Complete mitochondrial genome of the sea cucumber Apostichopus japonicus (Echinodermata: Holothuroidea): The first representative from the subclass Aspidochirotacea with the echinoderm ground pattern

Complete mitochondrial genome plays an important role in the accurate revelation of phylogenetic relationships among metazoans. Here we present the complete mitochondrial genome sequence from a sea cucumber Apostichopus japonicus (Echinodermata: Holothuroidea), which is the first representative from the subclass Aspidochirotacea. The mitochondrial genome of A. japonicus is 16,096 bp in length. The heavy strand consists of 31.8% A, 20.2% C, 17.9% G, and 30.1% T bases (AT skew = 0.027: GC skew = 0.062). It contains thirteen protein-coding genes (PCGs), twenty-two transfer RNA genes, and two ribosomal RNA genes. There are a total of 3793 codons in all thirteen mitochondrial PCGs, excluding incomplete termination codons. The most frequently used amino acid is Leu (15.77%), followed by Set (9.73%), Met (8.62%), Phe (7.94%), and Ala (7.28%). Intergenetic regions in the mitochondrial genome of A. japonicus are 839 bp in total, with three relatively large regions of Unassigned Sequences (UAS) greater than 100 bp. The gene order of A. japonicus is identical to that observed in the five studied sea urchins, which confirms that the gene order shared by the two classes (Holothuroidea and Echinoidea) is a ground pattern of echinoderm mitochondrial genomes. Bayesian tree based on the cob gene supports the following relationship: (outgroup, (Crinoids, (Asteroids, Ophiuroids, (Echinoids, Holothuroids)))). (C) 2009 Elsevier B.V. All rights reserved.

Bioenergetic responses of sub-adult sea cucumber Apostichopus japonicus (Selenka) (Echinodermata: Holothuroidea) to temperature with special discussion regarding its southernmost distribution limit in China

1. This paper investigated the bioenergetic responses of the sea cucumber Apostichopus japonicus (wet weights of 36.5 +/- 1.2 g) to different water temperatures (5, 10, 15, 20, 25 and 30 degrees C) in the laboratory. 2. Results showed that theoretically the optimal temperatures for energy intake and scope for growth (SFG) of sub-adult A. japonicus was at 15.6 and 16.0 degrees C, respectively. The aestivation threshold temperature for this life-stage sea cucumber could be 29.0 degrees C by taking feeding cessation as the indication of aestivation. 3. Our data suggests that A. japonicus is thermo-sensitive to higher temperature, which prevents it from colonising sub-tropical coastal zones. Therefore, water temperature plays an important role in its southernmost distribution limit in China. 4. The potential impact of global ocean warming on A. japonicus might be a northward shift in the geographical distribution. Crown Copyright (C) 2009 Published by Elsevier Ltd, All rights reserved.

Effects of salinity on energy budget in pond-cultured sea cucumber Apostichopus japonicus (Selenka) (Echinodermata: Holothuroidea)

Pond farming for sea cucumber has developed rapidly along the northern coast of China in the recent years. Holothurians inhabiting ponds undergo seasonal fluctuations of salinity. This study deals with the bioenergetic responses of pond-cultured sea cucumbers Apostichopus japonicus (wet weight of 37.5 +/- 1.8 g) to different water salinities [22, 27, 31.5, and 36 practical salinity units (psu)] at 15 degrees C in the laboratory to determine the influence of water salinity on growth and energy allocation in this species. Results show that ingested energy and scope for growth (SFG) were highest at 31.5 psu and then decreased when water salinity was below or above this point. Although energy ingested was lowest at 36 psu, the lowest SFG occurred at 22 psu (only 102.68 +/- 14.26 J g(-1) d(-1)) because animals reared at 22 psu spent much more consumed energy on feces (72.19%), respiration (21.70%), and excretion (2.59%), leaving less energy for growth (3.52%). Results suggest that pond-cultured sea cucumbers could tolerate chronic salinity fluctuations at a range of 22 to 36 psu and grew better between 27 and 31.5 psu, but decreased at salinities above and below the mentioned salinity range. Crown Copyright (C) 2010 Published by Elsevier B.V. All rights reserved.

