Samples of Coelorinchus caelorhincus were collected by bottom trawl during MEDITS (“Mediterranean International Trawl Survey”) in June 2003 in the northern and central Adriatic Sea. A total of 175 specimens of C. caelorhincus were used for analysis, of which 90 were males, 84 females and 1 indeterminate. Pre-anal length (PAL) in males ranged between 39 and 77 mm (x¯=50.91±7.63 mm) and in females between 29 and 115 mm (x¯=55.86±16.3 mm). The length-weight relationship for the whole sample was W=0.0004PAL2.65 (r2= 0.922) indicating negative allometric growth. The age structure of C. caelorhincus was determined from sagittal otolith readings. Maximum otolith length (LO) increased proportionally to fish length (LO=2.585+0.09PAL, r2=0.946). Age ranged from 2 to 8 years, with the majority of specimens being 3 (30%) and 4 (31%) years old. The von Bertalanffy growth parameters were: L8 = 128 mm, K = 0.105 year-1 and t0 = -1.277 year.

Dielectric properties and sensory assesment of sea bass (Dicentrarchus labrax, L.) stored under six different conditions over a period of 75 hours were investigated. Declines of torrymeter values over time were established under all storage conditions, but showed variability. The correlations between torrymeter readings and Quality Index Method (QIM) results were studied. Significant negative correlations were found between QIM results and torrymeter readings for samples stored in sea water (20-22 oC), storage room (16-18 oC), refrigerated room (2-4 oC) and sea water (10-12 oC). QIM and torrymeter values in slurry ice and ice box samples were not in correlation.

Age, growth and diet of brown comber, Serranus hepatus, were determined from specimens collected in Izmir Bay, Aegean Sea. Total length ranged from 5.20 to 11.70 cm, while weight varied between 1.89 and 24.97 g. The length-weight relationship was W=0.0157*L2.998. Age was determined by otolith readings, where a maximum age of 4 years was observed. The von Bertalanffy growth parameters were estimated as L8=11.90 cm, k=0.56, to=–1.14. Stomach content analysis revealed that the species is carnivorous, with benthic crustaceans constituting the main food in the overall diet composition.

This paper presents inter-annual fluctuations in the population structure, condition, lengthweight relationship and abundance of sardine, Sardina pilchardus (Walb., 1792), the most important fish species in the Adriatic Sea. The random samples were obtained from the nursery ground (Zrmanja River estuary, n=2 893) and spawning ground (off Dugi Otok, n =1 628) of the sardine. Representative samples of catches obtained by purse seine fishing were collected during the 2002- 2006 period. Total lengths ranged from 5.0 to 19.5 cm (mean lengths between 7.35±1.005 and 13.87±1.102 cm; Zrmanja River estuary) and 11.5 to 19.5 (mean lengths between 15.22±1.826 and 16.19±0.854, off Dugi Otok). The length-weight relationships of sardine from the Zrmanja River estuary and off Dugi Otok point to positive and negative allometry, respectively. A comparison of the allometric condition factor (Ka) of sardine specimens, which ranged from 13.0 to 16.0 cm, showed higher values in the area off Dugi Otok ( Ka =0.467) than in the area of the Zrmanja River estuary (Ka=0.331), especially during 2003 (Ka =2.653). In terms of the fish abundance index, seasonal fluctuations were noticed. The highest values were observed in the area off Dugi Otok during autumn and in the Zrmanja River estuary during spring.

The morphologic and genetic variations of Engraulis encrasicolus (L. 1758) were studied based on morphometric, meristic and allozyme analyses. Samples were collected throughout the Black, Marmara and Aegean Seas. Discriminant function analysis of both morphometric and meristic characters indicated the existence of four morphologically differentiated groups of E. encrasicolus. The Aegean Sea and Marmara Sea samples were the most isolated from all others for morphometric and meristic characters. Genetic analyses indicated great variability but suggested low levels of differentiation in the eastern Black Sea samples. However, the low genetic distance between this and other samples suggests the existence of hybridization between the Azov and eastern Black Sea populations. Nonetheless, genetic analysis showed that these levels were significant and the population structure should be analysed using markers able to detect a greater degree of population differentiation

