Branko Glamuzina

Cannibalism as a factor affecting the survival of intensively cultured sea bass (Dicentrarchus labrax) fingerlings

Abstract The large percentage of intensively cultured sea bass fingerlings apparently lost to cannibalism indicates that this source of mortality probably contributes significantly to poor survival. The growth rate of ungraded fingerlings produces increasing differences in size which run parallel with increasing cannibalism, especially after the weaning period. Sea bass fingerlings, if not fed early in the morning, showed increased cannibalistic activities; 37% of the larger fish filled their stomachs with smaller siblings. The predator must be twice the length of the victim for ingestion. The extent of cannibalism is found to depend on feeding frequency.

Preliminary studies on reproduction and larval rearing of common dentex, Dentex dentex (Linnaeus 1758)

Abstract The paper describes preliminary results on maturation, artificial spawning, embryonic development and larval rearing of common dentex, Dentex dentex (L.), in captivity. The spawning season of fish maintained under controlled conditions lasted from the beginning of May until the end of June. Since all smaller fish were either males or immature, and bigger fish were females, it can be stated that common dentex is a proterandrous hermaphrodite. Both sexes matured spontaneously in captivity, giving small quantities of gametes. A positive response to hormonal treatment (HCG) was observed. Average number of eggs per injected female was 97 000 per kg of wet weight. The maturation of oocytes is not synchronized and so eggs were produced in several spawnings over 13 days. The functional mouth opening of larvae varied between 98 and 124 μm. However, feeding with rotifers, even though selected through a 120-μm net, was not very successful. In the larval stages, pronounced euryhalinity was not observed. Survival of larvae was best at an ambient temperature of 19°C and salinity of 38‰.

Incidence of spinal deformities in natural populations of sandsmelt, Atherina boyeri (Risso, 1810) in the Neretva river estuary, middle Adriatic

Information is presented on the occurrence of spinal deformities in natural populations of sandsmelt, Atherina boyeri in the Neretva River estuary, middle eastern Adriatic. During 1998 and 1999, the spinal deformity levels varied between 2.02% and 10.30% in four samplings, and 3.58% in total catch. The spine is deformed in one to a few places from vertical to horizontal angles, and the deformities are visible on the fish body immediately after catching. The possible reasons for such deformities are discussed.

Preliminary information on feeding and growth of pompano, Trachinotus ovatus (Linnaeus, 1758) (Pisces ; Carangidae) in captivity

Although the chances of successfully farming Trachinotus ovatus on a commercial scale are limited by the low food conversion rates, this species deserves further applied studies on the basis of their quick adaptation to confinement and their tolerance of captivity conditions.

Resolving taxonomic uncertainties using molecular systematics: Salmo dentex and the Balkan trout community

The genetic structure of Salmo dentex and its phylogenetic relations to sympatric salmonids in the Neretva and Skadar River basins were evaluated using mitochondrial DNA (mtDNA) control region, eight microsatellites, and somatolactin (SL) gene. In the Neretva River basin of Bosnia–Herzegovina, the results based on mtDNA analysis showed extensive haplotype sharing between S. marmoratus, S. dentex, and S. trutta, and were therefore not conclusive; however, F-statistics and assignment testing based on nuclear DNA markers indicated that S. dentex of the Neretva basin were grouped in a genetically unified cluster with S. marmoratus in the Neretva basin. Using the same analytical approach, S. dentex from the Skadar basin in Montenegro appeared to be genetically distinct from S. marmoratus in the same basin and indistinct from local S. trutta. Molecular data also indicated that S. dentex of the Neretva basin in Bosnia–Herzegovina are not closely related to S. dentex of the Skadar basin in Montenegro. Based on these results, we hypothesize S. dentex to be a particular life history form of S. marmoratus in the Neretva basin and of S. trutta in the Skadar basin. These results clearly demonstrate that S. dentex does not represent a monophyletic lineage and should not be considered a distinct species.

Early development of the hybrid Epinephelus costae ♀×E. marginatus ♂

Abstract Early development of the F1 hybrid between the goldblotch grouper, Epinephelus costae female and dusky grouper, E. marginatus male was compared to that of the maternal species under similar rearing conditions. Percent fertilisation and percent hatch were not significantly different. Mean hatching time of the hybrid was significantly faster than the goldblotch grouper. Percent of deformed blastomeres in the 4–8 cell stage was significantly higher in hybrid eggs. Survival of eggs, larvae, and larval growth and the behavior of both types were not significantly different. Results suggest that this hybrid may be suitable for aquaculture purposes.