The influence of diets containing dried bivalve feces and/or powdered algae on growth and energy distribution in sea cucumber Apostichopus japonicus (Selenka) (Echinodermata : Holothuroidea)

In recent years, bivalve feces and powdered algae have been used as the food sources of holothurians in China. In this study, growth and energy budget for sea cucumber Apostichopus japonicus (Selenka) with initial wet body,veights of 32.5 1.0 g (mean +/- SE, n=45) when fed with five different granule diets containing dried bivalve feces and/or powdered algae in water temperature 13.2-19.8 degrees C and salinity 30-32ppt were quantified in order to investigate how diets influence growth and energy distribution and to find out the proper diet for land-based intensive culture of this species. Results showed that diets affected the food ingestion, feces production, food conversion efficiency and apparent digestive ratios, hence the growth and energy budget. Sea cucumbers fed with dried feces of bivalve showed poorer energy absorption, assimilation and growth than individuals fed with other four diets; this could be because feces-drying process removed much of the benefits. Dried bivalve feces alone, therefore, were not a suitable diet for sea cucumbers in intensive cultivation. The mixed diets of feces and powered algae showed promising results for cultivation of sub-adult Apostichopus japonicus, while animals fed with powdered algae alone, could not obtain the best growth. According to SGR of tested animals, a formula of 75% feces and 25% powdered algae is the best diet for culture of this species. Extruded diets were used in the present experiment to overcome shortcomings of the traditional powdered feeds, however, it seems a conflict exists between drying bivalve feces to form extruded diets and feeding sea cucumbers with fresh feces which contain beneficial bacteria. Compared with other echinoderms, in holothurians the energy deposited in growth is lower and the energy loss in feces accounts for the majority of the ingested energy. Such detailed information could be helpful in further development of more appropriate diets for culture of holothurians. (c) 2006 Elsevier B.V. All rights reserved.

Phyllophorus (Phyllophorus) maculatus, a new species of sea cucumber from the Yellow Sea (Echinodermata : Holothuroidea : Dendrochirotida)

Phyllophorus (Phyllophorus) maculatus new species is described from a depth of 22-45 meters near the western edge of the Yellow Sea. The body is cylindrical, with body wall ossicles present only in the anal region. Ossicles are four-pillared tables with low spires and indented disc margin. A revised key to the eleven phyllophorine (Family Phyllophoridae, Subfamily Phyllophorinae) species now known from China is presented.

Rediscovery of the sea cucumber "Toxodora" pacifica Ohshima, 1915 (Echinodermata : Holothuroidea : Apodida)

The apodous holothurian species originally described by Ohshima ( 1915) as Toxodora pacifica has been rediscovered, and its known geographic range extended from Suruga Bay, Japan to the western side of the Yellow Sea, China. As the genus name Toxodora is no longer available, a new genus name, Neotoxodora Liao, Pawson, and Wei, is proposed. The type material of Neotoxodora pacifica is lost, and a Neotype is named for this species.

Food utilization of adult flatfishes co-occurring in the Bohai Sea of China

Stomach contents were examined of 4527 adult individuals of 12 flatfish species collected during the 1982 - 1983 Bohai Sea Fisheries Resources Investigation. Their food habits, diet diversity, similarity of prey taxa, trophic niche breadth and diet overlap were systematically analysed. Ninety-seven prey species belonging to the Coelenterata, Nemertinea, Polychaeta, Mollusca, Crustacea, Echinodermata, Hemichordata and fish were found and five of them were considered to be principal prey for flatfishes: Alpheus japonicus, Oratosquilla oratoria, Alpheus distinguendus, Loligo japonicus and Crangon affinis. Among the flatfishes, Paralichthys olivaceus was piscivorous, whereas Pseodopleuronectes yokohamae and Pseudopleuronectes herzensteini both had polychaetes and molluscs as their main prey groups. Pleuronichthys cornutus was classified as a polychaete-mollusc eater, with a strong preference for crustaceans. Verasper variegatus, Cynoglossus semilaevis, Eopsetta grigorjewi and Cleisthenes herzensteini ate crustaceans. Kareius bicoloratus was classified as a mollusc-crustacean eater: Cynoglossus abbreviatus, Cynoglossus joyneri and Zebrias zebra were grouped as crustacean-fish eaters. However, Z. zebra also took polychaetes and C. abbreviatus and C. joyneri preyed on some molluscs. Trophic relationships among the flatfishes were complicated, but they occupied distinctive microhabitats in different seasons and selected their specific prey items, which was favourable to the stability of the flatfish community in the Bohai Sea.