Doo-Jin Hwang

Behavior and Frequency Analysis of Aurelia aurita by Using in situ Target Strength at a Port in Southwestern Korea

This study was carried out to determine the in situ target strength and behavioral characteristics of moon jellyfish (Aurelia aurita) using two frequencies (38 and 120 kHz) that present a 2- frequency-difference method for distinguishing A. aurita from other marine planktonic organisms. The average TS was shown as -71.9~ -67.9 dB at 38 kHz and -75.5~-66.0 dB at 120 kHz and the average ΔMVBS120-38 kHz was similar at -1.5~3.5 dB. The TS values varied in a range of about 14 dB from -83.3 and -69.0 dB depending on the pulsation of A. aurita. The species moved in a range of -0.1~1.0 m and they mostly moved horizontally with moving speeds of 0.3~0.6 m·s-1. The TS and behavioral characteristics of A. aurita can distinguish the species from others. The acoustic technology can also contribute to understanding the distribution and abundance of the species.

Seasonal variations of nutritional components in cockles (Tegillarca granosa) processed from the Southern Coast of Korea

Abstract Cockles (Tegillarca granosa) species that found throughout the Indo-Pacific region and this study was conducted in South Korea from late autumn (November 2015) through early spring (April 2016). The proximate composition, mineral content, free amino acid, and fatty acid (FA) profiles and the nutritional quality of the cockles were studied at different stages during the processing. The contents of protein (11.7–13.9/100 g), lipids (1.1–2.5/100 g) and ash (1.6–2.7/100 g) varied significantly (p < 0.05) based on seasonal variations and processing steps. Taurine, glutamic acid, lysine and arginine were the most abundant amino acids in the amino acid profiles. All samples contained limited concentrations of Cr, Pb, Cd, As, and Co. The FA profiles showed that n-3 polyunsaturated FA (PUFA) were the major fatty acids (28.7–37.0% of total FA, which was predominantly DHA and EPA (7.9–17.4%). Saturated FA (SFA) and monounsaturated FA (MUFA) levels were also observed throughout the experiment, as well as n − 3/n − 6 and PUFA/SFA ratios. The data obtained from this study may be useful to indicate the periods of the harvest season more suitable for consumption and the importance of processing chain on quality of cockle.