Development of artificial diets for delivery of water-soluble nutrients to altricial fish larvae

In the present study, the potential of low-melting point lipids, namely methyl palmitate (MP) and menhaden stearine (MS), were studied for delivery of water-soluble materials to fish larvae. Addition of the solid emulsifier, sorbitan monopalmitate (SMP) resulted in higher RE compared to the liquid emulsifier sorbitan sesquioleate (SSO). Additions of SMP were found to have a positive effect on the stability of lipid spray beads (LSB) at concentrations >10% (w/w) of lipid. LSB were shown to retain riboflavin with the highest RE when the lipid matrix was composed of a mixture of MP+10% SMP+1O% ethyl cellulose (w/w). Use of MP facilitated digestive breakdown of LSB by larvae of zebrafish, Brachydanio rerio, and glowlight tetra, Hemigrammus erythrozonus, as indicated by release of riboflavin from ingested LSB. LSB composed of MS performed better than LSB composed of MP when particulate glycine was incorporated within LSB. Highest retention efficiencies (RE) and delivery efficiencies (DE) were achieved by LSB composed of 100% MS. RE and DE of LSB were further improved when glycine was encapsulated as aqueous droplets rather than in a particulate form. The overall performance of LSB containing tyrosine showed that nutrients with similar water-solubilities to tyrosine can be very effectively delivered to early fish larvae. Visual observation indicated that LSB composed of 100% MS were broken down by larvae of clownfish, Amphiprion percula. Zein-bound particles (ZBP) were not efficient in delivering riboflavin to fish larvae due to high leaching rates. In an attempt to improve ZBP, we developed complex particles (CP) containing LSB incorporated in a dietary mixture bound by zein, to obtain a single particle type. The potential of LSB for delivery of free amino acids (FAA) was evaluated when LSB were incorporated within CP. RE and DE for tyrosine were significantly greater than those for alanine, glycine and serine. There was a significant inverse correlation between RE for FAA and their solubilities where FAA with low solubilites resulted in higher RE. Development of CP with high RE and DE for amino acids is an important step towards formulating a diet to allow early weaning of fish larvae onto artificial diets

Growth and survival of zebrafish, Brachydanio rerio, larvae fed on two types of microparticulate diets

Effects of diet and container type on growth and survival of altricial zebrafish, Brachydanio rerio, larvae were determined. Microfeast® L- 10 (MF) supported growth and survival of zebrafish larvae during the first 10-12 days. Best results were obtained with larvae fed on a combination of MF and Artemia nauplii in Imhoff, 1.2 1 cones. The characteristics of two types of microparticulate diets were determined. MF was encapsulated within cross-linked protein walled capsules (CLPWC) or gelatin-alginate beads (GAB). Retention efficiencies were determined by encapsulating a nontoxic dye (Poly-R 478) within CLPWC or GAB. Retention efficiencies of both particle types suggested that high molecular weight, water soluble nutrients could be delivered to freshwater fish larvae without major losses. Acceptability experiments included determination of gut fullness and feeding incidence of larvae using a computer-aided image analysis system. Acceptability of GAB by first feeding zebrafish larvae was significantly greater than that for CLPWC. Acceptability of CLPWC increased in larger size larvae and was similar to that for GAB. It was determined that both particle types were digested by first feeding zebrafish larvae. Diet size selection of first feeding and 15 day-old zebrafish larvae was determined with CLPWC using a model developed to account for both settlement of capsules and ingestion by larvae. Results indicated that while first feeding larvae preferred 21-45 [micro]m capsules, 15 day-old larvae preferred capsules in the 46-75 [micro]m size range. Growth experiments with CLPWC showed that up to 40% substitution of Artemia nauplii could be accomplished without reduced growth and survival of zebrafish larvae after a feeding period of 8 days. Twenty percent substitution of Artemia nauplii could be achieved with GAB without reduced growth and survival. Higher substitutions of Anemia with either particle types resulted in inferior growth and survival of zebrafish larvae

New Mediterranean biodiversity records (March 2016)

In this Collective Article on “New Mediterranean Biodiversity Records”, we present additional records of species found in the Mediterranean Sea. These records refer to eight different countries mainly throughout the northern part of the basin, and include 28 species, belonging to five Phyla. The findings per country include the following species: Spain: Callinectes sapidus and Chelidonura fulvipunctata; Monaco: Aplysia dactylomela; Italy: Charybdis (Charybdis) feriata, Carcharodon carcharias, Seriola fasciata, and Siganus rivulatus; Malta: Pomacanthus asfur; Croatia: Lagocephalus sceleratus and Pomadasys incisus; Montenegro: Lagocephalus sceleratus; Greece: Amathia (Zoobotryon) verticillata, Atys macandrewii, Cerithium scabridum, Chama pacifica, Dendostrea cf. folium, Ergalatax junionae, Septifer cumingii, Syphonota geographica, Syrnola fasciata, Oxyu- richthys petersi, Scarus ghobban, Scorpaena maderensis, Solea aegyptiaca and Upeneus pori; Turkey: Lobotes surinamensis, Ruvettus pretiosus and Ophiocten abyssicolum. In the current article, the presence of Taractes rubescens (Jordan & Evermann, 1887) is recorded for the first time in the Mediterranean from Italy. The great contribution of citizen scientists in monitoring biodiversity records is reflected herein, as 10% of the authors are citizen scientists, and contributed 37.5% of the new findings.peer-reviewe