Molecular and morphological comparison of larvae and juveniles of five species of callionymids, with ontogenetic evidence on the monophyly of Repomucenus (Callionymidae).

Dragonet fishes (Callionymidae) are benthic inhabitants of shallow waters, even in tidal pools, down to depths below 900 m in all subtropical, tropical and temperate oceans. The family comprises 200 species in 20 genera worldwide, of which 18 species in 6 genera occur in Korea. Classification within the family Callionymidae has been controversial because of the differing proposals of Fricke and Nakabo (Fishes of Japan with pictorial keys to the species, 1983). For example, Fricke suggested genus Repomucenus and Bathycallionymus, whose genera contains most callionymid species in Korean waters, as junior synonym of genus Callionymus while Nakabo (Fishes of Japan with pictorial keys to the species, 1983) suggested as valid. In such cases, when classifications of adults have taxonomic contention, examination of larval characters may prove informative. Therefore, in this study, the authors conducted comprehensive molecular and morphological analyses on larvae and juveniles of five species in the genus Repomucenus and discussed their taxonomic status within the family Callionymidae. Larval and juvenile callionymids show high morphological similarities during their ontogenetic development. Nonetheless, the following morphological differences were observed in melanophore distribution and preopercular spine development: (a) stellate or punctate melanophores in Bathycallionymus kaianus vs. branched melanophores in genus Repomucenus, (b) melanophores on the abdominal cavity gradually disappearing in B. kaianus vs. gradually becoming prominent in Repomucenus and (c) preopercular spine development giving rise to one perpendicular spine in B. kaianus vs. two or three spines in Repomucenus. Molecular analysis based on 16S ribosomal RNA showed similar results to the morphological analysis. Genera Bathycallionymus and Repomucenus showed significant genetic distance (d = 0.113-0.120); moreover, genus Callionymus, which was suggested as a senior synonym of genus Bathycallionymus and Repomucenus by Fricke (Journal of Natural History, 2014, 48, 2419-2448), also showed considerable difference (d = 0.226-0.246). In the present study, the monophyly of genus Repomucenus seemed well supported by the results of morphological and molecular analyses of larval stage Callionymidae.

Frist observation and effect of fishery of seabed litter on sea bed by trawl survey Korea waters.

Fisheries activities for supplying marine productions were excessively overwhelming. Furthermore in the competitive industrialization, the impact on marine ecosystems and fisheries resources are severe due to the increase of various seabed litter such as plastic materials, styrofoam and plastic bottles and the deterioration of the marine environment. Despite these seriously situation, very few studies of some sea of Korea have been carried out on sedimentary waste fishing. Also some fisheries and there are few reports on plastics present on the seabed of around Korea. This study investigated the distribution of seabed litter collected from the seabed and characteristics of each area by using the trawl gear of the survey vessel from February to November 2018. The weight of all seabed litter collected during the investigation was 62,541.5 kg km-2, with a range of 0.2-15,019.7 kg km-2. The most amount of seabed litter was collected from sea block 106 in the South Sea, followed by sea blocks 76 and 82 in the East Sea. Through this study, which was conducted for the first time in all sea in around Korea, it can be used as basic data to understand the current status of seabed litter in the seabed and to establish effective policies at the led by the government.