Academic literature on the topic 'Charybdis japonica'

Abstract Three primary factors affecting genetic patterns of marine species in the Northwestern Pacific Ocean have been proposed: isolation and population expansion during Pleistocene glacial cycles, ocean currents facilitating the gene flow, and the Yangtze River outflow imposing a physical barrier to gene flow. Here, we examined these factors affecting population structuring of the Asian paddle crab, Charybdis japonica, in the Yellow Sea, East China Sea, and adjacent areas. Genetic variation in nine populations of C. japonica (n = 169) was determined from partial mitochondrial cytochrome c oxidase subunit I sequences. Among the 14 haplotypes identified, a dominant haplotype H1 was present in all populations, and a relatively abundant localized haplotype H2 was found in four of the northern populations. Furthermore, the frequency of the common haplotype H1 decreased from south to north. A genetic discontinuity was detected in Haizhou Bay, which divided species into two groups (north group and south group). The lack of genetic structure in the south and north groups indicates high dispersal of C. japonica within groups. Local marine gyres in Haizhou Bay might be responsible for the divergence of the north and south groups. Our study highlights the importance of local marine gyres for influencing genetic structure in marine coastal species in the Northwestern Pacific, especially in species spawning inshore.

Abstract Cathepsin C is a crucial lysosomal cysteine proteinase that takes part in protein degradation and proenzyme activation. In this study, cDNA of cathepsin C in Charybdis japonica (A. Milne-Edwards, 1861) (designated as Cj-cath C) was cloned and characterized. The results showed that the open reading frame (ORF) of Cj-cath C was 1356 bp and encoded a protein of 451 amino acids. Cj-cath C contained two catalytic residues, a Cathepsin C exclusion domain and a Peptidase_C1 domain. The Cj-cath C was widely expressed in all tissues, with highest expression in hepatopancreas and heart. The transcript levels of Cj-cath C in the hepatopancreas and haemolymph were up-regulated after stimulation by Vibrio anguillarum Bergeman, 1909 and reached a peak value at 6 h post-infection, followed by a gradual decrease. These observations indicate that Cj-cath C might be a constitutive and inducible acute-phase protein that is involved in the immune defense of C. japonica.

The Enemy Release Hypothesis proposes that introduced species often achieve larger individual sizes and greater population abundance in their introduced range because they have escaped their natural enemies - predators and parasites - that regulate populations in their native range. The main objective of this study is to test the Enemy Release Hypothesis (ERH) by investigating the identity, prevalence and intensity of parasites in two marine species introduced to New Zealand - the recently introduced but spatially restricted Asian portunid crab, Charybdis japonica, and the longer-established Asian nesting mussel, Musculista senhousia. Host choice of a native generalist parasite presented with the non-native and native mussels, and prey selection by a native predator presented with these bivalves will be examined. This is the first study of its kind in New Zealand. The parasite fauna of the only established New Zealand population of C. japonica (Waitemata Harbour, Auckland), was compared to that from (a) a population of C. japonica from its native region (Japan) and (b) to multiple populations of the native New Zealand crab Ovalipes catharus, a native New Zealand portunid. Results showed the introduced crab harboured only one species of endoparasite (a nematode), and two types of melanised lesions. Neither the parasite nor the lesions were present in the native crab populations. The native crab was host to only one parasite species, which occurred at very low prevalence, and was present in only one of the six populations examined from throughout New Zealand. Carapace width in the introduced crab was no larger than that reported in literature from its native are, but was larger than carapace widths of the Japanese sample. M. senhousia was examined from five sites within New Zealand. Parasites in M. senhousia were compared with a sympatric native bivalve, Austrovenus stutchburyi, two native mytilids, (Perna canaliculus and Xenostrobus pulex) and with samples of M. senhousia from Italy and the USA where it is introduced, and Japan where it is native. Two native generalist parasites, the pea crab Pinnotheres novaezelandiae, and a copepod, were found within M. senhousia in New Zealand, but only at low prevalence. A greater array of organisms was associated with the native bivalves. No parasites were recovered from any of the overseas samples of M. senhousia, including the Japanese samples. This may be caused by the preservation medium used, but could be a true reflection of the parasite fauna in these populations. The site where the two native parasites were exploiting M. senhousia was the only site sampled where two native mussels, P. canaliculus and X. pulex, also occurred. Consequently, effects of these two generalist parasites on the three mussel species were examined. In P. canaliculus, presence of native pea crabs was associated with lower tissue dry weight and greater shell depth. Shell width and depth were both greater in the presence of copepods. However, the prevalence of pea crabs and copepods was much lower in M. senhousia compared to the two native mussels, indicating some release from the effects of these parasites for the non-native species. Experimental choice tests showed that the pea crab, P. novaezelandiae, does not actively select M. senhousia as a host, preferring the larger native mussel, P. canaliculus. Rates of infection of M. senhousia are, therefore, likely to remain low in natural habitats where there are large numbers of native hosts. In addition, a generalist predator, the crab O. catharus, showed no preference when foraging on the three mussel species under experimental conditions. Thus, some predation pressure may be exerted on M. senhousia by this native crab in the natural environment. Investigation of multiple populations of both native and non-native species has shown large variation in parasite prevalence and intensity among populations of each species. After examining C. japonica and the comparable native O. catharus, evidence to support the ERH was found to be weak. As the native crab was relatively free of parasites, it seems unlikely that parasite infection is important within native populations and therefore, the success of C. japonica is unlikely to be caused by comparatively greater freedom from parasites (a central tenet of the ERH). There was also no evidence for host-switching by native parasites into the introduced C. japonica population. In contrast, native parasites were present at very low prevalence in the non-native mussel M. senhousia. Length of time since introduction can be an important factor in host switching between native and introduced hosts, but unless prevalence of these parasites is high, the introduced species still escapes from enemies that could control a population. Therefore every non-native species needs to be examined using multiple populations to investigate variation in parasite fauna, prevalence and intensity, as the same species, if introduced numerous times, could potentially show contrasting results for the ERH unless multiple populations are examined.