Effects of fish farming waste to sedimentary and particulate organic matter in a southern Mediterranean area (Gulf of Castellammare, Sicily): a multiple stable isotope study (δ13C and δ15N)

Abstract Carbon and nitrogen stable isotope analysis was used to investigate the dispersion area of waste material coming from fish farming activities in the western Mediterranean. Tests were conducted to see if uneaten feed and faecal material isotopic signals, originating from fish farms, could be detected in particulate organic matter (POM) and sedimentary organic matter (SOM). The detectable dispersion distance (from under cages as far as 1000 m) of cage-derived organic material was also examined. To do this, carbon (δ13C) and nitrogen (δ15N) composition in POM and SOM collected around the cages, in some control areas and in the waste material, was measured. Mean POM δ13C was −22.9±0.2‰…

Acquacoltura

Diel Feeding Features of Juveniles of Two Sparids in the Stagnone di Marsala Coastal Sound (Western Sicily, Italy)

Diet composition, feeding rhythms, gastric evacuation rates, daily rations of Diplodus puntazzo (Gmelin 1789) and Sarpa salpa (Linneo 1758) juveniles were studied in order to investigate their trophic ecology, niche breadth and overlap. These Sparids were collected in the Stagnone di Marsala (Western Sicily), in April 1997, in a 24 hour sampling period. Gastric content of 86 specimens of D. puntazzo (standard length = 31.9 ± 6.6 mm; body wet weight = 1.0 Ī 0.5 g) and of 100 specimens of S. salpa (standard length = 32.3 ± 2.9 mm; body wet weight = 0.6 Ī 0.2 g) were examined. Amphipoda and Tanaidacea were the most frequent prey items in stomach content of D. puntozzo, while Hydrozoa, Bryozoa …

Use of stable isotopes to investigate dispersal of waste from fish farm as a function of hydrodynamics.

Stable isotopes were used to examine differential effects of fish farm waste on the water column and sediments. To achieve this objective, we chose 3 marine fish farms located along the coast of Sicily (Mediterranean Sea) as point-source disturbances, and a control area. The hypothesis that carbon and nitrogen isotope composition of particulate (POM) and sedimentary (SOM) organic matter varied with increasing distance (from cages to 1000 m) was tested at 3 levels of hydrodynam- ics: low (mean velocity of current (MVC) ~12 cm s -1 ), intermediate (MVC ~22 cm s -1 ), and high (MVC ~40 cm s -1 ). Different isotopic signals from allochthonous (fish waste) over natural (phytoplankton, terrigenou…

Notes on the Biology and Ecology of Opeatogenys gracilis (Canestrini 1864) (Pisces: Gobiesocidae) from Coastal Environments in Sicily (Mediterranean)

A particularly large number of specimens of the Mediterranean coastal fish Opeatogenys gracilis (Canestrini 1864) (Pisces: Gobiesocidae) were collected from Posidonia oceanica mats of the “Stagnone di Marsala” sound (western Sicily) and in the Gulf of Carini (northern Sicily). A study was made of biometric and meristic characters and, for the first time for this species, diet composition. The biometric and meristic data did not distinguish between specimens from the two study sites. In accordance with its benthic habit, O. gracilis feeds on small phytal prey living on Posidonia oceanica leaves. The preferential food items throughout the year were Copepoda Harpacticoida.

The effect of mariculture facilities on biochemical features of suspended organic matter (southern Tyrrhenian, Mediterranean)

Abstract A comparison of a Mediterranean aquaculture impacted area and control areas was made to assess the effect of fish farm waste discharge on the biochemical features of the water column. Trophic variables commonly used in marine ecology such as total suspended matter, suspended chlorophyll- a , biochemical features of particulate organic matter (proteins, lipids and carbohydrates) and biopolymeric carbon were chosen as the best descriptors of trophic conditions. An initial analysis of data from the impact area was carried out in order to test the effect of farm waste using a gradient of distances downstream from the fish farm cages (50 m, 300 m, 1000 m). The results were then compared…

A Biochemical Genetic Study of Isoenzyme Polymorphism within and between Two Populations of Atherina Boyeri Risso

Allozymic variation of 20 loci was investigated in two samples of Atherina boyeri collected in the Mediterranean Sea from the coast of Trappeto and Marsala Lagoon (Sicily, Italy). Five loci were polymorphic (PGM*, EST-1,2*, SOD-2*, PGI-2*) and appeared to be in Hardy-Weinberg equilibrium. A significant Fst mean value (0.02) (G = 23.77, P < 0.05, df = 5) showed that the samples can be considered as two distinct local populations and supports previous morphometric discrimination.