The marine Lake Rogoznica is a small, karstic habitat with potential anthropogenic influence, situated in the eastern-central Adriatic coast. In this naturally eutrophic, hypoxic and periodically anoxic lake, an investigation of the microplankton community was performed during the 1995- 1998 period when the ecology of the lake was greatly influenced by strong stratification and the appearance of anoxic conditions in the entire water column. The microplankton community (maximum abundance 1.06 x 107 cells L-1) was composed of 40 taxa, mainly diatoms (62.5%) and dinoflagellates (29%). The research provided evidence of exceptionally dense populations and the seasonally-recurrent appearance of two rare microflagellates: Prorocentrum arcuatum Issel (dinoflagellate) and Hermesinum adriaticum Zacharias (heterotrophic microflagellate). The development of H. adriaticum and P. arcuatum mostly increased during the summer under conditions of nitrate deficiency, while the co-dominant diatom Chaetoceros curvisetus Cleve appeared during the spring when higher nitrate concentrations were present. Canonical Correspondence Analysis (CCA) indicated the importance of temperature, oxygen, silicate and nitrate on the incidence of these dominant species. The investigation of these microflagellates has allowed for the gaining of insight into their ecophysiological characteristics as well as the monitoring of their distribution in the Mediterranean, which has possibly expanded due to climate changes.

Physical and chemical characteristics of the water column and sediments at sea bass/sea bream farm located on the middle Adriatic island of Brac were investigated during the 2001-2006 period. Measurements and samplings were performed at stations inside the farm area and at reference station, approximately 1 km distant from the farm. Investigated parameters in the water column were temperature, salinity, transparency, suspended matter concentration, oxygen saturation and nutrient concentrations. Parameters measured in the sediments were granulometric composition, redox-potential, organic matter, organic carbon and total nitrogen content, phosphorus (P) species concentration (biogenic apatite P, authigenic apatite P, detrital apatite P, P bound to iron oxides and hydroxides and organic P).
Transparency in the water column at all stations followed the natural seasonal course, although constantly lower values at the farm stations relative to the reference site indicate a certain impact of fish farming on this parameter. Impact on chemical parameters was moderately expressed in the surface and middle layer of the water column through the deficiency of oxygen and increased concentrations of dissolved inorganic nitrogen, orthophosphate and urea due to fish excretion and degradation of their metabolic products.
Sediment inorganic P concentrations were enhanced under the cages compared to the reference site, while organic P was mainly within the range of “natural” middle Adriatic concentrations. Sequential analysis of inorganic P species showed an increased portion of biogenic apatite P and decreased detrital apatite P at the farm stations with respect to the inorganic P pool at the reference station as a direct consequence of fish farming. Sediment redox-potential, granulometric composition, organic matter content, carbonates as well as organic carbon and total nitrogen content reflected natural sediment characteristics rather than fish farm influence.

The zooplankton assemblage was investigated in April 2006 at 9 stations along, and in front of, the highly stratified salt-wedge Krka river estuary, using 53- and 125-µm mesh Nansen nets. Tintinnids, copepods and their developmental stages and mollusc larvae dominated the zooplankton community, with 28 tintinnid and 41 copepod taxa recorded in the investigated area. Both tintinnid and copepod communities showed a general decrease in abundance and increase in species number from the head to the mouth of estuary, with a clear dominance of estuarine-neritic species. The most abundant tintinnids were Tintinnopsis campanula and Favella ehrenbergii. Small cyclopoid copepod Oithona nana dominated in the upper reaches, presumably feeding opportunistically on abundant organic matter accumulated at the permanent halocline. The contribution of calanoids intensified towards marine stations, except in the eutrophicated Šibenik harbour area in the middle reaches, where cyclopoid Oithona nana again proliferated. An assessment of the sampling performances of the 53- and 125-µm nets and data on zooplankton population structure indicated that the 125-µm mesh size plankton net in combination with Niskin bottles would give the optimal insight into the ecology of all zooplankton components in future investigations of this and similar highly stratified estuaries

The recruitment of leaping grey mullet, Liza saliens juveniles in the Neretva River estuary (middle eastern Adriatic Sea, Croatia) started in July, was highest in August, decreased in September, and was unobserved later. The juveniles firstly occupied mouths of rivers and channels and then started migrating to more freshwater habitats. By feeding investigation, the harpacticoid copepods were the dominant prey in the stomachs of L. saliens juveniles during the period from August to December and nematodes replaced those as the dominant prey from January to April. Plant material in the stomachs started to appear at 24 mm of standard length, and was common prey in fish larger than 26 mm. In comparison with other Adriatic mullet’s species, the leaping grey mullet juveniles first started to recruit during July and August, while other grey mullet species appeared later (in September) in the Neretva River estuary. Such intraspecies spawning and recruitment segregation together with the optimal quantity and quality of available and preferable prey could provide an explanation for the recent success and propagation of this species in this area