Chthamalus malayensis is a common intertidal acorn barnacle widely distributed in the Indo-West Pacific. Analysis of the mitochondrial cytochrome c oxidase subunit I (COI) sequences of samples from its distribution range revealed 3 genetically differentiated clades: the South China Sea, Indo-Malay and Taiwan clades. The clades have an allopatric distribution and differed by ~7.5 to 14% in COI. They also differed in zonation patterns and abundances within vertical ranges. The genetic and ecological differences suggest that the 3 clades probably represent distinct species. There were signatures of postglacial demographic expansion, yet the timing of expansion varied among clades, which is attributable to the differences in their geographical distributions. The Indian Ocean population of the Indo-Malay clade apparently attained its present range by postglacial re-colonization from the Pacific and, as a result, genetic differentiation among populations in the 2 oceans is low (Φ CT = -0.01, p = 0.49). There were differences in cohort structure between populations in India and the Malay Peninsula. Together, this suggests a considerable level of contemporary gene flow over an evolutionary, but relatively restricted dispersal on an ecological time scale. Cohort structure also varied among Malaysia and Singapore, the South China Sea and Taiwan waters, indicating distinct larval supplies among the 3 clades, possibly determined by different ocean current systems. This physical dispersal of larvae interacts with local biological factors in determining the on-shore distribution and genetic structure of the barnacle populations. Our findings highlight the importance of combining ecological and genetic data to understand factors that mould biodiversity patterns.

As active ingredients of anti-fouling paints that are widely used on ship hulls, organotin compounds, in particular tributyltin (TBT), are well-known endocrine disruptors causing sex changes in marine organisms and widespread in coastal waters and sediments worldwide. In this study, a comprehensive ecological risk assessment (ERA) of organotins was conducted in Hong Kong waters through determining the imposex status, sex ratio and tissue burdens of these compounds in the neogastropods, Thais clavigera and Thais luteostoma collected from 29 coastal sites. We also investigated the historical trend of organotin effects on these gastropods, and performed a probabilistic ERA based on tissue burden of TBT in the animals. Our results demonstrated that imposex indices were positively correlated with the body burden of organotins in the gastropods. Across all sites, the sex ratio (female:male) decreased significantly with increasing imposex levels or tissue burden of organotins, implying that such pollutants can result in a male-biased population, potentially leading to local extinction in extreme cases. Based on the ERA, 5.4% of all populations of T. clavigera are at risk due to exposure to TBT; the risks include growth inhibition, impairment of immune functions and reduced fitness. Seriously impacted areas included Aberdeen, Repulse Bay, Butterfly Beach, Mui Wo and Ha Mei Wan. A comparison with historical data revealed that there had been some improvement in the areas with low marine traffic, and distant from the major harbour/port. This could partly be due to the restriction on the use of TBT on small vessels (<25 m in length) since 1992. Nevertheless, the organotin contamination still remains severe in areas with high marine traffic or adjacent to large harbours/ports. In particular, the situation in the northeastern waters of Hong Kong has been getting worst since 1996 that is probably associated with the rapid development of the cargo container port at Yantian in China.

Summary 1.Traditional approaches to understanding species responses to environmental conditions have focused on the isolated effects of single stressors, despite the fact that in nature organisms experience a variety of conditions. 2. In tropical monsoonal areas, intertidal animals can face hot desiccating conditions during emersion preceded, or followed by, intense rainfall. The combined effects of these stresses on physiological responses and protein profiles were investigated in a limpet, Cellana grata. 3. With short exposure (60 min) to single stressors, heat stressed limpets had elevated heart rates and more concentrated haemolymph and mantle water osmolalities than under normal temperatures or awash. Animals under rain had reduced haemolymph and mantle water osmolalities, but similar heart rates to unstressed animals. 4. After 120 min, unstressed animals did not differ in their physiological responses. Heat stressed limpets, however, had faster heart rates and more concentrated haemolymph and mantle water osmolalities, whilst those under rain had the lowest osmolalities, but similar heart rates to unstressed animals. 5. Limpets under rain followed by heat stress had faster heart rates, but lower haemolymph and mantle water osmolalities compared to animals under normal temperatures or heat stress. Limpets that were heat stressed, followed by rain, had similar heart rates to animals awash, under rain or normal temperatures but lower haemolymph osmolalities than other treatments, with the exception of limpets under rain. 6. There was a positive relationship between haemolymph and mantle water osmolalities, except for animals under rain, where mantle water osmolality was lower than the haemolymph, suggesting some isolation of body fluids from the external medium. 7. Haemolymph protein ⁄ peptide mass spectra of heat stressed animals (either before or after rain) were similar, while all other treatments differed, suggesting differential expression and regulation of proteins. 8. Heat stress invokes a more active physiological and protein level response than rain, but their combination had an interactive effect on limpets' metabolism. 9. Identifying the effects of multiple stresses at a variety of biological levels highlights the interactive effects which impact species, and provides a more complete understanding of how species may respond to environmental changes in their natural habitats.

No abstract

The Stomatopoda (Crustacea: Malacostraca) from the South China Sea region are of commercial importance and although limited studies have been conducted on the adults, no research has ever been attempted on the larval stages because of the lack of identification keys or taxonomic descriptions. In the first study of its kind in the region, DNA barcoding was used successfully to identify unknown stomatopod larvae from plankton samples. Sequences of two mitochondrial genes, namely the cytochrome c oxidase subunit-I (COI) and the large ribosomal subunit (16S) rRNA, were applied as the barcodes to match DNA sequences from unknown larval morphotypes against those of known, locally occurring adult species. Intraspecific variations for the COI and 16S rRNA genes were found to be <2.4% and <2.1% respectively in terms of Kimura 2-Parameter (K2P) divergence of the adults, whereas variations between genera ranged from 13% to 24% and 3% to 11% respectively. These results imply that both genes are suitable for use in species identification of stomatopods; thus 14 of the 16 larval morphotypes (87.5%) obtained in Hong Kong waters can be identified to seven species through DNA barcoding. The findings of this study would also facilitate future research on the larval ecology and phylogenetic relationship of these crustaceans.