Settlement of Bivalve Spat on Artificial Collectors (Net Bags) in Two Commercial Mussel Parks in the North-Western Adriatic Sea

Abstract

Among aquaculture activities, shellfish culture is considered more sustainable and beneficial in terms of food security. Currently, only a few bivalve species are reared and there is a need to explore the possibility to introduce new candidates for shellfish farming. Due to the lack of information on bivalve recruitment in the North-Western Adriatic Sea, in this study, the possibility to collect natural spat of commercial species was investigated. Artificial collectors (net bags) were deployed in two sites, Pellestrina and Caleri (North-Western Adriatic Sea), within two commercial mussel parks, during the spring–summer and summer–autumn periods. At both sites, collectors were placed at a distance of 1 m from each other, from 5 to 14 m depth. The influence of season, site and depth on bivalve recruitment was inspected and the presence of invasive species was also evaluated. In all, 28 bivalve taxa were found, and a higher settlement rate was observed in summer–autumn compared to the spring–summer period. Mytilus galloprovincialis, Flexopecten glaber, Mimachlays varia and Aequipecten opercularis were the most abundant species in spring–summer. In the summer–autumn period, in both sites analysed, a very high quantity of Anadara transversa and F. glaber were found. Indeed, these species were dominant at Pellestrina and Caleri, respectively. Another non-indigenous species, Arcuatula senhousia, was also detected. Relevant amounts of Pectinidae spat, F. glaber in particular, were collected and the optimal depth range for the scallop spat collection was found to be between 8 and 14 m. Our results highlight the relevant potential of Pectinidae spat collection along the North-Western Adriatic coasts, even though the presence of invasive species needs to be monitored.

From Isolated Valves to a Potential Marine Living Resource: History, Documented Distribution and Sustainable Population Enhancement Possibilities of the Smooth Scallop (Flexopecten glaber) on the Romanian Coast

“…The deployment of artificial collectors at sea is a widespread technique for settling wild scallop spat and subsequently culturing different pectinid species worldwide [33,34,[39][40][41]. Natural recruitment may ensure the permanent availability of scallop spat, addressing the problem of high seedling variability, which is a major constraint for scallop aquaculture activities.…”

“…In the north-western Adriatic, spawning is documented to occur mostly between July and September, with minor spawning events between April and May [22]. The settlement of viable larvae occurs some weeks after the species spawning period [41]. In the Ionian Sea, spawning is reported between February and early August; the larvae swim for three to four weeks before settling, at water temperatures ranging from 15 • C to 18 • C [34].…”

“…Each set of collectors consists of a rope on which 10 net bags are placed 1 m from each other. The upper end of each rope is then tied to a longline submerged at 4 m depth so that collectors remain submerged from 5 to 14 m [41]. Using any of the collectors described, the highest number of spat settled closer to the seabed and density decreased towards the surface [34,41,45].…”

“…The upper end of each rope is then tied to a longline submerged at 4 m depth so that collectors remain submerged from 5 to 14 m [41]. Using any of the collectors described, the highest number of spat settled closer to the seabed and density decreased towards the surface [34,41,45]. This tendency of spat to settle in deeper substrates may be explained by the need to avoid strong wave action, water turbulence and excessive fouling [48,49].…”

Larval Settlement on Marine Surfaces: The Role of Physico-Chemical Interactions

“…Marčeta et al (2022) [3] evaluate the influence of season, site, depth, and invasive species with respect to the natural settlement of Pectinidae bivalves on artificial substrata consisting of net bags in commercial mussel parks, presenting these organisms as promising new candidates for eco-sustainable shellfish farming.…”