Diet Composition and Variability of Wild Octopus vulgaris and Alloteuthis media (Cephalopoda) Paralarvae: a Metagenomic Approach

Abstract

The high mortality of cephalopod early stages is the main bottleneck to grow them from paralarvae to adults in culture conditions, probably because the inadequacy of the diet that results in malnutrition. Since visual analysis of digestive tract contents of paralarvae provides little evidence of diet composition, the use of molecular tools, particularly next generation sequencing (NGS) platforms, offers an alternative to understand prey preferences and nutrient requirements of wild paralarvae. In this work, we aimed to determine the diet of paralarvae of the loliginid squid Alloteuthis media and to enhance the knowledge of the diet of recently hatched Octopus vulgaris paralarvae collected in different areas and seasons in an upwelling area (NW Spain). DNA from the dissected digestive glands of 32 A. media and 64 O. vulgaris paralarvae was amplified with universal primers for the mitochondrial gene COI, and specific primers targeting the mitochondrial gene 16S gene of arthropods and the mitochondrial gene 16S of Chordata. Following high-throughput DNA sequencing with the MiSeq run (Illumina), up to 4,124,464 reads were obtained and 234,090 reads of prey were successfully identified in 96.87 and 81.25% of octopus and squid paralarvae, respectively. Overall, we identified 122 Molecular Taxonomic Units (MOTUs) belonging to several taxa of decapods, copepods, euphausiids, amphipods, echinoderms, molluscs, and hydroids. Redundancy analysis (RDA) showed seasonal and spatial variability in the diet of O. vulgaris and spatial variability in A. media diet. General Additive Models (GAM) of the most frequently detected prey families of O. vulgaris revealed seasonal variability of the presence of copepods (family Paracalanidae) and ophiuroids (family Euryalidae), spatial variability in presence of crabs (family Pilumnidae) and preference in small individual octopus paralarvae for cladocerans (family Sididae) and ophiuroids. No statistically significant variation in the occurrences of the most frequently identified families was revealed in A. media. Overall, these results provide new clues about dietary preferences of wild cephalopod paralarvae, thus opening up new scenarios for research on trophic ecology and digestive physiology under controlled conditions.

Effects of co-supply ratios of swimming crab Portunus trituberculatus zoeae and Artemia on survival and growth of East Asian common octopus Octopus sinensis paralarvae under an upwelling culture system

“…These observations suggest that the P . trituberculatus zoea is an attractive prey for common octopus paralarvae, which is in accordance with the fact that they feed on decapod crustacean larvae in the natural habitat (Olmos‐Pérez, Roura, Pierce, Boyer, & González, ; Roura, González, Redd, & Guerra, ). Although there have been a number of reports documenting the effectiveness of supplying crab zoeae as feed for paralarvae (Garrido et al, ; Iglesias et al, ; Roo et al, ; Villanueva, ), P .…”

“…A large number of zoeae exoskeletons were deposited daily on the filter mesh and tank bottom, the remains of external digestion (Hernández-García, Martín, & Castro, 2000;Villanueva, Riba, Ruíz-Capillas, González, & Baeta, 2004). These observations suggest that the P. trituberculatus zoea is an attractive prey for common octopus paralarvae, which is in accordance with the fact that they feed on decapod crustacean larvae in the natural habitat (Olmos-Pérez, Roura, Pierce, Boyer, & González, 2017;Roura, González, Redd, & Guerra, 2012). Although there have been a number of reports documenting the effectiveness of supplying crab zoeae as feed for paralarvae (Garrido et al, 2018;Iglesias et al, 2004Iglesias et al, , 2014Roo et al, 2017;Villanueva, 1994Villanueva, , 1995, P. trituberculatus appeared to have great potential as paralarval prey in the mass production of juvenile octopus because of their high fecundity (attaining over a million zoeae per female) and the availability of ovigerous females from fishery landings (Hamasaki et al, 2006).…”

DNA metabarcoding unveils multiscale trophic variation in a widespread coastal opportunist

“…Metabarcoding using universal primers is generally considered as a simple, rapid and relatively inexpensive method to define in detail the feeding ecology of organisms (Berry et al, 2015;Kartzinel & Pringle, 2015;Pinol et al, 2014). The fraction of the brown shrimp DNA detected in its own gut was low allowing for the detection of prey items without using predator-specific blocking primers (average: 28%; compared to, e.g., Olmos-Péerez, Roura, Pierce, Boyer, & González, 2017;Pinol et al, 2014). Metabarcoding has several clear advantages over traditional trophic methods including the better detection of soft-bodied, small and cryptic taxa, higher speed of analysis (Berry et al, 2015;Casper et al, 2007;Chariton et al, 2015;Symondson, 2002), and traceability of identifications, which do not rely on the availability of morphological taxonomic expertise.…”

Small copepods could channel missing carbon through metazoan predation

“…Cleary et al, 2015). Recently, a slight modification of the primers used in this work was applied in a NGS study to detect prey in planktonic cephalopod paralarvae revealing up to 122 molecular OTUs (Olmos-Pérez, Roura, Pierce, Boyer, & González, 2017).…”