Analysis of growth and nutritional quality of sea worms (Nereis virens) as a mass cultured natural feed on different substrate media thicknesses

Herwati VE, Elfitasari T, Rismaningsih N, Riyadi PH, Tarangkoon W, Radjasa OK, Windarto S. 2021. Analysis of growth and nutritional quality of sea worms (Nereis virens) as a mass cultured natural feed on different substrate media thicknesses. Biodiversitas 22: 3299-3305. Sea worms (Nereis virens) grow slowly. The thickness of the substrate used in mass culture affects their growth, because N. virens is a deposit feeder that feeds on organic matter provided by other organisms; therefore, the growth rate slows down if the substrate thickness is not suitable. This study aimed to determine and analyze the growth and nutritional quality of N. virens as a natural feed in mass culture at different substrate media thicknesses. This study was conducted at the Marine Science Techno Park (MSTP) UNDIP, Jepara, Central Java. The test animals were two-month-old sea worms, weighing 0.15 to 0.5 g/individual. The maintenance media was the mangrove mud substrate. Feeding was carried out at a fixed feeding rate, twice a day at 07.00 and 19.00 hrs, and the animals were maintained at a density of 45 individuals/L for 35 days. The experimental research method was a completely randomized design with four treatments and three replications: treatment A (media thickness of 4 cm), B (media thickness of 6 cm), C (media thickness of 8 cm), and D (media thickness of 10 cm). The parameters studied were absolute growth, specific growth rate (SGR), efficiency of feed utilization (EFU), feed conversion ratio (FCR), protein efficiency ratio (PER), survival rate (SR), proximate analysis, profile of amino acid and fatty acids. The results showed that the highest absolute weight (6.76 g); SGR (6.34%); EFU (69.73%); FCR (1.36%); PER (1.74%); SR (97.04%); and nutritional quality (55.75% protein, 22.62% fat, 45.66 ppm methionine, and 7.7% eicosapentaenoic acid values were obtained when N. virens was mass-cultured in a medium with a thickness of 8 cm (Treatment C). Thus, the thickness of the media substrate had a significant effect (P < 0.05) on the absolute weight, SGR, EFU, FCR, PER, and SR in N. virens.

A comparative study on the nutritional value of three Polychaete species used in Shrimp Aquaculture

The potential use of polychaete worms are as a dietary source of protein, lipid, amino acids, and vitamins for aquaculture species and also used for alternative feeds of fish meal and fish oils. Many recent studies have been documented the nutritional benefits of polychaetes for aquaculture species, for their satisfactory food intake and reproductive performance in brood stock.Most of the polychaetes were used in hatcheries are wild caught. The commercial harvesting of polychaetes may leads to the disturbance in the benthic community and the ecosystem and also may leads to the depleting population in the ecosystem. Further the development of polychaete culture is therefore of economic importance beyond that the associated bait supply industry which is acted as the initial catalyst for this development. Hence, the present study has been made with three different polychaete species, to assess the nutritional value of the three species, one from imported (Nereis virens) and two locally available species (Perenereis cultrifera and Glycera sp) for commercial uses of the shrimp aquaculture industry.Key words : Polychaete worms, Perenereis species, fatty acids. amino acids, Minerals.

The influence of prey density and fish size on prey consumption in common sole (Solea solea L.)

We examined the influence of prey density and fish size on prey consumption in common sole (Solea solea L.) foraging on buried ragworm Alitta virens (Sars) (formerly known as Nereis virens (Sars)). The tested prey densities of 0.8, 2.2, 4.3 and 6.5 individuals dm−2 were exposed to common soles of either 100 g or 300 g. At each prey density common sole foraged for 48 h. At both common sole classes studied, a positive correlation between prey consumption and prey density was observed (P < 0.001). Relationships however differed between 100 and 300 g common sole. In 300 g common sole the relationship between prey consumption and prey density was linear (P < 0.001), whereas in 100 g common sole the relationship between prey density and prey eaten was polynomial (P = 0.018). Small common sole reached satiety prey consumption rates at nearly every prey density while large common sole did not reach satiation rates even at highest prey densities. The data suggest that in nature, polychaetes such as A. virens may contribute to the diet of small common sole even when they are only moderately abundant. In contrast, polychaetes may not be an ideal prey for larger common sole as indicated by the absence of satiety regardless of prey density.