant modal components were evidenced. The von Bertalanffy growth parameters for the whole population were estimated at L _∞ = 454 mm, K = 0.08 and t ₀ = ?2.57. The present results are in agreement with the information available for the other Mediterranean stocks suggesting common biological features.     

On secondary hyperparathyroidism in orang-utans, Pongo satyrus (Linnaeus, 1758)

Orang-utan crania with alterations in bone structure which could be determined morphologically were studied and evaluated. The alterations in bone structure were referred to in the literature up to about 1939 as "rickets"; when vitamin D was given to the animals, the alterations diminished, until they were almost unnoticeable. From about 1941/52, the alterations were diagnosed as "Morbus Paget". Research on orang-utan crania has become possible through comparison of a larger number of single symptoms, occurring in a number of individuals. Out of a larger sample, the study was carried out on 5 individuals, showing these alterations in varying degrees. The individuals also covered various age groups, both sexes and both subspecies of orang-utans. The findings permit a diagnosis of secondary (or tertiary) hyperparathyroidism (= Morbus Engel-von Recklinghausen = fibrous cystic osteitis). The study also showed that orang-utans fall prey to Morbus Engel-von Recklinghausen in a shorter period and suffer more severely than humans. The frequency of orang-utans suffering from this disease, which are kept captive in zoos, is statistically far higher than the occurrence in humans. Orang-utans living under natural conditions do not suffer from the disease at all; according to the study of 500 animals. The authors also believe that there is a psychogenic basis for the occurrence of Morbus Engel-von Recklinghausen in zoo animals; psychological conditions such as apathy, disinterest, etc. are part of the illness, and these symptoms are also shown by animals having no outward signs of fibrous cystic osteitis. The authors believe that improved prophylaxis of orang-utans in zoos would lead to discovery of Morbus Engel-von Recklinghausen in early stages, and allow early therapy to arrest the disease. This is necessary for preservation of the species.     

The Medusa of Velella velella (Linnaeus, 1758) (Hydrozoa, Chondrophorae)

A mature medusa of Velella velella (Linnaeus, 1758) is reportedfor the first time from the North Atlantic; previously adultmedusae were known only from the Mediterranean. This specimen,collected by SCUBA divers, is the largest specimen recordedto date. Distinctive features are: two opposite adaxial-axialpairs of perradial capitate tentacles; two marginal bulbs lackingtentacles; conical manubrium with 4 perradial longitudinal gonads;perradial exumbrellar cnidae tracts; cnidome of stenoteles andmacrobasic euryteles; and zooxanthellae within the subumbrella.Since this specimen was collected near the surface and has zooxanthellae,it is likely that V. velella medusae are epipelagic.     

Larval development of three blenniid species Aidablennius sphynx, Coryphoblennius galerita and Lipophrys canevai (Pisces: Blenniidae: Blenniini) in the western Mediterranean

The early stages of development of three blenniid species, Aidablennius sphynx (6.7–15.8 mm BL), Coryphoblennius galerita (4.3–13.9mm BL), and Lipophrys canevai (3.5–10.4 mm BL) are described from specimens collected in the western Mediterranean. The characteristics used for identification included meristic, developmental, morphological and pigmentation characters. Distinguishing characters of these species useful in differentiating them from other species of blenniids for which early stages are known in the Mediterranean are presented. Information on the occurrence of larvae and juveniles of these species off the Catalan coast (north-western Mediterranean) is also given.     

Larval development of theterebellid polychaete Eupolymnia nebulosa (Montagu) in the Mediterranean Sea

The morphology of young stages of Eupolymnia nebulosa (Montagu, 1818) is observed using SEM. Significant changes occur at several times after egg laying. The transition from endotrophy to exotrophy takes place when the larvae are about 13–15 days old. At the same time, the primary tentacle appears as a hemispherical bud; the first setae to emerge are transitory and club-shaped. They are shed when the larvae are about 50 days old. Observations on the development of the uncinigerous torus of the 11th segment (the first one bearing uncini with the main fang in an alternated direction) indicate that the uncini appear at the dorsal extremity of the torus and then move toward the medio-ventral axis as they increase in size. The uncini are shed when they reach the ventral extremity of the torus. These changes may result in taxonomic confusions unless the complete sequence of development is known.     

Crustacean parasites and epizoa of the sperm whale, Physeter catodon Linnaeus, 1758 (cetacea, Odontoceti), in the Gulf of Lion (Western Mediterranean)

The authors point out for the first time, fixation of the Cirriped Conchoderma virgatum (Spengler, 1790) on an Amphipod Cyamid parasite of a young sperm-whale, Physeter catodon Linnaeus, 1758, stranded on the gulf of Lion coast (Western Mediterranean). Using the scanning electron microscope, they furnish precisions on the morphology and they furnish some observations concerning reproduction and biogeography of this Amphipod, Neocyamus physeteris (Pouchet, 1888).