In this paper, we report data from the first year of rearing of a set of filter feeder bioremediator organisms: macrobenthic invertebrates (sabellid polychaetes and sponges), coupled with macroalgae, realized in a mariculture fish farm. This innovative integrated multi-trophic aquaculture (IMTA) system was realized at a preindustrial level in the Gulf of Taranto (southern Italy, northern Ionian Sea), within the framework of the EU Remedia Life project. Long lines containing different collector typologies were placed around the fish breeding cages. Vertical collectors were utilized for both polychaetes and sponges, whilst macroalgae were cultivated in horizontal collectors. Data on the growth and mortality of the target species after the first year of rearing and cultivation are given together with their biomass estimation. Polychaete biomass was obtained from natural settlement on ropes previously hung in the system, while sponges and macroalgae were derived from explants and/or inocules inserted in the collectors. The description of the successional pattern occurring on collectors used for settling until reaching a “stable” point is also described, with indications of additional filter feeder macroinvertebrates other than polychaetes and sponges that are easily obtainable and useful in the system as bioremediators as well. The results demonstrate an easy, natural obtaining of large biomass of sabellid polychaetes settling especially from about a 4 to 10 m depth. Sponges and macroalgae need to be periodically cleaned from the fouling covering. The macroalgae cycle was different from that of invertebrates and requires the cultivation of two different species with about a 6-month cycle for each one. The present study represents one of the first attempts at IMTA in the Mediterranean area where invertebrates and macroalgae are co-cultured in an inshore fish farm. Possible utilization of the produced biomass is also suggested.

Recent studies have shown that marine algae represent a great source of natural compounds with several properties. The lipidic extract of the seaweed Chaetomorpha linum (Chlorophyta, Cladophorales), one of the dominant species in the Mar Piccolo of Taranto (Mediterranean, Ionian Sea), revealed an antibacterial activity against Vibrio ordalii and Vibrio vulnificus, common pathogens in aquaculture, suggesting its potential employment to control fish and shellfish diseases due to vibriosis and to reduce the public health hazards related to antibiotic use in aquaculture. This extract showed also an antioxidant activity, corresponding to 170.960 ± 16. mmol Trolox equivalent/g (oxygen radical absorbance capacity assay—ORAC) and to 30.554 ± 2.30 mmol Trolox equivalent/g (Trolox equivalent antioxidant capacity assay—TEAC). The chemical characterization of the extract, performed by 1D and 2D NMR spectroscopy, highlighted the presence of free, saturated (SAFAs), unsaturated (UFAs) and polyunsaturated (PUFAs) fatty acids. The high content of ω-6 and ω-3 PUFAs confirmed also by gas chromatography indicates the potentiality of this algal species in the production of fortified food. The antibacterial activity seems related to the presence of linolenic acid present at high density, while the antioxidant activity could be likely ascribable to molecules such as carotenoids and chlorophylls (characterized also by thin-layer chromatography), known for this property. The presence of polyhydroxybutyrate, a biopolymer with potentiality in the field of biodegradable bioplastics was also detected. The exploitation of C. linum for a future biotechnological application is also encouraged by the results from a first attempt of cultivating this species in an integrated multi-trophic aquaculture (IMTA) system.

Aquaculture expansion is limited by the negative environmental impact of the waste and the need for alternative sources in the diet of reared fish. In this framework, for the first time, the survival rates, biomass gain, and fatty acid profiles of the polychaete Sabella spallanzanii and the macroalga Chaetomorpha linum, reared/cultivated as bioremediators in an integrated multitrophic aquaculture system (IMTA), were evaluated for their potential reuse applications. Results showed that these organisms represent a natural source of omega-3 and omega-6. On account of the overall results and the high biomass obtained as by-products, a preliminary study was performed employing both S. spallanzanii and C. linum as new dietary ingredients to feed different sized Dicentrarchus labrax. Fish survival rate, biomass growth, and specific growth rate were determined resulting in no significant differences between control and treated fishes. Histological analyses showed no alterations of the stomach tunica mucosa and submucosa in treated fishes. The eco-friendly approaches applied in the here-realized IMTA system could guarantee the achievement of sustainable by-products represented by the bioremediators S. spallanzanii and C. linum, as well as their reliability as a natural source of compounds beneficial to fish and human health.

In this study, we report the first finding of the non-indigenous seaweed Caulacanthus okamurae (Rhodophyta) in the Ionian and Adriatic Seas (Mediterranean). Specimens were identified through molecular analyses based on the plastid ribulose-1,5-bisphosphate carboxylase/oxygenase (rbcL) marker. The sequences obtained during this study represent the first molecular evidence of the presence of this taxon in the Mediterranean Sea. Stable populations have been detected in some areas of the Mar Piccolo of Taranto (Italy) and in the whole lagoon of Venice, forming dense patches of low turf that reach high biomasses. Turf-forming algae are common in the intertidal zones of tropical regions, but are rare in temperate ones. The particular environmental conditions of transitional water systems, such as the Mar Piccolo of Taranto and the Venice Lagoon, together with the water temperature increase observed in the last years could have favored the settlement and spread of this introduced species.