Intergeneric hybridization in Sparidae: 1. Sparus aurata ♀ × Diplodus puntazzo ♂ and Sparus aurata ♀ × Diplodus vulgaris ♂

Abstract Eggs of gilthead sea bream (Sparus aurata) were inseminated by the sperm of sharp-snout sea bream (Diplodus puntazzo) and common two-banded sea bream (Diplodus vulgaris). Under controlled conditions, at 19.5°C, embryogenesis and yolk sac resorption in both intergeneric combinations took less time than embryogenesis and yolk sac resorption in Sparus aurata. Survival and growth of larvae of Sparus aurata, Sparus aurata ♀ ×Diplodus puntazzo ♂ and Sparus aurata ♀ ×Diplodus vulgaris ♂ were established during yolk sac resorption. During the active feeding period, between days 6 and 30 after hatching, neither growth nor survival differed significantly among the studied species and crosses. Sparus aurata ♀ ×Diplodus puntazzo ♂ larvae grew slightly but not significantly faster.

Six Years from First Record to Population Establishment: The Case of the Blue Crab, Callinectes Sapidus Rathbun, 1896 (Brachyura, Portunidae) in the Neretva River Delta (South-Eastern Adriatic Sea, Croatia)

The data presented in this paper are based on the observation of 52 individuals of Callinectes sapidus Rathbun, 1896, collected in August and September 2010 by local fishermen using gillnets and traps in the area of the delta of the river Neretva (Croatian coast, south-eastern Adriatic Sea). Carapace width (CW) and carapace length (CL) frequency distributions indicate 3 age cohorts (modes) (CL: 7.2 cm, 8.4 cm, 9.0 cm ; CW: 12.2 cm, 14.9 cm, 16.7 cm). The carapace width (CW) - to - weight (W) relationship was calculated (for both sexes) as W = 0.816 CW2.281 (r2 = 0.785). The current substantial records, the occurrence of ovigerous females and juveniles (observations of fishermen by visual census), as well as the fact that the species was regularly caught in the estuarine area, together constitute evidence of an established population of this species in the investigated area. Further, continuous monitoring of this population and of the potential dispersal of this species in adjacent areas, would be of interest to provide richer information on population structure and dynamics of the blue crab in Adriatic waters.

Amnesic shellfish poisoning biotoxin detection in seawater using pure or amino-functionalized Ag nanoparticles and SERS

Domoic acid (DA) biotoxin responsible for the amnesic shellfish poisoning (ASP) has been unambiguously detected in seawater in a broad range of concentration, with both pure and amino-functionalized Ag nanoparticles employed for surface enhanced Raman scattering (SERS). To achieve this, a comprehensive SERS study on DA dissolved in distilled water has been conducted. SERS of DA dissolved in seawater in concentrations ranging from 3.3 × 10(-4) to 3.3 × 10(-8) mol l(-1) exhibited specific signal, completely different to those of the corresponding DA aqueous solutions, due to the seawater interference in the overall SERS effect. In order to assess the capability of the technique as a cheaper alternative for rapid and unambiguous detection of the DA biotoxin in seawater, three detection schemes have been proposed. DA was detectable at 0.33 nmoll(-1) concentration (0.33) dissolved in distilled water and 0.033 nmol l(-1) (0.033 ppb) in seawater respectively, much lower than the admitted level by the current regulation. A solvent specific interaction of DA with the NPs was concluded, since DA aqueous solution added to Ag nanoparticles provided different SERS signal compared to that of DA directly dissolved in seawater. Employing amino-functionalized Ag nanoparticles with 4-aminothiophenol as SERS tag, SERS signal of DA on amino-AgNPs revealed significant specificity associated with the aromatic primary amine interaction of the SERS tag with DA, thus allowing DA detection in seawater at 4.16 × 10(-4) mol l(-1) concentration, much higher than in the case of pure NPs. To highlight the findings, a brief literature review to date on the DA biotoxin detection was also provided.

Study on the effects of rearing density, temperature and salinity on hatching performance of the European sea bass, Dicentrarchus labrax (Linnaeus, 1758)

Study on the effects of rearing density, temperature and salinity on hatching performance of the European sea bass, Dicentrarchus labrax (Linnaeus, 1758)are described.